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黄土既有非饱和性,又有结构性。首先在控制基质吸力的条件下进行了原状黄土与重塑黄土的非饱和直接剪切试验,分析了两种结构性状非饱和土的基质吸力对净应力强度指标、Fredlund抗剪强度公式中参数b、以及Bishop抗剪强度公式中参数的影响。表明两种土的黏聚力随基质吸力的增大而增大,b和均随基质吸力的增大而减小;在相同基质吸力条件下,原状黄土的黏聚力、b和均大于重塑黄土。其次,通过无侧限抗压试验,测试了不同含水率原状黄土、重塑黄土和饱和黄土的单轴抗压强度,得到了不同含水率下原状黄土和重塑黄土的构度值。最后,探讨了非饱和黄土的构度与基质吸力、净应力强度指标、参数b和之间的关系。得到非饱和黄土的b和值随构度分别有单调的变化规律;相同构度值条件下,原状黄土的b和值均大于重塑黄土的值,反映了两种非饱和土结构性状的差异。
Loess both unsaturated, but also structural. The unsaturated direct shear tests of undisturbed loess and remolded loess were carried out under the control of the substrate suction. The net stress intensity index of matrix suction under two kinds of structural unsaturated soils were analyzed. The parameter b , And the parameters in the Bishop shear strength formula. It shows that the cohesion of the two kinds of soil increases with the increase of matrix suction, b and both decrease with the increase of matrix suction. Under the same substrate suction, the cohesion, Plastic loess. Secondly, the uniaxial compressive strength of undisturbed loess, remolded loess and saturated loess with different water contents was tested by unconfined compressive test, and the constitutive values of intact loess and remolded loess at different water contents were obtained. Finally, the relationship between the configuration of unsaturated loess and the matrix suction, the net stress intensity index and the parameter b is discussed. The results show that the b and the values of unsaturated loess vary monotonously with the degrees of structure respectively. Under the same conformation value, the values of b and the values of undisturbed loess are larger than those of remolded loess, which reflect the differences of the structural characters between the two unsaturated soils .