Grouting and Ground Treatment

The author's first encounter with the use of Low Mobility Grout was in 1952 when it was used to fill some small voids under a structure. Subsequently, it was found that structures and slabs could be precisely jacked with such grouts which had the distinct advantage of developing into a homogeneous mass and staying near to their point of placement. This led to Compaction Grouting which is now by far the greatest use of these grouts. The author's experience in developing applications for such grouts, the current state of the art, and a look into the future of their use, is provided.

The deep mixing method is often classified into two, dry method and wet method based on the hardening agent (binder). The former utilizes the dry powdered binder whereas the latter utilizes the water-binder slurry. Naturally there are some differences in the execution machines between dry and wet methods. But to the author's knowledge, there is no substantial difference in the characteristics of treated soils between them. The apparent difference in the design procedure and application comes from the purpose of improvement, which in turn gives rise to the difference in the installation patterns and in the order of strength required. The present article summarizes the current state of practice of deep mixing and discusses the tasks for the coming decade mostly based on the experience gained in Japan.

This paper addresses permeation grouting for the improvement of rocks and soils, in terms of strengthening or reduction of permeability, and compensation grouting for the displacement of structures during subsurface exploration. The historical evolution of these two grouting processes is described leading up to present-day practice. Applications, grouting materials, methods of injection, plant and equipment, limitations, monitoring, and verification are included together with significant case histories for each type of grouting. Part 2 deals with compensation grouting ("The Development of Practice in Permeation and Compensation Grouting: A Historical Review (1802 – 2002): Part 2: Compensation Grouting").

This paper addresses permeation grouting for the improvement of rocks and soils, in terms of strengthening or reduction of permeability, and compensation grouting for the displacement of structures during subsurface exploration. The historical evolution of these two grouting processes is described leading up to present-day practice. Applications, grouting materials, methods of injection, plant and equipment, limitations, monitoring, and verification are included together with significant case histories for each type of grouting. Part 1 deals with permeation grouting ("The Development of Practice in Permeation and Compensation Grouting: A Historical Review (1802 – 2002): Part 1: Permeation Grouting").

Ground Treatment by Deep Mixing has been used since mid 1970s and has a number of proven applications. Comprehensive research has been performed and the interest in the method is increasing and spreading over the world. This is to a great extent based on the fact that the method has more engineering possibilities than many of the competitive methods and that the research performed has given knowledge about binders appropriate to many soft soils including organic soils, design methods and execution techniques. A consequence is for example that the Dry Deep Mixing Method was the most frequently used ground improvement method in the 1990s for the large investment program for infrastructure projects in Sweden. The experience of deep mixing is very favourable both from technical and economical viewpoint.

The grouting of rock used to be a quite empirical constructional technique aimed to improve somewhat the physical properties of the masses which are actually part of the civil engineering project. Different "grouting schools" or "ways of thinking" did develop and a considerable number of recipes were dictated by "great old men" and enforced later on by regulations of any kind. Only in the last decades the grouting process started to be studied in a more scientific way and a number of well-founded results are now on hand. Nevertheless, improvements are still possible and even required so to be put into practice in order to optimise the grouting process in adapting it better to the actual rock conditions as well as to the real objectives of the project.

Jet grouting has found wide application with its radically different approach from other geothechnical groutings, employing erosion for easy grouting into void-created. Although keeping the principle of jet grouting can only lead to guaranteeing the quality of works, little attention has been paid for it due to ignorance. The author discusses these aspects theoretically and practically, for acquiring desired products in shape, size, and quality, and also briefs the development of jet grouting which helps deep mixing methods retain the way to sufficiently interlock, produces larger columnar bodies, obtains exact geometries, and has given birth to an epochal system for creating various polygonal columns in soil improvement.

Compaction Grouting is a method of ground improvement using the injection of low slump (<25 mm) soil cement into weak soils to compact the soil by lateral displacement. This technique, as practiced by the Contractor, uses a 50-mm diameter steel casing driven to the bottom of the weak zone and withdrawn in 300-mm stages. Each stage receives a specified volume of grout, typically 1451/0.3 m (5 cf/lf), which creates a bulb of grout that locally compacts the soil to some radius around the hole. This paper describes the development of the GIN concept's application to compaction grouting of loose sand embankments.

On Superbowl Sunday 2000 an extreme windstorm with sustained gusts of 80 km/hr induced random and potentially damaging cable motions in the supporting cables for a 350 m high, 680 tonne broadcast tower. Observed amplitudes in the 50 mm diameter support cables were reported to be on the order of up to 10 m. The tower is supported at the base on a spread footing and by three cable anchor systems placed 120 degrees apart. Relatively high moisture contents in the soft silt and clay were encountered within the foundation zone for the piles at the northeast anchor. Similar conditions were observed in the backfill soils covering the deadman anchor on the south. A simple pullout analysis indicated that the northeast and south anchor would fail under the design loading. Selection of the appropriate remedial option was primarily driven by the need for uninterrupted broadcast operations. The support cables and anchors are essential for tower support, and could not be dismantled without disassembling the tower itself. Consequently, consideration of remedial options required the ability to effect repairs without disturbance to the tower support system. A remedial system consisting of a precise compaction grouting pattern for in-situ ground improvement combined with load transfer by pin piles to bedrock was implemented at the northeast anchor. Compaction grouting was used at the south deadman anchor to add weight and increase soil strength properties within the active earth fill wedge.

Since the early 1960s, compaction-grouting techniques have been widely accepted as a means to density cohesionless soils and to lift settled structures. Compaction grouting techniques have been used less frequently in silts and cohesive soils, primarily due to the slow dissipation of pore water pressure. When used in silts and clay, careful monitoring of the water level is required. This paper documents the use of compaction grouting to density uncontrolled loose saturated fill and to lift a settled structure.

This paper discusses the selection, design and implementation of compaction grouting to density a zone of loose sands and silts below a proposed expansion to the Adkins Water Treatment Plant in Six Mile, South Carolina. The water treatment plant is owned and operated by Greenville Water System. The expansion included construction of a duplicate set of sedimentation basins and filters adjacent to the existing basins. Each set of basins is about 183 m (600 ft.) in length and 34 m (110 ft.) in width spanning across a shallow natural valley. The paper summarizes the history of the project from identifying the previous settlements, through selection of the remediation technology, to construction performance.

Low strain testing was performed on grout columns on three compaction grouting projects. The purpose of the testing was to investigate the capability of low strain testing to detect the depth, shape and continuity of compaction grout columns. The methods and objectives of the compaction grouting varied among the three projects.

Despite its many applications, compaction grouting has been suffering from the minimal empirical guidelines to predict the treatment effectiveness. This paper discusses the effects of soil parameters, soil compressibility, replacement ratio and injection sequence on the groutability and effectiveness of compaction grouting, through analyses of the results of a field test conducted under the old taxiway of Tokyo International Airport. The test consisted of eighty-seven compaction grout piles injected in three cases of different spacings, pile diameters and grouting procedures. Based on the analyses presented, unique relationships between the groutability, of compaction grouting and the soil parameters are identified. Also, empirical correlations for estimating the treatment effectiveness, based on the initial soil properties, are presented. Another finding is that the injection sequence may be controlled to provide confining action for the subsequence injections. The confined injections can effectively improve the highly compressible soils much more than the unconfined ones. In addition, it is recommended to avoid the condition, beyond which particle crushing becomes the dominant mechanism of deformation.

Many factors must be considered in the design of inclusions to be created by Limited Mobility Displacement (LMD) grouting. Inclusions can serve many functions from simple displacement of the surrounding soils to cause compaction, to forming structural columns and improving continuity of rock masses. The creation of inclusions is dependent upon the grout properties, subsurface conditions, and the design objectives. Practical limitations dictate the controllable size of inclusions, while grout and soil properties, and construction procedures control the strength and shape of injected masses. This paper reviews analytical tools for design of inclusions and presents recommendations for their use.

The development of high-speed railroad corridors in the United States is being considered by Congress as a fuel efficient and economical alternative to air or highway passenger travel. The existing infrastructure is, in many cases, suitable for freight traffic but not for the more exacting geometry standards of high-speed rail passenger trains. In many cases the proposed passenger service would use existing trackage heretofore carrying only slower moving freight trains (e.g., the newly opened service on the Northern New England Corridor (The Downeaster) between Boston, Massachusetts, and Portland, Maine). Instability in the roadbed can cause changes in track geometry at a rate unacceptable for safe or economical high-speed operation over existing lines. This project was conducted to demonstrate that existing ground stabilization techniques could be utilized to economically improve track performance for high-speed service. Rail traffic and the resulting limited track time available for maintenance in high-speed corridors dictate that embankment stabilization methods must be employed with minimum traffic disruption. The Federal Railroad Administration (FRA) Office of Railroad Development initiated a demonstration project to identify an unstable railroad embankment and effect a remedy. The purpose of the project was to develop experience with and demonstrate the capabilities of ground improvement techniques for reducing track maintenance requirements. The line segment selected for demonstration had a history of track settlement that continued after the line was rehabilitated for passenger service. After only a few years of renewed service, it became evident that the embankment was still subject to chronic settlement that required frequent resurfacing. A sub-surface investigation determined that a variable-thickness peat layer underlying the embankment caused the settlement.

Near surface tunnelling in built-up urban areas has lead to the development of special geotechnical measures to protect buildings from damage resulting from undue (total and differential) settlements. In contrast to passive ground improvement techniques, compensation grouting is an active method applied to counteract subsidence induced by tunnel excavation. Compensation grouting is done in two stages: In the first stage grouting between the ground surface and the tunnel is performed for "conditioning" the soil. After the immediate response of the system is ensured, settlements monitored with accurate measurement devices are compensated in the actual grouting phase. In this paper compensation grouting operations for a tunnel excavation underneath a station building are described in a case study. The efficiency of compensation grouting is discussed for this practical example. To show the basic effects of compensation grouting, finite element calculations are provided for different stages of the grouting process and compared with in-situ measurements.

The United States Postal Service's (USPS) Eastpointe Facility in Clarksburg, West Virginia is located at the site of a former strip mine. Reclamation activities prior to construction were accomplished by backfilling the stripped area with the excavated materials after the coal seam had been removed. Subsurface investigations performed for the design of the facility identified settlement concerns due to loose fill and the existence of nested cobbles and boulders. To address this concern the site was reportedly over excavated and replaced with a controlled engineered fill. Placement and compaction methods utilized during placement of this controlled fill are unknown. Constructed in 1989, the 9,300 m² single story steel frame structure is supported by columns founded on spread footings. The floor of the building is a grade supported concrete slab isolated from the primary foundation system. Differential settlement of up to 150 mm has occurred causing structural damage and serviceability problems. This paper details, from a construction perspective, the applied grouting technology utilized to stabilize the structure, along with an analysis of the performance achieved. The work was substantially completed in the fall of 2001.

Compensation grouting used to protect seven masonry buildings near deep excavation in Shanghai, China is presented in this paper. Grout was injected between the diaphragm wall and the buildings to compensate for ground loss and stress relief caused by the excavation. The design and construction of compensation grouting during adjacent deep excavation are detailed. This project demonstrates that compensation grouting is a cost-effective and promising method to protect properties near deep excavations in soft clay.

Laboratory grout injection tests were performed in clay to investigate the effect of grout injection rate on soil-grout behaviour during and after injection for both `compaction' type and `fracture' type grouting, with particular emphasis on compensation grouting in clays. Injection of low mobility grout was simulated by expanding a latex balloon, whereas injection of high mobility grout was simulated by injecting epoxy resin directly into clay specimens. For balloon expansion case, there was a minor effect of injection rate on pressure-injection volume and grout efficiency-time relationships. For epoxy injection case, on the other hand, fracture initiation and propagation mechanisms were affected by the magnitude of injection rate and hence the pressure-volume and grout efficiency-time relationships were injection rate dependent.

