Effects of grain dissolution–diffusion sliding and hydro-mechanical interaction on the creep deformation of soft rocks

Abstract

The creep deformation behaviour of soft rocks is one of the most important research fields in geotechnical engineering. In this study, a theoretical model was developed to investigate the coupled effects of the grain dissolution–diffusion sliding and the hydro-mechanical interaction on the creep behaviour of soft rocks. Experimental results validated the model. The results demonstrate that the creep of soft rocks is primarily dependent on the shear stress on the sliding surface, the average thickness of the hydrated film and the amplitude of the cosinusoidal sliding surface. These three parameters can be used to describe the meso-mechanism of soft rock creep stages, i.e. the transient creep stage, steady-state creep stage, and accelerated creep stage. In addition, this study’s findings show that the chemical potential field promotes the mineral dissolution and diffusion on the grain sliding surface and changes its morphology, thereby resulting in the redistribution of stress.