Investigation into the gas adsorption-loading coupling damage constitutive model of coal rock

Abstract

Coal and gas outburst is the result of comprehensive action of in-situ stress, gas and mechanical properties of coal rock. The coupling effect of loading and gas adsorption eventually leads to the coal rock failure. Based on the principle of strain equivalence and considering the coupling effect of gas adsorption and stress loading, an adsorption-loading coupling damage model is established which breaks through the bottleneck of only considering single influencing factor. Taking briquette samples with controllable properties as the research object, uniaxial compression tests of coal rock at different gas adsorption pressures are carried out, and the model is verified based on the test results. The results of model calculation and tests show that the meso damage stage of coal body can well correspond to the macroscopic deterioration phenomenon and it is in good agreement with the stress-strain curve.It is proved that the model has good applicability and can accurately describe the damage and failure process of coal rock.