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George Z Voyiadjis - One of the best experts on this subject based on the ideXlab platform.
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3d finite element analysis of the geosynthetic reinforced soil integrated bridge system grs ibs under different loading conditions
Transportation geotechnics, 2018Co-Authors: Murad Abufarsakh, Allam Ardah, George Z VoyiadjisAbstract:Abstract In this study, a three-dimensional (3D) Finite Element (FE) analysis was developed to simulate the fully-instrumented geosynthetic reinforced soil integrated bridge system (GRS-IBS) at Maree Michel Bridge in Louisiana. The 3DFE computer program PLAXIS 3D 2016 was selected to simulate the GRS-IBS behavior under different loading conditions. A second order-hyperbolic elasto-plastic soil model was used to simulate the granular backfill materials. The soil-structure interaction was simulated using zero thickness interface elements, in which the interface shear strength is governed by Mohr-Coulomb failure criterion. Three different loading conditions were considered in this study: (a) at the end of bridge construction (Case 1); (b) surface loading (Case 2); and (c) at abnormal loading (Case 3), which is equal to the dead load of the bridge structure plus three times the service loading. The predicted results were compared with the field measurements at the end of bridge construction. Moreover; the predicted results of the 3D-FE analysis were compared with those predicted using the 2D-FE analysis. A good agreement was obtained between the 3D-FE and 2D-FE numerical results and the field measurements. The predicted results using the 3D-FE showed that the range of maximum Reinforcement strain under service loading ranges between 0.6% and 1.5%, depending on the location of the Reinforcement Layer. The maximum lateral deformation at the face was between 3 mm (0.07% lateral strain) under service load case and 7 mm (0.3% lateral strain) for abnormal load case. The maximum settlement of the GRS-IBS due to the service loading was 9 mm (0.3% vertical strain). The axial Reinforcement forces predicted by FHWA (Adam et al., 2011) design methods were compared with those predicted by the 3D-FE and 2D-FE analysis. The results showed that the FHWA analytical method is 1.5–2.5 times higher than those predicted by the FE analysis, depending on the loading condition and Reinforcement location.
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numerical evaluation of the performance of a geosynthetic reinforced soil integrated bridge system grs ibs under different loading conditions
Geotextiles and Geomembranes, 2017Co-Authors: Allam Ardah, Murad Abufarsakh, George Z VoyiadjisAbstract:Abstract This paper presents the results of a finite element (FE) numerical analysis that was developed to simulate the fully-instrumented Geosynthetic Reinforced Soil Integrated Bridge System (GRS-IBS) at the Maree Michel Bridge in Louisiana. Four different loading conditions were considered in this paper to evaluate the performance of GRS-IBS abutment due to dead loading, tandem axle truck loading, service loading, and abnormal loading. The two-dimensional FE computer program PLAXIS 2D 2016 was selected to model the GRS-IBS abutment. The hardening soil model proposed by Schanz et al., (1999) that was initially introduced by Duncan and Chang (1970) was used to simulate the granular backfill materials; a linear-elastic model with Mohr-Coulomb frictional criterion was used to simulate the interface between the geosynthetic and backfill material. Both the geosynthetic and the facing block were modeled using linear elastic model. The Mohr-Coulomb constitutive model was used to simulate the foundation soil. The FE numerical results were compared with the field measurements of monitoring program, in which a good agreement was obtained between the FE numerical results and the field measurements. The range of maximum Reinforcement strain was between 0.4% and 1.5%, depending on the location of the Reinforcement Layer and the loading condition. The maximum lateral deformation at the face was between 2 and 9 mm (0.08%–0.4% lateral strain), depending on the loading condition. The maximum settlement of the GRS-IBS under service loading was 10 mm (0.3% vertical strain), which is about two times the field measurements (∼5 mm). This is most probably due to the behavior of over consolidated soil caused by the old bridge. The axial Reinforcement force predicted by FHWA (Adams et al., 2011b) design methods were 1.5–2.5 times higher than those predicted by the FE analysis and the field measurements, depending on the loading condition and Reinforcement location. However, the interface shear strength between the Reinforcement and the backfill materials predicted by Mohr-Coulomb method was very close to those predicted by the FE.
