The Subsidence Mechanisms of Primary Key Stratum with Different Factors: a Case Study

The primary key stratum (PKS) is an important research object in ground control, and all strata up to the surface are controlled by it. However, the geological conditions of coal mining are complex, and coal mining under different geological conditions will cause different degrees of impact on PKS. This paper takes the Meihuajing coal mine as an example, theoretical analysis, numerical simulation and geological condition analysis are comprehensively applied to study the subsidence mechanisms of PKS under the influence of different factors. The results show that subsidence of the PKS is directly proportional to the coal thickness (M) and buried depth (D), and inversely proportional to the distance between the coal seam and the primary key stratum (H). The order of the disturbance degree with each factor on the maximum subsidence of the PKS is M > D > H. It is demonstrated that the disturbance impact of coal seam mining on the PKS in an area with thick coal seams needs to be paid more attention. The research results guided adjusting and reducing the disturbance impact of mining on the PKS.