The history of dam foundation grouting in the U.S., which began with a project in New York in the late nineteenth century, is—to some extent—one of objectives not fully achieved. It also is one of innovative procedures and insightful ideas only some of which were applied, and of questionable procedures that look all too familiar to today's grouting practitioners. An early suggestion that a closely adjacent two-row grout curtain consisting of closely-spaced grout holes might be preferable to a three-row curtain clearly was not incorporated in the design of Teton Dam, but has been incorporated in the design of a few dams constructed in recent years. The early twentieth century concept of injecting essentially endless volumes of high w:c ratio grouts survived unto the late twentieth century, despite a realization in some quarters that such grout would travel far beyond the area requiring treatment and would either not set up at all or would merely form "films." By the time Boulder Dam was constructed, the design of grouting programs was considered to have became "systematic." However, in this case, remedial grouting entailing deepening the curtain and injecting very substantial volumes of grout subsequently was found to be necessary. There have since been many other cases in which the initial grouting was done "systematically" (using now outmoded concepts and procedures) and in which remedial grouting ultimately proved to be required.

WAC Bennett dam is a zoned earth embankment slightly greater than 600 ft (183 m) in height. Two sinkholes, of which the deepest descended about 400 ft (120m) from the crest, were discovered in the core of the dam in 1996. Compaction Grouting was chosen as the best remedial method, and was used. Because even the slightest chance of hydraulic fracturing of the core could not be tolerated, grouting was carefully designed and controlled including: precision drilling of the deep holes to within a verticality tolerance of one degree; continuous analytical evaluation of the grouting based on real time computer monitoring; careful control of the grout mix and especially its aggregate component; and, rigid control of the grout injection rate. The dam core was also monitored during grouting using a broad range of instrumentation, both on and within the embankment. Procedures were verified by a full-scale test before working on the dam.

The various techniques which constitute the Deep Mixing Method (DMM) are being used to treat, improve, and retain a variety of soil types on an international basis. A recent U.S. Federal research program has generated a detailed review of technology worldwide, and the broad findings of the research are presented in this paper. Major areas of focus are application, technology, and QA/QC and verification.

The proposed $2.4 billion replacement of the Woodrow Wilson Bridge, which carries Interstate I-95 across the Potomac River, will require significant realignment and widening of approach interchanges in Virginia and Maryland. Just west of the bridge on the Virginia side, the footprint of the I-95/Route 1 Interchange will be doubled. Maintenance of traffic flow and a looming completion deadline require rapid construction of new embankments over thick deposits of very soft ground. Deep soil mixing will be used to make soil-cement columns for support of the new highway embankments, to protect existing features, and to provide a staging area for subsequent interchange bridge construction. During the design phase, the project team considered a variety of solutions to address design and construction requirements. The design phase investigation included typical subsurface explorations, laboratory soil tests, bench-scale mixing tests, field test columns, and a test embankment built over an array of field test columns. The reliability of in situ ground improvement was a significant concern to the owner. Findings from the design phase investigations were used with simple reliability estimates to reduce uncertainties and provide the data needed to make practical design decisions. This paper describes design alternatives, the bench scale tests, the field trial columns, and the test embankment. The impact of these activities on design and construction of the approach embankments is also presented.

Ground stabilization by the Scandinavian dry injection process was introduced into the United States in 1996. This environmentally friendly process that produces no spoil at the ground surface has since been used on several major projects that are briefly described in this paper. These projects include stabilization for a 15 m high roadway embankment on weak Lake Bonneville deposits in Salt Lake City, Utah, stabilization of silty sand for purposes of liquefaction mitigation and stabilization of weak, organic, Young Bay Mud in San Francisco California as part of the extension of the Bay Area Rapid Transit (BART) system to the San Francisco airport, and stabilization of a railroad embankment over organic soils in the Hackensack Meadows of New Jersey. The performance of these projects is summarized herein. Important advances in the dry injection process resulted from these experiences and are described in this paper.

In a variety of circumstances, the use of deep mixing methods for the construction of excavation support systems is often the method of choice based on design requirements, site conditions/restraints and economics. These circumstances include the presence of adjacent structures that can tolerate minimal lateral movement; the presence of loose unraveling or flowing sands; the need for a competent cutoff wall to prevent the lowering of the adjacent groundwater and its induced settlements of other structures; and the need to simultaneously underpin an adjacent structure, while constructing an excavation support wall. Other systems such as traditional soldier beams and lagging walls would yield unsatisfactory performance, the installation of vibrated or driven sheetpiles could cause vibration induced settlements of adjacent structures, while concrete diaphragm walls are time consuming and expensive. Based on conditions, the use of multiple-auger or single auger deep mixing methods, jet grouting methods, or the combination of several methods may be required. To illustrate applications of deep mixing in a variety of conditions, several case histories are presented. On projects in Wisconsin and Pennsylvania, the multiple auger deep mixing method was successfully utilized to limit lateral movement of adjacent structures, prevent the loss of support due to unraveling soils and control groundwater.

This paper furnishes general guidelines for design and installation of ground treatment and stabilization using soil-cement technologies. The methods of soil-cement production addressed herein include wet mixing, dry mixing, and jet grouting. Design and installation factors which enter into the selection of the appropriate method are itemized and described. Design factors include the ability to achieve the required geometry, compatibility of the geology to the treatment method, practicality of obtaining the required engineering properties or performance, impacts of the installation process on concurrent construction activities, effects of the treated ground on subsequent construction activity, effects of ground treatment process on existing facilities, and the ability to verify compliance with performance criteria. Installation factors include cost, preparation of contract documents, quality control and assurance, and other construction-related elements.

Engineers have been finding increased application for soil cement columns on several projects in the United States. Most of the application has been in the areas of excavation support and the control of groundwater seepage. There has been very limited application in the area of foundation support for structures primarily because of the lack of established design and installation criteria. In 1997, the Japan Building Center issued a publication containing guidelines for using soil cement columns as foundation elements. These guidelines were based on data, including some from load tests, gathered over a period of about 15 years from about 9,000 projects where soil cement columns were used as foundation elements. In this paper, design procedures based on the Japanese guidelines, with particular emphasis on designing for earthquake loading are introduced. A design level or design base earthquake is considered. The design procedures are described for individual soil cement columns, soil cement columns spaced in a group, and for soil cement columns tangential or secant to each other in a group. A proposed quality control program that should lead to the establishment of appropriate installation criteria is also introduced. The design and installation aspects presented in the paper should advance the cause of soil cement columns as economical alternatives to conventional foundation elements.

Mass stabilization is an environmentally friendly soil improvement method where the stabilizer is mixed into organic soil or soft clay. Mass stabilization is carried out by a mixing tool previously installed on an excavator machine. Mixing in both horizontal and vertical directions is carried out so that an homogeneous stabilized soil block is formed through the effect of the stabilizer. The thickness of the block is varied according to the height of the embankment, between 1 and 5 m. Embankments can be founded on mass stabilized soil in the same way as on natural firm soil layers, such as moraine or gravel. The 5 performed mass stabilization projects are summarized in this paper. Of these 5 projects, 1 was performed in Finland and 4 were performed in Sweden.

At low frequencies (around 20 Hz) the maximum level of train-induced ground vibration is highly dependent on train weight as well as train speed. This limits the axle loads and speed allowable for train traffic. Stabilization of the soft soils under the track by for example lime-cement columns is one of the methods that can be used for reducing the level of vibrations. This method has been successfully adopted at Ledsgård, a site in south-western Sweden in order to solve the problem of extensive ground vibrations due to the passage of X2000 high-speed trains. Using result from measurements both before and after the countermeasure and a 3-D FEM model, the effectiveness of the method in mitigating train induced ground vibrations on soft soil is discussed in this paper.

The reconstruction of the Capital Beltway in Alexandria, VA requires substantial widening of the existing embankment into the adjacent swampy grounds that are underlain by 3m to 9m (10ft to 30ft) of highly compressible soft organic clay. The construction schedule does not permit sufficient time for using P.V. Drains in much of the U.S. Route 1 interchange area, so deep mixing was selected to provide the necessary ground stabilization. For stability, series of shear wall panels are used, formed by overlapping soil-cement columns elements. A large area of the embankment will be placed on individual columns of soil-cement that are used solely for load support, thus greatly reducing settlement. The design analysis applied to the stability and the settlement control applications are described.

Many soil admixture stabilization methods have been developed and used for many on-land and marine constructions in the world, in which soft clayey or sandy soil is mixed with a chemical stabilizing agent such as cement or lime. Various studies have been conducted on subjects such as the physical and mechanical properties of treated soil and the interaction between treated soil and untreated soil. The authors started research projects on the long-term strength change of cement treated soil under several exposure conditions. In this study, the strength distribution within the treated soil exposed to fresh water, seawater, and untreated clay was measured to investigate the influence of the exposure conditions on the decrease in strength and the expansion of the deteriorated area within the soil. The calcium content distributions in the specimens were also measured on the treated soil to investigate the mechanism of strength reduction by comparing with the strength distribution.

Deep mixing method is a kind of soil stabilization technique using cement and/or lime as a binder, constructing treated soil columns, wall or massive block in soft ground. The method has been applied in practice since 1975. So far, many researches have been carried out to investigate mechanical characteristic of treated soil based on laboratory and field samples aged less than a couple of years. However, long-term change of mechanical, physical or chemical characteristic of treated soil is not entirely made clear yet. In this study, in-situ treated soil columns were investigated in detail. These columns, each having 1 m in diameter and 8 m long, were constructed by dry method of deep mixing about 17 years ago in a site in Hokkaido. The primary purposes of the study are two-fold; one is to investigate the long-term strength increase within the sound part of treated soil columns and the other is to investigate the possibility of deterioration at the periphery of columns. In the central portion of the columns, the steady strength increase after 17 years was confirmed. The leaching of Ca from treated to untreated soil was observed. However, the extent and magnitude of strength reduction at the periphery of the columns was very small at the present test site.

In April 1995, a site in West Drayton near Heathrow Airport in the UK was treated by in-situ stabilisation/solidification using cement-based grouts and implemented using a soil mixing auger. The site was cored at 2 months and then at 4.5 years after treatment and samples were tested for various physical and chemical properties. These included strength, leachability, leachate pH, permeability, freeze-thaw and wet-dry durability and microstructural analyses. The time-related performance over a five-year period has therefore been established. In addition, research work is being carried out to develop accelerated ageing methods to enable the correlation between real-time and accelerate-time behaviour to simulate the much longer-term performance. Two methods are being considered namely elevated temperatures and accelerated carbonation. In this paper the five-year performance of three soil grout mixes is presented and the feasibility of the two accelerated ageing methods is assessed.

In connection with a large Swedish research programme concerning different aspects of deep stabilisation of soft soils, a number of permeability tests have been performed on certain soft soils stabilized with different type of binder in the laboratory. The permeabilities of the stabilized samples were measured in permeameter tests and in CRS oedometer tests. Although exhibiting a fairly large scatter in results, the tests showed that the permeability changed with time and with the amount of binder. They also showed that the permeability to some extent varied with the type of binder used. Comparisons made with other permeability investigations on stabilized soils have shown both agreement and deviations from the results in the present study. It was found that changes in permeability in the stabilized material to a large extent could be linked to the increase in strength and decrease in water content.

This paper has identified four major factors causing property changes in surrounding soils during and after installation of deep mixing columns: soil fracturing, disturbance, thixotropy and consolidation, and diffusion of chemical agents. Laboratory and field tests were conducted to evaluate these changes during and after installation of deep mixing columns in soft Ariake clays. Both laboratory and field test data indicated that property changes existed within an influence zone ranging from the edge of the column to a distance of about twice the radius of the columns in surrounding clay. Within this influence zone, water content decreased with a closer distance to the columns while pH values and concentration of cations increased. Test results also showed that shear strengths of the surrounding clays decreased during the installation but regained after a short curing period (about 10 days in this study) and continued increasing in a long period. The increase of shear strengths in 30 days could reach 30% by average over the initial strength of the clays.

Among many soil mixing systems, the most common is the deep soil mixing system that uses cement slurry as an additive reagent. This is because, 1) relatively simple equipment is needed, 2) satisfactory mixing is achievable, and 3) quality control is not difficult. At the present time, however, strength properties of soil cement produced by deep mixing are not well understood. For example, their relationship with mixing methods is not well established nor is the concept of uniformity of soil cement. Strength test data of soil cement cores from two project sites were obtained with cooperation from the project owners and specialty contractors. The projects involved two deep mixing systems using cement slurry; the multi-shaft CDM (Cement Deep Mixing) and the single-shaft SBM (Shear Blade Mixing) systems. The first project is the soil improvement at Berths 55/56 at the Port of Oakland in California, which used the Cement Deep Mixing system. The second project is the foundation soil improvement of a six-story commercial building in Niigata, Japan, which used the SBM system. For these projects, many core samples of soil cement were obtained for quality control. The subject of this paper is statistical analyses of the strength test data of the core samples. Histograms were used to analyze the strength distributions. A method to determine the design strength is presented which utilizes the standard deviation and the coefficient of variation of the strength test data.

