基于MEMS传感器测试的黏性土-混凝土力学特性研究

Clay-concrete mechanical characteristics based on MEMS sensors

为更好地测量桩与土界面处的孔隙水压力和径向土压力,在混凝土试块表面安装硅压阻式微电子机械系统(MEMS)传感器,安装方式为开孔嵌入式。通过大型直剪实验系统对不同湿度条件下,含水率分别为18%、20%、25%和28%的粉质黏土-混凝土界面进行力学性能研究,分析了粉质黏土-混凝土界面的抗剪强度特性受水分特性的影响。对混凝土界面性能进行实验研究,结果表明,随着黏性土含水率的增大,界面抗剪强度、剪切破坏位移和界面残余剪切应力均呈先增大后减小趋势,含水率在20%~28%存在一个最优含水率使得界面抗剪特性最优。由此可知,粉质黏土-混凝土界面的抗剪强度特性受含水率影响十分明显,实验结果可为静压桩的工程实践提供借鉴与参考。

In order to better measure the pore water pressure and radial earth pressure at the interface between the pile and the soil,a silicon piezoresistive micro-electro mechanical system(MEMS)sensor was installed on the surface of the concrete block,and the installation method was embedded in the hole.The mechanical properties of the silty clay-concrete interface with moisture contents of 18%,20%,25%and 28% under different humidity conditions were studied by a large-scale direct shear test system,and the influence of moisture properties on the shear strength characteristics of silty clay-concrete interface was analyzed. The experimental study on the interface properties of concrete shows that with the increase of the moisture content of the cohesive soil,the interface shear strength,shear failure displacement and interfacial residual shear stress all increase first and then decrease. There is an optimal moisture content between 20% to 28%,which makes the interface shear resistance optimal. It can be seen that the shear strength characteristics of the silty clay-concrete interface are significantly affected by the moisture content. The test results can provide reference for the engineering practice of static pressure piles.