Research on Development Law of Overburden Rock Fracture in Steeply Inclined and Very Thick Coal Seam Mining

Abstract

Compared with mining the horizontal coal seam and gently inclined coal seam, steeply inclined and very thick coal seam mining has many differences. Since the fracture development law is not clear, resulting in the application effect limitation of gas extraction, prevention and control of air leakage and other technics. In order to improve the efficiency of gas extraction and prevention of air leakage, laboratory similarly model test and numerical simulation were adopted to study the development law of overburden rock fracture, and the results with similarly model test and numerical simulation was identical. The result showed that: Its fracture development law showed a typical "V" structure, roof collapse and overlying strata movement rule were consistent well with separation and fracture development law. When mining the shallow level, the development degree of fracture was relatively low. With the increase of mining depth, the degree of development of fracture and separation rising. After mining 2~3 levels, vertical cracks appear in the working face overburden and it gradually developed up to the ground with the increase of mining depth. Compared with mining the shallow level, the range and development degree of roof separation in mining the deep shallow was higher.