基于修正应力法的横观各向同性摩尔-库仑准则及被动土压力公式

Cross-anisotropic Mohr-Coulomb criterion and formula of passive earth pressure based on modified stress method

采用修正应力法考虑各向异性对土的抗剪强度的影响,该方法引入组构张量调整不同方向应力分量的相对大小,使得各向异性土在修正应力空间中等效成各向同性土。用修正应力张量代替真实应力张量,就能将摩尔-库仑强度准则发展至横观各向同性,公式的形式不发生改变,强度参数仍为与加载方向无关的常量。通过对比根据3种不同的修正应力公式得到的内摩擦角与加载方向的关系曲线,分析了组构值对内摩擦角变化规律的影响,在偏平面上绘出了连续规则的强度包线,并预测了不同各向异性岩土类材料的三轴压缩和真三轴试验结果。最后,根据横观各向同性摩尔-库仑准则计算水平沉积地层中挡土墙上的被动土压力,得到了简洁的显式表达式,验证了修正应力法的实用性。

The modified stress method is adopted in this paper to consider the effect of anisotropy on soil strength.This method introduces the fabric tensor to adjust the relative magnitudes of stress components in different directions,so that anisotropic soil can be equivalent to isotropic soil in the modified stress space.By substituting the modified stress tensor for the ordinary stress tensor,the Mohr-Coulomb strength criterion can be developed to be cross-anisotropic.The form of the criterion remains unchanged,while strength parameters are still constant and independent of the loading direction.This paper compares the relation curves between the internal friction angle and the loading direction according to three different modified stress formulas and analyzes the effect of fabric on the variation of the internal friction angle.Continuous and regular failure envelops are drawn in the deviatoric plane.Meanwhile,triaxial compression and true triaxial test results of different anisotropic geomaterials are predicted.Finally,the cross-anisotropic Mohr-Coulomb criterion is used to calculate the passive earth pressure on the retaining wall in the horizontally sedimentary stratum.The obtained expression is simple and explicit,which verifies the practicability of the modified stress method.