Overburden Rock Movement Laws of Lower Thick Protecting Stratum Mining Among Coal Seam Groups

In order to study the effect of overburden rock movement laws on the stability of 3-1 lower coal seam after that 4-1 thick coal seam is mined in advance as protecting stratum, UDEC discrete element numerical software is used to simulate the impact degree of the face advance on the roof and 3-1 lower coal seam. According to the engineering practice, it shows that the mining in lower thick seam has a great influence on gas release and roof pressure relief.