Geo-China 2016: Innovative Technologies for Severe Weather and Climate Change

This paper aims to describe two different techniques used to straight reinforced concrete buildings complex in Santos, Brazil, which is composed by two towers. At the end of the year 1998, before the recovery works, Tower A was 2,08m out of the vertical position while Tower B was almost the same. Towers A and B are 57m high. First, a safety assessment analysis was undertaken through a modern computational program. The analysis has shown that the strengthening of the structure of the Tower A was urgent, since the building could be in risk of structural collapse after ten years. The Tower B wasn’t in near risk because Tower B is largest than Tower A. The inclination of these buildings was corrected using different techniques presented in this paper.

The in-situ static load tests of one straight pile with diameter of 1m and one rooted pile with diameter of 1.5m were carried out by piling-up method, and another rooted pile with diameter of 2.5m was tested by Osterberg method. The result showed that no obvious failure feature occurred in Q - s curves of piles tested by piling-up weight method. The axial force attenuation of rooted pile was much faster than straight pile in soil layer where existed roots. The potential of soil could be utilized by roots embedded in pile to improve the vertical bearing capacity of pile. The results could be referred to design and analysis of rooted pile.

Bogotá is located on a high plain (2600m asl) with a soft, highly compressible, plastic clay 250 m thick or more. It is surrounded by 300 m high hills, or higher, and at the foothills the soil profile has soft clay layers of varying thickness. This is a complex type of soil profile, and more often than desired it has resulted on foundation problems for buildings from 2 to 25 stories high. This paper describes the foundation failure due to excessive differential settlements or tilt towards the east, in this case the thicker lacustrine deposit, of a 17 stories high, very rigid concrete wall structure, part of an apartment complex, and the solution. The building is founded on the large piles some of which did not reach the sound clay stone foundation. Once the problem was detected, the structure was underpinned, using micro-piles or root piles to the deeper, sounder soils to support the walls on the eastern area, then an excavation under the footings at the western side was performed to discover the upper 3 m of the foundation piles, which were cut, while the structure was supported on hydraulic jacks and steel bar-pipes, Then the foundation above the piles was lowered 20 cm to its proper horizontal planes. The process is described in detail. Including sophisticated structural and geotechnical instrumentation and very detailed computer finite elements model used. The structure was successfully recuperated and the horizontal plane obtained as predicted by engineers participating.

The micropiles technique plays an important role in ground improvements. This technique can be used effectively in both new and existing buildings to treat foundation problems. Micropiles are often installed in restricted access and limited headroom situations. Micropiles are used in most soils to transfer the building loads to bearing layers. As a result of progress in drilling equipment it has become possible to design and execute micropiles with load capacities in excess of 300 tons and diameters in excess of 25 cm. This research focuses on the feasibility of using micropiles technique in the underpinning of foundations of existing buildings. A site located in Mansoura, Egypt was selected for this study where micropiles were installed to underpin the foundations of a building consisting of 13 floors. There was a significant bidirectional eccentricity caused a nonuniform stress distribution under the raft foundation. In presence of thick soft clay layers a large amount of differential settlement occurred followed by fast sudden tilting of the building. Micropiles were installed in a specific arrangement to transfer that part of the applied load to the sand layer and to reduce the applied stress on the upper clay layers. As a result the overall bearing capacity of both raft and micropiles was significantly increased to an extent enough to accommodate the applied loads safely. To evaluate the micropiles improvement technique both settlement and tilting results were routinely recorded for ten months after installation. The results showed that the settlement has completely stopped and the building has stabilized.

Serious foundation settlement issues occurred for houses constructed on a collapsible alluvial fan in western Colorado. Moisture changes in the soil at multiple residences were measured over a 15 year period. The paper presents data from these long term observations and comments regarding contribution of various sources of water to observed damage.

