中文摘要：

岩土体抗剪强度是分析评价斜坡稳定性的关键指标。为了弄清可溶盐在黄土抗剪特性中的作用程度及控制机制,以兰州重塑黄土为对象,基于直剪试验,研究了黄土抗剪强度及其参数在不同溶滤次数下的变化特征。结果显示,可溶盐对非饱和黄土抗剪强度及黏聚力具有明显非线性弱化作用,而对内摩擦角的影响则相对微弱。其中,抗剪强度与黏聚力随可溶盐的变化规律存在临界分段现象,其降低幅度在溶滤1次时达到最大值,在溶滤5次后近似于0;而降低速率以易溶盐含量2 620 mg/100 g干土为分界值,呈先快后慢的变化特征。上述关系的内在机制是,在溶滤初始阶段,黄土抗剪特性弱化主要源于易溶盐与部分难溶盐分解;随溶滤次数增加,则更多依赖于易溶盐分解与基质吸力减弱。

英文摘要：

It is well known that shear strength of soil plays a key role in analyzing the stability of slope. To clarify the variations of shear strength and parameters of the loess after leaching for different times, a series of direct shearing tests is conducted on samples from Lanzhou loess. Results show that, shear strength and cohesion of unsaturated loess decreases significantly nonlinearly with the decrease of soluble salts, and inner friction angle is slightly changed. Specifically, the reduction reaches the maximum value after leaching 1 time and trends zero after leaching 5 times. It is also found that the reduced rate is large when soluble salt content is greater than 2 620 mg/100 g and then reduces. The decrease of loess＇ s shear strength comes primarily from the decomposition of soluble salts and calcium carbonate at the initial stage, and it relies on the dissolution of soluble salts and weakening of matric suction afterwards.