Temporal-Spatial-Strong Law Of Earthquake And Overburden Structure Movement Characteristics In The Second Panel Of Zhengtong Coal Industry

With the increase in the depth and intensity of underground mining,the dynamics of coal rock masses such as mine shocks are also increasing.As the geological structure of the deep coal measure strata is more complicated,the self-weight stress and tectonic stress of the surrounding rocks also increase correspondingly,resulting in dramatic changes in the stress environment of the rock mass.After mining in four working faces in Erpan District of Zhengtong Coal Mine,the phenomenon of mine shocks has greatly increased,and there have been many impact dynamics of broken bottom drums and bolts.Therefore,the paper takes these four working faces as the research background,analyzes the structure of the overlying rock after the four working faces are mined sequentially,and conducts statistical analysis and research on the microseismic data measured on the spot.The main progress of the thesis is as follows:According to the mine seismic data measured in the three working faces 201,202,and 203 measured by the on-site microseismic monitoring system,it is found that the number of energy levels also changes with the change of the working face advancement.When the advancement of the working face increases,the total energy also rises.There is a certain linear relationship between the advancement of the working face and the frequency of microseisms.When the working face advances to the "square" area and the period comes to press,high-energy mine earthquakes frequently occur.In the range of 100 m ~ 150 m in front of the working face,it is the area where the seismic source is concentrated.For different positions of the working face,especially in the fold area,the stress distribution is different,and the corresponding source distribution is also different.The energy level of the source is related to the concentration of stress.The development height of the source is also increasing with the increase of the goaf.After the coal seam is mined,the overlying rock above the mined-out area will have larger breakages and movements,and the overlying rock will take the form of a "masonry beam" structure.The size of the mined-out area is closely related to the breakage of the key layer above;at the same time,when the working face is close to the mined-out area,the overlying rock above the face will also be affected by the overlying strata of the mined-out area,and a “cooperative movement”.According to the numerical simulation results,it can be seen that as the area of the goaf continues to increase,the vertical stress on the side of the solid coal pillar continues to increase,and the stress rises from 32 MPa to 54 MPa,and the overburden has an "M" type structure.When the working face is mined along the strike,the peak value of the leading bearing stress increases from 30 MPa to 47 MPa,and the increase in stress makes the probability of impact appearing greatly increased.At the same time,the initial breaking distance of the direct roof of the working face and the period of the old roof are calculated according to the range of the crack ring.Through the analysis of the mining shock data of the working face 204,it is found that the mining shock characteristics of this working face comply with the obtained law.At the same time,according to the recorded seismic shock waveforms,the CT inversion of the shock wave was carried out,and it was concluded that the range of 100 ~ 150 m on the side of the transportation chute of the 204 working face and the end of the working face is the area with higher wave speed.Concentration,and the stress concentration area also shows periodic changes.At the same time,the area with a higher wave speed changes continuously as the working surface advances.Through the above analysis and research,the change law of the stress field and vibration field around the mining area can be determined,which can provide a basis for the research on the dynamic disaster mechanism of coal and rock,and can also lay a foundation for the prevention and control of mine dynamic disasters.This thesis has 53 figures,10 tables and 96 references.