Study On Paste Backfill Mining Subsidence For Zhou Yuan Shan Coal Mine

The coal reserves are less in the eastern part and southern part of our country, anda large number of safety pillars were leaving in the mining process. Therefore theseplaces have serious “under three” pressed coal problem. The Zhou Yuanshan mine hasthese problems, there has23.062million t “under three” pressed coal90%of the mineto maintain reserves. So urgent to mine it’s “under three” pressed coal. In order toprovide a theoretical basis for mining the Zhou Yuanshan coal “under three” pressedcoal and provide a reference for the same type of gently inclined “under three” seammining, dissertation study of the filling material and paste filling mining to surfacesubsidence.To analysis the advantages and disadvantages of the “under three” mining method,including strip mining, slice mining, room-and-pillar mining, coordinated mining andfilling exploitation, choice the paste backfill mining to solve the Zhou Yuanshan coal“under three” pressed coal. The paste backfill mining has the characteristics of reducesubsidence effects, the coal recovery rate, solve gangue covers an area and pollutionof the environment.There are a lot of spoil heaps around the mine and fly ash in the power plant nearthe mine. Use these two materials to do the aggregate of paste filling material.According to the different material formulations make18kinds the paste fillingmaterial specimen, and conduct the strength test for different age’s specimen, test1d3d28d. Experimental study of the initial setting time, the initial setting strength andthefinal setting strength of the different proportions program filling paste. Basis offield the filling material pumpable period of not less than2.5hours, chose the finalsetting strength of5.18MPa recipe(water: cement: gangue: fly ash=22.5%：10%：57.5%：10%, and the additives additive amount is1%of the total).Use of FLAC3D numerical simulation of paste backfill mining to the overburdenand surface subsidence:(1) Accordance with the size of the all caving method miningaffected area to establish numerical model.(2) Using the probability integrationmethod done the Zhou Yuanshan coal mine24mining area mining subsidenceprediction of all breaking down and filling method. To determine numericalsimulation calculation parameters through analysis the probability integration methodcalculated, mechanical test parameters of rock samples and all caving methodFLAC3D numerical simulation results.(3) Fitting curve equation depending on thedesired filling material strength parameters, to calculate the5d10d20d25dcompressive strength and calculate the parameters used in the numerical simulationbased on rock mechanics empirical formula.(4) Using these parameters do thenumerical simulation for different mining methods and different final setting strengthof filling body.(5) Consider the roof subsidence before filling and the filling strengthgradually enhanced process in the calculation.Analysis the calculation results and surface deformation figure concluded that:(1)The strike filling mining surface deformation is less than the dip filling mining.(2)When conduct strike filling mining the working face lower subject to1.23MPapressure, if the coal mine don’t have the dedicated paste filling bracket should give priority to dip fill mining.(3) Backfill mining subsidence basin center is different withordinary mining method, it is close to the center of the mining area.(4) When conductthe dip filling mining, the subsidence basin center is more close to the fist miningareas.(5) When the filling body final setting strength greater than5.5MPa thesubsidence values remain basically unchanged, if the strength is between5.5MPa to4.6MPa small amount of subsidence values change, the subsidence values changebegan gradually increasing when it is less than4.6MPa.According to the theoretical analysis and numerical simulation conclusions,select the filling material that its final setting intensity is5.18MPa and dip fillingmining to mine the “under three” pressed coal.