大应变静力触探数值模拟及锥形因子影响因素分析

摘要

以模拟圆锥在不排水黏土中的静力贯入和分析其影响因素为目标,假设土体为均质弹性—完全塑性材料且服从Mises屈服准则,采用任意拉格朗日—欧拉(ALE)网格划分技术确保锥尖土体在大应变条件下的网格质量,进行大应变有限元数值模拟,并分析了稳定状态下土体刚度指数、原位应力状态和锥尖粗糙程度对塑性区半径与锥形因子的影响,获得了锥形因子表达式.模拟结果表明:塑性区随着刚度指数的增大而增大,锥尖周围塑性区的径向扩张处于柱形孔扩张和球形孔扩张之间,更接近于球形孔扩张;锥形因子随土体刚度指数、锥尖粗糙程度的增大而增大,随土体原位应力状态参数的增大而减小;得到的锥形因子表达式可以量化土体刚度指数、原位应力状态和锥尖粗糙程度的影响,具有较高的精确度.%Simulation of static penetration of cone in the undrained clay and analyses of its influence factor are taken as the research objectives.It is assumed that the soil is idealized as a homogeneous elastic and perfectly plastic material obeying the Von-Mises yield criterion.An Arbitrary Langrangian-Eulerian (ALE) technique is adopted to preserve the quality of mesh under the condition of large-strain for performing large strain finite element numerical simulation.The influences of the rigidity index,in situ stress state and the cone roughness on the radius of the plastic zone and the cone factor under steady-state conditions are analyzed and a theoretical correlation for the cone factor is developed in this study.The simulation results show that the plastic zone increases with the increasing rigidity index,the radial expansion of the plastic zone around the cone tip is between the cylindrical cavity expansion and the spherical cavity expansion,which is closer to the spherical cavity expansion.The cone factor increases with the increasing rigidity index and the cone roughness while the cone factor decreases with the increase of in situ stress state parameter.The formula for the cone factor proposed in this article can be used to quantify the effects of the soil rigidity index,in situ stress state and the cone roughness with reasonable accuracy.The research results are helpful to understand the mechanism of CPT and improve the calculation accuracy of the undrained shear strength.