Dov Leshchinsky's research while affiliated with University of Delaware and other places

Publications (166)

Conference Paper
Full-text available
This paper presents the findings of an experimental study conducted to define the boundary conditions of composite behavior of Geosynthetic Mechanically Stabilized Earth (GMSE) bridge abutments. The study involved the development of a new soil-geosynthetic interaction device capable of generating data required to assess the mechanical interactions...
Article
This paper presents and interprets experimental results of soil–reinforcement interaction tests conducted using a new device developed to assess the mechanical interaction among neighboring reinforcements in geosynthetic-reinforced soil masses. Testing involved a soil mass reinforced using three reinforcement layers, one of which was actively tensi...
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This paper presents and interprets experimental results of soil–reinforcement interaction tests conducted using a new device developed to assess the mechanical interaction among neighboring reinforcements in geosynthetic-reinforced soil masses. Testing involved a soil mass reinforced using three reinforcement layers, one of which was actively tensi...
Conference Paper
Full-text available
Current design criteria for geosynthetic-reinforced soil walls are generally based on factored load and resistance norms, for both internal and external stability analyses, which refer to the ultimate limit state. The serviceability limit state is generally overlooked in the design of geosynthetic-reinforced soil walls, especially for those with fa...
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This study evaluated the responses of geosynthetic-reinforced soil (GRS) abutments subjected to bridge slab loading under working stress conditions using two-dimensional finite difference numerical software. A parametric study was conducted to investigate the effects of different combinations of reinforcement spacing Sv and reinforcement stiffness...
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This study presents an evaluation of the connection load (To) and stress-strain conditions right behind the facing of a Geosynthetic Reinforced Soil-Integrated Bridge Structure (GRS-IBS) based on field instrumentation data obtained from an abutment constructed in Virginia. The observations from this site are compared against other projects in Delaw...
Article
This paper presents a case study of a geosynthetic-reinforced soil (GRS) integrated bridge system (IBS) in which the vertical stresses during and after construction were monitored via instrumentation. The purpose of the study was to evaluate the effects of reinforcement spacing, width of the beam seat, and seasonal variations on the vertical stress...
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This paper presents, evaluates, and discusses experimental results of soil–reinforcement interaction tests conducted using a new device developed to assess the mechanical interaction between soil and reinforcement considering varying reinforcement vertical spacings. The experiments involved testing a geosynthetic-reinforced soil mass with three rei...
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This paper develops an analysis procedure for turning corner in Geosynthetic-Reinforced Soil Structures (GRSS's). The procedure includes the calculations of the required strength and length of the reinforcement for internal stability. The calculations are based on the variational limit equilibrium analysis of three-dimensional (3D) stability of slo...
Article
A new device was developed to comprehensively assess the interaction between soil and reinforcement as well as the interaction between neighboring reinforcement layers in a reinforced soil mass, under both working and ultimate interface shear stress conditions. An understanding of these two interactions is required to assess the mechanical behavior...
Article
In this study, both two-dimensional (2D) and three-dimensional (3D) numerical analyses were carried out to evaluate the performance of geosynthetic-reinforced soil (GRS) piers. The numerical models were first calibrated and verified against test results available in the literature. A parametric study was then conducted under both 2D and 3D conditio...
Article
Full-text available
Traditionally, application of the conventional logarithmic spiral in limit equilibrium (LE) analyses has been limited to homogenous materials. Herein, a modification of the conventional logarithmic spiral LE approach is proposed to account for transitions in soil conditions and provide insight into the internal statics associated with this approach...
Article
Current design procedures of Geosynthetic-Reinforced Soil Structures (GRSS's) are for walls/slopes with long straight alignments. When two GRSS segments intersect, an abrupt change in the alignment forms a turning corner. Experience indicate potential instability problems occurring at corners. The purpose of this study is to explore the effects of...
Article
Slopes forming convex corners are often constructed in practice. Observed failures of such corners possess three-dimensional (3D) characteristics. Hence, assessing corner stability requires 3D analysis. This study used a variationally derived 3D mechanism to analyze the stability of convex turning corners. Results of 3D stability analysis are prese...
