补水条件下冻融作用对地基填土抗剪强度的影响

Effect of freeze-thaw on shear strength of compacted clayey soil under water supply

为研究补水条件下冻融循环作用对压实黏土抗剪强度的影响,以地基填土为研究对象,进行了开放系统条件下不同初始状态试样的冻融循环试验,并测定试样冻融过程中的变形和冻融后的水分分布。开展三轴压缩试验,研究了冻融循环次数、初始干密度、初始含水率以及冻结温度对压实黏土黏聚力和内摩擦角的影响。试验结果表明,试样冻融4次后冻胀—融沉变形稳定,冻融5次以后,含水率分布基本不变;黏聚力和内摩擦角均随冻融次数增加逐渐减小,并在冻融5次后稳定,补水冻融作用对土体黏聚力的劣化影响更显著;黏聚力和内摩擦角随试样干密度的增加大致呈线性增加的趋势;在一定的含水率范围内,冻融1~3次后土体黏聚力和内摩擦角随初始含水率增加而增大,冻融5次以后黏聚力和内摩擦角基本不受初始含水率变化的影响;黏聚力随冻结温度的降低先减小后增大,而内摩擦角随冻结温度降低而增大。

In order to study the effect of freeze-thaw cycles on the shear strength of compacted clayey soil under water supply,the freeze-thaw tests with different initial states under open system were carried out on specimens from subgrade filling soil.The deformation and moisture distribution of the specimens during freeze-thaw cycles and after freeze-thaw cycles were measured.The triaxial compression tests were conducted to study the effects of freeze-thaw cycles,initial dry density,initial moisture content and freezing temperature on cohesion and internal friction angle of compacted clayey soil.The results show that after 4 nos.of freeze-thaw cycles,the frost heave and thaw settlement become stable,and the distribution of moisture content is basically unchanged after 5 cycles.The cohesion and internal friction angle both decrease with the increase of freeze-thaw cycles and stabilize after 5 freeze-thaw cycles,and the deterioration effect of freeze-thaw cycles with water supply on the cohesion is more significant.The cohesion and internal friction angle increase linearly with the increase of initial dry density.Within a certain range of moisture content,the cohesion and internal friction angle increase with the increase of initial moisture content after 1 to 3 freeze-thaw cycles,then the cohesion and internal friction angle are not affected by the change of initial moisture content after 5 cycles.The cohesion decreases first and then increases with the decrease of freezing temperature,while the internal friction angle increases when freezing temperature decreases.