Allam Ardah - One of the best experts on this subject based on the ideXlab platform.
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3d finite element analysis of the geosynthetic reinforced soil integrated bridge system grs ibs under different loading conditions
Transportation geotechnics, 2018Co-Authors: Murad Abufarsakh, Allam Ardah, George Z VoyiadjisAbstract:Abstract In this study, a three-dimensional (3D) Finite Element (FE) analysis was developed to simulate the fully-instrumented geosynthetic reinforced soil integrated bridge system (GRS-IBS) at Maree Michel Bridge in Louisiana. The 3DFE computer program PLAXIS 3D 2016 was selected to simulate the GRS-IBS behavior under different loading conditions. A second order-hyperbolic elasto-plastic soil model was used to simulate the granular backfill materials. The soil-structure interaction was simulated using zero thickness interface elements, in which the interface shear strength is governed by Mohr-Coulomb failure criterion. Three different loading conditions were considered in this study: (a) at the end of bridge construction (Case 1); (b) surface loading (Case 2); and (c) at abnormal loading (Case 3), which is equal to the dead load of the bridge structure plus three times the service loading. The predicted results were compared with the field measurements at the end of bridge construction. Moreover; the predicted results of the 3D-FE analysis were compared with those predicted using the 2D-FE analysis. A good agreement was obtained between the 3D-FE and 2D-FE numerical results and the field measurements. The predicted results using the 3D-FE showed that the range of maximum Reinforcement strain under service loading ranges between 0.6% and 1.5%, depending on the location of the Reinforcement Layer. The maximum lateral deformation at the face was between 3 mm (0.07% lateral strain) under service load case and 7 mm (0.3% lateral strain) for abnormal load case. The maximum settlement of the GRS-IBS due to the service loading was 9 mm (0.3% vertical strain). The axial Reinforcement forces predicted by FHWA (Adam et al., 2011) design methods were compared with those predicted by the 3D-FE and 2D-FE analysis. The results showed that the FHWA analytical method is 1.5–2.5 times higher than those predicted by the FE analysis, depending on the loading condition and Reinforcement location.
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numerical evaluation of the performance of a geosynthetic reinforced soil integrated bridge system grs ibs under different loading conditions
Geotextiles and Geomembranes, 2017Co-Authors: Allam Ardah, Murad Abufarsakh, George Z VoyiadjisAbstract:Abstract This paper presents the results of a finite element (FE) numerical analysis that was developed to simulate the fully-instrumented Geosynthetic Reinforced Soil Integrated Bridge System (GRS-IBS) at the Maree Michel Bridge in Louisiana. Four different loading conditions were considered in this paper to evaluate the performance of GRS-IBS abutment due to dead loading, tandem axle truck loading, service loading, and abnormal loading. The two-dimensional FE computer program PLAXIS 2D 2016 was selected to model the GRS-IBS abutment. The hardening soil model proposed by Schanz et al., (1999) that was initially introduced by Duncan and Chang (1970) was used to simulate the granular backfill materials; a linear-elastic model with Mohr-Coulomb frictional criterion was used to simulate the interface between the geosynthetic and backfill material. Both the geosynthetic and the facing block were modeled using linear elastic model. The Mohr-Coulomb constitutive model was used to simulate the foundation soil. The FE numerical results were compared with the field measurements of monitoring program, in which a good agreement was obtained between the FE numerical results and the field measurements. The range of maximum Reinforcement strain was between 0.4% and 1.5%, depending on the location of the Reinforcement Layer and the loading condition. The maximum lateral deformation at the face was between 2 and 9 mm (0.08%–0.4% lateral strain), depending on the loading condition. The maximum settlement of the GRS-IBS under service loading was 10 mm (0.3% vertical strain), which is about two times the field measurements (∼5 mm). This is most probably due to the behavior of over consolidated soil caused by the old bridge. The axial Reinforcement force predicted by FHWA (Adams et al., 2011b) design methods were 1.5–2.5 times higher than those predicted by the FE analysis and the field measurements, depending on the loading condition and Reinforcement location. However, the interface shear strength between the Reinforcement and the backfill materials predicted by Mohr-Coulomb method was very close to those predicted by the FE.
