Roof Movement Analysis In The Backfill Mining Area Based On Nonlinear Elastic Foundation Beam

The exportation of “Three Under” trapped coal resource has been solved by solid backfill mining menthod and it is necessary to study the roof movement in the mining area based on the compaction characteristics of backfill material during the development of this innovative technique.This paper starts with study of the experiment test and filed measurement of nonlinear elastic foundation coefficients of the backfilling gangue,then followed the stress-deformation amount field measurement curve,the nonlinear elastic foundation coefficients are obtained.Based on these,theoretical analysis,numerical simulation,field measurement are applied to establish the stress analysis model of immediate roof on nonlinear elastic foundation coefficients.Finite difference method and Newton iteration method are used for solving the deflection and internal force of immediate roof.Also how the advancing length of working face influence the deflection and internal force of the immediate roof are studied.From the research above,the accuracy of the nonlinear elastic foundation coefficients are verified.The following results are obtained:(1)The paper comes up the mentod to represent the anti deformation ability of backfill gangue with differernt elastic foundation coefficients.Based on the stress-deformation amount,the equation of nonlinear elastic foundation coefficients and its counter force,and the stress analysis model of immediate roof based on nonlinear elastic foundation coefficients are established;(2)The finite difference method and Newton iteration method are used for solving the deflection and internal force of immediate roof.The results has been compared with immediate roof based on linear elastic foundation coefficients.Then the deflection and internal force of two kinds of immediate roof under differernt elastic foundation coefficients under different advancing distance.A numerical simulation model is built to simulate the roof movement of nonlinear elastic foundation coefficients and how the advancing length of working face influence the deflection and internal force of the immediate roof are studied;(3)The field measurement of 7203 W backfill mining working face in ZhaiZhen Coal Mine has provided the roof subsidence law and it has been used for verifying the accuracy of representing the anti-deformation ability of backfill gangue by nonlinear elastic foundation coefficients.