11 - Rock failure process analysis method (RFPA) for modeling coal strata movement

Abstract

Rock failure process analysis (RFPA) method was used to simulate the deformation and fracture characteristics of overburden strata, the evolution of gas permeability, and the gas flow in the protected coal seam, in which stress, damage, and seepage coupling are taken into account. In this chapter, two case studies were presented. One case study is on the fracturing and caving of overburden strata induced by longwall mining to study the overburden movement and associated abutment pressures distribution over coal face, and another case study is on the pressure relief gas drainage by mining the protective coal seam at coal mine to evaluate the effectiveness of the long-distance pressure relief gas drainage during extraction of the protective coal seams at great depths. RFPA model not only well reproduces the overburden movement process, reveal the rupturing mechanism of overburden strata and captures periodic weighting of the roof even though there is not any preexisting cracks or fractures in the model, but also captures the enhancement of the gas permeability of the protected coal seam. The results show that rock failure process analysis method is of significant help in better understanding of coal strata movement characteristics and the associated gas flow mechanism in both theory and practice.