Performance-based design (PBD) has become increasingly important in recent years, especially for the design of foundations rested on sub-soils that are susceptible to liquefaction at seismically active areas. Shallow foundations may fail due to excessive settlement because of liquefaction of the underlying loose saturated cohesion-less sands. Building codes usually do not address the issue of liquefaction-induced settlement of shallow foundations. In this paper, a framework is proposed for calculating the liquefaction-induced settlement of shallow foundations resting on heterogeneous two-layered liquefiable soil by conducting a series of 3D. hydro-mechanical dynamic analyses in a fully coupled manner employing an advanced constitutive model that can account for anisotropic behavior of sand and effect of soil fabric. After model verification, based on a database gathered from conducting a large number of numerical modelings regarding the behavior of shallow foundations on two-layered soil, in two cases of dense sand over loose sand and vice versa, equations are proposed for calculating the amount of the foundation settlement that occurs due to liquefaction. The proposed equations can be used either for performance-based design of shallow foundations on liquefiable soil strata, or for controlling the settlement of shallow foundations under earthquake that are designed through conventional methods.

The DX pile is a new type of pile which has been adopted to fit the situations of various projects and gets well economic benefits. However, with such advantages, the new developed DX pile was still in the phase of popularization and needs more demonstrated study to provide confidence experience in foundation construction. Based on in-situ practices, this study made comparison of the bearing capacity between DX pile testing method and β method. The results of assessment pointed out that the bearing capacities of DX piles estimated by β method are all less than the actual data obtained from DX pile testing method that came from β method which is more conservative to estimate bearing capacity of the DX pile. Rating at the same size of pile, the DX pile can gain 40% bearing capacity more than the ordinary column piles. With the pile bearing capacity of 470T, this higher bearing capacity of DX pile can reduce the pile diameter ranging from 1.5m to 1m and shorten pile length from 56m to 47.3m; totally save 40% cost approximately.

With the growing trend of urbanization, it has become common practice to construct structures close to each other. This situation may lead to construction of heavily loaded shallow foundation very close to another structure resting on deep foundations. In such cases, the stress zone of the shallow foundation due to heavy load on it would influence the adjacent deep foundations. However, not much published literature is available for the interaction of shallow and deep foundations constructed next to each other. A comprehensive study was carried out by the authors for a similar real life scenario consisting of the construction of a mat foundation adjacent to a group of drilled shafts. They concluded that the drilled shafts will be effected in terms of additional lateral loads and drag forces due to the load on the mat foundation. This paper presents a part of the results of the comprehensive study that shows distribution of horizontal stress and drag forces on the drilled shafts due to heavy load applied on the adjacent mat foundation. Also, the effects of neighboring shafts on the drag forces have been presented.

With agencies facing reduced funding and exponential increases in costs to reconstruct their pavements they are faced with the need to search for alternatives that efficiently extend the effectiveness of their limited resources. This presentation will focus on some of these alternatives with quantifiable data showing the extension of service life and how to get better returns for the investment. The "filling" of cracks in asphalt pavements, has been a maintenance and construction function for many years. Until recent years, the "filling" approach was accepted as a medial maintenance task knowing the value was a short term direction. The question we must ask ourselves today is, "Do we want to "fill" the crack or do we want to "seal" the crack? Not all cracks are the same; consequently, there should be different techniques and materials to address the different requirements.

The dynamic modulus (E*) is the main input to express the influence of climate and traffic speed and loading on hot mix asphalt (HMA) in the Mechanistic-Empirical Pavement Design Guide (MEPDG). However, E* samples’ preparation and testing require extensive time and costly equipment that is not usually available in regular laboratories. Thus, over years researchers developed models for E* predictions. The main purpose of this research is to compare the prediction accuracy of candidate E* predictive models and artificial neural networks (ANNs) model based on laboratory measured E* data. Laboratory E* tests were conducted on 25 Superpave mixes which were recruited from different ongoing construction projects in the Kingdom of Saudi Arabia (KSA). Dynamic shear rheometer tests (DSR) were conducted on the binders contained in the investigated mixes. ANNs trained using the laboratory measured E* data with the same set of parameters used in other popular predictive equations: the modified Witczak and Hirsch models were then used to predict E* values. The ANNs E* predictions using the modified Witczack model set of parameters show higher prediction accuracy compared to the regression models.

