Study on slip damage law between overburden layers of backfilling collaborate with caving fully-mechanized mining

Backfilling collaborate with caving fully-mechanized mining (BCCFM) has exerted a dual technical advantage of fully-mechanized coal mining and backfill mining,achieves green environmental protection while ensuring high productivity and high efficiency. At present,the research on the movement and deformation of overlying rock in collaborative mining has achieved certain results,but it neglects the influence of interfacial slip effects on the overlying strata movement. Based on the principle and process of the filling and caving collaborative mining technology,and according to the structural characteristics of the collaborative mining overlying rock,this paper established a sliding mechanics model of the composite rock beam in the collaborative mining overlying rock,and solved the deflection,slip and shear of the double-layer composite rock beam,analyzed the influence of the coefficient of elasticity foundation k on the four parameters,obtained the slippage law of overlying strata under different conditions of backfilling ratio by physical similarity simulation experiment. The research shows that when the backfill and caving cooperative mining method is adopted,due to the influence of the simultaneous arrangement of the backfill section and the caving section in the same working face,the four theoretical solutions of the double-layer composite rock beam are abruptly compared with the single mining method of the caving method. The statistical value of the four factors change with k in the same law,the curve can be divided into three parts：rapid reduction zone,slow reduction zone and smooth zone. The calculation shows that the critical backfilling ratio of the filling section under the influence of the slip effect is 93.75%; the theoretical calculation and physical simulation results are compared and analyzed,and it is known that the overlying rock in the filling section and the caving section moves to the center of the cooperative working face,which verifies the rationality of the slip model.