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Improved SPH boundary conditions and simulation for large deformation of soil[J].计算力学学报,2018,35(3):364~371

Improved SPH boundary conditions and simulation for large deformation of soil
Improved SPH boundary conditions and simulation for large deformation of soil

DOI：10.7511/jslx20170621003

 作者 单位 骆钊 中交第二航务工程局有限公司, 武汉 430040中交公路长大桥建设国家工程研究中心有限公司, 北京 250073 汪淳 上海交通大学 船舶海洋与建筑工程学院, 上海 200240

沙土滑坡往往会造成重大的人身财产损失，研究这类土体大变形问题对防灾工程具有指导意义。光滑粒子流体动力学SPH（Smoothed Particle Hydrodynamics）方法是一种拉格朗日型无网格粒子法，十分适用于模拟大变形问题。在SPH方法中，合适的边界处理方法一直是个难点，传统的边界虚粒子法或排斥力法较难模拟复杂边界。本文引入了一种能处理任意形状边界的方法——统一半解析壁面边界条件处理方法USAW（unified semi-analytical wall boundary conditions），通过在控制方程中引入修正因子并保留边界面积分项来弥补边界缺失。为了更准确模拟问题域边界，提出无质量边界粒子的新概念。利用该方法成功模拟了土体滑坡算例，验证了方法的可靠性，并避免了边界零粒子层问题。通过数值模拟，分析了内摩擦角和黏聚力等土体物性参数对滑坡过程的影响。最后，应用该方法研究了滑坡冲击楔形体时的压力响应。

Landslides may cause serious loss of life and property.Study on the large deformation of soil has great significance to disaster protection engineering.Smoothed Particle Hydrodynamics (SPH), a Lagrangian mesh-free particle method, is suitable for solving such large deformation problems.However, boundary treatment is a key issue in SPH due to the Lagrangian nature of the method.It is difficult to simulate complex boundaries by traditional boundary treatment methods, such as the virtual particle method and the repulsive force method.In this paper, an approach for arbitrary boundaries, i.e.the unified semi-analytical wall (USAW) boundary condition, is employed to solve the particle deficiency problem near the boundary by the introduction of a correction factor and the boundary surface integral.To model the boundary of problem domain more precisely, boundary particles without mass are proposed.Landslides are simulated successfully by the new method, and comparisons with traditional boundary treatment approaches are made.It is found that our method can avoid the zero particle layer problem and is suitable for the simulation of arbitrary wall boundaries.Characteristics of soil dynamics in landsides with respect to some physical parameters, such as internal friction angle and cohesion, are revealed.At last, the method is applied to study the pressure response of a wedge impacted by the landslide.