Article
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Geosynthetic-reinforced retaining (GRR) walls typically have vertical reinforcement spacing of 0.6 m, and this relatively large spacing has been known to cause comparatively high connection forces. To reduce this connection force, short geosynthetic reinforcement layers (referred to as secondary reinforcement layers) are installed between blocks wh...
Article
Geosynthetic reinforced soil integrated bridge system (GRS-IBS) design guidelines recommend the use of a reinforced soil foundation (RSF) to support the dead loads that are applied by the reinforced soil abutment and bridge superstructure, as well as any live loads that are applied by traffic on the bridge or abutment. The RSF is composed of high-q...
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The paper describes numerical models that were developed to simulate the performance of two instrumented mechanically stabilized earth walls constructed in Izmir, Turkey. These walls were constructed with gabion facing, hybrid reinforcement layers, and fill on a rigid foundation. The hybrid reinforcement layers comprised primary reinforcement (geog...
Conference Paper
Geosynthetics have been extensively used to reinforce soil structures, such as embankments, slopes, walls, foundations and roads. Proper evaluation of the interaction between geosynthetic reinforcement and backfill is important to understand the mechanisms of geosynthetic-reinforced soil (GRS) structures. Pullout tests have proven to be an effectiv...
Conference Paper
Full-text available
While significant emphasis has been placed in the technical literature on the interaction between soil backfill and geosynthetic reinforcement, companion phenomena that may develop in a reinforced soil mass due to reinforcement vertical spacing may have been overlooked. This paper integrates the results of experimental and field evaluations aimed a...
Article
Full-text available
Geocells, one type of geosynthetics manufactured in a form of three-dimensional interconnected cells, have been reported to effectively provide lateral confinement to infill material to increase the modulus and bearing capacity of base courses. Most studies so far have been focused on the behavior of geocell-reinforced bases under static loading. G...
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This paper revisits the variational limit equilibrium (LE) analysis of three-dimensional (3D) slope stability in the context of limit analysis (LA). It proves the kinematic admissibility of the 3D mechanism in LA, although it was derived from LE variational extremization. It also includes algorithms in the realm of LA that are associated with the v...
Article
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With a suction stress-based effective stress representation, stability analysis of unsaturated engineered and natural slopes can be performed effectively in the same manner as the classical limit-equilibrium (LE) methodologies. This paper presents an analytical framework for effective stress LE analysis of unsaturated homogeneous slopes under stead...
Conference Paper
Several reinforced soil retaining walls of height 15.3 m were modeled in the Columbia University centrifuge under an acceleration field of 50-g. Nevada sand was used as backfill material and gabion blocks were used as wall facing to replicate the wire mesh system. A fiber glass mesh of length 35 cm was used to model the reinforcement layers having...
Article
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This study presents a methodology to determine the stability and optimal profile for slopes with concave cross section under static and seismic conditions. Concave profiles are observed in some natural slopes suggesting that such geometry is a more stable configuration. In this study, the profile of a concave slope was idealized by a circular arc d...
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This paper presents a new method to determine the optimal profile of facing elements in geosyntheticreinforced soil structures. Flexibility of some facing systems and advances in construction technology allow construction of reinforced soil structures with a non-planar cross section. In this study, the facing profile of a concave geosynthetic-reinf...
Article
The common procedures for stability analysis of slurry-supported trenches are typically two-dimensional (plane strain), despite the fact that observed failures in the field possess three-dimensional (3D) characteristics. A limit equilibrium (LE) solution for the stability of a slurry-supported trench is presented, where failures are constrained to...
Article
This paper presents a variational limit equilibrium closed-form solution for the stability of slurry-supported trenches in cohesive soil, frictional cohesive soil, and cohesionless soil. Study results indicate that the critical slip-surface geometry is either planar or log spiral. The normal stress distribution, which indicates the likely depth of...
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Several design guidelines adopt limit state methods (e.g., earth pressure or limit equilibrium slope stability methods) to estimate the reinforcement loads for Geosynthetic-Reinforced Soil Structures (GRSSs). Field measurements usually reveal lower tensile loads in the reinforcements than that predicted by conventional design methods. Consequently,...
