Investigation on risk fields assessment in the longwall working face with single side roof cutting along the gob

Abstract

AbstractThe number of mines using roof cutting and pressure relief technology to extract mine deep coal resources is increasing daily. Most of these mines are facing the risk of high gas emission and residual coal spontaneous combustion disasters, and the composite disasters caused by these two risks also threaten the safety of mine production. On the basis of constructing a model for the evolution of porosity and permeability in a single side roof cutting along the gob, this study studied the occurrence locations of gas explosion risk areas, oxidation and heating risk areas, and composite disaster areas under different air supply and gas emission conditions, and summarized the evolution laws of composite disaster risk areas. The research results show that the roof rock collapse caused by roof cutting and pressure relief technology reduces the permeability of porous medium, which significantly reduces the sensitivity of the width of the oxidation temperature rise zone and the composite disaster area to the air supply. The increase in air supply causes the position of the composite disaster risk zone inside the goaf to shift toward the deep part of the goaf, while the width remains basically unchanged. The increase in gas emissions has suppressed the occurrence of coal spontaneous combustion in the goaf, while also keeping the gas concentration in a large area outside the upper limit of gas explosion. The research content enriches the research system of gas and oxygen flow fields in the goaf cutting face, and has positive significance for the promotion and application of goaf cutting technology and the understanding of secondary disasters caused by it.