膨胀土-混凝土界面剪切特性研究及界面系数修正

为对不同含水率下与不同法向应力下的膨胀性土的界面抗剪强度-界面剪切位移曲线进行分析，通过设计室内膨胀土-混凝土界面直剪试验，研究各含水率对膨胀土-混凝土界面各力学性质的影响。结果表明：不同含水率条件下的应力应变曲线均无应变软化现象，基本符合应变硬化模型；含水率的增长，对界面抗剪强度有较为明显的劣化影响，应力应变曲线的峰值也随之愈发滞后；同一含水率的界面抗剪强度与法向应力较好地符合摩尔-库伦强度准则，随着含水率的逐渐增长，界面抗剪强度也呈现递减态势；界面黏聚力先呈增长态势，后呈逐渐减小态势；界面等效剪切模量呈现下降趋势，同时通过微观角度对界面黏聚力和界面内摩擦角引起的界面强度变化规律进行了机理性的分析。界面内摩擦角则随着含水率增加逐渐地呈现反比例函数降低态势，引入界面摩擦系数，进一步细致分析界面摩擦力学性质，同时修正了界面黏聚力和法向应力对界面摩擦带来的较大影响，针对于浅层边坡土体与桩基础的摩擦估算，考虑到法向荷载对于界面摩擦系数影响较为合理。

Study on shear characteristics of expansive soil-concrete interface and correction of interface coefficient

In order to analyze the interface shear strength-shear displacement curve of expansive clay under different water content and different normal stresses, the influence of water content on the mechanical properties of the expansive soil-concrete interface was studied through the indoor expansive soil-concrete interface. The results showed that the stress-strain curves under different water content conditions have no strain-softening phenomenon, which basically conforms to the strain-hardening model. The increase in water content has a more obvious deterioration effect on the shear strength of the interface, and the peak value of the stress-strain curve also lags behind. The interface shear strength and normal stress of the same water content are in good agreement with the Mohr-Coulomb strength criterion. With the gradual increase in water content, the interface shear strength also shows an decreasing trend. The cohesion of the interface increases first and then decreases gradually. The equivalent shear modulus of the interface shows a downward trend. At the same time, the change rule of interface strength caused by interface cohesion and interface internal friction angle is analyzed by microscopic angle. With the increase of water content, the internal friction angle of the interface gradually shows an inversely proportional function decreasing trend. The interface friction coefficient is introduced to further analyze the mechanical properties of the interface friction. At the same time, the great influence of interface cohesion and normal stress on the interface friction is corrected. For the friction estimation of shallow slope soil and pile foundation, it is reasonable to consider the influence of normal load on the interface friction coefficient.