Article
A wall of mechanically stabilized earth (MSE) with large concrete panel facing, reinforced with polyester straps, is an emerging technology in the United States. To enable the design of this wall system through AASHTO's methodology, the system's classification of extensibility must be established. Therefore, a section of such a wall was instrumente...
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Design and construction of geosynthetic reinforced simple slopes are a common practice. These types of slope commonly use a single inclination, termed a linear slope. Design of linear slopes is frequently done using limit equilibrium (LE) analysis. The scenario of two tiered slopes, one with a vertical upper tier and another with an inclined lower...
Conference Paper
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In its 2012 edition, AASHTO has made radical changes in the seismic design of MSE walls. The most notable change allows, under some broad conditions, an exemption from seismic design. This exemption is applicable to a rather large seismic acceleration of 0.4g. The objective of this work is to examine whether a statically acceptable design will inde...
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Introduced is a unified limit state design framework for geosynthetic-reinforced slopes and walls. It is demonstrated that limit state design is an essential step in design even though the usual perception is that the performance of such structures is “better than expected.” A brief critical overview of commonly available analysis methods is presen...
Article
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This paper calculates the thrust of lateral earth pressures exerted by unstable slopes comprised of c-phi soil and subjected to seismic (pseudostatic) loading conditions. Although the proposed method can be used for seismic stability analysis of geosynthetic-reinforced earth structures (GRESs), the formulation and results are also applicable to man...
Conference Paper
Full-text available
External stability analysis of geosynthetic-reinforced earth structures (GRESs) under seismic loading conditions requires calculation of the total (i.e., static and seismic) thrust acting on the retained soil mass. The total thrust is used to assess sliding and eccentricity of the earth structure. Current guidelines for seismic design of GRESs reco...
Article
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A majority of the existing analytical approaches for displacement-based seismic design of geosynthetic-reinforced earth structures (GRESs) have been developed by considering only a translational mode of failure (external sliding stability), and consequently do not provide a means for assessing the seismic displacement of GRESs due to rotational mov...
Conference Paper
Full-text available
Design codes have recently recognized the need for using a displacement-based methodology for the seismic design of geosynthetic-reinforced earth structures (GRES), particularly when designing these structures for strong seismic events (e.g., PGA > 0.3 g). This paper illustrates the application of a recently-developed analytical-numerical framework...
Conference Paper
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When performing pseudo-static finite element (FE) analyses to assess seismic slope stability, there are two commonly used methodologies: the gravity-induced method and the strength reduction technique. The primary difference between these techniques is in the path that is traveled to bring the soil structure to the verge of failure. In the gravity-...
Technical Report
Full-text available
This is the only publicly released document related to Transportation Research Board National Cooperative Highway Research Project 24-11(02) into the use of EPS-block geofoam for slope stabilization. It is a much-reduced version of the 2011 final report that was never released to the public.
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A number of Geosynthetic-Reinforced Soil Retaining Walls (GRS RWs) collapsed during heavy rainfalls and earthquakes in Japan. In the US, most collapse cases are in the private sector. The collapse is due to insufficient redundancy resulting from excessively economical, therefore inadequate, structure type, design and construction. As the actual soi...
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This paper presents an integrated analytical method for calculating the resultant unfactored geosynthetic force in reinforced earth structures under seismic loading conditions. The method utilizes a pseudostatic limit equilibrium approach for assessing the internal stability of a reinforced earth structure, assuming a potential rotational failure a...
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This paper reports on the seismic performance of three geosynthetic-reinforced segmental retaining wall systems backfilled with a silty sand mixture, using a shaking table excited by 1995 Kobe earthquake loadings. The preparation of the backfill mixture and its properties, the tested wall configurations, the reinforcement layouts and instrumentatio...
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A scale modeling technique is presented for simulating the uplift behavior of piles in sand, which satisfies stress and strain similitude with full-scale prototypes. A hydraulic gradient approach was used to increase the body forces in the scale model tests, until the stresses became representative of reasonable field-scale conditions. The associat...
