由爆炸引起的隧道衬砌与土体相互作用机制的数值模拟分析

Numerical Simulation Analysis of Interaction Mechanismbetween Tunnel Lining and Soil caused by Explosion

为探究爆炸引起的隧道衬砌与土体相互作用机制,基于埋深15 m、含有全饱和颗粒土的单个圆形混凝土线弹性管片组成的隧道模型,对隧道内的管片衬砌与土体在中等幅值的爆破压力脉冲引起的动态变形进行了数值模拟分析。利用有限元程序Abaqus/Standard并结合二维平面应变理论进行建模,同时考虑绝对孔隙压力为零时孔隙水空化,通过精细化单元空间离散,分析了管片衬砌和土体中的应力和变形。研究结果表明:孔隙水空化引起的强非线性对土体性能具有重要影响。具体表现为:孔隙水空化能够显著降低土体的体积模量,并导致大空化带的形成,使得孔隙水从非空化状态向空化状态转变,或从空化状态向非空化状态转变,导致压缩-拉伸过程中土体的应变-应力关系呈现高度非线性,在气蚀区收缩和最终关闭期间,该非线性会在水气混合物溶液中产生高梯度和奇点。

In order to investigate the interaction mechanism between tunnel lining and soil caused by explosion,a tunnel model is presented based on a single circular concrete linear elastic segment buried at a depth of 15 meters and containing fully saturated granular soil,and the dynamic deformation of segment lining and soil induced by blasting pressure pulse of medium amplitude in tunnel is analyzed by numerical simulation.The Finite Element Code Abaqus/Standard is used to model the pore water cavitation with the two-dimensional plane strain theory and the absolute pore pressure is zero,the stress and deformation in segment lining and soil are analyzed.The results show that the strong nonlinearity caused by pore water cavitation has an important effect on the properties of soil mass,as follows-pore water cavitation can significantly reduce the bulk modulus of soil mass and lead to the formation of large cavitation zone,the change of pore water from cavitation state to cavitation state or from cavitation state to non-cavitation state results in the highly nonlinear strain-stress relationship of soil in the compression-tension process,the nonlinearity produces high gradients and singularities in the vapor-water mixture solution.