Earthquake-induced soil liquefaction poses significant risks to the stability of geotechnical structures worldwide.An understanding of the liquefaction triggering,and the post-failure large deformation behaviour is es...Earthquake-induced soil liquefaction poses significant risks to the stability of geotechnical structures worldwide.An understanding of the liquefaction triggering,and the post-failure large deformation behaviour is essential for designing resilient infrastructure.The present study develops a Smoothed Particle Hydrodynamics(SPH)framework for earthquake-induced liquefaction hazard assessment of geotechnical structures.The coupled flowdeformation behaviour of soils subjected to cyclic loading is described using the PM4Sand model implemented in a three-phase,single-layer SPH framework.A staggered discretisation scheme based on the stress particle SPH approach is adopted to minimise numerical inaccuracies caused by zero-energy modes and tensile instability.Further,non-reflecting boundary conditions for seismic analysis of semi-infinite soil domains using the SPH method are proposed.The numerical framework is employed for the analysis of cyclic direct simple shear test,seismic analysis of a level ground site,and liquefaction-induced failure of the Lower San Fernando Dam.Satisfactory agreement for liquefaction triggering and post-failure behaviour demonstrates that the SPH framework can be utilised to assess the effect of seismic loading on field-scale geotechnical structures.The present study also serves as the basis for future advancements of the SPH method for applications related to earthquake geotechnical engineering.展开更多
泥石流是我国西南山区常见的地质灾害。架空输电杆塔在泥石流的冲击下往往发生基础破坏甚至会造成杆塔倒塌。首先采用光滑粒子流体动力学(smoothed particle hydrodynamics,简称SPH)方法和有限元方法(finite element method,简称FEM)相...泥石流是我国西南山区常见的地质灾害。架空输电杆塔在泥石流的冲击下往往发生基础破坏甚至会造成杆塔倒塌。首先采用光滑粒子流体动力学(smoothed particle hydrodynamics,简称SPH)方法和有限元方法(finite element method,简称FEM)相耦合的三维数值方法模拟了泥石流对杆塔基础的冲击作用;在与相关模型试验结果验证的基础上,开展了不同泥石流密度、黏度系数及初始速度条件下对输电塔基础的冲击力作用的参数分析;研究结果表明:随着泥石流初始速度的增加,冲击力峰值会随之增大;前排基础的冲击力峰值均大于后排基础;泥石流冲击过程特性受到泥石流密度和黏度系数影响。与稀性泥石流相比:黏性泥石流冲击基础后,基础下游真空区相对要小;此外,将数值模拟结果与Kwan冲击力公式及铁二院推荐的冲击压力设计公式预测值进行对比分析可以发现:Kwan冲击力公式能较好地预测出基础所受泥石流冲击力的平均趋势,最大预测误差低于30%,铁二院公式预测的稀性和黏性泥石流的冲击压力平均偏低分别约17%和28%。相关研究结果有望为泥石流频发区域输电塔基础的设计和风险评估提供一定的参考依据。展开更多
针对飞机典型部位在遭到高速破片攻击后结构整体的战伤状态及破片的剩余行为开展数值模拟。应用LS-DYNA软件,结合有限单元方法(finite element method,FEM)和光滑粒子流体动力学(smoothed particle hydrodynamics,SPH)两者的优势,建立...针对飞机典型部位在遭到高速破片攻击后结构整体的战伤状态及破片的剩余行为开展数值模拟。应用LS-DYNA软件,结合有限单元方法(finite element method,FEM)和光滑粒子流体动力学(smoothed particle hydrodynamics,SPH)两者的优势,建立自适应的FEM-SPH耦合模拟方法,并构建2种飞机典型部位的计算模型,采用六面体网格局部细化方法实现了核心位置的精确模拟,并进行试验来验证数值模型;开展了一系列高速冲击战伤模拟,对比了不同工况下破片高速冲击结构后形成的碎片云和破口形貌,并对破片的剩余速度和质量进行分析,确定了破片在结构蒙皮上的临界跳飞角。结果表明:自适应FEM-SPH耦合算法的计算结果与试验结果吻合良好,能够对破片高速冲击战伤进行有效准确模拟;碎片云分布形状随破片速度增加变得狭长,冲击角度会改变碎片云和结构破口形状朝向;碎片云高度和扩散速度随破片速度或角度的变化趋势基本一致并都呈线性关系;破片的速度减少量不随初始速度变化,质量减少量则与冲击速度正相关,两者与冲击角度都负相关;破片临界跳飞角与冲击速度大小基本呈线性关系。展开更多