Murad Abufarsakh - One of the best experts on this subject based on the ideXlab platform.
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3d finite element analysis of the geosynthetic reinforced soil integrated bridge system grs ibs under different loading conditions
Transportation geotechnics, 2018Co-Authors: Murad Abufarsakh, Allam Ardah, George Z VoyiadjisAbstract:Abstract In this study, a three-dimensional (3D) Finite Element (FE) analysis was developed to simulate the fully-instrumented geosynthetic reinforced soil integrated bridge system (GRS-IBS) at Maree Michel Bridge in Louisiana. The 3DFE computer program PLAXIS 3D 2016 was selected to simulate the GRS-IBS behavior under different loading conditions. A second order-hyperbolic elasto-plastic soil model was used to simulate the granular backfill materials. The soil-structure interaction was simulated using zero thickness interface elements, in which the interface shear strength is governed by Mohr-Coulomb failure criterion. Three different loading conditions were considered in this study: (a) at the end of bridge construction (Case 1); (b) surface loading (Case 2); and (c) at abnormal loading (Case 3), which is equal to the dead load of the bridge structure plus three times the service loading. The predicted results were compared with the field measurements at the end of bridge construction. Moreover; the predicted results of the 3D-FE analysis were compared with those predicted using the 2D-FE analysis. A good agreement was obtained between the 3D-FE and 2D-FE numerical results and the field measurements. The predicted results using the 3D-FE showed that the range of maximum Reinforcement strain under service loading ranges between 0.6% and 1.5%, depending on the location of the Reinforcement Layer. The maximum lateral deformation at the face was between 3 mm (0.07% lateral strain) under service load case and 7 mm (0.3% lateral strain) for abnormal load case. The maximum settlement of the GRS-IBS due to the service loading was 9 mm (0.3% vertical strain). The axial Reinforcement forces predicted by FHWA (Adam et al., 2011) design methods were compared with those predicted by the 3D-FE and 2D-FE analysis. The results showed that the FHWA analytical method is 1.5–2.5 times higher than those predicted by the FE analysis, depending on the loading condition and Reinforcement location.
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numerical evaluation of the performance of a geosynthetic reinforced soil integrated bridge system grs ibs under different loading conditions
Geotextiles and Geomembranes, 2017Co-Authors: Allam Ardah, Murad Abufarsakh, George Z VoyiadjisAbstract:Abstract This paper presents the results of a finite element (FE) numerical analysis that was developed to simulate the fully-instrumented Geosynthetic Reinforced Soil Integrated Bridge System (GRS-IBS) at the Maree Michel Bridge in Louisiana. Four different loading conditions were considered in this paper to evaluate the performance of GRS-IBS abutment due to dead loading, tandem axle truck loading, service loading, and abnormal loading. The two-dimensional FE computer program PLAXIS 2D 2016 was selected to model the GRS-IBS abutment. The hardening soil model proposed by Schanz et al., (1999) that was initially introduced by Duncan and Chang (1970) was used to simulate the granular backfill materials; a linear-elastic model with Mohr-Coulomb frictional criterion was used to simulate the interface between the geosynthetic and backfill material. Both the geosynthetic and the facing block were modeled using linear elastic model. The Mohr-Coulomb constitutive model was used to simulate the foundation soil. The FE numerical results were compared with the field measurements of monitoring program, in which a good agreement was obtained between the FE numerical results and the field measurements. The range of maximum Reinforcement strain was between 0.4% and 1.5%, depending on the location of the Reinforcement Layer and the loading condition. The maximum lateral deformation at the face was between 2 and 9 mm (0.08%–0.4% lateral strain), depending on the loading condition. The maximum settlement of the GRS-IBS under service loading was 10 mm (0.3% vertical strain), which is about two times the field measurements (∼5 mm). This is most probably due to the behavior of over consolidated soil caused by the old bridge. The axial Reinforcement force predicted by FHWA (Adams et al., 2011b) design methods were 1.5–2.5 times higher than those predicted by the FE analysis and the field measurements, depending on the loading condition and Reinforcement location. However, the interface shear strength between the Reinforcement and the backfill materials predicted by Mohr-Coulomb method was very close to those predicted by the FE.
