Abstract: Based on the background of the increasingly serious composite disaster of coal and rock mass impact-outburst in the deep, and closely surrounding the key scientific problem of the evolution mechanism of coal-rock flow (gas) -solid coupling mechanical behavior under multi-field conditions, a true triaxial multi-parameter test system for coal and rock containing gas has been developed independently. The test system can fully simulate true three-dimensional stress environment and loading characteristics of coal and rock in the deep. It is hoped that the test system can clarify the mechanical behavior of coal and rock during loading and failure, the spatio-temporal evolution law of acoustic emission and charge induction signals, grasp the mechanism of impact-outburst compound disaster breeding, and establish scientific means of disaster prevention and control. The experiment system consists of 6 sub-systems, i.e. loading-unloading, load-displacement monitoring, methane environment application-monitoring, electric control, acoustic emission and charge induction. It has the characteristics of high-stress, true triaxial, multi dimension, high precision, good stability, multiparameter and multi loading-unloading path. Experiments of coal under different gas pressures, lateral pressure ratio and unloading path are carried out with the system, analysis of total stress-strain curve, acoustic emission and charge induction signal. The results show that the strength of peak and residual, ductility of coal are changed by methane; the anisotropy characteristics gradually weakened with the decrease of lateral pressure ratio; strain developed in the direction of low stress; the lateral pressure ratio and the loading/ unloading path are important stress environmental factors influencing mechanical behavior of coal rock. The system provides a reliable experimental basis for the follow-up study of fluid-solid coupling mechanical behavior of coal rock containing methane.

Key words: coal rock containing methane, true triaxial experimental system, fluid-solid coupling, lateral pressure ratio, acoustic emission-charge signal monitoring