Study on Relation Between Abutment Pressure and Overlying Strata Cracks Evolution at Fully-mechanized Sublevel Caving Face

In order to study the relation between abutment pressure distribution and overlying strata mining fissure field, the similar simulation experiment is used to simulate variation of stress field and overlying strata cracks evolution during coal mining. The results show that caving zone, fractured zone and bending zone appear in overlying strata after coal seam mining. The height of caving zone is 22 m, and the hight of fractured zone is 46 m. Abutment pressure in goaf is dynamic changing, abutment pressure in front of the working face can be divided into five zones: stress decreasing zone, stress increasing zone, stress fluctuating zone, stress concentration area and stress steadiness zone. Abutment pressure in goaf affected by key stratum, fissures are well developed before key stratum rupture. After key stratum rupture, the middle part of goaf is compacted and fracture density decreased. But fracture near cutting-hole and working face are still well developed.