Effects of Sample Disturbance on Strength and Consolidation Parameters of Soft Clay

Abstract

Statistical properties such as the mean value and the coefficient of variation of undrained shear strength and consolidation parameters of disturbed soils were investigated through laboratory testing. A series of unconfined compression tests and standard consolidation tests were performed on natural deposits of Kuwana clay. The values of consolidation yield stress, p c , and compression index, C c , become larger than the actual values for a range of the ratio of q u values of disturbed samples to the undisturbed sample, q u -ratio, being greater than 0.8, and vice versa for a range of q u -ratio being smaller than 0.8. The effects of sample disturbance on coefficient of consolidation, c v , coefficient of volume compressibility, m v , and coefficient of permeability, k, are different for the range of consolidation pressure, p , up to p c . Therefore, the q u -ratio is affected only by these consolidation parameters, and is independent of I p , p, and q u values. For the normally consolidated region, the c v , m v , and k values of remolded soil are about 70%, 40%, and 80% smaller than those of the undisturbed soil, respectively. The relationship between consolidation parameters and sample disturbance is given as a function of the q u -ratio. A comprehensive procedure to obtain the statistical values of strength and consolidation parameters of undisturbed specimens from those of disturbed samples is presented.