Study On Mechanical Behavior Of Coal Mine Gangue Filling Material In Compaction Deformation

Solid filling mining technology is an important technical means of green mining in coal mines.It has played a significant role in the prevention and control of coal mine disasters by filling the goaf with gangue to control strata movement and pressure manifestation.After the gangue filling body enters the goaf,the macro and micro mechanical behaviors such as stress and strain,which are affected by roof pressure,directly determine the control effect of surrounding rock.How to characterize the stress and strain mechanical behavior in the process of gangue compaction is a technical problem to be solved urgently in the rapid detection of the compaction rate of coal mine gangue filling mining.Based on this,theoretical analysis,laboratory test and numerical simulation are synthetically selected to analyze the mechanical behavior of coal mine solid gangue material in compaction deformation,and the micro-evolution characteristics of electric sensitivity and force chain transmission in the process of filling gangue compaction are systematically studied.The main achievements are as follows:(1)The physical and chemical properties of solid filling gangue were tested by scanning electron microscopy(SEM),and the effect of its micro-structure on the compaction deformation characteristics of the material was studied.Through uniaxial loading test of coal mine gangue filling material under lateral confined compression,the stress-compression quantity,stress-bulk density and compaction constitutive relationship are studied,and the effects of particle size ratio and saturation conditions on the compressive strength characteristics of solid filling gangue are analyzed.(2)Starting from the direction of energy consumption in the compaction process of gangue filling material,the energy equation is established and the stress-strain relationship is obtained.The correctness of fitting the stress-strain curve into logarithmic form in the compression process of gangue is verified in physical sense.Based on the relationship between porosity variables and electrical conductivity,the mechanical-electrical coupling model of coal mine gangue filling materials under natural and saturated conditions was deduced.(3)Through the resistivity test of gangue samples with different proportions and different states during uniaxial loading,it is found that the dynamic change of stress-compression-resistivity of coal mine solid gangue during compression has a certain synchronicity;the influence of particle size distribution and saturated state gangue samples on the resistivity characteristics under uniaxial compression is analyzed,and the resistivity increases with the proportions.Considering the effect of water-containing state on the resistivity of gangue,the resistivity of gangue samples under water-containing state is lower than that under natural state because of the sensitivity of conductivity to water.(4)Using the numerical simulation software of particle flow,a method of constructing the particle flow model of Gangue by using flexible cluster element is proposed.Considering the influence of loading rate and saturation state,the numerical simulation of uniaxial compression is carried out.The stress-strain and fracture mode in the analysis results are in good agreement with the experimental results.The distribution of force chain and the evolution law of cracks in the model are studied.It is found that most of the force chains concentrate near the larger particle units,forming a "skeleton force chain" phenomenon,and cracks mainly occur near the larger particle units.