Deep mixing method has been applied to improve soft ground for over 25 years in Japan. However, the possibility of deterioration of treated soils has not been studied in detail. In this paper, long-term strength change of treated soil was investigated. The paper consists of three parts. In the first part, the strength characteristic of in-situ treated soil after 17 years is investigated. In the second part, Ca (calcium) leaching phenomenon from treated soil to surrounding soil is investigated in situ. And in the third part, the numerical prediction method for Ca leaching from treated soil is proposed. It is confirmed that after 17 years the treated soil has sufficient strength characteristics, although it is slightly influenced by Ca leaching. The related property change to Ca leaching from treated soil can be expressed using numerical analysis considering ion migration model and Ca leaching model.

A core drilling method using PQ-size triple tube core barrel and fine diamond flush face bit with side water discharge was successfully used to recover representative specimens of extremely variable hardness soil-cement made by deep mixing. A soil-cement hardness identification procedure using the scratch test derived from soft rock identification procedures was employed in the field to quickly categorize the soil-cement core for strength and consistency or degree of heterogeneity.

In this paper column penetration tests for lime-cement columns in deep mixing are reviewed. In principle, column penetration tests and reversed column penetration tests are considered. Improved test techniques are presented and discussed based on tests from two test sites in Sweden. The investigations indicate that the reversed column penetration test is the most suitable method for the primary quality test with reference to the uniformity and continuity of the columns. The probe should, however, be installed by the lime-cement column machine short after the manufacturing of the column to avoid disturbances in the mixing process and to enable a random test selection.

Due to variations in mixing procedures and environmentally related soil factors in laboratory and field conditions, strength properties of deep mixed soil columns are different from the design strengths obtained from laboratory tests. Hence, there is a need to assess deep mixing (DM) operations in field conditions prior to infrastructure construction. For quality assurance, in situ intrusive methods are preferred over field sampling and laboratory test methods since the in situ methods are repeatable, reliable, and quick. This paper presents various intrusive in situ methods including standard penetration test, cone penetration test, pressuremeter tests and various other field test methods and their applications in quality assurance studies of deep mixed columns. Advantages and limitations of these methods are discussed. Future research needs for better evaluations are mentioned.

Bearing capacity of bored cast-in-situ piles by post pressure grouting can be effectively improved through the grout pipes placed within the piles when concrete is 10–20 days old. Based on tests for seven grouted piles respectively cast in the bearing layers of sand and clay, this paper summarized the process of pressure grouting and investigated in-situ tests of these grouted piles. The principles of controlling the maximum of grouting pressure and the volume of grout injected were also presented in this paper. The interactions between improved skin friction and end resistance of grouted piles were studied. All piles by pressure post-grouting proved completely satisfactory in performance of bearing capacity even when the ultimate load is up to twice or more. The results show that post pressure grouting is an effective method to improve bearing capacity of ordinary bored cast-in-situ piles.

An instrumented bored pile was installed and load tested to clarify the mechanism of base grouting and determine its effectiveness. The load transfer characteristics, and mobilization curves for skin friction resistance and end bearing resistance were determined from the strain gauge data. The performance of the base grouted bored pile was compared with data for two conventional slurry stabilized bored piles and a barrette installed in similar ground conditions. Significant increase in pile toe stiffness and skin friction resistance was observed for the grouted pile. Analysis of the results suggests that, in addition to improvement of the pile toe bearing condition, it was possible for grout to flow upwards along the pile shaft-soil interface during grouting at very high pressures, thereby enhancing the skin friction resistance as well. Both toe resistance and shaft resistance were simultaneously mobilized right from the start of loading. A review of base grouting records for 32 working piles indicated that there was an approximate correlation between cement consumption, the number of grouting stages and the volume of pile shaft.

In this paper the use of permeation grouting for pile foundation improvement is discussed. To begin with, the main principles of the method are explained. After this, the set-up and results of a full scale test are outlined, discussing amongst others the effective stresses, pore water pressures and pile and soil displacements during the installation of tube-à-manchettes (TAMs) and during the actual grouting. The changes in the bearing capacity of wooden pile foundations as a result of the grouting are also discussed. Finally, the practical applicability and costs of permeation grouting for renovating a typical Amsterdam historic structure are discussed.

To enable the construction of a new lock beside a highly loaded pier, an underpinning of about 3.200 m³ was made by microfine cement grouting. The characteristics of different microfine cement grouts were first examined in a trial field test. Settlements caused by the construction works were highly controlled. They were measured by a real-time monitoring system over three years. To remediate and compensate unavoidable settlements a system for compensation grouting was necessary. The recorded values of settlement and heaving allow for an examination of the parameters of different drilling techniques and the efficiency of compensation grouting.

The successful execution of a large and important number of specialty geotechnical construction processes necessitates the efficient and safe drilling of holes through any and all ground conditions. Inappropriate means and methods may in fact worsen the ground properties or structural conditions the construction technique is intended to enhance. There is a potentially bewildering variety of drilling methods and associated technical concerns. This review is intended as a fundamental guide to various aspects of the technology, including drilling methodologies, flushing, deviation, monitoring, and specifications.

In anchor pullout design, conservative soil and rock shear strength parameters are usually adopted. Presumptive values of soil/grout and rock/grout bond strength are available in different design manuals. In this study, in-situ pullout test data for anchors in soil and rock type worldwide were collected from published sources and information provided by specialty wall contractors. The measured pullout test data were compared to estimated pullout resistance using the Post-Tensioning Institute (PTI) presumptive bond strength values. Statistical analysis was performed to determine the probability of success and the corresponding reliability indices using the minimum, average and maximum PTI ground/anchor bond strength values for cohesive soils, cohesionless soils and different rock types. A minimum safety factor of 2 recommended by the PTI to the ground/grout bond strength was found not conservative where the maximum presumptive bond strength values were used in clays and sands, and the average and the maximum presumptive bond strength values were used in rocks. Based on the results of this study, an average minimum factor of safety was recommended for ground/grout bond strength.

Use of micropiles has increased rapidly in Scandinavia. Applications of grouted micropiles cover underpinning works, construction of detached houses and soil nailing. Today, main part of Scandinavian micropiles are type of impact driven without grouting, when as grouting is common phase of installation for drilled micropiles. New codes of practice have been published recently in Sweden and Finland. A new approach for grouted impact driven micropiles has been made in the innovation of the CSG pile. Continuously shaft grouted or CSG micropiles have been grouted simultaneously during embedding of piles. Grouting has been implemented using pressure pumps as well as utilising self pressuring feature of the driving method. Steel micropiles have been driven down with steel stress of 100 to 400 MPa in each blow and a part of stress has been distributed to surrounding grout. Even 4 MPa or 40 bar pressure peaks have been monitored causing very efficient penetration of grout into surrounding soil material.

Over a three-year period, a section of railroad tunnel, near Ryndon, NV, had undergone significant deformation of the tunnel lining due to inadvertent undermining of the footings during removal of concrete invert struts to improve vertical clearance and rectify a series of mud fouling problems in the track structure. Emergency response steel invert struts were successful in arresting liner movement. However, seepage and resultant mud pumping remained a serious problem that would influence the long-term stability of the tunnel. The permanent liner stabilization program consisted of the installation of high capacity minipiles and tieback anchors along the affected tunnel length, coupled with a program of enhanced drainage. This paper presents the design and implementation of the fast track rehabilitation program.

It is now possible, under reasonably favorable geologic conditions, to design and construct grout curtains as fully engineered elements having specific design properties and achieving specific, end performance results. This paper summarizes the procedures, tools, and techniques to utilize the Quantitatively Engineered Grout Curtain (QEGC) Design Approach. Recommendations are provided for curtain design parameters based on evaluation of the set of integrated project characteristics that affect the outcome of grouting. The potential favorable impacts on technical and cost effectiveness afforded by a quantitative design approach are illustrated by simple examples.

On June 5, 2001, a major leak was discovered beneath the California Aqueduct embankment at Mile Post 4.25, discharging more than 4,200 L/min (1,100 gpm) at its peak. This situation prompted emergency action to control the leak to avert breaching the embankment. The leak was plugged after pumping 42 m³ (55 yd³) of concrete to fill the large piping void. Then a geologic exploration was conducted to delineate problematic zones beneath the embankment, followed by several grouting techniques used to investigate and improve the distressed foundation. The comprehensive grouting program included 27 compaction grout holes to explore and densify the soft alluvium foundation, 13 permeation grout holes to investigate and fill voids in the underlying fractured bedrock, and abandonment of an obsolete seepage collection system beneath the Aqueduct. This paper shows chronologically how data collected from the grouting program, geologic exploration, and construction records were used to better understand the mechanisms of the piping failure.

The Ivex Packaging Corporation purchased a paper-recycling mill in Chagrin Falls, Ohio. The 100-year old dam was constructed of masonry and timber cribbing, and had shown a history of wear in recent years. Seepage flows through the embankment and right abutment, and into the process building were a steadily increasing problem requiring constant attention. To combat this problem, a combination of grouting techniques was used, including sleeve port pipe grouting, and limited mobility grouting. Difficulties encountered during construction required close coordination with the plant personnel, grouting specialist contractor, and the engineers to adjust the hole pattern, grout materials, and injection methods as work proceeded. Following four weeks of grouting, seepage flows were stopped through the right abutment. This paper describes the process for development of a grouting plan adapted to the particular site conditions, and the field adjustments made during construction. These adjustments included modification of type of grout and grout placement methods, especially where significant flows were found to be untreatable using low viscosity grout.

A deep grouted cut-off was constructed as part of the 140 m high, concrete-faced rockfill dam at Antamina in the high Andes of Peru. Foundation conditions comprised upstream-dipping, contorted argillaceous rocks in the left abutment, varying to limestone with karstic solutioning in the right abutment. This potential for karst was of concern for ensuring the integrity of the dam cut-off and governed much of the rationale for defining curtain depths and for ensuring flexibility of grouting procedures. This, the first of two papers on the dam, concentrates on the design aspects of the curtain and foundation grouting philosophy. Curtain performance on impoundment to full height is then reviewed. The accompanying paper ("Curtain Grouting for the Antamina Dam, Peru: Part 2 — Implementation and Field Modifications") describes the curtain construction.

Curtain grouting for the 140 m high dam at the Antamina Mine in the Peruvian Andes involved nearly 40,000 m of drilling and injection of 2,800 tons of cement. The curtain is 780 m long and as much as 95 m deep. This paper, the second of two, addresses execution of the grouting including required design modifications. The accompanying paper ("Curtain Grouting for the Antamina Dam, Peru: Part 1 — Design and Performance") presents the design and achieved performance of the curtain during reservoir impoundment. Grouting was specified using the GIN system. However, this led to formation damage and little reduction in the hydraulic conductivity of the rock. Following detailed analysis of the ground response to grout, using electronically acquired pressure/flow data, grouting procedures were revised to blend the best of the GIN approach with the key components of the Australian Method. Routine water pressure tests verified curtain closure. Final conductivities were less than 1.5 Lugeons (including the karst region), with many zones about 0.1 Lugeons.

Construction of shallow foundations in karstic geology always carries risks. In many cases, the perceived risks are high enough for the engineer to recommend alternative deep foundations or ground modification. The difficulties associated with construction of deep foundations in karst have led to the development of Limited Mobility Grouting (LMG) methods to improve the subsurface conditions and, in many cases, to permit the use of shallow foundations. This paper reviews the aspects to be considered for selection of foundation alternatives in karst, and presents three case histories where LMG has allowed the use of shallow foundations for major structures.