This paper presents an investigation into the low temperature performance of epoxy asphalt (EA) binder and mixture. The creep characteristics of EA binder at low temperature were determined by the bending beam rheometer test. The thermal stress restrained specimen test, bending strength test and bending creep test were utilized to characterize the low temperature performance and cracking resistance of EA mixture. Results showed that the low temperature grade of the EA binder is -16°C according to Superpave performance-graded binder specification. EA mixture exhibits approximately elastic behavior at temperatures below 0°C. The EA mixture shows much higher fracture strength and bending strength along with comparable fracture temperature compared to conventional asphalt mixtures.

The aim of this paper is to present the potential for increasing the use of bitumen modified with ground tyre rubber in road construction and discuss the benefits of doing so. The paper seeks to identify any barriers to the increased use of the crumb rubber modified (CRM) binder within the context of Queensland, Australia. Application of ground tyre rubber in asphalt and sprayed seals provides a high value application of recycled material. The available body of knowledge shows that the use of CRM binder in both asphalt and sprayed seals can lead to improved field performance, specifically in terms of durability and cracking resistance. Significant environmental benefits may also be achieved in the form of reduced road noise, reduced CO₂ emissions, and reduced use of non-renewable road construction materials. Laboratory and field testing were conducted as part of this project.

Thermal conductivity is an important material parameter that determines the thermal conditions in pavement and influences cracking, rutting, and fatigue. The test standard (ASTM C177) is not suitable for pavement samples. Research at Arizona State University has developed a test method that uses cylindrical samples to measure thermal conductivity. This paper proposes an improved and simplified ASU laboratory test procedure for measuring the thermal conductivity of pavement material using a cylindrical core sample, including a shorter core sample, a smaller hole drilled in the center, rubber retainers to place thermal couples on the outer face of the core and saturated sand to fill the voids in the inner hole. The test generally requires three hours to reach a steady state of heat flow. This test method is verified by more than 50 samples from four different locations across the United States.

Climate change and environmental pollution pose challenges to the sustainable development of human society. Acid rain phenomenon occurs persistently in Hong Kong, and is one of the major impact factors that may affect asphalt pavement service performance, leading to the reduction in service life. This paper presents the use of an innovative accelerated damage testing machine with acidic solution of different pH values ranging from 3.0 to 7.0 to study the effects of acidic solution on the performance of the asphalt mixtures. The study involves laboratory tests to examine the service performance of the conventional wearing course of asphalt mixtures. The accelerated damage testing machine can effectively simulate the acid rain effects on the asphalt pavement in laboratory under the quality control of using dynamic permanent deformation test and mass loss ratio.

Controlled modulus columns (CMC) ground improvement technique is a novel approach to reduce ground settlement. To install CMC, a rotary displacement auger is used to form a vertical cylindrical cavity, by displacing the surrounding soils laterally, followed by grout injection. While the method reduces spoil generation, excessive lateral soil displacement may damage the adjacent structures and freshly-grouted CMCs. Although there has been growing interest in quantifying such effects, only a handful of studies have been attempted. This paper presents results of a numerical investigation on the CMC installation effect on an existing bridge pile using the three-dimensional finite difference software package FLAC^3D. The bridge pile response to the lateral soil movement induced by the CMC installation are presented and discussed.

This study takes a real-time monitoring system of the Da-Jia River Railway Bridge as the background of research. Historic results and management methods implemented in the real-time monitoring systems of existing railway bridges are reviewed. Improvement methods are proposed addressing external uncertainties sustained by the system itself, such as environment, temperature, slackened nuts, etc., which in turn, gradually cause influence the measured data. The study employs a US patented new compound material — Greenpower, to enclose the instrument mount, replacing the traditional fixing method that uses bolts and nuts, eliminating uneven internal stress in stainless steel plates caused by temperature change which causes reading deviations. The purpose of this study is to avoid the unnecessary miss-repost, provide ameliorative methods, and offer the most accurate, effective and simple management mechanism so that the monitoring system can achieve the disaster prevention and mitigation.

