Based on the technique of in-situ gob-side entry retaining with entry-in packing in fully-mechanized top-coal caving mining face(GEREPTF),the mechanical model of the surrounding rock for GEREPTF is established according to the key strata theories.

Aiming at the abnormal strata behavior in the advance entry of 1303 fully-mechanized working face in Xinglongzhuang coal mine,the movement rule,characteristic,step distance of fracturing,position and mode of fracturing of the overlying strata in mining process is analyzed by using the key strata theory.

The key strata control the process of the overlying strata movement and the dynamic expanding of the mining-induced fracture in coal mining stope,and then it will influence the gas dynamic emission of the adjacent layers in the mining-induced fractured rock mass.

Resolving of thin base rock-gradient layer composite board and single key stratum;

Stable characters of key stratum in stagger arrangement roadway layout top-coal caving mining;

Primary exploration of key layer postion effect in long-distanc stress-relieved exploitation;

Base on the key layer theory and mining subsidence theory of the strata control,with the simulated material simulation test and the FLAC and UDEC numerical simulation calculation,the paper studied how to set the top boundary scope of the model for the strata displacement simulation.

Under the guidance of key layer theory in strata control,the conditions of stiffness and strength for key layer are established by using elastic slab theory.