Throughout the United States and especially on the east coast, development pressures have increased construction atop carbonate rocks. A myriad of concepts and techniques for identifying and remediating karst hazards has been proffered, many reasonable, some not so. Only remediation by grouting is discussed herein. The difference between effective and ineffective technique for both the identification and remediation of karst are related to the nature of the subsurface, the likely failure mechanism, and the type of construction. Bedrock character, bedding orientation, tectonic alteration, glacial activity, nature of the overburden, as well as the location and size of soil or rock cavities, will influence the failure mechanism in some way. In addition, the nature of any planned or existing construction can modify the manner, extent and procedures of the grouting operations. Any cost-effective grouting program in solutioned carbonates must consider all of the above concerns. Grouting can be as simplistic as filling the "throats" of isolated sinkholes with an appropriate "flowable fill" to a full-fledged exploratory/grouting program using compaction and/or slurry grouting techniques below a major structure. Developing an accurate cost estimate varies from quite difficult to impossible. Case histories of successful remediation operations that consider these concepts are presented herein.

Four types of seepage cutoffs have been successfully utilized in limestone formations: open-cut excavated cutoffs, diaphragm wall cutoffs, secant pile cutoffs, and grouted cutoffs. After falling somewhat out of favor due to lack of success on some projects, recent advances in materials, procedures, and techniques have resulted in practitioners regaining confidence in grouting. This paper examines cutoff methods with respect to geologic compatibility and the issues, problems, and limitations for each type of cutoff. Four recent case histories of successfully grouted seepage cutoffs are discussed: the reservoir rim cutoff at Tims Ford Dam, Tennessee, the Patoka Lake spillway in Indiana, Wujiangdu Hydroelectric Project in China and a multi-material cutoff in an operating quarry in West Virginia.

Limited Mobility Grouting (LMG) has been a relatively recent technology that began in the United States. Applications of this method of ground improvement are still evolving. The Bryce Jordan Center, Penn State University, State College, PA, is an example of the use of LMG in karst for rock supported spread footings. Although a deviation from the traditional compaction grout roots of LMG, the application provided assurance that the foundation rock was consistent/continuous. This paper provides a brief discussion of the exploration methods used to assess the site variability, and the development of the foundation design. This approach was developed as a cost saving alternative to drilled shafts, and represents the first recent structure where the State owner of this facility had allowed foundations other than drilled piers for buildings in karst. The paper includes discussion of the design methodology and estimating procedures, as well as construction experience. Conclusions related to the construction activities, difficulties, and results are included. The design methodology builds on the work of Schmertmann and Henry to develop a strength-based approach to unifying the rock mass to limit settlements under foundation loadings. The success of the method has been demonstrated by six years of satisfactory performance. As a unique application of LMG to rock foundations, particularly on a structure of this magnitude with column loads up to 2500 kips (11,000 kN), this case study serves as an example of successful innovation with an evolving technology.

This paper aims at briefly presenting a methodology for characterization of fractured rock for grouting design using hydrogeological methods. The conceptual model is based on a grouting fan and is built up by fractures inferred from hydraulic tests and geological mapping. Instead of the commonly used Lugeon value, the specific capacity (Q/dh i.e., flow divided by difference in hydraulic head) is central since it has shown to be a robust parameter, which can be related to transmissivity and fracture aperture. Fracture aperture is important for grouting design due to its influence on both penetration length and grout take. The methodology described for estimation of transmissivity and aperture distributions has potential for further development for computer use, which would enable a fast analysis of data from hydraulic tests and geological mapping at a working site. Based on aperture distribution and expressions describing the spreading of grout, the choice of input parameters such as grout properties, pressure and borehole distance could be improved. Furthermore, the transmissivity and aperture distributions for probe holes give a general description of rock, which is used for the interpretation of data from individual grouting boreholes. This description of fractured rock for grouting should be a good basis for further discussions and development as well as facilitating the choice of strategy.

Large effort has been put into understanding how cement grout penetrates and hydraulically seals a fractured hard rock. Whether the grout sealing will endure the stress re-distributions due to rock excavation is, however, sparsely discussed. This paper presents a research program that investigated the principal rock mechanical differences between grouted and ungrouted joints to obtain input data for modeling. From direct shear tests of grouted and ungrouted rock joint replicas, it was found that cement grout acts basically as a `lubricant' in a joint subjected to shear stress. The `hydraulic failure' of a grouted rock joint was found to be a function of dilation and coincides with the joint peak strength. Numerical modeling was performed to study the consequences in tunneling. Under adverse geological conditions, failure of grouted joints may propagate into the surrounding rock mass up to twice the tunnel diameter. The investigation showed that the shear resistance of a grouted hard rock joint was lower than an identical ungrouted joint. At low normal stress levels, an initial strengthening cohesive effect was noted.

Void fill grouting is a technique which has been extensively used by CTL/Thompson, Inc. to mitigate mine subsidence potential resulting from abandoned underground coal mine workings. The technique involves rotary drilling from the surface down into the mine workings and pressure injection of grout into underground mine voids and rubble zones to fill voids. Communities of Rock Springs, Glenrock and Hanna, Wyoming were built over abandoned coal mines. Over time, the rock comprising the roof of the mine begins to fracture and collapse into the open mine. This process continues until the space is either occupied by rubble or the caving reaches the surface, threatening public health and safety. To successfully mitigate the potential of subsidence reaching the surface, a thorough understanding of the subsidence mechanism is required and the proper mitigation method selected. The paper describes typical subsidence mechanisms and mitigation methods. The depth to mining is important when determining whether or not subsidence will reach the surface. Also important are; the thickness of the mined seam, rock bulking . characteristics and strength of the overburden rock. This information can be obtained by investigative drilling, laboratory testing on material samples and careful analysis. The paper presents brief descriptions of analytical methods to determine critical mine depth. Once the critical depth to the mine is determined, a pilot drilling and grouting program is undertaken to determine the optimal hole spacing for mitigation. During construction, holes are drilled on a grid spacing as determined in the pilot program and low strength grout is injected through the drill holes into the mine workings. Critical items during grouting are; grouting sequence, slump variation, pressures, cutoff quantities and verification drilling. CTL/Thompson, Inc. has successfully used this technique in Rock Springs and Glenrock, Wyoming for over 13 years with construction costs exceeding 35 million dollars. Verification drilling, and the lack of insurance claims or surficial subsidence features indicate that void fill grouting is an effective method to mitigate the effects of subsidence due to abandoned underground mines.

Mining grouting in South Africa has always been associated with deep mines. Certain techniques and equipment used are a result of the very high pressures resulting from the large depths of South African Mines. Some of the techniques specifically developed within the South African mining environment are Precementation of deep shafts up to 2400m; cover grouting to develop or sink under or through rock formations in safety; the successful impermeabilisation of rock masses with `thin, unstable" cement grouts; and the conveyance of cement-sand slurries over many kilometres. This paper presents the development over many years and the State-of-the-Art of South African mining grouting and endeavours to present a more rational evaluation and appreciation of the achievements of the early grouting engineers. It also presents a more rational approach in grouting particularly for mining conditions, keeping in mind recent developments in grouting engineering and possible developments in future.

Some grouting projects are of particular interest because grouting was not initially considered in the range of alternative solutions. And some grouting projects are interesting because they involve unusual physical or technical challenges. To be worthy of note, a grouting project has to be wildly successful against long odds. Occasionally, a grouting project meets all three criteria and is of interest to the engineering community at large. This paper presents brief case histories of five such projects, with the goal of encouraging engineers to consider grouting in the "short list" of possible solutions to geotechnical problems.

This paper sets out a brief case history of the design of a cement-bentonite cut-off wall grout for use in very aggressive groundwater conditions and presents a basic procedure for the estimation of the design life of a grout barrier under such conditions. The paper then considers two perhaps unexpected effects of grouts, the formation of a soap-like material in silicate grouted ground which hindered slurry tunnelling operations and the release of ammonia from jet grouted ground.

Measures of success for any grouting program should include superior technical performance and cost effectiveness. These can be achieved by designing grouts with properties that are specifically tailored to the application. This requires a fundamental understanding of the fluid and set performance characteristics needed for a specific application. For high mobility cement based grouts (HMG), these properties include bleed, segregation, resistance to pressure filtration, control of particle agglomeration, anti-washout characteristics, rheology, evolution of cohesion with time, set time, matrix porosity, ultimate strength, resistance to chemical attack, and durability. A description of how each property is quantified, evaluated and optimized is provided, and related to appropriate standards. A three-step process for the design and quality control of an HMG project is outlined. The first step is a laboratory-scale testing program to determine basic formulations, optimized for performance characteristics and cost. The second step is full-scale trial batching performed on site with the materials and equipment that will be used on the project. The third step is quality control testing during production grouting to ensure that the grouts being used are being batched correctly and will perform appropriately in situ. A digest of mix HMG designs used on recent projects is provided for illustration and reference.

In addition to many environmental benefits, fly ash utilization provides end-products with superior engineering and physical qualities as well as economic benefits, considering the utilization potential in construction-related applications such as cement production and concrete products in the form of highway pavement concrete, structural concrete, and roller compacted concrete, bricks, blocks and paving stones; artificial lightweight aggregate, structural fills or embankments, stabilization of waste materials, mineral filler in asphalt paving, flowable/structural fill and grouting mixes. The fly ash, being a cementitious coal combustion by-product, promises high volume utilization in grouting applications by addition of other mineral admixtures when necessary. The fly ash grouts provide required engineering performance in improving ground stability by increasing strength and shearing resistance as well as reducing the permeability of soils treated with enhanced technical, rheological, durability and economic advantages over sand and cement grouts. The fly ash grout is also cost-effective when alternative suspension, emulsion or solution materials are considered. In this study, fly ash grout composite formed of various combinations of high volume fly ash, cement, lime and high range water reducing chemical admixture has been investigated to define short-term engineering performance in terms of physicochemical (chemical compound analysis, unit weight, void ratio, specific gravity, linear shrinkage, hydraulic conductivity) and mechanical properties (unconfined compressive strength and flexural strength), excluding durability as the long term engineering performance. The overall short-term engineering performance indicates high volume fly ash utilization potential in grouting applications.

Additives and admixtures are used in cement and non-cement-based grouts to modify their fluid and set characteristics. The ability to modify all fluid and set characteristics increases the durability, strength and penetrability of grout. Well designed formulations create balanced stable suspension grouts that reduce the cost of any grouting operation through increased grouting effectiveness by minimizing the cohesion and maximizing the penetrability of a grout via proper application of additives and admixtures.

Improvement of the mechanical and hydraulic properties of soils by grouting is one of the most widely used techniques in soil stabilization. The use of added pozzolanic materials such silica fume, and fly ash as well as clay to improve the physical, mechanical, and fluidity properties of cement grouts has been researched in recent years. In this study, the usage of grout additives fly ash and clay in soil grouting, and the effects of these grouts on soil strength have been researched in laboratory tests. First, grouts with added fly ash and clay in different amounts were prepared, and then these grouts were injected into soil samples. The unconfined compressive strength of grouted samples was determined for 7 and 28 days of curing time. It is shown that fly ash and clay improved fluidity of the grouts. The results of fly ash and clay grouted samples were compared with the cement grouted samples and the test results were evaluated against each other.

The use of ultrafine cement-based grout has been gaining importance for rock and soil grouting over the last few years. One of the more dramatic technical innovations in the grouting industry that has been sought is the ability to mill, on-site, a fine or ultrafine cement-based grout using regular cement, and locally available additives (fly-ash, pumice, slag, bentonite, clay, tailings, catalysts, sand). This paper presents the results of extensive research and testing program executed during the development of a mobile Particle Size Reduction Mill (PASREM). The search for an inexpensive and effective milling machine for on-site production of ultrafine cement-based suspension grout has been ongoing since the early 1990's. The application of on-site milling would solve the problems associated with the use of classic pre-prepared ultrafine cement. This includes the agglomeration of particles that often results in a grout with a higher average particle size than desired, reducing penetrability of the grout, and the high cost of ultrafine cement. On-site milling would also allow for the use of many locally available products and additives that could enhance the final grout and reduce the cost of producing the grout. PASREM is a mobile milling machine used to produce ultra fine cements from readily available portland cements and additives. This process is preferably done by injecting a balanced cement-based suspension grout through the PASREM, immediately prior to grouting. This is further referred to as the wet milling process. The PASREM process can also be used to mill the aforementioned dry powders to microfine size, to produce a classic (bagged) microfine cement.

