The Experts below are selected from a list of 24378 Experts worldwide ranked by ideXlab platform
Erxiang Song - One of the best experts on this subject based on the ideXlab platform.
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reinforcement load and deformation mode of geosynthetic reinforced soil walls subject to Seismic Loading during service life
Geotextiles and Geomembranes, 2011Co-Authors: Xiangyu Wang, Erxiang SongAbstract:Abstract A Finite Element procedure was used to investigate the reinforcement load and the deformation mode for geosynthetic-reinforced soil (GRS) walls subject to Seismic Loading during their service life, focusing on those with marginal backfill soils. Marginal backfill soils are hereby defined as filled materials containing cohesive fines with plasticity index (PI) >6, which may exhibit substantial creep under constant static Loading before subjected to earthquake. It was found that under strong Seismic Loading reinforced soil walls with marginal backfills exhibited a distinctive “two-wedge” deformation mode. The surface of maximum reinforcement load was the combined effect of the internal potential failure surface and the outer surface that extended into the retained earth. In the range investigated, which is believed to cover general backfill soils and geosynthetic reinforcements, the creep rates of soils and reinforcements had small influence on the reinforcement load and the “two-wedge” deformation mode, but reinforcement stiffness played a critical role on these two responses of GRS walls. It was also found that the “two-wedge” deformation mode could be restricted if sufficiently long reinforcement was used. The study shows that it is rational to investigate the reinforcement load of reinforced soil walls subject to Seismic Loading without considering the previous long-term creep.
Sun Bin - One of the best experts on this subject based on the ideXlab platform.
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multi scale modeling and trans level simulation from material meso damage to structural failure of reinforced concrete frame structures under Seismic Loading
Journal of Computational Science, 2016Co-Authors: Sun BinAbstract:Abstract An adaptive concurrent multi-scale method with three-level model is developed to simulate the trans-scale damage process of large concrete structures from meso-damage in material level to local damage and failure in component level and eventually to global deterioration in structural level. Adaptivity ensures level-change due to evolving damage for better effective without user intervention in the computation. To verify the effectiveness of the method, the trans-scale process of a RC (reinforced concrete) frame structure under Seismic Loading from meso-damage up to structural failure is simulated and compared with experiment. The results show that, the developed method can be used to reveal the Seismic mechanisms of concrete structures by considering the trans-level coupling process from meso-damage to local failure in vulnerable component and eventually to structural failure in a concurrent way; and it is reliable in simulation on the Seismic performance of large scale concrete-based structures with the adaptive capability as well as better computational efficiency for Seismic risk mitigation plans.
Xiangyu Wang - One of the best experts on this subject based on the ideXlab platform.
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reinforcement load and deformation mode of geosynthetic reinforced soil walls subject to Seismic Loading during service life
Geotextiles and Geomembranes, 2011Co-Authors: Xiangyu Wang, Erxiang SongAbstract:Abstract A Finite Element procedure was used to investigate the reinforcement load and the deformation mode for geosynthetic-reinforced soil (GRS) walls subject to Seismic Loading during their service life, focusing on those with marginal backfill soils. Marginal backfill soils are hereby defined as filled materials containing cohesive fines with plasticity index (PI) >6, which may exhibit substantial creep under constant static Loading before subjected to earthquake. It was found that under strong Seismic Loading reinforced soil walls with marginal backfills exhibited a distinctive “two-wedge” deformation mode. The surface of maximum reinforcement load was the combined effect of the internal potential failure surface and the outer surface that extended into the retained earth. In the range investigated, which is believed to cover general backfill soils and geosynthetic reinforcements, the creep rates of soils and reinforcements had small influence on the reinforcement load and the “two-wedge” deformation mode, but reinforcement stiffness played a critical role on these two responses of GRS walls. It was also found that the “two-wedge” deformation mode could be restricted if sufficiently long reinforcement was used. The study shows that it is rational to investigate the reinforcement load of reinforced soil walls subject to Seismic Loading without considering the previous long-term creep.
Laura Caldeira - One of the best experts on this subject based on the ideXlab platform.
