Study of stability of key stratum in stagger arrangement roadway layout mining

Through theoretical analysis and FLAC^3D numerical simulation of disordered layer location coal mining method of first and succeeded working face on the overlaying strata movement rule are analyzed,draw on the experience of key strata mature theory formula,Overburden in the calculation is simplified to thin plate model and combined the mechanical properties of beam,the face of above key strata of the limit span is obtained,After the first mining face mining,overburden caving form as the arch,into the wind lane of disordered layer location succeeded working face which was arranged in the stress reducing area of the first working face goaf below,When mining the succeeded working face,the first and the succeeded working face roof together as a whole,the two strata on the working plane down behind eventually formed a large arch,two face key stratum is a single long face characteristics of key stratum,after a mining disordered layer surface subsidence is slow uniform.