| Based on the background of the coordinated develo pment of coal mining and ecological environment in typical coal-fired power bases,this paper takes broken rock blocks as the research object,and uses the combination of theoretical analysis,numerical simulation,physical simulation and laboratory test t o study the mechanical deformation characteristics and void evolution characteristics of different types of broken rock blocks.A three-dimensional visualization numerical model of broken rock blocks based on real shape is established,and the crack evolut ion and particle breakage during the compression deformation process of broken rock blocks are reproduced.The internal influence mechanism of axial pressure and particle size gradation on the spatial structure and mechanical properties of broken rock bloc ks is revealed.At the same time,combined with the indoor grouting filling simulation test,the diffusion law and mechanism of coal-based solid waste slurry in the gap of broken rock blocks are analyzed in detail.The engineering design method of grouting filling mining in caving zone is put forward,and the scientific guarantee measures of grouting filling effect in caving zone are formulated,which provides theoretical support for the demonstration application and industrial promotion of grouting filling mining technology in caving zone.The results of this study are as follows:(1)The instantaneous compressive strength test of broken rock in gob under different coaxial pressures is carried out,and the relationship between gangue lithology,grain size grading,axial pressure and loading rate and the compaction characteristics is obtained.The factor significance of instantaneous compaction characteristics of broken gangue is quantitatively analyzed,and the grain size distribution law in the compaction deformation process of broken gangue is clarified.The influence mechanism of lithology,grain size gradation,axial pressure and loading rate on the macroscopic mechanical behavior of instantaneous compaction of crushed gangue was revealed.(2)A precise modeling method for bulk gangue blocks based on real shape was proposed,a three-dimensional visualization numerical model for irregular broken gangue was established,which reproduced the crack evolution and particle breakage during the compression deformation process of the broken block,and analyzed the space-time evolution characteristics of block breakage,void structure and crack distribution during the bearing process of the broken block sample.The internal influence mechanism of axial pressure and particle size class on void structure and mechanical characteristics of fractured rock was revealed.(3)The particle flow image processing system of crushed gangue under uniaxial compression based on MATLAB image recognition technology is developed,and th e functional relationship between axial pressure,particle size grading and the void fraction of crushed gangue is obtained.The void fraction decreases with the increase of axial pressure;Small particle size has high degree of freedom and active movement,and is easy to migrate and fill the void formed by large particle size.Under axial pressure,the broken rock structure instability and optimization reconstruction occur,and the void size decreases and the stability increases.(4)The three-dimensional gap grouting filling simulation system for broken gangue is developed,the influence law of particle size grading and grouting pressure on grout diffusion is analyzed,the expression of grout diffusion energy loss is derived,the engineering design method of broken gangue grouting filling mining in caving zone is proposed,and the guarantee measures for the effect of broken gangue grouting filling in caving zone are formulated.The sectional mechanical model of broken rock in caving zone was established,the volume of residual space in caving zone was calculated,and the grouting time and filling horizon were determined.Figure: [98];table: [14];reference: [176];... |
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