Study on Creep Constitutive Model of Stratified Siltstone and its Application to Environmental Hazards Treatment

Abstract

Mining causes environmental hazards which have an adverse effect on ecological system and human living environment. Rock is the main body of underground coal mining, and among them stratified siltstone is very common. Creep and instability of underground stratified siltstone is one of the main inducing factors of ground fissures and ground surface settlement. In this study, on the basis of fully considering its stratified structure features, we built and theoretically analyzed the viscoelastic-viscoplastic constitutive model of stratified siltstone. Creep tests and numerical simulation under multi-stress were conducted. Numerical simulation results under high, medium and low stress were consistent with the creep test results, it made up for the deficiency of traditional creep models in predicting plastic deformation at low stress level. Numerical simulation results showed that under different boundary conditions, the proposed model had advantage to more accurately simulate creep behavior of stratified siltstone compared with traditional models. Also, the numerical simulation results reveled creep characteristics of underground roadway surrounding rock, based on which a supporting scheme was put forward. In the stress adjustment stage, the strain rate dropped significantly from 14.6mm/d to 10.3mm/d. Then, it entered the deceleration creep stage. Creep of roadway surrounding rock and ground surface settlement stopped. The environmental hazards were solved to a great extent.