中文摘要：

针对实际工程中膨胀岩应力状态的变化情况,时南水北调中线膨胀岩开展了三轴循环加卸荷试验以及卸荷试验.试验结果表明,可以用一负指数函数来拟合膨胀岩应变增加量与循环次数的关系.膨胀岩初始损伤度越大,滞回圈面积越大.经历一次循环加卸荷之后,膨胀岩的峰值强度和残余强度的增加量随着初始损伤度的增大逐渐减小.经历多次循环加卸荷作用的膨胀岩,其峰值强度和残余强度比只经历一次加卸荷循环作用的低.卸荷量与变形模量降低量之间的关系可近似用一条直线来拟合.

英文摘要：

Cyclic loading and unloading experiments on expansive rock samples, collected at middle route of South - to - North Water Diversion Project, were carried out according to its stress variation in practical engineering. It is reasonable to fit the rela- tion of strain increment and cycling times of the loading - unloading with a negative exponent function. The larger of initial dam- age degree, the wider of the hysteresis loops are. In the ease of single loading and unloading process, the increment of peak strength and residual strength reduce with the growth of initial damage degree. In the case of multiple - cyclic loading and unloa- ding, the peak strength and residual strength of expansive rock are lower than those values in the single cyclic loading and unloa- ding processes. It is approximate to use a straight line to fit the relation between unloading amplitude and decrease of deformation modulus.