Advances in Transportation and Geoenvironmental Systems Using Geosynthetics

This paper presents and analyzes ten large solid waste landfill. Five are unlined or soil lined, and five are lined with one or more geosynthetic materials. The case histories are analyzed by a 3-D computer code adjusting variables (mainly interface shear strength) to arrive at a FS = 1.0. A triggering mechanism, unique to each site, is then applied resulting in a FS < 1.0. The same variables and triggering mechanisms are then used in a 2-D computer code with FS-values further decreasing by different amounts. The ratio of 3-D to 2-D factors-of-safety is called a wedge factor. Conclusions reached are as follows: (1) Interface shear strengths are the overriding considerations in varying FS-values. Accurate determination cannot be overemphasized. (2) The triggering mechanisms were all liquid related, i.e., leachate buildup within the waste mass, wet clay beneath the geomembrane, or excessively wet foundation soil. (3) The average wedge factor of all case histories without, then with, the triggering mechanisms is 1.24.

Results of 72 UU and CU direct shear tests on kaolin clay interfaces with two geosynthetic materials are presented. Tested are conducted using smooth High Density Polyethylene (HDPE) and textured HDPE geomembranes. Each interface is tested under four normal stresses: 25, 100, 250, and 500 kPa. The effects of compaction moisture content and pre-shear compression/consolidation conditions on the interface properties are investigated. A discussion on fundamental aspects related to interface shear strength and efficiency is presented. Results indicated that an increase in the clay compaction moisture content leads to a decrease in the shear strength of the sheared as-compacted interfaces. The overall efficiency of the clay/textured HDPE interface is approximately 1 when tested under UU condition, indicating that failure plane is passing through the clay particles. Under CU condition, the pre-shearing compression/consolidation process allowed interlocking between the clay particles and the geomembrane's texturing. Such interlocking yielded an interface efficiency higher than 1 (interface efficiency is defined as the ratio of the interface shear strength to the clay shear strength at the same testing conditions.) In CU tests, and for saturated and wet of optimum compacted kaolin/ textured HDPE, an increase in the shear strength of the interface and in the overall efficiency is estimated due to an increase in the length of the failure path along which shearing takes place.

A series of gas permeability tests were performed on partially saturated needle punched and stitch bonded geosynthetic clay liners (GCLs) with nitrogen (N₂) as the gas permeant fluid. The results of this investigation highlighted the influence of the water content and the hydration process on the gas flow kinetics through geosynthetic clay liners. For the GCLs and conditions examined, it was found that the intrinsic permeability and permittivity decreased as the moisture content increased. The presence of a surcharge seemed to reduce gas flow through GCLs at moisture contents higher than around 50 %, however, below this value the surcharge had no effect. Furthermore, it was found that the stitch bonded GCL led to higher gas permeability than the needle-punched material.

The case study presented in this paper concerns the performance of an existing contaminated soils landfill site lined with a double geomembrane system. The main steps of the case study were: 1) perform a complete characterization of the natural soil layer underlying the site; 2) design an effective groundwater flow model; 3) calibrate the model based on field data; 4) use a contaminant transport model considering various pessimistic scenarios in order to assess the performance of the lining system. The results show that the lining system performs as required and that the risk of contaminant migration is negligible. The excellent hydrogeological conditions of the site play an important role in this performance.

Vertical barrier walls backfilled with soil, bentonite, and/or cement are used to control lateral migration of contamination plumes in geoenvironmental applications. The effectiveness of such barriers can be enhanced by orders of magnitude with a geomembrane placed within or adjacent to the soil/bentonite, soil/cement, or other component to form a composite system in the same manner as with a composite landfill liner or cover. This paper discusses methods of installing geomembranes, contrasts geomembrane walls with other types of barriers, provides information on quality assurance procedures, and presents a ranking matrix of economic and environmental benefit/cost. The paper also discusses the efficiency of using a geomembrane for (i) a flawlessly constructed, (ii) a typically constructed, and (iii) a poorly constructed, traditionally backfilled vertical wall. This is followed by a review of selected installations and their performance, and some generalized conclusions.

