The Experts below are selected from a list of 32955 Experts worldwide ranked by ideXlab platform
Chris R Lawson - One of the best experts on this subject based on the ideXlab platform.
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location of Failure Plane and design considerations for narrow geosynthetic reinforced soil wall systems
Journal of GeoEngineering, 2011Co-Authors: Kuohsin Yang, Jorge G Zornberg, Wenyi Hung, Chris R LawsonAbstract:The design of a Geosynthetic Reinforced Soil (GRS) wall for internal stability against pullout Failure requires computing the reinforcement embedment length. Therefore, the location of Failure Plane is an important input for this design. The current FHWA MSE wall design guidelines assume the location of Failure Plane based on Rankine theory. While this assumption holds true for conventional walls it is unconservative for GRS walls under constrained spaces, also known as “narrow GRS walls”. This paper presents a limit equilibrium study to accurately locate Failure Planes within narrow GRS walls. The critical Failure Planes within narrow GRS walls are searched using Spencer’s method with a function of noncircular Failure Plane. The predicted results from limit equilibrium analyses are verified by the experimental data from centrifuge tests conducted on narrow GRS walls. The results indicate that the critical Failure Plane is bilinear: The Failure surface being formed partially through the reinforced soil and partially along the interface between the GRS and the stable wall face. The results show the inclination angles of the Failure Planes for narrow GRS walls being 10~ 20 less than those calculated by Rankine theory. The effect of wall aspect ratio on the inclination angle of the critical Failure Plane is investigated for the cases studied in this paper. Design considerations against pullout Failure for narrow GRS walls are also discussed at end of this paper.
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location of Failure Plane and design considerations for narrow geosynthetic reinforced soil wall systems
Journal of GeoEngineering, 2011Co-Authors: Kuohsin Yang, Jorge G Zornberg, Wenyi Hung, Chris R LawsonAbstract:The design of a Geosynthetic Reinforced Soil (GRS) wall for internal stability against pullout Failure requires computing the reinforcement embedment length. Therefore, the location of Failure Plane is an important input for this design. The current FHWA MSE wall design guidelines assume the location of Failure Plane based on Rankine theory. While this assumption holds true for conventional walls it is unconservative for GRS walls under constrained spaces, also known as “narrow GRS walls”. This paper presents a limit equilibrium study to accurately locate Failure Planes within narrow GRS walls. The critical Failure Planes within narrow GRS walls are searched using Spencer’s method with a function of noncircular Failure Plane. The predicted results from limit equilibrium analyses are verified by the experimental data from centrifuge tests conducted on narrow GRS walls. The results indicate that the critical Failure Plane is bilinear: The Failure surface being formed partially through the reinforced soil and partially along the interface between the GRS and the stable wall face. The results show the inclination angles of the Failure Planes for narrow GRS walls being 10~ 20 less than those calculated by Rankine theory. The effect of wall aspect ratio on the inclination angle of the critical Failure Plane is investigated for the cases studied in this paper. Design considerations against pullout Failure for narrow GRS walls are also discussed at end of this paper.
Masaru Tateyama - One of the best experts on this subject based on the ideXlab platform.
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seismic earth pressure exerted on retaining walls under a large seismic load
Soils and Foundations, 2011Co-Authors: Kenji Watanabe, Junichi Koseki, Masaru TateyamaAbstract:ABSTRACT In recent years, serious damage has been done to retaining structures because of large earthquakes. In order to establish practical methods for evaluating the seismic earth pressure, which is one of the important external forces acting on retaining structures during large earthquakes, a series of shaking table tests was conducted on retaining wall (RW) models. The experiments revealed that the seismic active earth pressure was considerably smaller than that obtained by the Mononobe-Okabe theory, particularly under a large seismic load. Furthermore, it was demonstrated that the seismic earth pressure had an upper limit, which was determined by the force equilibrium of the soil wedge at the critical state when the RW lost its stability. On the basis of the test results, a new method to evaluate the seismic earth pressure for practical designs under a large seismic load has been suggested. This proposed method provides a reasonable earth pressure as well as an angle of Failure Plane, those of which depend on the seismic stability of the retaining wall. It has been confirmed that earth pressure obtained by the proposed method agrees well with the measured seismic earth pressure exerted on several retaining walls with different degrees of stability.
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simplified procedure to evaluate earthquake induced residual displacement of geosynthetic reinforced soil retaining walls
Soils and Foundations, 2010Co-Authors: Susumu Nakajima, Kenji Watanabe, Junichi Koseki, Masaru TateyamaAbstract:Based on a series of shaking table model tests, it was found that the effects of 1) subsoil and backfill deformation, 2) Failure Plane formation in backfill, and 3) pullout resistance mobilized by the reinforcements on the seismic behaviors of the geosynthetic reinforced soil retaining walls (GRS walls) were significant. These effects cannot be taken into account in the conventional pseudo-static based limit equilibrium analyses or Newmark's rigid sliding block analogy, which are usually adopted as the seismic design procedure. Therefore, this study attempts to develop a simplified procedure to evaluate earthquake-induced residual displacement of GRS walls by reflecting the knowledge on the seismic behaviors of GRS walls obtained from the shaking table model tests. In the proposed method, 1) the deformation characteristics of subsoil and backfill are modeled based on the model test results and 2) the effect of Failure Plane formation is considered by using residual soil strength after the Failure Plane formation while the peak soil strength is used before the Failure Plane formation, and 3) the effect of the pullout resistance mobilized by the reinforcement is also introduced by evaluating the pullout resistance based on the results from the pullout tests of the reinforcements. By using the proposed method, simulations were performed on the shaking table model test results conducted under a wide variety of testing conditions and good agreements between the calculated and measured displacements were observed.
