中文摘要：

以甘肃省永靖非饱和马兰黄土为研究对象,利用非饱和直剪仪对研究区不扰动黄土进行控制基质吸力和净竖向压力为常数的固结慢剪试验,得到了不同基质吸力和净竖向压力下的非饱和黄土抗剪强度,分析探讨了非饱和黄土抗剪强度与基质吸力的关系。结果表明：随着基质吸力的增加,土体的抗剪强度增大,其中黏聚力c随基质吸力呈线性增长,而内摩擦角随基质吸力变化很小,且在本次试验控制的吸力范围内研究区非饱和黄土φb可近似为一常数并小于内摩擦角,说明在该范围内研究区非饱和原状黄土的抗剪强度随着基质吸力以一恒定的斜率持续增长。

英文摘要：

Taking the unsaturated loess of Yongjing County in Gansu as a study object,This paper conducted the direct consolidation slow shear test with controlling the matric suction and the net vertical pressure for unsaturated and undisturbed loess by using a developed direct shear meter. The shear strength was obtained by controlling different matric suction and the net vertical pressure. The relationship between the unsaturated loess shear strength and the matric suction was analyzed and inquired. The results shows that the loess shear strength increase with the increasing matrix suction,and the cohesion linearly increases with the increasing matrix suction,but the internal friction angle changes little with the matrix suction. Under the control of the matrix suction in the test,the φbvalue is approximately constant and is less than the internal friction angle,indicating that the unsaturated loess shear strength in the study area has a constant slope increase with the change in the matrix suction.