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earth pressure coefficients for design of geosynthetic reinforced soil structures
Geotextiles and Geomembranes, 2011Co-Authors: Castorina Silva Vieira, Maria De Lurdes Lopes, Laura CaldeiraAbstract:Abstract There are several methods proposed in the last two decades that can be used to design geosynthetic reinforced soil retaining walls and slopes. The majority of them are based on limit equilibrium considerations, assuming bi-linear or logarithmic spiral failure surfaces. Based on these failure mechanisms, design charts have been presented by several authors. However, the use of design charts is less and less frequent. The paper presents results from a computer program, based on limit equilibrium analyses, able to quantify earth pressure coefficients for the internal design of geosynthetic reinforced soil structures under static and Seismic Loading conditions. Failure mechanisms are briefly presented. Earth pressure coefficients calculated by the developed program are compared with values published in the bibliography. The effect of Seismic Loading on the reinforcement required force is also presented. To avoid the use of design charts and based on the obtained results, approximate equations for earth pressure coefficients estimation are proposed. The performed analyses show that the failure mechanism and the assumptions made have influence on the reinforcement required strength. The increase of reinforcement required strength induced by the Seismic Loading, when compared to the required strength in static conditions, grows with the backfill internal friction angle. The effects of the vertical component of Seismic Loading are not very significant.
Gonghui Wang - One of the best experts on this subject based on the ideXlab platform.
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residual shear strength variability as a primary control on movement of landslides reactivated by earthquake induced ground motion implications for coastal oregon u s
Journal of Geophysical Research, 2014Co-Authors: William H Schulz, Gonghui WangAbstract:Most large seismogenic landslides are reactivations of preexisting landslides with basal shear zones in the residual strength condition. Residual shear strength often varies during rapid displacement, but the response of residual shear zones to Seismic Loading is largely unknown. We used a ring shear apparatus to perform simulated Seismic Loading tests, constant displacement rate tests, and tests during which shear stress was gradually varied on specimens from two landslides to improve understanding of coSeismic landslide reactivation and to identify shear strength models valid for slow gravitational failure through rapid coSeismic failure. The landslides we studied represent many along the Oregon, U.S., coast. Seismic Loading tests resulted in (1) catastrophic failure involving unbounded displacement when stresses represented those for the existing landslides and (2) limited to unbounded displacement when stresses represented those for hypothetical dormant landslides, suggesting that coSeismic landslide reactivation may be significant during future great earthquakes occurring near the Oregon Coast. Constant displacement rate tests indicated that shear strength decreased exponentially during the first few decimeters of displacement but increased logarithmically with increasing displacement rate when sheared at 0.001 cm s−1 or greater. Dynamic shear resistance estimated from shear strength models correlated well with stresses observed during Seismic Loading tests, indicating that displacement rate and amount primarily controlled failure characteristics. We developed a stress-based approach to estimate coSeismic landslide displacement that utilizes the variable shear strength model. The approach produced results that compared favorably to observations made during Seismic Loading tests, indicating its utility for application to landslides.
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Seismic Loading impacts on excess pore water pressure maintain landslide triggered flowslides
Earth Surface Processes and Landforms, 2009Co-Authors: Gonghui Wang, Kyoji SassaAbstract:During the 2003 Sanriku-Minami earthquake, Japan, a flowslide was triggered on a slope of about 13.5o. The displaced landslide mass developed into a flowslide and deposited on a horizontal rice paddy after traveling approximately 130 m. To study the trigger and movement mechanisms of this landslide, field investigation and laboratory ring-shear tests were performed. Field investigation revealed that the landslide originated from a fill slope, where a gully was buried for cultivation some decades ago, and shallow ground water was present. Undrained monotonic and cyclic ring-shear tests on a sample (pyroclastic deposits) taken from the source area revealed that the soil is highly liquefiable, and its steady-state shear strength can be little affected by overconsolidation. Using the Seismic records of the earthquake, probable Seismic Loadings on the sliding surface were synthesized and applied to the samples in ring-shear tests, which were performed under undrained or partially drained conditions. The undrained and partially drained tests revealed that shear failure can be triggered by the introduction of Seismic Loading and formation of excess pore-water pressure. The generation of excess pore-water pressure along with increase of shear displacement and the inhibited dissipation of excess pore-water pressure due to the thickness of the saturated soil layer above the sliding surface probably enabled the continued post-failure landsliding. Copyright © 2008 John Wiley & Sons, Ltd.
