Ground Stress Measuring And Analysis In Dongtan Mine

Ground stress is the ultimate force source which affects all the ground project stability and one of the main subjects that the engineering geology long-time studies. This item adopts a convenience and more economy ground stress testing method-sound emission method (AE method), measuring the third mine section ground stress of Dongtan coal mine, estimating the maximum principal stress, the level minimum principal stress, and normal principal stress of third coal roof 40m and motherboard 30m range including the soft rock and coal bed; making the inversion analysis of the stratum range of -500m~-700m, obtaining the distributing rule of third mine section field, providing the designing gist for tunnel supporting and stope mine press controlling.Geology constitution analysis indicates that the third mine section of Dongtan mine is the section of structure stress field, and the maximum principal stress is north west west-south east east orientation; the result of the third mine section eight ground stress measure points indicates that the orientation of level maximum principal stress is 105.7 0 ~ 148.7° .The two conclusions are mainly conformity.The distributing rule of the third mine section ground stress value: while the mining depth is less than 780m, the level maximum principal stress is 15~19MPa, moreover the coal bed motherboard is bigger than roof, but around the fault the size and orientation of ground stress change a lot; while the mining depth is 780m about, the normal principal stress almost amount the level maximum principal stress; while the mining depth is more than 780m, the normal principal stress is more than level maximum principal stress.The max principal stress isoline graph of inversion analysis indicates that the old roof and old floor rock stratum of the coal bed sometimes locates in much higher stressed zone; the max. of mine section maximum level principal stress presents to FS46 and FS51 fault around and the south-west of the section, almost 24MPa; the max. of the minimum principal stress presents to mid fault FS51; the max. of the maximum sheer stress presents to fault FS46 and FS51 and the south of the third mine section, almost 15MPaTunnel dispose orientation should parallel with level maximum principal stress or keep small included angle intersecting, avoids both vertical orientation; in the condition that cannot obviate both vertical orientation or big included angle, tunnel supporting should be strengthened according to the ground stress size of tunnel prop position.