Compressibility-undrained shear behavior relationship for reconstituted sandy clays

Abstract

The sandy clay consisted of hosted clay and sand particles. Isotropically consolidated undrained triaxial compression shear (ICUTCS) tests were performed on two clays with varying sand fractions (SF = 0–60%) and initial water contents of hosted clays (w_{0(hosted clay)} = 1.2-1.4w_{L(hosted clay)}, where w_{Lhosted clay} is the liquid limit of hosted clay). The void ratio of hosted clay (e_{hosted clay}) and undrained shear strength (S_u^*) curve is used to establish the compressibility (e_{hosted clay} -p_c΄) and shear strength (S_u^*- p_c΄) relationship for reconstituted sandy clays. p_c΄ is the isotropic consolidation stress. SF affects e_{hosted clay}, further influencing S_u^* of sandy clays. At the same w_{0(hosted clay)} and p_c΄, when SF ≤ SF_threshold, S_u^* of sandy clays is equal to that of reconstituted clays and the sandy clay is sand particles dispersed distribution stage; when SF>SF_threshold, as SF increases, S_u^* of sandy clays gradually decreases due to the direct contact or clayey bridges between sand particles and the sandy clay is in structural effects of sand particles existing stage. SF, p_c΄ and w_{0(hosted clay)} affect S_u^* of sandy clays by changing e_{hosted clay}. The S_u^*-e relationship of sandy clays is dependent on SF and w_{L(hosted clay)}. The w_{L(hosted clay)} can consider types of hosted clays. An empirical method for predicting S_u^* in reconstituted sandy clays during different p_c΄ is presented. The predicted values are almost identical to the measured data, with errors within ± 10%.