Study On Gague Backfill Mining Mechanism Of Overburden Rock Deformation And Fracture

With China’s coal mine high-intensity, extensive mining, due to coal mining caused by coal gangue occupied land, land collapse, surface damage and other issues more and more prominent. Gangue filling and mining technology is an important development direction of green mining, not only can solve the problem of coal pillar recycling and surface gangue stacking, but also can control the surface movement deformation. Study on the mechanism of deformation and failure of overburden in waste rock filling and mining is of great importance to the popularization and application of filling and mining In this paper, the method of indoor experiment, numerical simulation, theoretical analysis and field detection is used to reveal the deformation and failure mechanism of overburden in the goaf. The main conclusions are as follows:(1) The physical and mechanical properties of the charged waste rock and the deformation characteristics of the roof were studied systematically. The compaction characteristics and rheological properties were obtained by the indoor compression test. The results show that the stress-compression ratio curve of the gangue is logarithmic and the deformation modulus and stress are similar to the linear relationship. The deformation modulus increases with the increase of the stress.(2) Based on the FLAC3D numerical simulation method, the stress distribution and deformation and failure of the overburden are studied,and the dynamic damage evolution law of overlying strata is revealed.The waste rock filling in the goaf has an important role in controlling the deformation and failure of the overburden, and the height of the overburden is reduced by 63% after filling and mining. Roof settlement of about 60% of the traditional mining. During the compression of the filling body, the reaction force is generated to the surrounding rock,which improves the stress state of the surrounding rock and improves the strength and bearing capacity of the surrounding rock, and slows down the development of the strata.(3) Through the establishment of the thin plate mechanics model,the supporting reaction force of the gangue to the roof is taken into account, and the deflection surface equation of the overlaying deformation of the gangue is deduced, and the mechanism of the deformation and failure of the overburden in the goaf is revealed. And the problem of the deformation and deformation of the strata is analyzed by using the simplified elastic foundation beam theory. The elastic foundation coefficient and the underfill volume of the overburden are analyzed quantitatively.(4) Based on the continuous monitoring of the roof settlement and the overburden deformation and rupture of the gangue filling and mining,the settlement law of the roof and the deformation and failure characteristics of the overburden are analyzed. The settlement value of the measured roof is about 12% of the height of the roof, and the roof subsidence is close to the maximum at 20m behind the coal face. With the development of the working face, the overlying strata appeared to break the layer, and the height of the fractured rock was about 6 times higher than that of the mining height. It is shown that the filling body limits the further movement of the overburden by preventing the deformation and displacement of the lower roof.