The effect of principal stress ratio on creep behaviour of over-consolidated clay under plane strain conditions

All right reserved. The effect of principal stress ratio on creep behaviour of over-consolidated soil was studied through tests on undisturbed soft clay samples under plane strain conditions. The over-consolidation shear stress ratio (OCRq), defined with the generalized shear stress, was found to be a function of the principal stress ratio and the pre-consolidation pressure. OCRq can provide a better and more direct description of the creep behaviour of over-consolidated soft clay under plane strain conditions compared with the over-consolidation spherical stress ratio(OCRp). There is a one-to-one relationship between the creep coefficient and the OCRq: as the OCRq increases, the corresponding creep coefficient decreases. For the same OCRq, over-consolidated soils with smaller principal stress ratios will have larger creep coefficients. For different principal stress ratios, the over-consolidated soft clays will have smaller generalized shear stress than normally consolidated ones. Under certain conditions, the generalized shear stress increases with decreasing principal stress ratio and the corresponding over-consolidated soil will have greater long-term creep deformation.