重塑非饱和黄土的变形、强度、屈服和水量变化特性

Deformation,strength,yield and moisture change of a remolded unsaturated loess

共做了３种应力路径的三轴试验，即：控制吸力的各向同性压缩试验、控制净平均应力的三轴收缩试验和同时控制吸力与净室压力的三轴排水剪切试验。研究结果表明：应力路径对土的变形和水量变化有较大影响；土－水特征曲线依赖于净平均应力；与净法向应力相关的摩擦角在各种吸力下近似等于饱和土的有效摩擦角；剪切强度与吸力的关系是非线性的；三轴剪切条件下的水量变化指标接近常数；屈服净平均应力和屈服偏应力随吸力增大；在净平均应力不变的条件下屈服吸力是一常数但不一定等于土样在历史上曾受过的最大吸力。根据试验资料，提出了一个新的吸力增加屈服条件，并建议了一个确定三轴剪切条件下的屈服应力的新方法。

This paper studies the deformation, strength,yield and moisture change of a remolded unsaturated loess. Three types of stress path tests using a modified triaxial apparatus were conducted, i.e., an isotropic compression test with controlled suction, a triaxial shrinkage test with controlled net mean stress and a triaxial drained shear test with controlled suction and net cell pressure. The results show that stress paths have significant effect on the deformation and moisture change of unsaturated soil, the soil water charateristics curve is dependent on net mean stress,the shear strength versus suction relationship is non linear,the parameter for water content change under triaxial shear condition is approximately a constant, the net mean yield stress and deviatoric yield stress increase with suction, and the yield suction is not necessary equal to the maximum suction experienced by the soil specimen under constant net mean stress. Based on the test data, a modified yield criterion associated with suction increase is proposed. In addition, a new method to identify the yield stress under triaxial shear condition is suggested.