Cement-based grouts are used at the Prestressed Concrete Cylinder Pipe (PCCP) joints to seal and protect the steel cylinder from the surrounding environment during the service life of the pipes. If a proper grout-water mix was not used, the grout could lose water, harden prematurely and shrink in the joint, causing long-term maintenance problems. Hence, it is critical to develop field test methods to ensure the quality of the grouts used in the water pipe joints. In this study both field and laboratory samples were used to determine the properties of a non-shrinkage cement grout. The laboratory study was undertaken to evaluate the effect of water content on the working and mechanical properties of a non-shrinking grout used for interior and exterior joint sealing of PCCP pipes. By varying the water content, the behavior of various grout mixes was investigated. Over 130 field samples were tested and the results are compared to those of the laboratory samples. Field specimens exhibited a very large variation in the compressive strength as compared to the laboratory specimens. A relationship between unit weight, water content and compressive strength of the grout has been developed. The variation of compressive strength with curing time for various grout-water-mixes has been developed. Based on these test results, using a grout/slurry balance to ensure quality of the grout in the field has been recommended.

The paper illustrates some of the results obtained from an extensive experimental program, conducted on grouts manufactured with a pozzolanic microcement (D₉₈ = 10 μm) and an acrylic-based superplasticizer, and consisting of: a) injection tests in laboratory prepared sand columns, and b) rheological tests performed employing a high resolution rheometer. The data presented in the paper highlights the effects of varying the water-cement ratio of the mixtures (w/c = 1 to 2.75), the admixture dosage, (0–1.6% in terms of active polymer by mass of cement) and the injection pressure (p_inj = 50 and 200 kPa). An attempt is made to link the results of the injection tests to the rheological properties of the grouts. It is found that, for the reference medium investigated (Ticino sand), at a given injection pressure, provided that the viscosity exceeds a threshold value, there is a unique and linear relationship between the height penetrated by the grout inside the sand column and its viscosity. A similar relationship, albeit shifted to higher values of the viscosity, applies for a lower injection pressure. Small changes in the viscosity of the grout dramatically affect the height of sand permeated by the grout. Medium-related effects are also addressed. Based on the results of injection tests in five sands it is observed that small changes in the sand's gradation significantly affect its groutability, with increasing difficulties associated with grouting less uniform sands. Overall, the height penetrated by the grout correlates with the hydraulic conductivity of the medium.

The aim of this paper is to present comparative laboratory studies conducted on commercially available OPC, Microcem H900 and silicate-ester grouts. It has been found that Microcem H900 has better flow properties, and bleed characteristics than OPC. Further more, its permeation into medium to coarse sand is as effective as silicate-ester grout and the strength of the sand gained by the injection of Microcem H900 into sands is higher than that of silicate-ester grouted sand.

Heritage masonry structures are an integral part of our landscape. Heritage structures located in Canada and the United States are relatively young compared to European heritage structures but they can show signs of deterioration due to our harsh climate. Repairing these structures using grout injection is a very interesting technique since it involves preserving the historical character of the structures. The formulation of injection grouts for such repair must be based not only on physical properties of the deteriorated mortar, but also on chemical properties. Compatibility between the existing medium and the repair material is a major factor in avoiding new deterioration related to poor mechanical behaviour of injected grout or chemical reactions with deteriorated mortar. Other parameters such as rheology, injectability and stability of repair grouts must be considered to ensure the effectiveness of grout injection. Many mineral additives and chemical admixtures are available for the formulation of cement-based grouts used to make repairs. Some of these products have been tested in the laboratory to optimise high-performance cement grouts used to repair heritage hydraulic masonry structures in Canada. The characteristics of these grouts and their performance during field work are presented in this paper. The effectiveness of the grouting treatment was controlled by sonic tomography conducted before and after grouting: several techniques are illustrated and their results are very sensitive to the actual grout intake in the different locations of the structure treated.

Shortly after putting into operation of the Gabcikovo Danube Project, the navigation locks began to leak. It was necessary to complete and modernise the monitoring system so that this would enable a more precise location of the leaking areas and also monitoring of efficiency of the performed rehabilitation activities. Additional sealing was done in several stages. Joints were sealed with polyurethane resins and the degraded gravel bedrock was sealed with traditional grouting.

Water reactive polyurethane grouts were introduced into the grouting industry during the late sixties by the Takenaka company in Japan under the trade name TACSS. It became possible to inject "one component" grouts without potlife that do not easily wash out and react with the ground water. Because of environmental scrutiny, the first series of TACCS were replaced by solvent-free, hydrophobic, MDI based polyurethane prepolymers. Whilst remarkable successes were booked in mining and geotechnical engineering projects, more and more these products were used for permanent seepage control for sealing concrete structures. Hydrophilic polyurethanes were also introduced in Japan predominantly for the latter application. They contained solvents and were TDI based. Their high reactivity and high dilution ratio with water made them attractive to practitioners. In 1980, the N.V. DeNeef Chemie obtained the exclusive rights for TACSS for most places on earth and the successes in stopping major leaks in tunnels changed classic grouting (sodium silicate cement combinations) and seepage control grouting (acrylamide grouting) because of practical and environmental considerations. After the N.V. Denys brought similar products to the industry in 1980, more manufacturers jumped on the bandwagon. By the mid-eighties there were more than 10 manufacturers of polyurethane grouts. Several new and improved hydrophobic water reactive urethanes were developed during the eighties as a result of this new trend. A few manufacturers created closed cell, water reactive hydrophobic polyurethanes. The era of custom-made formulations, tailored to the project, started. Water reactive hydrophilic polyurethanes came under close scrutiny because of longevity problems. The classic two-component polyurethane foams, used in mining were gradually introduced in geotechnical engineering. For permanent seepage control, in concrete structures two-component polyurethane elastomers became popular. The introduction of hydro-block in France for major inflow control was another remarkable development. Extensive research was performed, especially in Scandinavia to establish life time expectancy of hydrophobic water reactive polyurethane. Pioneering research was done to establish mathematical models to understand the flow of P.U. through fine fissures. This paper focuses on the engineering aspects of polyurethane grouting with in the background the history of these fascinating products. It elaborates on the various types of applications illustrated with case histories for each type.

Polyurethane grouts are used for controlling leaks in civil infrastructure facilities. Due to the wide range of environmental conditions in which the polyurethane grouts are used, there is increased interest in better characterizing the behavior of hydrophilic polyurethane grouts. Polyurethane grout selected for this study had a free volume expansion of over 800% for water-to-grout (W/G) mix ratio of 0.5. In this study the effects of W/G ratio and volume change (ΔV) on a solidified hydrophilic grout properties was investigated. Unit weights of cured polyurethane so prepared varied from 1.1 kN/m³ (7 pcf) to 10 kN/m³ (63 pcf). The behavior of cured polyurethane grout was studied under wet and dry cycles. Each cycle had a week of immersion in water followed by a week in air. During the test, weight change and volume change were measured up to forty wet-dry cycles. Parameters influencing the swelling and shrinkage of the grout have been identified. Using multiple regression analysis a relationship has been developed to represent the maximum swelling in terms of cured grout parameters.

Hot bitumen grouting technology has continually evolved since its early applications almost a century-ago in France, Germany and the USA to seal persistent leaks in tunnels, below dams and for erosion protection along canals. Advancements in the industry especially in the field of monitoring and grouting equipment has made the injection of hot bitumen in conjunction with cement based suspension grout, the most economical, practical and sure solution to stop major inflows through, below or around structures. These applications proved the effectiveness of the hot bitumen grouting technique to stop major water inflows and stabilize water bearing, cohesionless soils, in a fast, predictable and economical way. This paper elaborates on a few remarkable field applications, one of which was likely the largest grouting effort ever undertaken.

The Chi-Chi earthquake attacked Taiwan in September 21, 1999 caused liquefaction in some alluvial deposits inland and hydraulic fills along the coastline. In the areas with obvious liquefaction, sand boils were found on the ground surface and many buildings suffered severe settlement or tilting. To prevent buildings from future liquefaction damage, subsoil underlying the settled or tilted buildings can be improved by grouting method. Considering the groutability and durability of grouting material, a colloid silica grout was chosen as a potential grouting material to improve the liquefaction resistance of in-situ sandy soil. The liquefaction resistance of this colloid silica grouted sand was studied by a cyclic triaxial test apparatus. Test results showed that up to 4 ∼ 7 folds increase in liquefaction resistance of grouted sand compared with that of ungrouted sand was observed despite the strength of this colloid silica gel was very low. Higher stress ratio and more number of loading cycles were needed to initiate liquefaction in grouted sand specimens. But a lesser liquefaction induced strain was observed. Under cyclic loading, the deformation of grouted sand specimens increased gradually with loading cycles until initial liquefaction occurred compared to a sudden increase in axial deformation of ungrouted sand specimen when initial liquefaction happened. Cyclic mobility was observed in the grouted sand specimens.

Recently, as large constructions on the coast increase, application of a surface layer stabilization method, which is one of the improvement methods for dredged soft clay, have increased. However, there are few studies about this method. The purpose of this study is to clarify characteristics of ultra-soft marine clay and hardening agent, and to evaluate an optimal mixture ratio of hardening agent through the laboratory tests according to design of experiments. Laboratory test results were verified by statistical analysis and pilot tests. Laboratory tests were performed with hardening agents and test soils by the design of experiments, and regression equations according to relation of hardening agents materials and unconfined compressive strength were derived from the tests. Regression equations also verified its applicability to field by pilot tests. From the results of tests, it was found that hardening agent materials such as cement, slag, fly-ash, inorganic salts, häuyne, gypsum, etc. affect compressive strength. It was defined that optimal mixture ratio which satisfies the required compressive strength from the statistical analysis. Also, it was compared that the effect of ground improvement by cements and hardening agents through the pilot tests. This study will serve data for design or construction criteria of stabilization of surface layer on ultra-soft marine clay.

This paper suggests a method for measuring the penetrability of grouts. The proposed method evaluates the penetrability of the grout based on measurements with a newly developed device where the grouts ability to pass filters of different widths is measured. After evaluation two especially descriptive parameters are obtained, a minimum and a critical aperture. These two parameters describes the penetrability of the grout and can be used for comparing grouts and in modelling grout propagation. In the paper some measurements and evaluated results are presented. This is to study some governing factors for the penetrability of grouts but the main objective is to demonstrate the proposed method. The results confirms that the main factor governing the penetrability is the type of cement used and that variations in w/c ratio and addition of superplasticizers only have limited influence. Measurements on the filter cake shows that the thickness and the density are influenced by pressure and w/c ratio.

Polyurethane resins are widely used in infrastructure repair technologies, particularly to stop water inflow in underground tunnels. However, the longevity of these chemical grouts is not well documented, as their application is relatively new. This is particularly true in Canada, and especially in the Montréal area, where tunnel walls are subject to many freezing and thawing cycles in one year, initiating some debonding and water inflow followed by ice formation. This presentation is dedicated to the characterization of various polyurethane resins under such environmental conditions. Special laboratory tests have been developed to measure the bonding strength and shrinkage of these resins injected into cracked concrete or in improperly sealed expansion joints. These traction tests and cyclic expansion/contraction tests illustrated the major role of environmental conditions (humidity and temperature) on the effectiveness of these resins. Several well-documented applications have been conducted during the rehabilitation of two major road tunnels in Montréal. The most effective imperviousness was obtained with a semi-rigid hydrophobic polyurethane resin, but it is also very important to specify how to prepare the fissures and how to inject these resins.

Permeation grouting and controlled hydrofracture grouting are two soil grouting techniques used for the purpose of improving soil properties. Although there are many other techniques, the focus of this paper will be on permeation and hydrofracture grouting and will be referred to as soil grouting throughout the paper for simplicity. Soil improvements include stabilization, strengthening (bearing or bond) and permeability reduction. This paper will discuss the means and methods available for performing permeation grouting. The purpose of this discussion is to provide information for developing practical designs to meet project specific goals. The discussion will include topics such as grouting methods, mix designs, equipment, quality control, monitoring, injectability constraints and determinations. Soil grouting is an often misunderstood and overly simplified technology. This misunderstanding can result in inadequate design and construction methods. The ideas conveyed in this paper are based on the authors' experiences in a number of soil grouting projects as grouting consultants and contractors.

