Study On Inversion Of Full Time-space Stress Field And Division Of Outburst Dangerous Area In Sangshuping Coal Mine

Hancheng mining area is a typical outburst mining area in China.There have been more than 120 outbursts in Sangshuping Coal Mine under its jurisdiction.After research,the ground stress is the main cause of the outburst accident in the mine,so the accurate inversion of the mine stress field is of great significance to the safe production of the mine.In this thesis,Sangshuping Coal Mine is taken as the research object.Firstly,the mechanism of ground stress in the process of outburst is analyzed,and the influence of ground stress direction on outburst risk is studied by numerical simulation.Then,based on the geological data of Sangshuping Coal Mine,a numerical model of mining and excavation replacement in the whole mine was established,and the distribution law of the original rock stress field and its influence on the outburst risk were analyzed.The whole mine mining replacement inversion is realized,and the evolution path of mining stress and its influence on mine outburst risk are studied.The main conclusions are as follows :(1)The influence of ground stress on outburst accidents is explored.The characteristics of in-situ stress in coal and gas outburst accidents are analyzed,including the control effect of in-situ stress on gas pressure and the effect of in-situ stress on the physical and mechanical properties of coal.It is considered that in-situ stress is the dominant factor causing outburst accidents.Based on FLAC3D,the influence of geostress direction on outburst risk is analyzed.The conclusion shows that when the stress perpendicular to the advancing direction of the working face is large,the stress concentration in front of the working face is obvious,and the outburst risk is large.When the geostress parallel to the working face is large,the outburst risk is small.(2)The equal proportion numerical calculation model of the whole mine is established and the model assimilation is completed based on the field measured data.The outburst law of Sangshuping Coal Mine is analyzed.It is found that the larger the buried depth is,the more the outburst occurs,but more in the buried depth of 300-400 m.Based on the geological data of Sangshuping Coal Mine,a numerical calculation model of equal proportion mining and excavation replacement in the whole mine was established.The drilling cuttings method was used to test the mining disturbance stress.The width of the pressure relief zone was 8 m,and the advance peak was located 14 m in front of the coal wall.Based on the measured data,the input parameters of the numerical model were determined,and the assimilation of the model was realized.The original rock stress was tested by the hollow inclusion method.The results show that the σx in the south mining area is larger,and the value is 18.6 MPa.The σx and σy at the measuring points in the north mining area are larger,which are 23.8 MPa and 21.6MPa,respectively.(3)The stress distribution law of original rock and its influence on outburst are explored.Based on the inversion results of the original stress field of the numerical calculation model,the three-dimensional stress distribution law of the mine and its influence on the mine outburst accident are analyzed.It is found that it is not that the larger the vertical stress is,the easier the outburst is,but that the outburst accident is more likely to occur in the area where the surface mountain height changes rapidly.The outburst is seriously affected by the horizontal stress perpendicular to the working face.The south mining area is mainly affected by σx,and the north mining area is mainly affected by σy.Based on the MohrCoulomb failure criterion,the failure coefficient of coal and rock mass is derived,and the risk coefficient of mine outburst is defined based on the coefficient,and the dangerous area of mine outburst is divided.(4)The evolution path of mining stress and its influence on outburst accident are analyzed.The mining stress evolution path curve of the historical outburst point of the mine is drawn.It is found that most of the outburst accidents are disturbed by the mining near the mining face before the accident,and the continuous stress concentration is most likely to stimulate the outburst accident.Based on the evolution path of mining stress,BP neural network algorithm is used to divide the dangerous area of mine outburst.The results show that unreasonable mining replacement will lead to further increase of outburst risk and cause outburst accidents.This thesis has 55 figures,18 tables and 100 references.