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Geocell is a three-dimensional geosynthetic product that was originally developed to confine granular bases and minimize permanent deformation of unpaved roads. Many laboratory and field tests have demonstrated the effectiveness of geocell reinforcement in roadway constructions. However, the lack of a well-established design method that can quantif...
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The resultant force of lateral earth pressure is commonly used in the design of nearly vertical walls while flatter slopes are designed to be internally stable using a factor of safety approach. An unstable slope is considered to have an unsatisfactory factor of safety unless supported by internal and/or external measures. However, from an analytic...
Article
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Reinforced masonry block retaining walls are comprised of a narrow column of stacked blocks at their exposed end. This column is placed on a nonstructural leveling pad to facilitate the placement of facing units. Theoretically, this column can generate very large toe resistance to sliding. A recent publication indicates that an accepted design meth...
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Full-scale trafficking tests were conducted to evaluate the effect of novel polymeric-alloy geocell reinforcement on base courses for low-volume unpaved roads over weak subgrade. Three types of in-fill materials-crushed limestone (AB-3) aggregate, quarry waste (QW), and recycled asphalt pavement (RAP)-were used for the base courses over a weak subg...
Article
Recycled asphalt pavement (RAP) has been increasingly used as an energy efficient and environmentally friendly paving material and is currently the most reused and recycled material in the United States. RAP has been used in new hot mix asphalt (HMA) mixtures and in base courses for pavement construction. When RAP is used as a base course material,...
Technical Report
Full-text available
This document is the complete final report for Transportation Research Board National Cooperative Highway Research Program 24-11(02) into the use of EPS-block geofoam for slope stabilization. This document was never released in its entirety to the public. Only a synopsis was eventually published and released to the public in 2013 as NCHRP Results R...
Conference Paper
Recycled Asphalt Pavement (RAP) is a removed and reprocessed pavement material containing asphalt and aggregates. Literature indicates that RAP can be used as a base course material for pavement applications. Permanent deformation or rutting is one of the concerns in the use of RAP as a base course due to creep deformation. However, limited researc...
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Current design of geosynthetic reinforced soil is well-established, rendering safe and economical structures. However, there are some issues that need attention so as to improve the economics or to avoid pitfalls. This paper presents three such issues suggesting possible solutions and commentary. The first issue deals with the artificial definition...
Article
A comparison is presented between the results of centrifugal model tests and finite element analyses for the problem of load transfer to a rigid tie beam buried in sand. The finite element program utilized a nonlinear elastic (hyperbolic) soil constitutive relation, obtained from tests in simple shear. It was found that, for this particular type of...
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Accelerated pavement testing (APT) is an effective method in evaluating pavement performances by applying controlled wheel loading under environmental conditions. This note presents the findings from an accelerated pavement test on unpaved road sections involving geocell reinforcement of sand bases. A total of four unpaved road sections were constr...
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This paper presents the framework for the interim design guideline for the use of expanded polystyrene (EPS) block geofoam for slope stabilization and repair, based on the findings of the NCHRP Project 24-11(02) Phase I study. The overall objective of this research is to develop a design guideline as well as an appropriate material and construction...
Article
Geocell, one type of geosynthetics manufactured in the form of three-dimensional interconnected cells, can be used as a reinforcement to improve the behavior of base courses by providing lateral confinement to increase their stiffness and strength and reduce surface permanent-deformation. However, the use of geocells for base reinforcement is hinde...
Article
An instrumented geogrid-reinforced wall constructed on a highly compressible foundation was deconstructed 16 months after its completion, providing a unique opportunity to exhume and examine the instrumented geogrids that were used to construct the wall. The objectives of this post mortem study were: (1) to inspect the condition of the strain gauge...
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This paper summarizes the development of a three-dimensional numerical model for analyzing single geocell-reinforced soil. In this model, the infill soil was modeled using the Duncan-Chang model, which can simulate non-linearity and stress-dependency of soil. Geocell was modeled using linearly elastic plate elements, which can carry both bending an...