Since they first appeared in Japan about 30 years ago, ultrafine cements have become commonly available. Grouts containing these cements can be formulated to permeate most any granular soil including fine sand. In this application, they have substantial advantage over the more traditionally used chemical solution grouts, in that significantly higher strengths can be obtained, and at a lesser cost Additionally, cement grouts are non-toxic and do not suffer strength regression with time, as do most chemical grouts. Ultrafine cement can be of any one of three different origins, including common portland cement, slag based cement, and a combination portland-pozzolan blend. However, there are fundamental differences in the penetrability of grout derived from the cement of these different origins. Extensive research and experience has shown the grain size of the cement alone does not control the penetrability of the resulting grout into soil. Both grain shape and surface condition of the cement are important, as is the polar intensity. The results of an ongoing evaluation program, as well as actual case histories of projects utilizing ultrafine cement grout are presented.

In addition to the application of empirical injection criteria also one-dimensional injection tests have become a suitable technique for the evaluation of the groutability of sands. Both procedures have been applied to the injection of microfine cement suspensions for the sealing of construction pits in Berlin, Germany. The mostly unsatisfying results clearly indicate the limitations of the above mentioned evaluation practice. Starting from this background an extensive investigation program has been carried out at the Geotechical Institute at the Technical University of Berlin, Germany. Different combinations of sand and microfine cement grout have been used in one-dimensional and spherical injections, accompanied by rheological and grain-size analyses. This paper focuses on the filtration effects which represent the main difference between the penetration of chemical grouts and that of suspensions of microfine cements. The deposition of particles within the soil skeleton leads to a dynamic reduction of the hydraulically effective pore-space and to a change in the rheological properties. Although basically known, these effects are not considered in the formulation of injection criteria.

The Ilijan Power Plant is located in the island of Luzon in Philippines. Washington Group is the Engineering, Procure, and Construct (EPC) Contractor with Daelim as the Civil Sub-contractor. The cofferdam for the intake structure had dimensions of 36m x 30m and extended 9.0m below the ground water level. The subsurface conditions at the site are very complex and highly variable. Three alternating layers of dense cemented conglomerate and highly permeable open structured gravel/cobbles were encountered at the intake structure location. An order of magnitude permeability of 1 x 10^–1 cm/sec was estimated by simple pump tests from a large test pit at the site. The intake structure is about fifty meters (50m) from the Pacific Ocean thus excluding de-watering as a solution for construction. The paper describes details of subsurface conditions, the intake structure and various alternates considered for construction of a cofferdam. Schedule, reliability of the proposed solution and cost were the driving factors in the selection process with the first two being the higher priority. The selected solution had redundancy and recovery schemes planned to address unanticipated subsurface conditions and to assure timely completion of the intake structure as planned. The selected solution utilized steel sheet piles, jet grouted columns, soil anchors, and cement- sodium silicate grout mixture as a bottom seal plug placed at a significant distance below the bottom of excavation. On completion of these activities, the intake structure was built on schedule in a relatively dry condition with only two small sump pumps to handle minor seepage.

Humboldt Bay Power Plant was one of the first nuclear power plants built in the United States over 30 years ago. The reactor was constructed utilizing a 60 ft. diameter caisson with internal divider walls, which was, sunk approximately 70 ft. below sea level, mucked out, plugged with a 6 ft. thick underwater tremie concrete placement and then pumped out. By design, the tremie concrete was covered by a 6 inch layer of drain rock, a 6 inch concrete slab, and in some areas a 3/16 inch steel liner plate which functioned as a tank for holding liquid (water) within the structure. The drain rock and a series of drainpipes through the divider walls routed any leakage to a sump where it could be pumped out.

This paper presents a discrete fracture approach for analysis of foundation grouting in fractured rock. In this approach the grout injection boreholes and the fractures intersecting them are modeled explicitly. Grout is injected into the fractures directly and indirectly connected to the grout injection boreholes. This approach is more realistic than conventional analyses which rely on a reduction in "effective" conductivity, without considering the geometry of fracture pathways through the rock mass. The approach is applied to determine the relative effectiveness of 2 or 3 rows of grout holes for the same grouted length.

All Slovak dams that are included in the ICOLD register were constructed in geological conditions of the Carpathian flysh except of one that was built in a volcanic rock. Their subsoils were treated by grouting courtains. This paper describes water pressure tests as unsuitable tests for determining of grout curtain effectiveness, construction conditions of dams, testing problems and results of monitoring. Determining the effectiveness of the grout courtain based on the groundwater level changes, uplift conditions, filtration velocities and developments of seepage during the operations of the reservoirs.

The Merimere Reservoir is a surface water supply source located approximately 3 kilometers northwest of the city of Meriden, Connecticut. The reservoir, constructed circa 1870, is impounded by an earthen dam to the north and by an earthen dike to the south. The earthen dike, which is the subject of this paper, has a concrete core wall and consists of fill resting on a low saddle of natural ground. The dike is approximately 45 m (150 ft) long and 6.6 m (22 ft) high. Evaluations of the reservoir revealed that the earthen dike was leaking at a rate of 950,000 to 1,135,000 liters per day (250,000 to 300,000 gallons per day). Several investigations were performed to determine the cause of leakage and provide remedial measures to reduce the seepage. The field investigations consisted of geologic mapping for outcrop joint trends, acoustic-emission monitoring, a seismic refraction survey, subsurface investigation and an investigation to locate the concrete core wall at the center of the dike. Bedrock outcropping at the west side of the dike is sandstone and at the east side is basalt. Based on the field investigations and engineering studies, it was concluded that the most probable location of the seepage was the highly jointed and faulted basalt along the eastern side of the dike. In order to reduce seepage through the basalt fractures, a pressure-grouting program was implemented. Cement grout formed a cutoff wall below and around the interface of the core wall and basalt bedrock. Grouting was performed in a triangular pattern in three rows with a spacing of approximately 1.5 m (5-ft). In order lo evaluate the effectiveness of the grouting program, a "V-notch" weir was constructed immediately downstream of a seepage boil prior to grouting. This weir was used to measure the quantity of the seepage flow before and after grouting in order to evaluate the reduction in the seepage and the effectiveness of the grouting program. The grouting program completed at the Merimere Dike markedly reduced the seepage around the dike by over 85 percent to approximately 80,000 liters per day (21,000 gallons per day), a level to which the city of Meriden has deemed acceptable.

A brief description along with a number of case histories of each of the different types of ground treatment procedures used during the construction works associated with the extensions to the Madrid Metro over the last eight years are described in this paper. An account is given of how different adverse conditions and situations can be overcome by means of these grouting techniques, ensuring at all times the safety of the excavation processes, be they using tunnelling machines or when excavating by hand, be they under buildings, roadways or pipelines

Grouting techniques are more widely accepted and used in urban tunnelling because the impact on existing structures is minimal or non-existent. The compensation of settlements due to tunnel excavations became a part of underground projects within the last twenty years as grouting techniques were adapted to the specific needs of controlled soil treatment. Not only permeation grouting is being used, but fracture grouting and compaction grouting are also being used in various geological and geometrical conditions. This paper deals with the elements of compensation grouting and the organizational aspects of grouting measures in combination with different tunnelling methods. Special emphasis is placed on the contractual approach to integrate compensation grouting in a design-and-built concept. The main objective is to give a general overview about the logical sequences of decisions to make regarding settlement control during tunnelling operations.

Phase I of the Glen Echo Creek Culvert Reconstruction Project, involved lowering the invert of an existing concrete arch tunnel along with replacing an existing corrugated metal pipe (CMP) with a new tunnel between 28^th and 29^th street in Oakland, California. All construction work was performed within the tunnel by hand mining techniques. Due to the close proximity to residential buildings, roadways and utilities, various grouting techniques were applied to minimize ground settlement, stabilize subgrade soils and reduce water seepage to facilitate hand excavation. This paper describes the design and execution of the various grouting programs implemented, as well as the grouting performance.

Tunnels 3 m (10 feet) in diameter used for road and railroad crossings of water pipelines in Hillsborough County, Florida suffered ground surface subsidence problems due to their shallow depth and sand soil cover. The soil depth above the top of the tunnels was typically no more than 3 m (10 feet). A controlled low strength cementitious grout was designed to fill the void between the tunnel and the liner plates, and to maintain pressure around the tunnel boring machine (TBM) equal to the overburden pressure. Pre-grouting could not be done due to the low permeability of the fine sand soils and the lack of surface access. Therefore, the grout had to be designed for injection from ports inside the TBM without causing damage to the machine. This paper describes the design of the grout and the testing program to document the engineering properties of the grout, as well as the field grouting procedures developed for the project. The results of field measurements and laboratory test results are also presented.

The Greater Cairo metre and El-Azhar road tunnels, the major project of underground structures in Cairo city, Egypt, have been constructed. During the construction of the Greater Metro Line 2 (Shubra El-kheima- Mubarak) and El-Azhar road tunnels, which are installed by the tunneling boring machine (TBM), Geotechnical challenges are expected to occur related to soil stability around the tunnels. One of these problems arises when parts of the metro and the road tunnels cross under an existing sewage tunnel during the construction. To control the potential problem, the National Authority for Tunnels (NAT) has applied grouting to the soil around the sewage, the metro and the road tunnels. In the present study, one of these problems is highlighted and a model is proposed to provide a prediction of the soil structure interaction using a 3-D model of the multi-crossing tunnel incorporating the effect of grouting. The cement-bentonite grouting is considered in this study. The objective of this study is to evaluate the usefulness of permeation grouting in reducing deformation around the sewage tunnel when the metro and the road tunnels pass underneath it at different crossing zones. To assess and understand effect of changing the soil stiffness by grouting on the behavior of the two tunnels, a parametric study has been performed. The study is conducted using a finite element method that models the three-dimensional behavior under both the effects of the tunnel crossings and effects of the grouting. A nonlinear stress-strain constitutive model is adopted to represent the soil surrounding the tunnel and a linear constitutive model is employed to represent the sewage tunnel liner. The effects are expressed in terms of the settlement and radial deformation of the sewage tunnel as the metro or the road tunnels pass underneath it for the cases with and without grouting. The 3-D model of predicting the behavior of the tunnel system under multi-crossing tunnels and grouting effect is described and the predictions are compared with the field measurements. The comparison reveals a good agreement between the computed and observed values.

Soil stabilization grouting was performed to facilitate tunneling under an existing active railway line. The design consisted of creating a circular annulus of cemented soils around the trajectory of the future sewer tunnel by performing permeation grouting through sleeve-port pipes. Since the original soils investigation data indicated that the soils were well-graded, undisturbed native soils, grout volumes were estimated based upon 20% accessible void space. A single pass with sodium silicate grout was anticipated. The sleeve-port pipes were installed by directional drilling methods. Careful monitoring of the drilling and casing grout injection processes revealed evidence of the presence of extensive fill along the tunnel trajectory. As a result of these observations, water pressure testing was added to the scope of work in order to better define the characteristics of the material to be grouted. The water pressure testing data revealed the material to be grouted had a very high permeability (greater than of 0.1 cm/sec). In order to manage the cost associated with the grouting work, a single pass of cement based suspension grouting was performed prior to the sodium silicate grouting. During the cement based grouting, high takes at low injection pressures were noted and as a direct result of these observations two passes with the sodium silicate grouts were performed. During the tunneling process, direct verification of both the existence of extensive gravel layers and of successful full permeation and stabilization of the high and low permeability soils was provided. The grouting methodology and the volume of grout used differed considerably from the original design. The final volume of grout used corresponded to an accessible void ratio of approximately 40%. The original design was consistent with the soils investigation data, however, if the program had not been modified for the actual ground conditions, it is unlikely that satisfactory ground treatment would have been achieved. The project demonstrates that careful monitoring and analysis of drilling and grouting data and modification of the design based upon these data are necessary components of a successful geotechnical construction process.

The principles of pregrouting as presented here are based on nearly 40 years of experience of pre- and post-grouting in rock tunnels in different parts of the world.

This paper presents the monitoring and the grouting works of an immersed road tunnel. As this underground structure is almost 30 years old, groundwater has gradually damaged and penetrated the concrete, bringing water problems in the winter as the water forms into ice that can fall on cars or damage electrical equipment. To understand the problem related to water infiltration and find solutions, instruments were installed to monitor the movement of a horizontal construction joint and exploratory drilling was conducted in the concrete ventilation tower structure. These investigations led to choosing two solutions: a first phase of cement grouting and a second phase of chemical grouting were carried out between 1998 and 1999. From the different available observation locations, both grouting methods gave satisfactory results for the stopping of water leakages in the ventilation towers.

