干湿循环周次对川西红黏土影响的固结不排水剪切试验

选用成都市新津区红黏土，开展了针对经不同干湿循环周次n_dw作用的土样的固结不排水剪切试验，研究地下水位季节性反复升降对川西红黏土力学特性的影响。结果表明:随n_dw的增加，土样应力-应变曲线依次经历三个典型应力响应状态，分别为“应变硬化”型-“应变过渡”型-“应变软化”；在不排水固结剪切路径下，土样孔隙水压随n_dw的增加呈现逐渐增长的变化趋势，且初期的增长速率较大，后期趋于平缓；随n_dw的增加，有效应力路径曲线从最初的近似“S”型逐渐演化为“镰刀”型，干湿循环作用对土样的体应变产生较为显著的影响，随n_dw的增加，干湿循环引起的土样体积压缩应变越小。

Consolidated Undrained Shear Test of Influence of Drying-wetting Cycles on Red Clay in Western Sichuan

In relation to red clay selected from Xinjin district in Chengdu, consolidated undrained shear tests were carried out on soil samples subjected to different drying-wetting cycles n_dw, and the influence of seasonal repeated rise and fall of groundwater level on the mechanical properties of red clay in Western Sichuan was studied. The results show that with the increase of n_dw, the stress-strain curve of soil sample experiences three typical stress response states in turn, which are "strain hardening", "strain transition" and "strain softening"; Under the undrained consolidation shear path, the pore water pressure of soil samples increases gradually with the increase of n_dw, and the growth rate is large in the initial stage and tends to be flat in the later stage; With the increase of n_dw, the effective stress path curve gradually evolves from the initial approximate "S" type to "sickle" type. The drying-wetting cycle has a significant impact on the volumetric strain of soil samples. With the increase of n_dw, the volumetric compressive strain of soil samples caused by drying-wetting cycle is smaller.