初始组构各向异性对砂土力学特性及临界状态的影响

采用离散元方法，利用半径扩展法和重力沉积法分别生成具有初始各向同性和各向异性内结构的试样，并开展三轴不排水压缩和拉伸试验，研究不同制样方法产生的初始各向异性对砂土宏微观力学特性及其临界状态的影响。运用组构张量对砂土的各向异性进行量化，分析不同初始组构各向异性对组构张量演化的影响并确定了组构张量的临界值。试验结果表明：初始组构各向异性对试样的剪胀性有重要影响，由于受重力影响形成初始各向异性，其各向异性程度越大、组构方向与加载方向越一致，剪胀性越显著；初始组构各向异性对试样的临界状态没有影响，砂土的组构张量具有唯一的临界状态值。

Effects of initial fabric anisotropy on mechanical behavior and critical state of granular soil

A series of triaxial undrained shear tests is conducted on the granular assemblies using discrete element method. The effects of initial fabric anisotropy caused by different sample preparation methods on the mechanical behavior and critical state of granular soil are investigated. The numerical samples are generated using the radius expansion method and the gravity deposition method, which can produce the samples with initial isotropic and anisotropic fabrics respectively. The fabric tensor is used to quantify the fabric anisotropy of granular soil and the influences of different initial fabric anisotropies on the fabric evolution are presented. The results show that initial fabric anisotropy has a great impact on the dilatancy of granular soil. The dilatancy of granular soil is more significant when the samples are more anisotropic or the direction of fabric anisotropy and loading direction are coincided. It is also observed that initial fabric anisotropy has no influence on the critical state of granular soil and the critical fabric tensor has a unique measure associated with the loading mode.