The expander body (EB) technology has been used successfully to increase the pile toe capacity of bored piles in loose to medium dense soil. An important advantage of the EB system is the ability to monitor the EB expansion process, which provides important information regarding soil strength and soil stiffness. This information, obtained for each installed pile, can be used to determine the actual shape and pile toe area. The expansion pressure can be used to design the pile base capacity. The expander body system has been recently improved by incorporating the possibility of post-grouting of the soil below the expanded pile toe. This improvement measure provides additional strength and stiffness to the pile toe and reduces pile settlement. Using a soil displacement auger, which avoids soil decompression and increases lateral soil stress, the shaft bearing capacity can increase, mainly in comparison with the traditional bored piles under bentonite. This paper describes the principle of the EB system and its combination with the full displacement system for the shaft. A high degree of quality control can be achieved by monitoring the entire pile installation process, including the displacement pile and the expander body.

The construction of a new embankment next to bridge abutments founded on pile foundations in soft clay might lead to a time dependent soil–pile interaction caused by soil displacements. If deep founded bridge abutments next to new constructed embankments are loaded by horizontal soil movements, the piles are stressed by heavy shear forces and bending moments and deformations of the abutment may occur, as case studies with many damages have shown. Current design and construction practices of piled bridge abutment bridges have been reviewed and important design parameters have been identified. Very limited design and construction guidelines are available and no unified design procedures exist. This paper focuses on the numerical investigation of the soil-pile interaction considering rate-dependent effects. In this context a variation of relevant factors on time-dependent passive lateral thrust on a single pile, e.g. relative displacement between the pile and the moving ground, cross-sectional shape, surface roughness and the velocity of the moving ground, are investigated.

Bridge designers are often confronted with non-uniform subsurface conditions where extreme variations in ground are present. These are very common in valleys and dry rivers where abutments are placed on rock and middle piers are supported on alluvial deposits. The challenge to the bridge designer is to decide which type of foundation and what depth to adopt in order to achieve an economic and yet safe design. This study highlights a protocol to assist designers to make the most appropriate choice regarding foundation type and depth. A case study of a bridge from south west of Saudi Arabia is considered for this study. A bridge consisting of two carriageways each 15 m wide and 200 m long supported on piers at 20 m spans is considered. The two abutments are elevated 23 m above the bottom of the valley. Twenty two boreholes of 20 to 25 m depth were conducted at different pier and abutment locations. The subsurface profile indicated different formations varying from silty gravel with sand to fragmented Schist and intact rock. The initial suggestion of the geotechnical advisers was to go for 15 m pile foundations to be placed on rock in all supports. It was found that an alternative foundation design can still be feasible with respect to allowable differential settlement and other criteria. Cost analysis was carried out to indicate the amount of savings using this protocol.

Based on the physical and mechanical properties test results of tunnel anchorage′s surrounding rock, geological conditions, mechanical parameter analysis and mechanical parameter selection of the rock; and through the three dimensional elastic-plastic simulation of tunnels anchorage and surrounding rock interaction system, deformation mechanism, failure mode and the safety factor of the surrounding rock have been studied. Research shows that deformation of the tunnel anchorage and plastic zone of the surrounding rock increase obviously with the increase of load. 7 P (P is the design load) is the cut-off point of displacement-load curve and plastic zone size-load curve. It is critical load of the tunnel anchorage, that is to say, the overload safety factor of the tunnel anchorage is 7. Under the condition of overload, the instability failure of anchorage system starts from the shear failure of excavation damage zone, and then the anchorage’s base slab excavation damage zone acts as the bottom sliding surface, plastic zone runs along the anchorage roof arch and sidewall rock through the earth surface. Results of this study can provide theoretical basis for the construction of tunnel anchorage.