Article
Back-to-back Mechanically Stabilized Earth (MSE) walls are commonly used for embankments approaching bridges. However, available design guidelines for this wall system are limited. The distance between two opposing walls is a key parameter used for determining the analysis methods in FHWA Guidelines. Two extreme cases are identified: (1) reinforcem...
Article
A finite-element procedure was used to simulate the dynamic behavior of four full-scale reinforced soil retaining walls subjected to earthquake loading. The experiments were conducted at a maximum horizontal acceleration of over 0.8 g, with two walls subjected to only horizontal accelerations and two other walls under simultaneous horizontal and ve...
Article
Full-text available
This paper presents the framework for the interim design guideline for the use of expanded polystyrene (EPS)-block geofoam for slope stabilization and repair based on the National Cooperative Highway Research Program (NCHRP) Project 24-11(02) Phase I study. The overall objective of this research is to develop a design guideline as well as an approp...
Article
Current reinforced earth structure designs arbitrarily distinguish between reinforced walls and slopes, that is, the batter of walls is 20 degrees or less while in slopes it is larger than 20 degrees. This has led to disjointed design methodologies where walls employ a lateral earth pressure approach and slopes utilize limit equilibrium analyses. T...
Article
Geocell, due to its three-dimensional structure, can effectively provide lateral confinement to infill material to increase the stiffness and bearing capacity of base courses and to reduce their permanent deformations under repeated loading. However, limited studies have so far been done to investigate the effect of infill material on the performan...
Article
A research was conducted to explore the use of geo-cells as an earth-retention structure. The research team included Professor Hoe Ling of Columbia University, Mohri of the National Research Institute of Rural Engineering in Tsukuba City, Japan, and Dov Leshchinsky. The objective of the study was to quantify a reasonable reduction factor (RF) on th...
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Full-text available
This paper demonstrates the use of a centrifuge modeling technique in studying slope instability. The slope models were prepared from sand, and sand mixed with 15 and 30% fines by weight, compacted at optimum water content. The validity of the modeling technique was confirmed using slope models of different heights, inclinations, and soil types. Th...
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This paper summarizes the seismic response of five large-scale retaining walls having a geocell facing. The walls were 2.8 m high and the backfill and foundation soil were a fine sand compacted to 90% standard Proctor density relative density of 55%. The first two walls were of the same geometry, with a tapered facing made of geocells each of heigh...
Conference Paper
The Cherry Island Landfill (CIL), located in Wilmington, DE, is undergoing a major expansion to increase its service capacity. To increase landfill volume, a mechanically stabilized earth (MSE) wall is being constructed along three sides of the site. Very soft, compressible soils characterize the subsurface conditions, creating the potential for la...
Conference Paper
Geosynthetics have been used for base reinforcement since 1970s. Numerous research has already been carried out for planar geosynthetic reinforcement but limited research has been conducted for three-dimensional geocell reinforcement. Literature review has also demonstrated a significant gap between the applications and theories of geocell reinforc...
Article
Common design of MSE walls is based on a lateral earth pressure approach. A key aspect in design is the determination of the reactive force in each reinforcement layer so as to maintain the system in equilibrium. This force leads to the selection of reinforcement with adequate long term strength. It is also used to calculate the pullout resistive l...
Article
Ideal design of an earthquake resistant earth structure would consider the time records of future seismic events. Objectively, such time records are difficult to predict especially when compared with prediction of the design peak ground acceleration (PGA), a single-value parameter. Furthermore, relevant soil properties are not easily obtainable in...
Article
This paper describes the interaction behaviour of soil/geogrid and soil/ concrete interfaces of a reinforced soil-retaining wall system under monotonic and cyclic loading conditions. A sand-clay mixture was tested with geogrids, which were manufactured from polyester and polyvinyl alcohol, and with concrete mortar in a modified direct shear device....
Chapter
Geocells have a three-dimensional cellular structure, which can be used to stabilize foundations in soft soil by increasing bearing capacity and reducing settlements. However, a considerable gap exists between the applications and the theories for the mechanisms of geocell-reinforced foundations. This paper presents a mechanistic analysis of a geoc...