| The open-stope subsequent filling mining method can use the large-diameter deep-hole blasting technology to achieve high-intensity mining of mineral resources,improve mining efficiency and reduce mining costs.At the same time,the effective and timely filling of the goaf can ensure mining safety and efficient recovery of resources.In the process of open stoping subsequent filling mining,backfill strength,the damage of filling body and the structural parameters of stope have important influence on the safe and efficient production of mines.The research on such problems has important engineering value and theoretical significance for ensuring mining safety and improving resource recovery.Based on the engineering background of Jinding Iron Mine in Shandong Province,this paper adopts the methods of laboratory test,theoretical analysis,numerical simulation and on-site detection(monitoring)to carry out in-depth research on the mechanical properties of ore rock,the strength prediction of fractured rock mass,the strength distribution law of stope filling body,the blasting effect and parameters and the structural parameters of subsequent filling stope.The main research contents and results are as follows:(1)Through the uniaxial compressive strength test,tensile strength test and corner-mold shear test of the ore rock specimens taken from the mine field,the relevant mechanical parameters of the ore rock in the stope are obtained.According to the CT scanning test of fractured rock mass,the three-dimensional particle flow code(PFC3D)is used to reconstruct the random micro-fracture network inside the ore-rock sample,and the uniaxial compression numerical simulation is carried out.A method for predicting the strength of ore-rock samples by using the projection area of micro-fractures in the maximum effective shear stress plane is proposed.The formula for estimating the rock strength according to the projection area of the fracture to the maximum effective shear stress plane is constructed,which provides basic data for the subsequent study of stope structural parameters and stability.(2)The small portable coring and strength detection equipment without external energy is used to detect the strength of underground filling body on site,which realizes the fast,efficient,low disturbance and accurate determination of the filling field,and solves the problem of on-site detection of filling body strength.(3)According to the field measurement results of backfill strength,BP neural network algorithm and nuclear magnetic resonance test are used to predict backfill strength with different drilling depths,and the correlation between pore characteristics and backfill strength with different heights is established.Finally,the spatial distribution law of backfill strength at different depths and heights of stope is obtained.Through the statistical analysis of the filling field test results and laboratory test data,the corresponding relationship between uphole and downhole of backfill strength suitable for the stope conditions of Jinding Iron Mine is established,which provides a basis for the strength design and prediction in the actual production of the mine.(4)FLAC3D software is used to simulate the stability of the stope under nine kinds of stope conditions and two kinds of working conditions of whether the filling body is exposed unilaterally.The maximum vertical displacement of the roof,the maximum tensile stress and compressive stress,the maximum horizontal displacement of the side wall(unilateral exposure of the filling body),the volume of the plastic zone of the filling stope and the plastic strain energy are used as the safety evaluation indexes.The CRITIC method is used to determine the weight of each index,and the optimization model of stope structure parameters and mining sequence based on the comprehensive closeness method and the fusion of safety and economic indicators is constructed.(5)Using the monitoring data of underground blasting vibration velocity,the attenuation law of underground blasting vibration is obtained by fitting the Sadaovsk formula.In addition,the ANSYS/LS-DYNA software was used to simulate the blasting effect of seven kinds of millisecond time and four kinds of hole parameters.Taking the blasting effect and vibration reduction effect as the index,the optimal filling length and millisecond time were determined.(6)The monitoring schemes of stress and deformation of cemented filling body in two-step mining with unilateral exposure and non-unilateral exposure are designed.The stress transfer and deformation law of filling body in the process of excavation and unloading of ore rock are monitored.The stability of roof and filling body in hollow area during two-step mining is evaluated,which provides feedback for backfill strength and structural parameter design of subsequent filling stope. |
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