The Toronto Transit Commission (TTC), one of the largest public transportation systems in North America has been plagued by leaking tunnels since the time they were constructed. The water infiltration problems was causing both delays and concerns for passenger safety as well as causing accelerated aging of the rail and rail fastening systems, deterioration and malfunction of electrical systems and their components, and decay of the structure itself. A professionally engineered state-of-the-art solution grouting program has brought the problem under control. The grouting program at the TTC, which was started up in May 1997, is one of the largest continuous on-going leak remediation grouting projects using solution grouts in North America. The leakage remediation program originally focused on solving the tunnel leakage problems but has since expanded to include water infiltration problems in the stations. The success gained to date can be attributed to a combination of several key components: the assembly of an in-house team of grouting expertise—from design engineer to field technician and the selection and meticulous use of the most suitable sealing materials available in industry for this specific and extremely difficult application. The unique challenge of performing all the leak remediation grouting work within the nightly two hour maintenance window without impacting on customer service was successfully accomplished using a strategically implemented, engineered grouting procedure. Time limitations and difficult ground conditions proved to be the two most difficult obstacles facing the grouting engineer. The grouting design had to take into account the multiple phase, multiple stage grouting, operations that were anticipated and required to successfully shut off the leakage problems.

During the construction of the rock tunnels at the South Link, Stockholm, Sweden, grout investigations were carried out. The aim was to develop alternative methods/concepts for sealing of tunnels compared to the methods/concepts described in the contract. The investigation started with a laboratory study, which outlined the most appropriate grouts for field trials. The field trials consisted of seven grout fans. The front of each fan was divided for equal pumping test values, and grouted with different concepts. The sealing result and the spreading of the grout were studied in 10 holes in the tunnel front and in 10 holes perpendicular to the tunnel. The holes were test pumped and studied with a borehole camera. From the investigation it was concluded that regardless the maximum grain size of cement (9.5, 16 or 30 μm) fine joints (< 100 μm) were still unsealed after grouting. In open joints or rock masses (>1 Lugeon) there was some indications that micro cement was more effective than the more coarse cement type. Higher stop pressure did not give a better sealing result and some parameters achieved at laboratory especially for micro cements were not possible to reproduce with ordinary field mixers.

An abandoned 1600-meter (mile-long) rock tunnel had to be completely filled with grout. The total tunnel volume was approximately 4500 cubic meters (6000 cubic yards). The tunnel was water-filled with access only at each end through narrow, 25-meter deep (80 ft), vertical shafts. Access for pumping was feasible only from one end of the tunnel, thereby requiring unusually long distances for pumping. Through an extensive laboratory testing and modeling program, different grouts were tested for suitability for this project. The ideal grout would have low viscosity, good stability and, after setting, low bleed, moderate strength and low permeability. Materials tested included cement-bentonite, cement-flyash and combinations including blast furnace slag cement. Data is presented on the various grout materials leading up to the choice of a cement-bentonite-slag cement blend as the optimal mix for the project. The unusual conditions at this project required the use of divers and remote-operated vehicles to inspect the tunnel and to place the initial cable that would allow grout pipes to be drawn into the tunnel. Each component of the grout system was engineered to provide adequate capacity to fill the tunnel in three to four days, working around the clock. A backup system using a sleeve pipe to provide secondary grout was devised and installed. The work in the field progressed more or less as planned, with a few unknowns cropping up to make for some difficult moments. As it turned out, the secondary grout line was necessary to complete the work. Grout samples were taken during the project for confirmation testing and borings were drilled into the tunnel after the work to verify that the tunnel was full. Data from this phase of the project are also presented. This project presented an unusual opportunity to plan and test components pre-construction. White there is no way to verify, the distances that the grout was pumped may represent some kind of record.

Generally, it is known that urethane injection is an excellent method in long-term durability and environmental characteristics for ground improvement. However, urethane grouting has short rise-time that is, reaction time of solution A and solution B is short, and the injection distance is very short. Therefore, urethane injection cannot be used for the site where locates deeply from the initial injection point in a ground. Other injection materials such as cement cannot apply an alternative material when rapid hardening is required. From this study, disadvantages of urethane injection could be improved by TAS method. From the results of field tests, it was known that TAS increases injection distance over 10m, which is longer than that of original urethane grouting. In addition, the rise-time of TAS is shorter than that of cement grouting, so rapid improvement can be gained from TAS. Short rise-time and long injection distance of TAS can give excellent applicability for tunnel construction.

During the past ten years, a number of advances have been made in jet grouting technology, worldwide. For the North American geotechnical community, by far the most significant advance occurred in 1998 with the introduction and application of the energy-intensive SuperJet grouting technique to install an in situ wale and strut system at the base of a cut and cover tunnel for the Atlantic City Expressway Extension. On this project, the ability of the SuperJet technique to create exceptionally large soilcrete elements with enhanced product quality realized a substantial time and cost saving. Since then, SuperJet grouting has been successfully applied in a range of situations and soil conditions previously considered to be economically outside the realm of traditional jet grouting. This paper discusses the evolution of jet grouting in North America in terms of equipment refinements, new applications, range of treatable soils and verification testing. Case studies are presented that illustrate the versatility of this emerging technology and its value as a cost-effective ground treatment tool.

An extensive pre-construction test program was performed to develop installation parameters that would result in overlapping jet grout columns with diameters of at least 1.5m. The columns were to be installed through approximately 40m of fill, organics and clay deposits; and 0.3m into the underlying glacial deposit. This paper describes the technical difficulties encountered during the test program; the different methods adopted to assess the effectiveness of the jet grouting; and the QA/QC criteria eventually adopted for installing and accepting the in situ grout columns.

The historic "Bibliotheca Albertina", built between 1885 and 1891 and situated in the centre of Leipzig, is one of the most beautiful landmarks in this great city of commerce renowned for its trade fairs. In the last two weeks of the Second World War the building was badly destroyed by bombs. Under the government of East Germany, several attempts to reconstruct the library failed. It was not until 1990, immediately after the reunification of Germany, that plans for the reconstruction finally took shape and construction works could begin. A variety of specialist foundation techniques was used on the project, such as secant and soldier pile walls, jet grout underpinning, temporary and permanent tie-backs, grouted deep soft gel and high-level horizontal base cut-offs, and micro piles to protect the base against uplift. The reconstructed and renovated library building was handed back to the University of Leipzig, founded in 1543, in an official opening ceremony on October 24th. 2002, the 111th. anniversary of the Library's original inauguration.

Jet grouting is widely used to enhance the stability of tunnels and excavations in soft clay in Singapore. Some of the design and construction issues associated with the grouting are discussed.

Jet grouting was adopted to stabilize excavation for the construction of an underground irrigation tank and amphitheater in soft clay. Triple fluid jet grouting was used to form jet grout columns of 1.7m diameter in the soft clay. Precutting with water jetting was necessary to ensure that the design column diameter was achieved in the upper filled ground consisting of very stiff well-compacted sandy clay. Seven trial columns were executed to determine the jetting parameters. Monitoring of lateral ground displacements indicated that the jet grout stabilization scheme was successfully implemented and that lateral displacement to excavation depth ratios can be maintained within 0.24%.

This paper briefly reports the two recent major jet grouting applications in Turkey where jet grouting was employed in order to control and limit the excessive settlement of the foundations and to reduce the risk of liquefaction are described. The main emphasis is given to selection of the jet grouting technique and the quality control tests carried out during jet grout installations. The paper also describes application types and details of the operational parameters such as injection pressure, number and size of nozzles, lifting and rotation speeds.

This paper discusses the development of a practical jet grouting method capable of obtaining a large diameter exceeding 5 meters, based on fundamental experiments for seeking the relationship between discharging energy and eroding capability, and for originating equipments for creating oversized columns. Authors also refer to a trial execution to find optimal geometries for contract works and a case history which proves superior to the conventional method.

Jet grouting has become a common method of ground improvement for microtunneling (MT) and horizontal directional drilling (HDD) in difficult ground conditions. Both MT and HDD performance is evaluated for two recent major Honolulu projects with complex geologic conditions where jet grouting served both temporary and permanent roles. While similar concepts have been applied with jet grouting at other microtunnel or tunnel sites, quantitative evaluation of improved MT or HDD performance appears lacking in literature. Effects from variations in jet grout column designs are presented based on field observations and collected data. Performance evaluation criteria is discussed for grouting and trenchless projects, illustrating benefits of combined uses.

Jet Grouting is a ground treatment technology that allows in-situ ground stabilization by mixing soil with grout. Grout is pumped into drilled holes at ultra high pressure to loosen and mix the grout into the soil. The result is columns of material having higher strength than the original soil. This technology was selected as the means of improving the stability of a high and steep excavated slope. This project also involved installation of vertical sand columns and intercepting horizontal drains to alleviate hydrostatic pressures in the slope and stabilization of the slope face with geocell reinforcement anchored by drilled soil nails. This paper outlines the design and construction process of a project that demonstrates a unique application of ground improvement technologies to allow construction of a new public highway.

The original construction of the Corpus Christi Naval Air Station (CCNAS) in Corpus Christi, Texas included a protected tarmac landing area for seaplanes used during World War II. This tarmac, which included ramps for the seaplanes to come from the sea, was constructed with a seawall as its protection against coastal storms. The seawall spans approximately 3 Km (10,000 feet) of sea front, and original construction included sea ramps along its length. Today, the seawall is limited in use and serves only as a storm front to combat the possibility of erosion to the remaining barracks that now house the Navy's helicopter fleets. There are some 7 barracks and one active taxiway located within the northern 1.4 Km (4,700 feet) of the bulkhead known as the Helicopter Operations Area. The remaining 1.3 Km (4,200 feet) of the bulkhead to the south protects the area behind the wall and offers public fishing. Recently the bulkhead has undergone excessive movements and rotation outward towards the sea affecting over 427 m (1,400 feet) of the northern half. This movement stimulated the investigation of the anchoring system and included repair recommendations for the two failed areas. These recommendations included the restriction of all traffic within 12.2 m (40 feet) of the wall and complete reconstruction of the 426.7 m (1,400 lineal feet) of wall using conventional coastal front construction techniques. Budgets for the conventional reconstruction of these 426.7 m (1,400 lineal feet) of bulkhead exceeded the Navy's budget, thus leading the Navy to search for an alternate stabilizing technique. This paper presents that alternate stabilizing technique, which utilized Super Jet Grouting to effectively and economically stabilize the Northern portion of the seawall bulkhead.

Ground treatment was required to consolidate soils for the formation of emergency evacuation cross passage adits between the two tubes of the Kowloon-Canton Railway Corporation, Tsing Tsuen Tunnels in Hong Kong. Jet grouting techniques were successfully employed to produce a sufficiently strong and watertight block of treated soil to permit safe and efficient excavation. The impact on the adjacent urban areas had to be considered and methods were developed to minimise the impacts to the public, traffic, services and adjacent structures, having regard to disturbance caused by excessive ground movements.

Subsurface conditions at the site of the planned La Rosita power plant in Mexicali, Baja California, Mexico, consisted of approximately 7 to 8 m of very stiff to hard clay overlaying a loose silt layer. Beneath the silt, very-dense sand and medium stiff to very stiff clay layers were encountered. Design calculations indicated that without piled foundations or ground treatment to improve the engineering properties of the silt layer, settlements of the plant foundations would exceed tolerable limits. SuperJet grouting was used to bridge the loose silt layer at depth to provide both foundation support and settlement control, successfully reducing the anticipated settlements to within acceptable values. The basis for the SuperJet program design was that the grout columns would transfer the loading from the upper stiff clay to the underlying dense sands. Optimum column spacing was determined based on the anticipated loading on each column, the estimated diameter of the columns, and the ability of the overlying stiff clay soils to bridge from one column to the next. SuperJet grouting was performed under all heavy foundations, including the stacks, heat recovery steam generators (HRSGs), combustion turbines (CTs), and steam turbine generator (STG). The SuperJet grouting program was successfully conducted between March and May 2001. The power plant is now under construction, and the measured settlements of the foundations have been within the anticipated range based on design calculations.