This paper describes the use of geosynthetics at two remote mine sites; one in the Andes Mountains of Chile, South America and the other in the Rocky Mountains of Colorado, United States. In Chile, a test pad was at gold mill processing facility a geomembrane was used to line the face of a tailings impoundment rock-filled dam to control seepage. A test pad was constructed at the site during construction to determine if an on-site alluvium deposit of coarse-grained soil, with cobbles up to 5 cm in size, would puncture through a geotextile cushion and into the geomembrane. In Colorado, tailings from a mill that produced lead concentrates during the mid 1900's were being capped using a Geosynthetic Clay Liner (GCL) buried under a soil layer to reduce infiltration. During the construction, the contractor proposed a method to place cover soils that would require 75-ton loaded scrapers to travel over the buried GCL on a 3H: 1V (3 horizontal and 1 vertical) slope. A full-scale test pad was constructed at this site to determine if the loaded scrapers would damage the underlying GCL. The paper describes how the test pads were constructed, what materials were used, and how they were loaded. After loading, the geosynthetics were exhumed to determine if damage occurred and if they could be used for the full-scale construction. In both test pads, the geosynthetics performed well and without evidence of significant damage. In each case, geosynthetics were used successfully to complete both mine projects.

The Cylinder Direct Shear is a new test method that has been developed for determining large displacement interfacial shear strengths of geosynthetics. The significance of the new test method is that many geosynthetics interfaces lose shear strength with increasing displacement. The new method is patented and is designed around the current 0.3-m (12-inch) direct shear per ASTM D-5321. It consists of testing the geosynthetic interface mounted on a cylinder instead of on a flat plate. The Cylinder Direct Shear has one geosynthetic mounted on the surface of the rigid cylinder and the second geosynthetic anchored to a stationary anchor bar and contained within a latex rubber membrane. The test assembly is mounted within a pressure chamber and a normal force is applied using the chamber pressure acting on the latex rubber membrane. Friction resistance is measured by recording the torque to rotate the cylinder while the normal force is applied and displacement is determined by measuring the rotation of the cylinder relative to the stationary anchor bar. Comparable results have been obtained using the same geosynthetic interfaces at similar displacements when compared with current 0.3-m direct shear testing. The primary difference of the Cylinder Direct Shear with the 0.3-m direct shear has been the ability to measure interface shear strengths using continuous unlimited displacement testing in the machine direction to displacements far beyond the 7.5 to 10 cm limitation of the current 0.3-m direct shear. Interface shear strengths of geosynthetics have been measured at displacements in excess of 6 m using the Cylinder Direct Shear Test.

An evaluation of leachate compatibility was performed to determine if site leachate would have a detrimental impact on the performance of a clay component of a lining system for a proposed tailings impoundment. A Geosynthetic Clay Liner (GCL) is proposed for incorporation in the lining system as part of a upper liner composite (1.5 mm [60 mil] High Density Polyethylene [HDPE] geomembrane and GCL) to be placed over a drainage layer (geonet and geotextile composite) and lower liner composed of 60 mil HDPE geomembrane. Clay soil from three GCL products were laboratory tested for compatibility with the site leachate. The leachate was obtained from an existing tailings pond and has Total Dissolved Solids (TDS) of 11,500 mg/l, a pH of about 8, and elevated Levels of chloride (4,800 mg/l), sodium (2,900 mg/l), calcium (450 mg/l), sulfate (100 mg/l), strontium (150 mg/l), magnesium (120 mg/l), and potassium (43 mg/l). GCLs and/or soil samples were obtained from two manufacturers. One manufacturer supplied a standard bentonite product with clay sandwiched between a woven and nonwoven geotextile, and they also supplied a contaminant resistant clay (soil only). The other manufacturer provided bentonite soil with a higher calcium to sodium ratio than is commonly used in GCL products (soil only provided as commercial product was not available). An index test program was conducted to evaluate if site leachate would have an impact on clay soil properties. The objective of the index tests was to provide an indicator to performance of the products when exposed to leachate and to assess the need for complete hydraulic conductivity testing of specimens in the future. The index testing program included grain size distribution (by hydrometer ASTM D 422), Atterberg limits using de-ionized water and site leachate, free swell using de-ionized water and site leachate, and fluid loss of clay using de-ionized water and site leachate. Index tests did not correlate well with hydraulic conductivity when all samples were considered together. However, when tests for the same material type where tested in de- ionized water or leachate, the changes in the index test did correlate with the hydraulic conductivity results. After completion of the index tests, samples were subjected to hydraulic conductivity testing using ASTM D 5084 procedures. Replicate samples of the standard bentonite and contaminant resistant bentonite were initially hydrated in de-ionized water and permeated in leachate. Additionally, replicate samples of all three products (standard bentonite, contaminant resistant bentonite, and high calcium bentonite) were initially hydrated in leachate and subsequently permeated with leachate. Testing was conducted for at least 7 pore volumes or until unacceptable hydraulic conductivity values were obtained. Test results showed that the hydraulic conductivity varied from their initial values through time for all samples. The hydraulic conductivity of the high calcium clay decreased as test duration increased (from 4 x 10^–8 to 1 x 10^–8 cm/s). Other samples exhibited slight to significant increase in hydraulic conductivity with time (from nearly zero change to 2 orders of magnitude).

