| China is a coal country,the exploitation and utilization of coal resources in the domestic economic development occupies an indispensable position.However,with the continuous progress of urban development in China,the pressing coal problem is becoming increasingly serious,which has greatly restricted the green and sustainable development of China.Therefore,in order to solve the low recovery rate of coal mining and effectively control the surface subsidence,strip filling mining has become an important research.This method can not only effectively solve the above problems,but also reduce the filling cost and solve the problems of insufficient filling materials,which is a green mining technology.In this paper,based on the deficiencies in the design of basic parameters of strip filling in shenyang Xima Coal Mine,the material ratio suitable for the goaf filling in Xima coal mine was obtained through the filling paste ratio and mechanical properties test.Through theoretical analysis,numerical simulation and prediction of surface subsidence,the laws of overburden movement and roof subsidence in strip filling mining are compared and analyzed.The main work and achievements are as follows:According to the ratio of filling paste and its mechanical properties,the ratio of filling materials suitable for goaf is selected with coal gangue,fly ash,cement and water as the main groups.The ratio is:coal gangue:fly ash:cement:water=10.21:4.1:2.5:3.8,the amount of annexing agent agent is 0.22%of the total mass.Under this ratio,the strength of backfill can reach3.89 MPa for 7d and 6.06 MPa for 28d,and the average elastic modulus is 1.2Gpa,which can meet the actual engineering requirements.In addition,after the ultimate strength in the full stress-strain curve of triaxial compression,the paste at this ratio appears a yield platform,presents obvious plastic flow,and has high residual strength.The finite difference FLAC 3D software was used to carry out numerical simulation research to study the deformation law of overlying strata and surface under the condition of strip filling mining,and to compare different filling rates and different mining methods based on the upward dip width of working face.The movement and deformation laws of overlying rock and surface under different influencing factors are summarized,and it is revealed that in the form of"mining,filling and mining",multiple mining disturbances have a greater impact on overlying rock and surface deformation than"mining and filling"mining.Through the stability analysis of the belt filling body and the overlying strata,it can be concluded that the stability of the strata above the key strata can be effectively maintained and the surface subsidence can be effectively controlled as long as the limit breaking distance of the key strata is greater than the width of the unfilled area.A simple mechanical model of"backfill and key stratum"was proposed to determine the unfilled spacing.The relationship between width and spacing of backfill was established by combining SMP criterion,stability principle of backfill and coordination of layout parameters.Is obtained by combining the situation of industrial west horse coal mine,banded pack pack plan and through the analysis of surface subsidence is expected to calculated the corresponding parameters of surface movement deformation,and by using probability integral to be expected,when traditional caving method is adopted by deformation of surface subsidence is expected to a maximum,the peak value,maximum value,maximum curvature,The predicted values are400.02mm,1.40mm/m,1.72mm/m and 0.02×10-3/m,respectively.Strip filling mining can effectively control surface deformation,and it can be found that compared with the original value,the maximum subsidence value,the maximum horizontal value and the maximum curvature value are effectively reduced by 1494.86mm,6.43mm/m and 0.09×10-3/m,respectively.The damage level of surface buildings is classⅰ.Therefore,the implementation plan is feasible. |
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