含水率对红粘土强度特性的影响

Effect of Water Content on Strength Characteristics of Red Clay

采用FDJ-ZO型非饱和土直剪仪,对不同含水率的红粘土进行抗剪强度试验,结果表明,红粘土在低含水率下的剪应力-剪切位移关系呈应变软化,在高含水率下呈应变硬化,且含水率较低时竖向压力对红粘土的应力-应变曲线亦有影响,随着竖向压力的增加,剪切软化现象逐渐减小;土体抗剪强度随含水率的增大呈非线性减小,减小速率先小后大,且含水率为20%是其抗剪强度减小快慢的分界点;土体粘聚力随含水率的增大呈二次多项式形式减小;土体内摩擦角随含水率的增大呈幂函数形式降低。

The shear strength of red clay under different water content conditions is tested by FDJ-ZO unsaturated soil direct shear apparatus. The results show that,(a) the shear stress-shear displacement relationship of red clay is strain softening at low water content and strain hardening at high water content, the vertical stress has an effect on the stress-strain curve of red clay when the water content is low, and with the increase of vertical pressure, the shear softening phenomenon gradually decreases;(b) the shear strength of soil decreases nonlinearly with the increase of water content, and the decreasing rate shows the characteristics of first smaller and then larger with a demarcation point of shear strength reduction at 20.0% water content;(c) the cohesion of soil decreases with the increase of water content in the form of a quadratic polynomial;and (d) the internal friction angle decreases with the increase of water content in the form of power function.