土与结构接触界面改进直剪试验研究

目的 研究土与结构接触界面力学行为随接触材料类型及含水率变化规律．方法 通过改进的直剪仪进行黏土自身、黏土与混凝土、黏土与石、黏土与砖4个含水率共64个试样的剪切试验．结果 得到了不同含水率不同正应力下土与不同结构接触界面的剪切应力应变曲线，当土体含水率增大时，黏土内部摩擦角缓慢减小，而黏土与混凝土和黏土与砖接触界面的摩擦角急剧降低；土体内部的黏聚力逐渐减小。而土与结构接触界面的黏聚力均先增大后减小，各接触类型接触界面的抗剪强度随土体含水率的增大均呈下降趋势．只在含水率为13％、法向应力为50kPa的黏土内部剪切时才出现剪胀现象．结论 土与结构接触界面的抗剪强度、摩擦角、黏聚力等力学参数与接触材料类型及土体含水率密切相关，研究结果为工程设计的计算参数取值提供了试验依据。

Experimental Study on Soil-structure Contact Surface Behavior by Improved Direct Shear Tests

In order to learn the changing law of shear behavior of soil-structure contact surface,an experimental study on soil-structure contact surface is carried out by considering various soil water contents and various structure materials.64 soil-structure contact surface specimen tests,which include four contact types such as soil-soil,soil-concrete,soil-stone and soil-brick contact surface,are conducted by using the improved direct shear.According to experimental data analysis,basic mechanical principles of soil-structure interface are obtained.With soil water content increasing,friction angle of soil-soil contact surface reduces very slowly;but the friction angle of soil-concrete and soil-brick contact surfaces reduces sharply.At the same time,soil inner cohesion force decreases gradually and monotonously,while cohesion force between soil and structure first increases and then decreases after reaching a peak value.Shear strength of most contact surface specimens decreases with large water content of soil.Dilation is only found during shear process of soil-soil contact face with 13% soil water content under 50 kPa normal stress.Experimental data shows that mechanical properties of soil-structure contact surface,such as shear strength,cohesion force and friction angle,closely depend on structure material and soil water content.This experimental research provides the good foundation for engineers to determine calculating parameters for engineering design.