Study Of Overlying Strata Migration And Influence Rules Of Rock Burst In Coal Mining Under Massive Igneous Sill

In recent years,coal mine roof-type rockburst accidents have occurred frequently.In order to study the influence of roof on rock burst,this paper will take the working face under massive thick igneous rock in AnJu coal mine as the research background.Made systematic analysis from three aspects: the stability of the massive igneous sill,the stress variation characteristics of country rock with working face,and the impact of rock burst under pyrolith.And study finding is as follows:(1)The decisive effect of overburden movement on huge thick igneous rock was first analyzed based on the key strata crimination theory.According to the change of the size of goaf,a mechanical model for the transition of huge thick igneous rocks from medium to thin plates is established.It is concluded that the huge thick igneous rock is mainly concentrated in stress during the initial mining stage and is in a stable state.In the continuous mining process,when the overhang scale ratio of igneous rock reaches 10 to 15 times,instability occurs in the state of sheet.And from the perspective of energy transfer,it is calculated that the energy of the first igneous rock breaking transfer to the coal body reaches about 6 times the energy level,which greatly increases the impact risk.(2)By using numerical simulation,the movement law of overburden rock and the evolution characteristics of the surrounding rock stress in the working face are analyzed from the degree of stress concentration and the range of subsidence.The obtained high-level igneous rock mainly plays the role of bearing,and mainly adjusts its own stress.As a loading object,the median igneous rock is disturbed to accumulate a large of elastic energy to induce rockburst more easily.The low-level igneous rock does not have strong bearing capacity,which increases integral stress level of the surrounding rock.It is also proposed that the stress rise of the surrounding rock comes from the transfer of the original stress after the mining disturbance and the bearing pressure exerted on the coal rock body under the bearing action of the huge thick igneous rock.(3)On the basis of the stress distribution characteristics by working face,the time correlation of the occurrence of rockburst in different regions under the influence of huge thick igneous rock is established.Two kinds of influence law,starting rockburst in igneous rock support stress superimposed high static stress area and breaking induced rockburst are proposed.Two types of high static stress spontaneous rockburst and dynamic and static load superimposition spontaneous type rockburst are proposed during the mining of 2311 working face.(4)Combined with the actual monitoring results during the mining process of 2311 working face under huge thick igneous rock,the stability of the huge thick igneous rock and the mutual disturbance to the working face were analyzed from the ground subsidence,microseismic and stress monitoring.It is concluded that the massive thick igneous rock is in a stable stage during the 2311 working face mining process.The surrounding rock stress is less affected by the igneous rock.The rise of the roof collapse height is accompanied by the occurrence of microseisms.The thesis provides a basis for the safe of mining under huge thick igneous rocks and the prevention of rock burst.The thesis has 94 figures,7 tables,82 references.