采用环剪仪对超固结黏土抗剪强度特性的研究

利用大型高速环剪仪，对不同超固结比、法向应力和剪切速率下的超固结饱和黏土的峰值强度和残余强度特性进行了研究，并对循环荷载作用前后残余强度的变化进行了初步探讨。试验结果表明，（1）超固结比对超固结黏土的峰值强度和残余强度有着明显的影响；（2）在剪切速率相同的条件下，土体达到残余强度时的位移取决于现存的应力状态，而与应力历史无关；（3）剪切速率越大，峰值强度随之增大，达到稳定残余强度时的剪切位移也随之增加，但剪切速率的变化对残余强度值几乎没有影响；（4）在循环荷载作用下残余强度不同程度的降低，最大降低幅度达12.2 %；当土体剪切面为不规则剪切带时，施加循环荷载后出现残余强度上升的现象。

Shear strength behavior of overconsolidated clay in ring shear tests

Detailed studies were conducted on shear peak strength and residual strength of overconsolidated saturated clays at different overconsolidation ratios, normal stresses and shear speeds by employing ring shear apparatus. The residual strength behaviors before and after applying cyclic loads were also investigated. Test results indicate that: overconsolidation ratios have obvious effects on shear peak strength and residual strength of overconsolidated clays; under the same shear speed, shear displacements reaching residual state depend on the present stress state, not being relevant with stress history; with shear speed becoming faster, both peak strength and shear displacement reaching residual state increase, while shear speed has no effects on residual stress; Residual strengths after applying cyclic loads decrease differently, the largest decrease up to 12.2 %. When shear surfaces are irregular shear bands, residual strengths increase after applying cyclic loads.