Permanent and temporary soil nail walls are gaining wide spread acceptance as a cost-effective subsurface soil retention system. Conventional soil nail wall designs generally include geocomposite drain boards behind the soil nail wall to drain subsurface water and dissipate hydrostatic pressures behind the wall. It is the authors experience that the design and installation of these geocomposite drain boards is based on local experience and practice with little consideration given to the actual conditions under which the drains will be required to perform. The current FHWA manual on the design and construction of soil nail walls provides limited technical discussion on the design of these geocomposite drain boards. However, similar drainage elements used as pavement edge drains have received attention lately with some failure case histories documented. The performance of these geocomposite drain boards is critical to the performance of the soil nail wall since it is assumed that these elements dissipate any hydrostatic pressures behind the wall. Unaccounted hydrostatic pressures behind the wall could lead to distress of the wall and the need for costly remedial efforts. This paper will present a discussion of the key design and installation considerations relevant to these geocomposite drain boards.

Along the boundary between the cities of Hong Kong and Shenzhen in southern China, the 28 km long, meandering Shenzhen River has intermittently caused serious flood damages. In order to reduce the risk of flooding to downtown Shenzhen and northern New Territories of Hong Kong, and to enhance the navigational potential of the river, regulation works were commenced in 1995. These works — including realignment, widening, deepening and embanking 18 km of the river — are scheduled for completion by 2005. On the Hong Kong side, about 10 km of flood protection embankments have been constructed on soft muds of thickness up to 12 m. Basal reinforcement with woven geotextiles was used to enhance the stability of the embankments and vertical prefabricated drains were installed to accelerate the consolidation of the muds. An extensive network of geotechnical instruments was also set up to monitor the performance of the embankments. This paper describes the engineering properties of the soft mud and presents the design and construction of the geosynthetically enhanced embankments. Typical monitoring results are given and the performance of the embankments is discussed.

Geotextiles have been extensively used in hydraulic structures as revetment filters subjected to wave loads. The alternating flow through the geotextile creates a flow regime very different from the uni-directional flow condition that has been extensively studied. The stability of the revetment system depends on many factors, such as the hydraulic properties of geotextile, the initial placement condition and particle size distribution of the subsoil, and the intensity of the wave loads. A new laboratory apparatus has been used to investigate the influence of the hydraulic conditions on the behavior of soil-geotextile interaction and the stability of the revetment system. One series of tests has been conducted simulating cyclic flow conditions normal to the soil-geotextile interface. Preliminary test results are presented and discussed in this paper.

This paper addresses the differences in the extent of clogging associated with fine particle transport in soils and geotextiles. A common experimental set-up was designed for soil and geotextile filtration. Tests were conducted using a nonwoven, needle-punched geotextile filter sample permeated with fine particle suspensions under constant flow rate. The results were compared with those from similar experiments using soil filters. Geotextile clogging was modeled using an extension of a soil-clogging model. The experimental results assisted in the evaluation of the critical velocity of particle deposition in geotextiles. Comparisons were made between the soil and geotextile clogging models for a better understanding of the clogging mechanisms. It is estimated that the critical velocity for geotextiles is on the order of 10^–3 cm/sec, considerably less than the corresponding value for filter soils (10^–1 cm/sec). Comparison between soil and geotextile filters shows the geotextile provides a better filtration function without excessive clogging for the same types and sizes of particle concentrations. The modeling simulation showed that both particle numbers and sizes should be considered instead of mass-based concentrations alone in order to estimate the extent of physical clogging.

