不同含水率状态下黏性土-混凝土界面剪切特性室内试验研究

利用青岛理工大学自行研制的恒刚度直剪仪,完成了18%、20%、25%、28%共4组不同含水率黏性土与混凝土大型直剪试验,重点对不同含水率和法向应力下剪应力—剪切位移关系曲线进行分析,探讨了含水率的变化对黏性土与混凝土界面力学特性的影响规律。试验结果表明:黏性土与混凝土界面的剪应力—剪切位移关系曲线受到含水率变化的影响。当含水率较高时,界面剪应力达到峰值后剪切变形表现为典型的弹塑性变形;当含水率较低时,界面剪应力—剪切位移关系曲线呈现出折线型关系。界面抗剪强度随含水率的增大而减小,但抗剪强度与法向应力始终保持线性关系,黏聚力受临界含水率25%左右的影响,小于临界含水率时,黏聚力随含水率的增大而增大,大于临界含水率后,黏聚力随含水率的增大而减小;摩擦系数受含水率的影响较小,变化幅度仅为5.5%。

Laboratory Experimental Study on Shear Behavior of Clayey Soil-concreteInterface under Different Moisture Conditions

Based on a self-made constant-stiffness direct shear instrument designed by Qingdao University of Technology, direct shear tests were conducted on four types of clayey soil-concrete interface with water contents of 18%, 20%, 25% and 28%. The shear stress-strain response was analyzed under different water contents and normal stresses, and the effect of water content on the properties of the clayey soil-concrete interface was discussed. Test results showed that water content affected the shear deformation of the clayey soil-concrete surface. When the water content was high, shear deformation exhibited a typical elasto-plastic deformation after the peak interface shear stress was reached. In contrast, when the water content was low the curve of interface shear stress versus shear displacement showed a shape of fold line. The interface shear strength decreased with the increase of water content, but a linear relationship held between shear strength and normal stress. The cohesion was affected by the critical water content of 25%; it increased with increasing water contents when the water content was less than the critical value. However, it decreased with increasing water contents while the water content was more than the critical value. Water contents exerted a limit impact on the frictional coefficient, whose variation was merely 5.5%.