考虑各向异性影响的冻土修正线性黏结接触模型开发及应用

Development and application of modified linear bond contact model of frozen soil considering anisotropy

针对冻土的各向异性特性,基于线性黏结接触模型,建立了能够反映冻土各向异性特性的修正线性黏结接触模型,并通过C++语言生成供颗粒流程序PFC^(3D)调用的离散元本构子程序DLL。首先对单一接触进行了拉伸、直接剪切测试,通过对比数值与理论结果,验证了考虑各向异性影响的冻土修正线性黏结接触模型的正确性。此外,模拟了不同温度条件下的冻土三轴压缩试验,并与试验得到的应力-应变曲线进行对比,结果表明,所提出的修正线性黏结接触模型对冻土具有较好的适用性。基于标定后的模型细观参数,开展了一系列的三轴压缩离散元数值模拟,利用模拟结果探讨了虚拟弱面法向倾角对冻土的应力-应变曲线特征、强度及抗剪强度指标的影响,并分析了有效配位数、细观组构量的演化规律。研究结果可为冻土各向异性宏-细观力学特性提供数值基础。

Aiming at the anisotropic characteristics of frozen soil,this paper established a modified linear bond contact model that can reflect the anisotropic characteristics of frozen soil based on the linear bond contact model,and generated a discrete element constitutive subroutine(DLL)for particle flow program(PFC^(3D))calls through C++.Firstly,tensile and shear stimulations were carried out on a single contact.By comparing numerical and theoretical results,the calculation accuracy of the modified linear bond contact model for frozen soil considering orthotropic was verified.In addition,the triaxial compression tests of frozen soil at different temperatures were simulated and compared with the stress-strain curves obtained from the tests.The results show that the proposed modified linear bond contact model has good applicability to frozen soil.Based on the calibrated meso-parameters of the model,a series of triaxial compression discrete element numerical simulations was carried out.Using the simulation results,the influences of the inclination of the virtual weak surface on the stress-strain curve characteristics,strength and shear strength indexes of frozen soil were discussed,and the evolution laws of effective coordination number and meso-fabric quantity were analyzed.The research results can provide a basis for using numerical methods to study the orthotropic macro meso-mechanical properties of frozen soil.