Geotextiles are widely used in coastal revetment work as a separator and a filter between the base soil and the armor stones. In order for them to function properly as hydraulic filters in coastal revetments, they must first be able to survive the construction process. The tensile strength and mass of geotextiles are often specified to meet the survivability requirements. But these parameters do not necessarily reflect the puncture resistance characteristics of the geotextiles. Hence, there is a need to understand the performance of these geotextiles in meeting the survivability requirements and to quantify the puncture resistance of geotextiles more confidently. An extensive field drop-test was recently completed in Singapore to study the puncture resistance of geotextiles. This field test comprised 784 controlled drop-tests using a standardized drop block released from heights ranging from 0.5m to 2.5m. Five different geotextiles (two woven and three non-woven) were tested, including three new double layer geotextiles. The drop tests were conducted for geotextiles laid over different soil conditions, with varying thickness of secondary armor stones. Both horizontal and sloping grounds were used. The extent of damage on the geotextiles was assessed based on statistical interpretation of a large number of drop-tests, taking into account the number and size of the punctures. The field test seeks to provide some standardization in conducting field drop test and evaluating the puncture resistance of geotextiles in the field. Results of the field test were compared with standard index tests currently in use. It was found that existing index tests, like the CBR test and tensile strength test, do not adequately reflect the geotextiles' ability to resist puncture and tear. However, results suggest that the puncture resistance of the geotextile can be evaluated reliably by the Energy Level of the geotextile.

The paper is focussed on the preliminary results of a program of full scale tests of geosynthetic reinforced retaining walls carried out by the Geotechnical Research Group at the Royal Military College of Canada (RMCC). The long term research program involves the construction of 10 walls. The paper describes the test program, some instrumentation details and presents selected results from the first four walls completed to date. Three of the walls were constructed with a column of dry-stacked modular concrete units and one nominal identical wall was constructed with a wrapped-face. All of the structures were surcharge loaded to stress levels well in excess of working load conditions. The data gathered from this program has been useful to identify important performance features of the reinforced soil structures and to identify possible sources of conservatism in current methods of analysis for geosynthetic reinforced soil structures in North America. The high quality data will also prove useful for calibration of numerical models.

This paper describes a unique field application in which a geosynthetic-reinforced soil system was designed and constructed to support both the foundation of a two-span bridge and the approaching roadway structure. The reinforced soil system not only provides bridge support, but it was also designed to alleviate the common bridge bump problem. This structure was considered experimental and comprehensive material testing and instrumentation programs were conducted. These programs would allow assessment of the overall structure performance and evaluation of CDOT and AASHTO design assumptions and procedures for reinforced soil structures supporting both bridge foundations and approaching roadway structures. Large-size direct shear and triaxial tests were conducted to determine representative shear strength properties and constitutive relations of the gravelly backfill used for construction. Three sections were instrumented to provide information on external movements, internal soil stresses, geogrid strains, and moisture content during various construction stages and after the structure opening to traffic. Results from a pilot (Phase I) instrumentation program and some preliminary results from a more comprehensive (Phase II) instrumentation program are presented in the paper. The results suggest that current design procedures lead to a conservative estimation of both the backfill material strength and horizontal earth pressures, and that the overall performance of this structure, before its opening to traffic, has been satisfactory.

Development of a new master planned community in a seismically active area required a 14.9 m high retaining wall to be constructed. The segmental retaining wall option was chosen based on economics, while the installation contractor and materials incorporated in the wall were chosen for their past performance and familiarity to the local regulatory agency. The design was developed using National Concrete Masonry (NCMA) methods. Construction procedures and details of monitoring are discussed. Post construction movements are provided for vertical and horizontal wall deformations. In addition, movements resulting from the October 1999 Hector Mine earthquake are documented. Monitoring of the wall will continue in anticipation of capturing the effect of additional seismic events.

This work presents the behaviour of geogrid reinforced bridge abutments in the BR-101 highway, in the state of Santa Catarina, Brazil. Unidirectional geogrid layers were used as reinforcement for the embankments. A coarse sand was employed as fill material and the foundation layer consisted of an organic soft clay. Because of the nature of the foundation soil and the proximity of existing structures, geotechnical instrumentation was installed to assess the reinforced structure displacements. The results showed that the presence of the reinforcement layers reduced the soft soil lateral displacements and the damages to the existing structures. A preliminary stability analysis of one of the abutments is also presented and discussed.

A vertical retaining wall. was constructed by reinforcing the backfill with two different types of geogrids. Reinforcements were instrumented with strain gauges, tensile load transducers, horizontal displacements sensors and total pressure transducers. The structure was monitored over a period of about 16,000 hours, starting from the early phase of construction until failure, which was induced by surcharging the wall with backfill. The collected data on soil stress, strain and displacement along reinforcements have been compared with the results of finite element analysis and conventional limit equilibrium design method. Depending on the reinforcement, the failure mechanisms have been identified.

