| As the throat channel of coal production in mines,the shaft lining is very important to the safe production of coal mines.At present,with the increase of the depth of the mine,the problem that the width of the shaft lining protection coal pillar is too large has become more and more prominent,and the reasonable protection of the coal pillar has become an urgent problem to be solved.Meanwhile,the shaft lining of the old mining area also faces the same problem.In addition,some old mining areas sometimes have to face problems such as building new wells near the goaf when the mining level is extended.It is necessary to first study and master the formation deformation induced by coal pillar mining and its influence on shaft lining safety,and then carry out research on corresponding shaft lining safety protection measures.Under this background,the research of this thesis is carried out.The thesis mainly adopts the numerical analysis method.The main research contents and results are as follows:First of all,this thesis carried out a numerical simulation study on the influence of protected coal pillar unilateral mining on the shaft lining.Through numerical simulation and trial calculation,a more reasonable three-dimensional numerical analysis model is established.According to the seven influencing factors such as the distance from the mining stop line to the shaft lining center,the buried depth of the coal seam as well as the thickness of the coal seam under the condition of a single stratum,and the elastic modulus of the upper stratum,the internal friction angle of the upper stratum with the cohesion of the upper stratum under the condition of stratum change to carry out a one-way numerical analysis.Simultaneously,the formation deformation induced by the mining of protective coal pillar with its influence on the stress and deformation of the shaft lining in the changing process of each factor are mastered.On this basis,through orthogonal numerical analysis,the influence degree of different factors on the shaft lining under multiple indexes is obtained.The results show that: within the horizontal value range of the calculated factors,the most influential factor on the horizontal displacement of the wellhead and the three-dimensional stress of the shaft lining at the buried depth of the coal seam is the buried depth of the coal seam.Moreover,the least influential factor is the dip angle of the coal seam.At the same time,the most influential factor on the vertical displacement of the wellhead is the elastic modulus of the formation,and the least influential factor is the dip angle of the coal seam.Secondly,in view of the main vertical shaft lining fracture problem of Qinhua coal mine,this thesis carried out a numerical simulation study on the influence of overmining of shaft lining protected coal pillar on the shaft,and obtained the influence law of overmining of shaft lining protected coal pillar on the shaft displacement and stress of six working faces around the shaft.The results show that the mining of the working face has the greatest influence on the vertical stress of the shaft lining,while the first five working faces have relatively little influence on the displacement and stress of the shaft lining,as well as the mining of the 10103 E working face has the greatest influence on the shaft lining.Then,through the fourth strength theory and the allowable value of shaft lining deformation to evaluate the safety of the shaft,determine the six working face after mining in a safe state.The reason for the failure of the shaft in the numerical calculation is that,in the actual engineering,the failure of the shaft lining is caused by the superposition and synthesis of the influence of three factors,including the overmining of the protective coal pillar at six working faces and the drainage of the stratum during mining,as well as the general weakness of the shallow stratum at the depth of 170 m.However,the influence of the latter two factors is not considered in the numerical calculation.Finally,based on the previous research on the influence of protected coal pillar mining on the shaft lining under different working conditions,this thesis proposes targeted shaft lining safety measures from two aspects of shaft lining design and later adaptive transformation.Then,aiming at setting up vertical compressible device and grouting behind the wall,the influence of these two measures on shaft lining displacement and shaft lining stress is discussed through numerical simulation,and the improvement effect of the two measures on shaft deformation and stress is analyzed.Combined with the comprehensive analysis of the difficulty of specific project implementation and the amount of engineering,it is believed that when the effect of the two measures is not significantly different,it is preferred to set up a vertical retractable device locally.This thesis has 94 figures,53 tables and 102 references. |