Sanjay Kumar Shukla - One of the best experts on this subject based on the ideXlab platform.
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optimum burial depth of geosynthetic Reinforcement within sand bed based on numerical investigation
International Journal of Geotechnical Engineering, 2020Co-Authors: Shadi Aria, Sanjay Kumar Shukla, Alireza MohyeddinAbstract:In model studies as well as in field projects, the burial depth of a geosynthetic Reinforcement Layer within a sand bed is often assumed to be approximately 0.3 times the width of the footing. Howe...
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strength enhancement of the subgrade soil of unpaved road with geosynthetic Reinforcement Layers
Transportation geotechnics, 2019Co-Authors: Meenakshi Singh, Ashutosh Trivedi, Sanjay Kumar ShuklaAbstract:Abstract Geosynthetic Reinforcement Layers are often used to improve the performance of pavement structures. The performance of an unpaved road is routinely measured in terms of the California bearing ratio (CBR), which is an index of strength of subgrade soil of unpaved road. In the present study, an experimental investigation was carried out to evaluate the performance of the subgrade soil by placing a single Layer and double Layers of geosynthetic Reinforcements (Glasgrid, Tenax 3D grid and Tenax multimat) horizontally at varying depths from the top surface of subgrade soil. Through a series of CBR tests in the laboratory, an attempt was made to determine the optimum depth of the Reinforcement Layer. The single Layer of Reinforcement has been placed at the middle, one-third and one-fourth of the height of the CBR specimen from the top surface of the soil in the CBR mould. The double Layers of Reinforcement were placed at one-fourth of the specimen height from the top surface and the bottom surface. The results show the significant contribution in terms of increased CBR value of the soil, resulting in reduced design thickness of the pavement Layers above the subgrade soil. It has been observed that for a single Layer Reinforcement the Tenax 3D grid performs better than other geosynthetics used in this study while the Tenax multimat performs best for double Layers. The results indicate that for the maximum benefit, the Tenax 3D grid Reinforcement should be placed in between 0.3H and 0.36H where H is the height of the soil specimen. For Glasgrid and Tenax multimat Reinforcements, the maximum effect of Reinforcement is obtained when they are placed between 0.41H and 0.62H.
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effectiveness of reinforcing a low height sandy slope with geosynthetic Reinforcement for landscape development
Arabian Journal of Geosciences, 2019Co-Authors: Emmanuel Baahfrempong, Sanjay Kumar ShuklaAbstract:Landscape projects often require steep sandy slopes of low height, say 1–3 m, in many parts of the world, including Australia. Geosynthetic Reinforcements may greatly help in constructing such steep slopes. In this paper, an attempt has been made to analyze the stability of a low-height medium dense sandy slope, reinforced with geosynthetic Layers, so that this sustainable construction practice may be routinely adopted worldwide. The slope stability analysis was carried out using the limit equilibrium method as available in a commercial software, Slope/W. The slope angle was varied from 40° to 60°, and the effect of the following factors was investigated on the stability of the slope: depth, length, tensile strength and number of Reinforcement Layers, and soil-Reinforcement interfacial friction coefficient. The analysis shows that installing a single geosynthetic Reinforcement Layer within the 40° slope at the optimum embedment depth (u) to slope height (H) ratio, u/H = 0.5, results in a stable slope with a factor of safety Fr(max) of 1.61, but this depth is not suitable for stabilizing the 50° and 60° slopes. Reinforcing the 50° and 60° slopes with two geosynthetic Reinforcement Layers at the optimum embedment depth of u/H = 0.14 and 0.5 in the 50° slope and u/H = 0.19 and 0.5 in the 60° slope improves the factor of safety over the unreinforced case, by 57% and 86%, to Fr(max) = 1.46 and Fr(max) = 1.36, respectively. An illustrative example has been provided to demonstrate the practical application of the developed graphical presentations, as the design charts, to practising engineers involved in landscape development.
