Nonlinear Damage Creep Model of Coal or Rock Containing Gas

Abstract

In order to study the creep properties of coal or rock containing gas, the creep properties of coal or rock without gas were studied firstly. Through analyzing the previous creep experiment results of coal or rock, one nonlinear damage creep model of coal or rock was founded based on the general Kelvin model. In this model, assumed that the damage is a function of stress level and time, and introduced one nonlinear hardened function into the general Kelvin model, the nonlinear damage fading creep equation and the nonlinear damage creep whole process equation were obtained. Besides this model, considering the composite structure of coal or rock, gas and gas absorption layer, and assuming that this structure has the stick-slip property under the outside load, so a stick-slip module was added in the general Kelvin model and a new nonlinear damage creep model of coal or rock containing gas was founded. Given the value of the material parameters in the two equations, the creep curves varied with the time were drawn under different axial compression. Through the theoretical curves, the nonlinear damage creep model in this paper was proved to be rational.

Study on the Precursor Characteristics of Instability Failure of Gas-Bearing Coal Based on Stress and Gas Seepage Volume

“…Therefore, it was of great significance to consider the influence of gas on the mechanical characteristics of coal. Many scholars proposed the constitutive equation of gas-bearing coal [20][21][22] and conducted experimental research. It was found that the presence of gas 2 Geofluids would reduce the strength of coal [23,24], the elastic modulus of coal decreased with increasing gas pressure [25], the increase of gas pressure would reduce the critical shear stress of coal, and enormous initial gas pressure and low external load would cause serious coal sample damage [26].…”