Experimental and numerical analysis of the time-dependent behaviour of argillaceous red sandstone under high in situ stress

Abstract

Understanding the time-dependent behaviour of soft rock under high in situ stress is essential to the evaluation of the long-term stability of the deep-buried tunnels in expressways or coal mines. This paper presents an experimental and numerical study of the time-dependent behaviour of argillaceous red sandstone under high in situ stress. First, several triaxial creep tests for strongly and moderately weathered specimens under the confining pressure of 20-40 MPa were conducted, and the variation of time-dependent damage with time was obtained by investigating the evolution of volumetric strain during the creep process. The test results verify that creep damage has a similar effect on both axial strain and lateral strain of argillaceous red sandstone. Second, a creep damage model that is able to describe nonlinear variation in creep strain and volume expansion for sandstone under high in situ stress was established. Last, the parameters of the proposed model were determined by a back analysis method. The results of back analysis show that the model is able to describe the nonlinear variation in creep strain and volume expansion during the creep process very well.

Simulation of the inelastic deformation of porous reservoirs under cyclic loading relevant for underground hydrogen storage

“…Several experiments have been conducted in the past to study creep deformations in rocks 37 – 42 . Viscoplastic models for rock/soil have also been proposed by several researchers 43 – 46 . Some of them also use viscoplastic formulations to model creep deformations 46 , 47 , since viscoplastic deformations tend to creep deformations when the yield limit tends to zero 30 .…”