The Jefferson County Department of Highways and Transportation recently constructed a 670 m (2,200-foot) long extension of Coal Mine Avenue in Jefferson County, Colorado. The roadway extension crosses over the Economy Mine, an abandoned coal mine located between 38 and 52 m (125 and 170 feet) below the ground surface. Existing sinkholes in the immediate vicinity of the Mine and above nearby mines in similar geologic conditions created substantial concern for the safety of motorists on the roadway. To reduce the risk, a structural concrete slab was designed and constructed to bridge potential sinkholes. This paper reviews geologic and mine conditions, and presents mitigation alternatives evaluated and design of the slab.

A 213-meter (700-foot) long soft subgrade section was built under a railroad test track at the Federal Railroad Administration's Transportation Technology Center (TTC), Pueblo, Colorado, to characterize soft subgrade deformations and to test various remedies for the heavy axle load environment. The test track is a 4.3-km (2.7-mile) loop and is used to test various track components under heavy axle freight trains (346 kN or 39-ton axle loads). The type of soil placed in the subgrade is Vicksburg "Buckshot" clay and has an average moisture content of 33 percent (10 percent above the optimum moisture content). Each year, approximately 100 MGT (million gross tons) of traffic is operated on the test track. To date, the following remedy techniques have been or are being tested, including increasing the granular layer thickness, geocell reinforcement and asphalt trackbed stabilization.

Mechanical stabilized earth (MSE) walls are often used in military and civilian applications to protect personnel and property from accidental detonation of stored explosives, munitions, and ammunition plants. The advantages of geosynthetics reinforced soil and Reinforced Earth® structures lie in their cost-effectiveness, rapid construction, and minimization of occupied ground area and high tolerance of differential settlements. Concrete faced Reinforced Earth® structure has very presentable concrete facing and was found to be able to withstand base shaking arising from earthquake. For protection against blast, geosynthetics reinforced soil walls are able to impede the propagation of a blast at ground level and absorb high levels of energy due to their tolerance for deformation before collapse. In using geosynthetics as facings and reinforcements, the reinforced soil structures not only can absorb fragments from cased weapon explosion, but they also do not suffer brittle fracture like concrete after blasting. Hence they minimize the dispersal of debris and are resistant to multiple blasting. A geosynthetics reinforced soil (RS) wall and a Reinforced Earth® (RE) wall with precast concrete facings were constructed and subjected to multiple blasts and their extent of damage was recorded and studied. After a series of blasts, the concrete facings in front of the RE wall collapsed and the soil mass slid down to the front. There were obvious pullout failures of the metal reinforcement strips as well as tension failure at the joints of the panel facings and reinforcements. However, the geosynthetics facing of the RS wall only suffered superficial damage due to high temperature and direct impact of fragments. Acknowledging the differences in failure modes of RS and RE walls under blast loading, it was obvious that geosynthetics reinforced soil walls with flexible geosynthetics wrapped around type of facing can be effectively used for blast resistant soil structures in military applications.

US national design guidelines distinguish between slopes and walls using the face angle as an arbitrary criterion. Angles less than 70° render reinforced slopes whereas steeper angles render reinforced walls. While the expected performance of reinforced walls and slopes may be different, the basic stability analyses should be the same. However, because of historical reasons, the evolution of design for either type of structure followed a different path. As a result, the outcome of analyzing a particular reinforced soil structure will be different when slope stability analysis or wall analysis are employed. This disagreement exists even near 70° where the two structures are basically classified as either walls or slopes. In fact, current slope stability approach yields much more conservative designs as compared with wall analysis. This is contrary to performance expectations that are normally stricter for reinforced walls. This paper suggests a basic step linking the two ‘types' of structures. Historical evolution of designs produced a non-rational difference in the definition of the factor of safety used in geosynthetic-reinforced walls and slopes. It is suggested to use the same definition; this definition has proven to yield safe wall structures for three decades. Parametric studies indicate that use of the ‘new' factor of safety in slopes may result in significant reduction of required strength and length. That is, strength may be reduced by a factor of two or more while length may be reduced by 30% or much more.