基金The insights gained through these works,particularly from projects IITD/IRD/CW14168,CW14469,and CW14378,have significantly contributed to the development of the analysis presented in this study。
文摘Earthquake-induced soil liquefaction poses significant risks to the stability of geotechnical structures worldwide.An understanding of the liquefaction triggering,and the post-failure large deformation behaviour is essential for designing resilient infrastructure.The present study develops a Smoothed Particle Hydrodynamics(SPH)framework for earthquake-induced liquefaction hazard assessment of geotechnical structures.The coupled flowdeformation behaviour of soils subjected to cyclic loading is described using the PM4Sand model implemented in a three-phase,single-layer SPH framework.A staggered discretisation scheme based on the stress particle SPH approach is adopted to minimise numerical inaccuracies caused by zero-energy modes and tensile instability.Further,non-reflecting boundary conditions for seismic analysis of semi-infinite soil domains using the SPH method are proposed.The numerical framework is employed for the analysis of cyclic direct simple shear test,seismic analysis of a level ground site,and liquefaction-induced failure of the Lower San Fernando Dam.Satisfactory agreement for liquefaction triggering and post-failure behaviour demonstrates that the SPH framework can be utilised to assess the effect of seismic loading on field-scale geotechnical structures.The present study also serves as the basis for future advancements of the SPH method for applications related to earthquake geotechnical engineering.
文摘泥石流是我国西南山区常见的地质灾害。架空输电杆塔在泥石流的冲击下往往发生基础破坏甚至会造成杆塔倒塌。首先采用光滑粒子流体动力学(smoothed particle hydrodynamics,简称SPH)方法和有限元方法(finite element method,简称FEM)相耦合的三维数值方法模拟了泥石流对杆塔基础的冲击作用;在与相关模型试验结果验证的基础上,开展了不同泥石流密度、黏度系数及初始速度条件下对输电塔基础的冲击力作用的参数分析;研究结果表明:随着泥石流初始速度的增加,冲击力峰值会随之增大;前排基础的冲击力峰值均大于后排基础;泥石流冲击过程特性受到泥石流密度和黏度系数影响。与稀性泥石流相比:黏性泥石流冲击基础后,基础下游真空区相对要小;此外,将数值模拟结果与Kwan冲击力公式及铁二院推荐的冲击压力设计公式预测值进行对比分析可以发现:Kwan冲击力公式能较好地预测出基础所受泥石流冲击力的平均趋势,最大预测误差低于30%,铁二院公式预测的稀性和黏性泥石流的冲击压力平均偏低分别约17%和28%。相关研究结果有望为泥石流频发区域输电塔基础的设计和风险评估提供一定的参考依据。
文摘针对飞机典型部位在遭到高速破片攻击后结构整体的战伤状态及破片的剩余行为开展数值模拟。应用LS-DYNA软件,结合有限单元方法(finite element method,FEM)和光滑粒子流体动力学(smoothed particle hydrodynamics,SPH)两者的优势,建立自适应的FEM-SPH耦合模拟方法,并构建2种飞机典型部位的计算模型,采用六面体网格局部细化方法实现了核心位置的精确模拟,并进行试验来验证数值模型;开展了一系列高速冲击战伤模拟,对比了不同工况下破片高速冲击结构后形成的碎片云和破口形貌,并对破片的剩余速度和质量进行分析,确定了破片在结构蒙皮上的临界跳飞角。结果表明:自适应FEM-SPH耦合算法的计算结果与试验结果吻合良好,能够对破片高速冲击战伤进行有效准确模拟;碎片云分布形状随破片速度增加变得狭长,冲击角度会改变碎片云和结构破口形状朝向;碎片云高度和扩散速度随破片速度或角度的变化趋势基本一致并都呈线性关系;破片的速度减少量不随初始速度变化,质量减少量则与冲击速度正相关,两者与冲击角度都负相关;破片临界跳飞角与冲击速度大小基本呈线性关系。