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a modified procedure to evaluate active earth pressure at high seismic loads
Soils and Foundations, 1998Co-Authors: Junichi Koseki, Masaru Tateyama, Fumio Tatsuoka, Yulman Munaf, Kenichi KojimaAbstract:ABSTRACT A modified and pseudo-static limit-equilibrium approach to evaluate active earth pressure at high seismic load levels is proposed. Although it is similar to the Mononobe-Okabe method, the proposed method considers the effects of strain localization in the backfill soil and associated post-peak reduction in the shear resistance from peak to residual values along a previously formed Failure Plane. The proposed method can reflect differences in the peak shear resistance of the backfill soil with different degrees of compaction; yields a realistic active earth pressure coefficient which is smaller than that predicted by the Mononobe-Okabe method using a residual shear resistance; can be adapted to analyses with a large horizontal seismic coefficient where the Mononobe-Okabe method using the residual shear resistance is not applicable; and renders a reduced and more realistic size of active Failure zone in the backfill soil at high seismic load levels compared to that predicted by the Mononobe-Okabe method.
Kuohsin Yang - One of the best experts on this subject based on the ideXlab platform.
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location of Failure Plane and design considerations for narrow geosynthetic reinforced soil wall systems
Journal of GeoEngineering, 2011Co-Authors: Kuohsin Yang, Jorge G Zornberg, Wenyi Hung, Chris R LawsonAbstract:The design of a Geosynthetic Reinforced Soil (GRS) wall for internal stability against pullout Failure requires computing the reinforcement embedment length. Therefore, the location of Failure Plane is an important input for this design. The current FHWA MSE wall design guidelines assume the location of Failure Plane based on Rankine theory. While this assumption holds true for conventional walls it is unconservative for GRS walls under constrained spaces, also known as “narrow GRS walls”. This paper presents a limit equilibrium study to accurately locate Failure Planes within narrow GRS walls. The critical Failure Planes within narrow GRS walls are searched using Spencer’s method with a function of noncircular Failure Plane. The predicted results from limit equilibrium analyses are verified by the experimental data from centrifuge tests conducted on narrow GRS walls. The results indicate that the critical Failure Plane is bilinear: The Failure surface being formed partially through the reinforced soil and partially along the interface between the GRS and the stable wall face. The results show the inclination angles of the Failure Planes for narrow GRS walls being 10~ 20 less than those calculated by Rankine theory. The effect of wall aspect ratio on the inclination angle of the critical Failure Plane is investigated for the cases studied in this paper. Design considerations against pullout Failure for narrow GRS walls are also discussed at end of this paper.
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location of Failure Plane and design considerations for narrow geosynthetic reinforced soil wall systems
Journal of GeoEngineering, 2011Co-Authors: Kuohsin Yang, Jorge G Zornberg, Wenyi Hung, Chris R LawsonAbstract:The design of a Geosynthetic Reinforced Soil (GRS) wall for internal stability against pullout Failure requires computing the reinforcement embedment length. Therefore, the location of Failure Plane is an important input for this design. The current FHWA MSE wall design guidelines assume the location of Failure Plane based on Rankine theory. While this assumption holds true for conventional walls it is unconservative for GRS walls under constrained spaces, also known as “narrow GRS walls”. This paper presents a limit equilibrium study to accurately locate Failure Planes within narrow GRS walls. The critical Failure Planes within narrow GRS walls are searched using Spencer’s method with a function of noncircular Failure Plane. The predicted results from limit equilibrium analyses are verified by the experimental data from centrifuge tests conducted on narrow GRS walls. The results indicate that the critical Failure Plane is bilinear: The Failure surface being formed partially through the reinforced soil and partially along the interface between the GRS and the stable wall face. The results show the inclination angles of the Failure Planes for narrow GRS walls being 10~ 20 less than those calculated by Rankine theory. The effect of wall aspect ratio on the inclination angle of the critical Failure Plane is investigated for the cases studied in this paper. Design considerations against pullout Failure for narrow GRS walls are also discussed at end of this paper.
Qiaoyong Zhou - One of the best experts on this subject based on the ideXlab platform.
