K₀-COMPRESSION OF RECONSTITUTED LOESS AND SAND WITH STRESS PERTURBATIONS

Abstract

A simple stress path - for uniaxial confined (K₀-) loading - has been chosen to demonstrate the effect of stress probing on the value of the coefficient of earth pressure at rest K₀. Two materials were used - reconstituted loess and medium sand - and two levels of hydrostatic stress probing (about 20 and 100 kPa). In the first case, with loess, no structural changes were observed. In the latter case, with sand, the soil structure changed partially. Various apparatuses were used : common and true triaxial and biaxial, and the results compared. Triaxial test results were identical and more or less confirmed Jaky's relation and the relationship proposed by the senior author, as well as biaxial tests with dense sand. Cam-clay overpredicted the K₀-values. K₀-coefficients measured on loose sand in the biaxial apparatus were lower than those of the triaxial apparatus. This difference was considered to be due to the stiffer response of biaxial specimens resulting from kinematic confinement.