干湿循环作用下镉污染红黏土的变形及强度特征

Deformation and strength characteristics of cadmium-contaminated red clay under dry-wet cycle

以桂林漓江流域的红黏土为研究对象,分别配置浓度为0%、0.1%、0.5%、2.5%的氯化镉溶液制成镉污染红黏土试样,在40℃条件下进行干湿循环,通过室内固结不排水三轴剪切试验研究了Cd^(^(2+))浓度及干湿循环耦合作用对红黏土的变形、强度特征的影响。结果表明:不同Cd^(2+)浓度红黏土的横向收缩率δ_(hs)、竖向收缩率δ_(ss)及体积收缩率δ_(v)随时间增长均呈“S”型曲线上升;不同Cd^(2+)浓度的红黏土剪应力峰值随干湿循环次数增加而增大;随着干湿循环次数的增加,镉污染红黏土黏聚力呈先增大后减小的趋势;Cd^(2+)在未进行干湿循环时就已完成了对红黏土结构的破坏,使内摩擦角达到极限值;Cd^(2+)浓度增大,强度特征破坏作用越明显。

Red clay in Lijiang River basin of Guilin with different cadmium ion concentrations subjected to dry-wet cycles at 40℃is taken as the research object in this paper.Triaxial test is conducted to study the effects of cadmium pollution and dry-wet cycles on the deformation and shear strength characteristics of red clay.The re-sults show that the horizontal shrinkage rate,vertical shrinkage rate and volume shrinkage rate of red clay is in-creased with time in an“S”shaped curve under different cadmium concentrations.The peak shear stress of red clay is increased with dry-wet cycles under different cadmium concentrations.With the increasing of dry-wet cy-cles,the cohesive force of cadmium-contaminated red clay tends to increase first and then decreases.Cadmium finishes its damage to the structure of red clay before the dry-wet cycles,so that the internal friction angle rea-ches the limit value,and the more increased of cadmium concentration,the more obvious the mechanical char-acteristics of the damage.