Volume 36, Issue 2 (March 2013)
Effect of Pre-Shear Stress Path on Nonlinear Shear Stiffness Degradation of Cohesive Soils
The nonlinear degradation of soil stiffness from very small to small strain is a key consideration for reliable prediction of ground behavior and its interactions with structures under dynamic excitation and working load conditions. Despite high sensitiveness of stiffness measurement to testing conditions, the effect of the pre-shear stress path on the stiffness degradation has not been properly discussed. Here we investigate the effect of pre-shear stress path on nonlinear shear stiffness degradation of cohesive soils. Reconstituted kaolinite specimens were consolidated to be the overconsolidation ratio (OCR) = 1, 2, and 4 along K0 and isotropic stress paths. The shear stiffness degradations of the specimens during undrained shear were measured using on-specimen linear variable differential transformers (LVDTs). Experimental results show that the pre-stress stress path has a strong influence on the degree of shear stiffness degradation at different OCRs. This influence is interpreted within the context of the rotation angle of shear stress path, which provides a good qualitative explanation of the inconsistent observations in the literature.