Scale effect stress–strain model of coal containing gas

Abstract

This paper reviews the relationship between mechanical properties and scale effect of coal specimens containing gas in stress condition. Firstly, the scale effect stress–strain model of coal was established based on Weibull theory and modified Terzaghi equation. And then, the scale effect stress–strain model of coal containing gas was proposed considering the effect of interfacial friction and expansion force of gas. Lative parameters of the model were obtained through experiments. The mechanical properties of coal specimens containing gas were analyzed, and the correctness of the theoretical model was validated. The results indicate that the theoretical curve of the coal specimens’ compressive strength varying with height–diameter ratio shows consistency with experimental curve. The theoretical scale effect stress–strain curve of coal containing gas agrees well with the experiment at the pre-peak. With the increase in the height–diameter ratio, the coal specimens’ compressive strength decreases and the elastic modulus increases. The coal specimens’ compressive strength and elastic modulus decrease with the gas pressure.