增湿时黄土的抗剪强度特性分析

采用固结不排水剪切方法，对非饱和原状Q3黄土进行了增湿情况下的三轴剪切试验，得到了湿陷性黄土的极限强度与初始含水量及围压的关系曲线，分析了增湿过程中黄土抗剪强度的变化规律。结果表明，原始含水量下非饱和原状黄土的强度包线是由两条直线组成的折线，高含水量时的强度包线仍符合莫尔-库仑理论准则。非饱和黄土的黏聚力随初始含水量的增大而迅速降低，而内摩擦角受初始含水量变化的影响较小。随初始含水量的增大，总应力指标始终小于相应的有效应力指标；并发现非饱和黄土的有效黏聚力 与初始含水量w之间的关系能较好地拟合为指数函数。最后简要分析了初始含水量和围压对抗剪强度指标的影响。

Analysis of shear strength characteristics of loess during moistening process

The consolidated undrained triaxial shear test is carried out on unsaturated undisturbed loess(Q3) in the case of moistening.According to the test results,the relation curves of ultimate strength of collapsible loess and initial moisture content and confining pressure are obtained;and the shear strength characteristics of loess during moistening process are analysed.It is concluded that the strength envelope of unsaturated undisturbed loess under original moisture content is composed of two beelines.However,the strength envelope under high moisture content still follows Mohr-Coulomb criterion.The cohesive force of unsaturated loess is decreased significantly with increasing initial moisture content,but its internal friction angle is affected slightly by the change of initial moisture content.With the increase of initial moisture content,total stress indices are always smaller than corresponding effective stress indices.It is found that the relation between effective cohesive force of unsaturated loess and initial moisture content can be exactly fitted with exponential function.Finally,the influence of initial moisture content and confining pressure on shear strength indices of loess is analyzed briefly.