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behaviour of geogrid reinforced soil retaining wall with concrete rigid facing
Geotextiles and Geomembranes, 2009Co-Authors: Guangqing Yang, Baojian Zhang, Peng Lv, Qiaoyong ZhouAbstract:Abstract Monitoring was carried out during construction of a cast-in-situ concrete-rigid facing geogrid reinforced soil retaining wall in the Gan (Zhou)-Long (Yan) railway main line of China. The monitoring included the vertical foundation pressure and lateral earth pressure of the reinforced soil wall facing, the tensile strain in the reinforcement and the horizontal deformation of the facing. The vertical foundation pressure of reinforced soil retaining wall is non-linear along the reinforcement length, and the maximum value is at the middle of the reinforcement length, moreover the value reduces gradually at top and bottom. The measured lateral earth pressure within the reinforced soil wall is non-linear along the height and the value is less than the active lateral earth pressure. The distribution of tensile strain in the geogrid reinforcements within the upper portion of the wall is single-peak value, but the distribution of tensile strain in the reinforcements within the lower portion of the wall has double-peak values. The potential Failure Plane within the upper portion of the wall is similar to “ 0.3H method ”, whereas the potential Failure Plane within portion of the lower wall is closer to the active Rankine earth pressure theory. The position of the maximum lateral displacement of the wall face during construction is within portion of the lower wall, moreover the position of the maximum lateral displacement of the wall face post-construction is within the portion of the top wall. These monitoring results of the behaviour of the wall can be used as a reference for future study and design of geogrid reinforced soil retaining wall systems.
Junichi Koseki - One of the best experts on this subject based on the ideXlab platform.
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seismic earth pressure exerted on retaining walls under a large seismic load
Soils and Foundations, 2011Co-Authors: Kenji Watanabe, Junichi Koseki, Masaru TateyamaAbstract:ABSTRACT In recent years, serious damage has been done to retaining structures because of large earthquakes. In order to establish practical methods for evaluating the seismic earth pressure, which is one of the important external forces acting on retaining structures during large earthquakes, a series of shaking table tests was conducted on retaining wall (RW) models. The experiments revealed that the seismic active earth pressure was considerably smaller than that obtained by the Mononobe-Okabe theory, particularly under a large seismic load. Furthermore, it was demonstrated that the seismic earth pressure had an upper limit, which was determined by the force equilibrium of the soil wedge at the critical state when the RW lost its stability. On the basis of the test results, a new method to evaluate the seismic earth pressure for practical designs under a large seismic load has been suggested. This proposed method provides a reasonable earth pressure as well as an angle of Failure Plane, those of which depend on the seismic stability of the retaining wall. It has been confirmed that earth pressure obtained by the proposed method agrees well with the measured seismic earth pressure exerted on several retaining walls with different degrees of stability.
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simplified procedure to evaluate earthquake induced residual displacement of geosynthetic reinforced soil retaining walls
Soils and Foundations, 2010Co-Authors: Susumu Nakajima, Kenji Watanabe, Junichi Koseki, Masaru TateyamaAbstract:Based on a series of shaking table model tests, it was found that the effects of 1) subsoil and backfill deformation, 2) Failure Plane formation in backfill, and 3) pullout resistance mobilized by the reinforcements on the seismic behaviors of the geosynthetic reinforced soil retaining walls (GRS walls) were significant. These effects cannot be taken into account in the conventional pseudo-static based limit equilibrium analyses or Newmark's rigid sliding block analogy, which are usually adopted as the seismic design procedure. Therefore, this study attempts to develop a simplified procedure to evaluate earthquake-induced residual displacement of GRS walls by reflecting the knowledge on the seismic behaviors of GRS walls obtained from the shaking table model tests. In the proposed method, 1) the deformation characteristics of subsoil and backfill are modeled based on the model test results and 2) the effect of Failure Plane formation is considered by using residual soil strength after the Failure Plane formation while the peak soil strength is used before the Failure Plane formation, and 3) the effect of the pullout resistance mobilized by the reinforcement is also introduced by evaluating the pullout resistance based on the results from the pullout tests of the reinforcements. By using the proposed method, simulations were performed on the shaking table model test results conducted under a wide variety of testing conditions and good agreements between the calculated and measured displacements were observed.
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a modified procedure to evaluate active earth pressure at high seismic loads
Soils and Foundations, 1998Co-Authors: Junichi Koseki, Masaru Tateyama, Fumio Tatsuoka, Yulman Munaf, Kenichi KojimaAbstract:ABSTRACT A modified and pseudo-static limit-equilibrium approach to evaluate active earth pressure at high seismic load levels is proposed. Although it is similar to the Mononobe-Okabe method, the proposed method considers the effects of strain localization in the backfill soil and associated post-peak reduction in the shear resistance from peak to residual values along a previously formed Failure Plane. The proposed method can reflect differences in the peak shear resistance of the backfill soil with different degrees of compaction; yields a realistic active earth pressure coefficient which is smaller than that predicted by the Mononobe-Okabe method using a residual shear resistance; can be adapted to analyses with a large horizontal seismic coefficient where the Mononobe-Okabe method using the residual shear resistance is not applicable; and renders a reduced and more realistic size of active Failure zone in the backfill soil at high seismic load levels compared to that predicted by the Mononobe-Okabe method.
