Analysis on the characteristics and influence of the 'arch' structure evolution of overlying strata in gob-side entry retaining under deep thick seam composite roof

摘要

The surrounding rock of gob-side entry retaining is prone to instability under deep thick compound roof.The deformation of its surrounding rock is affected by mining depth, mining thickness, coal seam dip angle, the length of working face and other factors.The stability of surrounding rock of gob side entry retaining is closely related to mechanical properties and dynamic evolution of the arch structure of overlying strata.The paper, according to surrounding rock geological condition of-720 m 1115(1) working face in Huainan Dingji Coal mine, uses FLAC3D numerical simulation for arch structure dynamic evolution of overlying strata under different advancing of working face, and analyzes significant deformation of surrounding rock led by "inner, outer" stress arch dynamic evolution, and finally, in order to control the surrounding rock dynamic instability of gob side entry retaining under thick compound roof, some corresponding control measures are put forward, namely, to support and improve the filling body strength and rigidity in time according to the temporal and spatial characteristics of overlying strata of gob side entry retaining, and in addition to provide multistep stereoscopic anchoring support in the thick compound roof and bolting grouting support to control floor heave of gob-side entry retaining.The comprehensive treatment method can be used to control surrounding rock severe deformation of gob-side entry retaining.Therefore,the relative stability of surrounding rock of gob-side entry retaining can be kept.