Study On Deformation Characteristics Of Gangue Backfill And Stability Of Overlying Rock In Deep Backfill Stope

The gangue filling coal mining technology has significant technical advantages in the control of overlying rock mine pressure and the disposal of gangue solid waste.It is of great significance to the research on the current deep filling mining technology.For this reason,this paper adopts a combination of laboratory tests,theoretical analysis,numerical simulation,and similar simulation methods,through the study of the three-directional bearing compression of the gangue filling material.The stability of the overlying rock in the deep gangue filling stope was discussed,and the following research results were obtained:(1)Self-developed large-scale gangue three-directional compression test system suitable for deformation analysis of gangue filling materials.Through experiments,the macroscopic axial strain and volumetric strain of all levels of gangue filling materials under different confining pressure and loading rate conditions were analyzed.Based on the mechanical behavior characteristics,the fitting relationship equation between strain and particle size gradation parameters,confining pressure and loading rate during the three-directional load-bearing compression process of gangue filling materials is established,which provides a basis for the rational selection of gangue filling bodies in deep sites.(2)The long-term effects of different stress levels,confining pressures,and gradations on the compaction creep characteristics of gangue filling materials were obtained through the threedirectional compaction creep test of gangue filling materials.Based on the statistical analysis of the gradation evolution characteristics of gangue filling materials The process of the crushing rate of gangue particles was established,and the creep power-law constitutive model of the gangue filling material under the double logarithmic coordinate was established,and the crushing and creep mechanism of the gangue filling material in the deep mine was revealed.(3)By establishing a numerical model of the real shape of gangue blocks in the form of Clump rigid clusters and Cluster flexible clusters,the microscopic deformation laws such as particle motion,skeleton force chain,and particle breakage during the three-directional load-bearing deformation of gangue filling materials were explored,revealing the internal relationship between the macroscopic load-bearing deformation and the microscopic particle movement and crushing of the gangue filling material was verified,and the three-directional load-bearing deformation characteristics of the gangue filling material were supplemented and verified.(4)Based on the mechanical contact relationship between the gangue backfill and the surrounding rock of the stope,the vertical bearing effect and lateral support of the gangue backfill on the surrounding rock were discussed,and the three-directional gangue backfill and surrounding rock with different contact states were established.The mechanical model,combined with the coupled numerical simulation results of deep gangue backfill mining,explored the stability of stope overlying rock and gangue backfill under different burial depths and filling rates.(5)Combined with the analysis of the bearing effect of the gangue backfill,the surrounding rock and coal pillar,the deep backfill and the surrounding rock(coal pillar)collaborative bearing system was established,and the overlying rock under the gangue backfill-surrounding rock cooperative bearing was explored through similar material simulation tests.Structural characteristics and the law of occurrence of mine pressure in stopes,put forward an on-site monitoring-feedback system for deep filling gobs,and provide theoretical and technical guidance for the field application of gangue filling in deep mines.The research results provide a theoretical basis for the law of stope pressure in deep backfill mining,the movement control of overlying strata,the selection and design of deep gangue filling materials,and the prediction of surface subsidence.Promote the popularization and application of deep filling mining technology.The paper has 139 figures,17 tables,and 153 references.