Reinforced soil structures are typically analyzed for stability using limit equilibrium calculations. Results from such analyses are sometimes ambiguous because of different assumptions made in addition to the presumption of the limit state. These ambiguities can be removed if the kinematic approach of limit analysis is used, in which a rigorous bound to a limit load, or a bound to the required strength of reinforcement, is sought. The required strength of reinforcement is the strength needed to maintain stability of the structure. The kinematic approach involves calculations of work dissipation in the soil and reinforcement as two separate terms in the energy balance equation. An alternative method includes description of reinforced soil as an anisotropic continuum. Because limit analysis provides a rigorous bound to the reinforcement strength, limit loads, or a safety factor, the geometry of the failure mechanisms considered can be optimized, so that the best bound is obtained (a solution closest to the exact solution). Considerations can be extended to calculations of critical accelerations of reinforced slopes subjected to seismic loads. Also, permanent displacements can be calculated using limit analysis with rigid-block time integration. Some fundamental aspects of plasticity-based analyses of reinforced soil will be discussed.

A new geogrid made of separate straps, welded together at the connections using a laser welding technique has been developed after years of intensive research. The newly developed and patented welding system is described in this paper. It allows the highly stretched and oriented straps to be welded together without losing the orientation of the molecules in the welded area. This is very important because otherwise a change of material properties will occur which will influence the long term strength and creep of the material. Further it results in very efficient use of material and therefore in a cost-effective material. The new geogrid combines the strong properties of stiff grids with the advantages of flexible geogrids and can be made of various polymers. In this way the most suited polymer can be selected to fulfil the required properties in the application. Further the welding technique results in rigid connections between the straps. PET straps are used for long term applications as slope reinforcement; PP straps for applications with short term strength requirements such as road reinforcement. The results of various index tests and long-term performance tests like creep, mechanical damage and pull-out are shown. The long-term tensile strength (T_al) is calculated using the method described in FHWA-SA-96-071.

The paper discusses a three-part method for the evaluation of the pullout capacity of a segmental retaining wall (SRW) unit and geosynthetic reinforcement. The method described herein evaluates the connection capacity of a) the SRW/Geosynthetic system, b) the material properties connection strength, and c) the sustained load or long-term connection strength. The method applies to both frictional and mechanical connections. Because the method includes evaluation of both system (short-term and long term) connection strengths and material strength properties, the 19-mm (3/4-inch) deformation criterion is not necessary.

Unpaved roads built over soft, weak subgrade have been used extensively in the Southeast Asian region as temporary site access roads, forest roads and low volume roads. In Singapore, unpaved roads are often preferred in military training areas for better concealment. Vehicular traffic on unpaved roads will cause the base layer and subgrade to deform vertically and laterally. In addition, stones will get pushed into the subgrade and pumping of fines into the base layer will occur under wet conditions, as there is no separation between the base material and weak subgrade. To stabilise unpaved roads, geosynthetics have been successfully used to improve the overall stability and trafficability of these roads. Geosynthetics placed at the interface between the base layer and the subgrade function as a separator as well as a reinforcement to improve the performance of weak subgrade. This paper presented the performance of geosynthetics in the stabilisation of unpaved roads in a laboratory model-tracking test. The effect of anchoring and pretensioning of geosynthetics would be examined. Six laboratory-tracking tests had been carried out for this purpose: one control test, three composite geotextile tests (un-anchored, anchored and with pre-tensioning) and two geogrid tests (un-anchored and anchored). During loading, subgrade settlement of each test was carefully monitored. To evaluate the performance of each stabilisation system, rut and heave resistance of each test were evaluated and compared to the performance of the control test.

An interesting failure involving geosynthetic basal reinforcement for embankments constructed on soft soil occurred at the Fresh Kills Landfill located on Staten Island, New York. The failure occurred in two stages, in May 1997 and April 1998, respectively. In this study, an attempt has been made to model the embankment from this case history using finite differenc software — FLAC (Fast Lagrangian Analysis of Continua, Itasca Consulting Group, 1996). The goal of such a study is to develop the Finite Difference model as an approximate design tool for future reinforced embankments. FLAC is a two-dimensional finite-difference code that uses an explicit time-marching method to solve governing field equations. The paper presents the results of such an analysis and compares them to the field results. Various stages of construction are simulated by applying different model loading conditions at different stages of the analysis. The development of excess pore water pressures with staged construction are captured by using the undrained mode of analysis. The limits of failure and zone of movement are found to be strikingly similar to the field observations. It is expected that the proposed research will contribute to the state of the art of analyzing and designing embankments reinforced with geosynthetics in basal layers.