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effect of width of geosynthetic Reinforcement within the granular cover on the load distribution over the tunnel lining
Civil Infrastructures Confronting Severe Weathers and Climate Changes Conference, 2018Co-Authors: Sanjay Kumar Shukla, Alireza MohyeddinAbstract:A realistic estimation of load distribution over the buried structures is necessary for proper analysis of tunnels, culverts and pipes/conduits. Tunnels with linings are often constructed in transportation and hydraulic engineering. For the design of tunnel lining, it is essential to know the load over the lining. Load distribution over the buried structures has been investigated scientifically during the past several decades. The method of investigation includes experimental, numerical and analytical methods. The finite-element models based on some commercial software have been developed for load analyses for design of the tunnel linings and buried structures. The geosynthetic is an effective Reinforcement Layer to reduce the load over the buried structure. Although some studies have indicated that the geosynthetic Layer can reduce the load over the buried structure, but no attempt has been made to determine the optimal width of the geosynthetic Reinforcement within the granular cover. Therefore, in this paper, an attempt is made to present effect of width of geosynthetic Layer on the load distribution over the tunnel lining. The study has been carried out by developing a numerical model of the problem. The commercial software PLAXIS 2D has been used for numerical modelling. The results have been presented in the form of design charts, mentioning the optimum width of geosynthetic Layer, so that they can be used by practising engineers.
Ora Leshchinsky - One of the best experts on this subject based on the ideXlab platform.
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limit state design framework for geosynthetic reinforced soil structures
Geotextiles and Geomembranes, 2017Co-Authors: Dov Leshchinsky, Ben Leshchinsky, Ora LeshchinskyAbstract:Abstract Conventional design of geosynthetic-reinforced soil structures is divided into two categories, walls and slopes, based on the batter of its facing system. Internal stability, characterized as sufficient Reinforcement anchoring and strength, is performed using earth pressure-based design criteria for reinforced walls while reinforced slopes are founded on limit equilibrium (LE) slope stability analyses. LE analyses are also used to assess the global or compound stability of both types of structures, accounting for the geometry of the reinforced, retained and foundation soils. The application of LE-based methods typically results in determination of a slip surface corresponding to the lowest attained Safety Factor (SF), known as the Factor of Safety (Fs); however, it yields little information about Reinforcement loading or connection load. In this study, use of the analyzed spatial distribution of SF known as a Safety Map, is modified to attain a prescribed constant Fs at any location in the reinforced soil mass. This modified framework, implemented through an iterative, top-down procedure of LE slope stability analyses originating from the crest of a reinforced structure and exiting at progressively lower elevations on the facing, enables the determination of a Tension Map that illustrates the required distribution of Reinforcement tension to attain a prescribed limit state of equilibrium. This tension map is directly constrained by a pullout capacity envelope at both the rear and front of each Reinforcement Layer, providing a unified, LE-based approach towards assessing an optimal selection of mutually dependent strength and layout of the Reinforcement. To illustrate the utility of the Limit State framework, a series of instructive examples are presented. The results demonstrate the effects of facing elements, closely-spaced Reinforcements, secondary Reinforcement Layers, and is compared to conventional design approaches.