Research On Dynamic Instability And Regulation Of Steeply Dipping And Extra-thick Coal Rock Mass

It is well worth in-depth studying the prevention and control of coal and rock dynamic disaster in fully mechanized caving of steeply dipping and extra-thick coal seams.The thesis closely focuses on the prevention and control of coal and rock dynamic disasters in fully mechanized top coal caving in steeply dipping and extra-thick coal seams.Taking the typical project of fully mechanized top coal caving in steeply dipping and extra-thick coal seams in the south of Wudong Coal Mine as the research background,it works at+450 level in the south of Wudong Coal Mine Faced with scientific prevention and control of dynamic disasters as the research goal,comprehensive use of research methods such as on-site investigation,theoretical analysis,mechanical experiment,numerical calculation and on-site application has achieved the following results:Using the combination of theory and case analysis,the typical accident occurrence location,microseismic event location and energy characteristics of+450 horizontal working face are sorted out,and the disaster characteristics of the dynamic disaster on the working face are analyzed.Appears to have obvious vibration characteristics;Appears to have obvious vibration characteristics;micro-seismic large energy events mainly occur in B2-B3 rock pillars and B3+6 coal seam roof;analysis of the disaster-causing mechanism leads to the sudden instability of B2-B3 rock pillars and B3+6 coal seam roof as a dynamic disaster.The occurrence of energy provides a source of energy,and the obvious horizontal structural stress field makes the elastic energy of coal and rock mass around the mining roadway and working face easier to accumulate.When the source of power disaster is transmitted to the mining area,the energy and coal and rock mass around the mining roadway and working face are concentrated.When the elastic energy superimposed exceeds the minimum energy of coal and rock mass destruction,a dynamic disaster occurs.Through carrying out laboratory rock mechanics experiments,using digital speckle technology and acoustic emission instruments to obtain physical and mechanical parameters,destruction processes and acoustic emission different conditions,and using scanning electron microscopy to study the micropores in coal samples And micro-cracks and other microstructures;it is concluded that saturated water can deteriorate the strength of coal rock samples and change the energy release during the failure process;saturated water and pressure relief holes can change the development and failure process of coal sample cracks;coal sample electron microscope scanning It shows that micro-fracture pores are less developed.Based on RFPA numerical calculation,the destruction process and acoustic emission characteristics of coal samples in different states and different homogeneities are studied.It is concluded that the coal and rock models with different homogeneity show different destruction processes and acoustic emission characteristics.The higher the homogeneity of the coal and rock samples in the same state,the higher the energy release rate and the more intense the energy release during the peak failure stage;The simulation shows that under the action of blasting stress wave,the rock mass near the blasting hole area is dominated by tensile failure,and the compression failure is more obvious in the far area.The blasting stress wave can cause a large number of cracks around the blasting hole in a short time,destroy the integrity of the rock mass,and quickly release the energy accumulated in the rock,which can effectively avoid the large-scale instability of the hard rock layer and release huge energy;The numerical simulation study on the weakening of the water injection intensity shows that under the action of water injection,there is an obvious stress reduction zone around the water injection hole,and there will be an obvious acoustic emission phenomenon around the water injection hole.As the water injection time continues,the acoustic emission phenomenon will gradually move toward the uninjected water.Regional expansion,water injection can destroy the integrity of the rock mass,increase the internal cracks in the rock mass,and can form a weakened rock mass strength zone,weakening the energy transmitted from the source of the dynamic disaster to the mining space.After the implementation of comprehensive prevention measures for on-site rock and coal engineering,high-energy-level microseismic events have become more low-energy microseismic events,and the average number of microseismic events per day and the average energy released are showing a downward trend.It can be released slowly,which achieves the goal of making coal and rock bodies violently destroyed and releasing static energy slowly,which effectively reduces the energy accumulation of hard rock layers and improves the safety of the working face.This achievement provides basic support for the prevention and control of power disasters and the guarantee of safe mining in fully mechanized caving face in steeply dipping and extra-thick coal seams,which has certain reference and reference value for power disaster prevention and control under similar engineering conditions.