A large cooling tower sits partially on bedrock and partially on very stiff clay, up to 14 m thick. Jet grout columns were installed in the clay beneath the tower foundations. This paper describes the selection of the jet grout installation parameters and the testing and production installation of the columns. An extensive settlement monitoring program allowed values of the elastic modulus of the grouted and nongrouted clay and the bedrock to be computed.

The subject site is located on steep slopes of Ortakoy valley, which has been filled with excavation materials obtained from the first Bosphorous Bridge and other nearby construction sites in time. There are two high-rise towers planned in the project, which are structurally and rigidly connected at the basement and at the upper three floor levels with a bridge type of passage. The basement of the high-rise towers lead to some 20 m (66 ft) deep excavations, partially in the fill, and partially in the original ground, which is greywacke, (alternating layers of claystone, siltstone and sandstone). As a result, the foundation level of the towers seated partially on greywacke and partially on the artificial, uncontrolled fill of varying thickness up to 15 m (49 ft). The site is seismically very active and any irregular displacement of the towers with respect to each other is intolerable. As a result, it was decided that the towers should have similar foundations with the subsoil under the towers having similar compression modulus values so that they will both contribute equally to respective displacements. For this purpose, improvement of the fill by means of jet grouting is considered to be the most appropriate procedure. Jet grouted columns are designed so that, they can provide sufficient capacity for superstructural loads i.e. load carrying members and also the improved soil would have similar modulus value with the greywacke bedrock. The quality control and quality assurance of the above criteria are done by means of jet grout loading tests, plate loading tests, and coring and compressive strength tests of the cores obtained from jet grouted columns presented in this article. The tests indicated a successful application of the improvement even in an uncontrolled artificial fill.

The signature feature of the Gerald Ratner Athletics Center at The University of Chicago is the roof—a flattened S-curve, which appears to float in the air, suspended by cables attached to five masts that peak 30 to 36 m (100 to 120 ft) from the ground. The masts are inclined at 10 degrees from vertical. Each mast supports several stranded steel cables. As with any suspension structure, displacements of the mast could significantly affect cable length and tension and unfavorably redistribute loads through the superstructure. Consequently, control of foundation settlement was key to the success of this project. Consolidation settlement of stiff silty clay, underlying a medium dense sand layer, was computed to lead to total settlement in excess of the project requirements for the masts. Ground improvement, consisting of triple-fluid jet grouting, was selected to reduce the compressibility of the silty clay, increase the stiffness of the sand deposit and maintain the viability of the shallow foundation system. This case history presents the subsurface conditions at the site, structure and foundation design development and the jet grout ground improvement.

The aim of this paper is to present some case histories where vertical jet grouting solutions were successfully adopted. On these cases ground treatment by vertical jet grouted columns was used as an alternative to traditional solutions on a wide number of scenarios, such as: deep foundations, underpinning, retaining, horizontal sealing slab and cofferdam structures. On each case, the following topics are pointed out: main scenario, geotechnical conditions, main design criteria, main construction issues and main advantages.

This paper summarizes the construction experience of a seismic retrofit project for the Posey and Webster Street Tubes near Oakland, California. The Posey and Webster Street Tubes serve as the main tunnels for the California Route SR 722 along the city streets connecting cities of Alameda and Oakland. The retrofit work consisted, among other things, jet grouting and chemical grouting of the soils supporting the tubes. The primary purpose of the grouting work was to strengthen and densify the soils immediately surrounding the tubes to avoid liquefaction of the soils and loss of support for the tubes during major earthquakes with magnitude of M-7.5 or greater. Some of the criteria used for measurement of success of the work consisted of testing the soils after grouting. The tests included density, unconfined compressive strength field permeability tests and visual inspection of the grouted columns. Several construction difficulties were encountered during jet grouting. This paper summarizes materials, equipment, soil and groundwater conditions, grouting operation, rate of production, costs, and time requirements for jet grouting operation at Posey and Webster Street Tube Joint No. 1. The paper provides a summary of the experience gained from the jet grouting operation and presents conclusions and recommendations useful for similar applications.

As a value engineered, design-build alternate to the original foundation design, an innovative jet grout foundation system was proposed to support various combinations of compressive, uplift and lateral loads of a new selective catalytic reduction (SCR) unit at an operational power plant. Site geology consists of fill over 9 m (30 ft) of clayey silt over dense sand and gravel. Due to the high magnitude of the SCR foundation loads, site geology, and construction access restraints presented by the existing structures and process piping, the original design specified minipiles. The original design also called for thick pile caps requiring extensive excavation support and underpinning of existing foundations. The proposed jet grout solution required reduced drilling, minimum excavation support and less underpinning thereby decreasing construction time and cost. An extensive field-testing program was developed to verify design calculations and assumptions for the jet grout alternate. Testing included a full-scale jet grout column compression test, tension test and in-situ coring. This paper presents a project overview along with a review of geotechnical conditions, the original design, the alternate jet grout foundation system, jet grout design assumptions and the confirmatory testing program.

Subsurface conditions at a power plant in Texas showed an area of soft clay under portions of two major structures that would lead to unacceptable differential settlement doe to consolidation. Instead of supporting the structures on pile foundations, super-jet grouting was used to stiffen the soft clay layer. This foundation option resulted in substantial savings and cut the construction schedule by about 2 weeks.

This case study reports the application of jet grouting as the ground treatment method for the construction of a cigarette factory in Tire Organized Industrial Zone located at the west of Turkey. Total treatment area covers approximately 20000 m² and designed to house a factory building, a two-storey administration building and a utilities building. The project is carried out according to international standards (mainly British) following quality control and quality assurance schemes. The site situated within the Kucuk Menderes alluvial plain, 70 km south-east of the Aegean coastal city of Izmir and classified as being within the 1^st Degree Earthquake Zone (greatest risk category). Stratigraphy of the site was shown to comprise uncontrolled fill overlying alluvial deposits, predominantly micaceous silt with interbedded sandy gravels and clays, overlying colluvial deposits, comprising stiff sandy clays, draped over the steeply dipping bedrock. Alluvial deposit thickness reaches a maximum of 12 m and the groundwater lies at a depth of 4.7 m, below the base of the fill. The maximum design loading for individual factory columns was too large for shallow foundations and hence deep bored pile foundations are implemented for the factory building. However, the slab-on-grades of the factory building and some auxiliary buildings are supported only on jet grout columns. The liquefaction risk beneath all buildings is eliminated by systematic jet grouting design based on specific area ratio reaching down to colluvium layer.

Drainage improvements at O'Hare International Airport, Chicago, IL included the installation of a drainage and storm water system to control the overflow from nearby Willow Higgins Creek. This involved construction of a weir structure at the creek and the channeling of water from the weir to a newly constructed reservoir via three, 3.7-m (12-ft) diameter, underground storm sewer lines. The sewer lines passed beneath an existing, 2.3-m (90-inch) diameter high-pressure water main, which was to remain in service throughout sewer line installation. The soil composition around the water main ranged from medium stiff clays to silty sands and sandy silts. Triple-fluid jet grouting was used to stabilize the variable soil profile beneath the water main in preparation for tunneling and installation of the sewer lines. The varying soil strata presented a challenge to the project team to establish a constant set of jet grouting parameters throughout the stabilized zone while keeping within the specified unconfined compressive strength range for the stabilized zone of 690 to 1380 kPa (100 to 200 psi) at 28 days.

Computer monitoring and analysis of grouting has come of age as a reliable and effective tool for better, faster, and less expensive grouting. This paper traces the development of computer monitoring and control systems, summarizes the benefits that can be realized from use of the systems, and presents the latest developments in specialized technology developed specifically for permeation grouting. Several case history applications of successful use of computer monitoring and analysis are presented. The Penn Forest Project, a new dam construction project in Pennsylvania, was a landmark project in the utilization of computer monitoring technology and is the only large project where full scale, side by side comparison of conventional monitoring techniques and computer monitoring systems is available This project provided clear, quantitative illustration of the many technical and cost benefits that result from computer monitoring. The Patoka Lake Seepage Remediation Project, located in southwestern Indiana, was another vital project in that it was the first grouting project requiring the use of computer monitoring undertaken by the U.S. Army Corps of Engineers (USACE), and in that it has helped set the standards for contracting methods and field application.

A mathematical model to simulate chemical grout injection, grout curtain formation in aiding rational design of chemical grout systems in saturated porous media is proposed. Three-dimensional modular groundwater flow simulation model (MODFLOW) and three-dimensional multi-species reactive transport (RT3D) model are combined and modules for the gelling process are incorporated to simulate the grouting process. The paper investigates the influence of varying degrees of soil heterogeneity and layering on grout barrier formation through numerically generated hydraulic conductivity fields. Layer persistence and range of conductivity can be specified during generation of conductivity fields. Grout barrier performance is assessed by simulation of grout injection in a three-dimensional domain followed by determination of post-grouted conductivity field and calculation of overall grout curtain hydraulic conductivity using a flow model. The simulation results show that spatial variability control the effectiveness of grout curtain performance. About 80–90% of the 25 hydraulic conductivity fields with high variability failed to reach the desired effective hydraulic conductivity.

Grouting has been used for many years as a sealing method for hard jointed rock and the method has been improved in a number of ways, but still there is a lack of parameters relating the sealing effort to the sealing efficiency. The grouting time is therefore here suggested as a parameter, which could be considered to improve the sealing result. It is also suggested that the grouting time is correlated to the rock mass joint system situation, where a long or short grouting time will for different rock mass joint situations mean different design. Both the grouted volume and the grouting time has an influence on the filling of the joint system in the rock mass. The time needed for sealing should be considered especially when the demand on sealing efficiency is high. The effect of grouting time is presented and discussed in some examples.

Passive site stabilization is a new technology proposed for non-disruptive mitigation of liquefaction risk at developed sites susceptible to liquefaction. It is based on the concept of slow injection of stabilizing materials at the edge of a site and delivery of the stabilizer to the target location using the natural or augmented groundwater flow. In this research, a box model was used to investigate the ability to uniformly deliver colloidal silica stabilizer to loose sands using low-head injection wells. Five injection wells were used to deliver stabilizer in a fairly uniform pattern to the loose sand formation. The results will be used lo design centrifuge model tests in which the stabilizer will be delivered in-flight using a robot.

Jet grouting as a "soil-modification" procedure is one of the most controllable injection systems, capable of modifying pre-designed volumes of soil with pre-designed volumes of grout. However, the degree of soil modification achieved is a function of the ratio of jetted grout to original soil and is controlled by many variables like: adjusting jetting pressure and duration, jetted volumes and power of penetration, soil volumes injected per minute, number of nozzles used, nozzle diameters, nozzle positioning and orientation, grout composition, grout viscosity and more. One of the most important if not the most vital check to be performed upon completing any jet grouting operation is the verification that the soil has been actually modified as specified and required by the engineering design. Electrotomography investigations (one of many types of geophysical investigations) coupled with advanced computer software procedures were used to assess the effectiveness, success, extent and quality of jet grouting work performed to provide foundations for new structures. The assessment of the extents of jetting dispersion and of grout permanence capable of effectively increase the load bearing capacity of large pockets of compressible peat and of soft silts were of particular concern. Electrotomography was performed to ascertain and confirm in advance the overall geotechnical characteristics of the soil to be modified by jet grouting; check the physical formation, the final location, the shapes, the interactions and the overall integrity and continuity of a set of jet-grouted columns laid on an equilateral triangular grid pattern as foundations of a new harbor terminal building; assess the final dimensions and the yield at various depths of a number of jet-grouted test columns; and provide tri-dimensional models (constructed by computer data elaboration) visually showing the percentile variations of the resistivity finally achieved by the soil modified by jet grouting.

An electro-kinetic permeation technique for injection of grouting materials into silty soils is introduced in this paper. Preliminary experimental data indicates that it is feasible to inject colloidal silica and silicate grouts into silty soils by means of a dc current. 1-D column experiments and 3-D model tests show that the soil grouted by silicate and colloidal silica by means of electro-osmosis showed significant improvement in strength. For 1-D condition, the grout penetration rate by electro-osmotic injection is about 10^–5 cm/s under an electric gradient of 1v/cm. Typical permeation grout penetration rate by hydraulic means in silty soils is about 10^–5 cm/s or less under a unit hydraulic gradient. Traditional permeation grouting in silty soils would require very high pumping capacity making it cost prohibitive, whereas preliminary bench-scale model tests indicate that electro-osmotic grouting is cost-effective.