Study On The Timeliness Of Compaction Characteristics Of Crushed Gangue

The compaction deformation of solid gangue backfill directly affects the displacement field and stress field of overlying strata in goaf.Studying the compaction mechanical properties of gangue backfill,discussing the creep deformation mechanism of gangue backfill,and analyzing the evolution law of stop field and stress field during the process of gangue filling mining are the basis for the safety assessment of surface buildings and structures above the goaf.The research topic of sexuality has important theoretical and engineering significance for the realization of"three down"safe coal mining.In this paper,the effect of gangue filling mining on overburden movement and deformation is systematically studied by laboratory test,theoretical study and numerical simulation.The compaction and creep properties of gangue backfill are obtained through laboratory tests,and the stress-strain relationship of gangue backfill is constructed.Winkler foundation beam theory was used to analyze the bending deformation law of goaf roof.The distribution and variation of goaf displacement field and stress field are analyzed by numerical simulation.Main results obtained through research:（1）Through the compaction creep test of gangue backfill,the influence laws of particle grading（Talbot index）and material ratio（water-cement mass ratio）on the compression modulus,porosity,compaction degree and crushing expansion coefficient of gangue backfill are analyzed,and a constitutive model of gangue backfill with lateral confined is constructed.（2）Through the compaction creep test of gangue backfill,the relation between the axial strain and porosity change with time was obtained,the nonlinear viscoelastoplastic creep model was established,and the influence of particle grading（Talbot index）on creep parameters was analyzed.（3）The movement characteristics of overburden in traditional caving mining and filling mining are analyzed.Based on the elastic foundation beam theory,a mechanical model of overburden movement in gangue filling mining is established,and the expressions of roof support stress in coal seam area and filling area are obtained.（4）The numerical simulation software FLAC^3D is used to establish a three-dimensional model of the mining area combined with the actual geological parameters of the stope.According to the data of gangue compaction test,the code of nonlinear compaction constitutive relation of gangue backfill is compiled by using FISH language built into FLAC^3D,and the displacement field and stress field of overburden are calculated.The effects of gangue grading（Talbot index）,filling rate and material ratio（water-cement mass ratio）on overburden deformation are analyzed,and an optimal grading scheme for gangue filling mining is obtained.