Study On Roof Stability Characteristics Under High Concentration Cemented Filling Mining Of Coal Mine Steel Slag

Solid waste filling mining can effectively control rock movement,inhibit surface subsidence,reduce geological disasters,and can handle and utilize certain solid waste,effectively improve the mechanical environment of the overlying strata of the mine,and reduce roof pressure.At the same time,the mining method is low in price and saves resources.It is an important way for mining enterprises to achieve safe and efficient production.Taking the working face of a mine in Fengfeng mining area of Handan,Hebei Province as the research object,based on the study of the reasonable ratio and mechanical properties of the high concentration cemented filling material of steel slag,combined with theoretical analysis and numerical simulation methods,the law of roof settlement and deformation before and after filling is revealed,and the evolution characteristics of mine pressure in the mining and filling process are analyzed.The main research contents and conclusions are as follows :(1)Based on the analysis of the physical and chemical properties of steel slag and recycled aggregate,the high concentration cemented filling material of solid waste was optimized.The strength of 28 groups of samples was measured by uniaxial compression test,and the reasonable ratio of high concentration cemented filling material of solid waste was obtained.The compression deformation test,variable angle shear test and Brazil splitting test were carried out on the reasonable ratio of filling materials,and the corresponding mechanical parameters were obtained.(2)In the basic theory of variational method,the influence of steel slag high concentration cemented backfill on the settlement deformation of hard roof is considered,and the mechanical model of roof on Winkler foundation is constructed.For the ’ OX ’ type failure under initial pressure,the boundary conditions of four-side fixed support and four-side simple support are used to solve the Galerkin deformation equation and the Navier deformation equation in the variational method.In addition,for the ’ CY ’ type failure under periodic pressure,the boundary conditions of three sides clamped and one side free and three sides simply supported and one side free are selected,which are solved by Ritz deformation equation and Levy deformation equation in variational method.Aiming at the Galerkin deformation equation,different deflection expressions are preliminarily selected and substituted into the deformation equation to obtain the analytical solution of the deflection of the hard roof.The test data is substituted into the analytical solution to verify the correctness of the model.Based on the mechanical model,the roof settlement deformation law and reasonable filling rate under filling mining are obtained,and the roof deflection changes before and after filling in the first failure stage are analyzed.(3)Two kinds of mining methods,one-time mining and simultaneous mining and filling,are used to simulate the mining law of the upper overburden strata in the strike of the working face,the tendency of the working face and the plane direction of the horizontal roof before and after filling.The changes of stress,displacement and plastic zone in z direction before and after filling under different mining distances are analyzed and compared.