Simulation Test System for Coal and Gas Outburst Triggered by Tunneling under Gas-Filling Condition and Its Application

Abstract

Abstract The physical simulation test is an important means for studying the conditions of outburst occurrence and understanding the evolutionary pattern of outburst. However, the existing physical simulation test device cannot realize the real simulation of coal and gas outburst. In this study, a simulation test system for coal and gas outburst triggered by tunneling under a gas-filling condition was developed. This system consists of five key units: a sealed counterforce unit, a stress-loading unit, a gas-filling unit, a tunneling unit, and an information-acquisition unit. Through the cooperation of these units, the technical difficulties, such as high-pressure gas filling and rapid-pressure replenishment, high-pressure gas sealing, servo tunneling and slag discharge, information acquisition, and inclined model preparation, were overcome. The test system can be used to simulate the outburst triggered by tunnel (Φ150 mm) excavation in a coal-rock model (dimensions: 1,300 mm × 730 mm × 730 mm) under stress loading (maximum of 5 MPa) and gas-filling (maximum of 3 MPa). The proposed test system was employed to simulate the “6.12” coal and gas outburst incident in Huainan, China. The simulated outburst was similar to the original outburst in the following ways: phenomenon and duration of outburst (4.36 s); the shape and location (above the tunneling face) of the outburst holes; the mass (24.5 kg) and ejection distance (16 m) of the coal rock; and the sorting behavior of the ejected coal and rock. Additionally, the information of several physical quantities, including stress, gas pressure, and temperature, was also obtained. The development of this test system is important for an in-depth investigation of the information and patterns of outburst precursors, and for understanding the mechanism of outburst occurrence.