Numerical simulation of creep deformations around a room in a deep potash mine

Abstract

A finite element technique is used in this work to simulate the closure of an in situ test room developed during excavation of a deep potash mine. For the calculations, a constitutive model for creep was determined from laboratory triaxial tests of salt and short cylinder compressive tests of potash, and was incorporated into a coupled thermomechanical formulation for analyzing creeping viscous flow. The model is a multimechanism representation of three thermally-activated deformation mechanisms acting in parallel. Because the field test was a well-documented, two-dimensional configuration and because the constitutive model was uniquely determined by independent laboratory data, the good agreement obtained between calculations and field data for the significant duration of the test is an important first step in verifying the simulation technique. The constitutive model and numerical methods presented here can be used to understand creep in deep potash mines, and (very importantly) can aid in the design of facilities for isolating radioactive wastes and storing petroleum reserves.