青海东西部典型盐渍土抗剪强度对比试验研究

Comparative experiment on the shear strength of typical saline soil in eastern and western Qinghai

为了探究青海省不同区域盐渍土强度特性的差异,以西宁硝湾和察尔汗万丈盐桥附近的盐渍土为研究对象,利用SLB-1型应力应变控制式三轴剪切渗透试验仪,研究了两个区域盐渍土在最优含水率状态下,不同围压和压实度条件下的强度特性,并通过微观机理阐述两个区域盐渍土抗剪强度产生差异的原因。结果表明:(1)在相同试验条件下,压实度为90%、93%、97%时,西宁硝湾盐渍土的黏聚力分别为119.6、131.7、140.6 kPa,而察尔汗地区盐渍土的黏聚力分别为31.1、41.3、42.6 kPa,因此两个区域盐渍土的黏聚力随压实度的增加逐渐增大,在相同压实状态下,西宁硝湾盐渍土的黏聚力大于察尔汗盐渍土的黏聚力,且增幅较大;(2)两个区域盐渍土内摩擦角均先减小后增大,且在93%时最小;西宁硝湾盐渍土的含盐量为0.56%,察尔汗地区盐渍土的含盐量为5.3%,含盐量是造成两个区域抗剪强度差异性的主要原因之一;(3)同一压实度状态下,西宁硝湾盐渍土的颗粒和土颗粒之间的间隙较小,西宁硝湾盐渍土的强度大于察尔汗盐渍土的强度。

In order to explore the difference of strength characteristics of saline soil in different regions of Qinghai province,the strength characteristics of saline soil near Xining Xiaowan and Qarhan Wanzhang salt bridge are studied by using SLB-1 stress-strain controlled triaxial shear permeability tester under the conditions of optimal water content,different confining pressure and compaction degree. The reason for the difference of shear strength between the two regions is explained by micro-mechanism. The results show that:( 1) Under the same test conditions,the cohesion of saline soil in Xining is 119. 6,131. 7 and 140. 6 k Pa respectively,while that in Qarhan is 31. 1,41. 3 and42. 6 kPa respectively when the compactness is 90%,93% and 97%. Therefore,the cohesion of saline soil in the two regions gradually increases with the rising of compactness. The cohesion of Xining Xiaowan saline soil is larger than that of Qarhan saline soil with significant rising under the same compactness.( 2) The internal friction angle of saline soil in the two regions decreases first and then increases which reaches the minimum when the compactness is 93%;the salt content of saline soil in Xining Xiaowan is 0. 56%,and that in Qarhan is 5. 3%. Salt content is one of the main reasons for the difference of shear strength between the two regions;( 3) The particle gap of Xining Xiaowan saline soil is smaller,and the strength of Xining Xiaowan saline soil is greater than that of Qarhan saline soil under the same compactness.