Acoustic Emission Prediction Of Rock Fracture And Application To Geostress Survey Of Kaiser Effect

The happening of mine disasters such as roof fall, water burst, rock burst and coal and gas outburst is closely related to the instability and fracture of rock, and acoustic emission (microseismic) is important precursor information of rock fracture. In laboratory, carrying out compressive acoustic emission experiment and using AE information to predict rock's fracture and instability are of important theoretical and actual meanings for adopting acoustic emission (microseismic) monitoring technology to predict and prevent mine disasters caused by rock fracture.Adopting electro-hydraulic servo testing system MTS815.03 and acoustic emission system SDAES-6, laboratory fundamental mechanical property experiment, acoustic emission experiment and numerical simulation about roof limestone No. 16 coal seam of Tianzhuang Colliery were researched in this paper. Through uniaxial compression acoustic emission experiment, discovered that, the compressive fracture rock is closely related to its closing of initial crack, produce, expansion and transfixion of new crack, and its acoustic emission characteristic well reflected the fracture and damage evolving characteristic. Meanwhile, the conclusion that rock acoustic emission Kaiser Effect point only exists in the elastic stage of deformation. Kaiser Effect point can remember the maximum stress suffered before, in this experiment, the maximum stress of 3 limestone samples' suffered before are 45.5%, 47.5%, 45.2% of ultimate stress respectively. And the results of numerical simulation to rock's deformation fracture and damage evolvement process was basically consistent with that of experiment. The Kaiser Effect point gained through numerical simulation is at 19th step, the loading is 597.4N, and remembered maximum stress is the 48.7% of ultimate stress of rock.Extracting maximum Lyapunov exponent from time series of AE parameters gained through experiment, certify that, the movement trend of compressive fracture evolving system of AE parameters is predictable, because it isn't in complete chaotic state that dependents on initial value. Form wavelet coefficient analysis, take two axial strains corresponding with backwards and forwards negative extremum of Lipschitz exponent a of AE events and energy as Kaiser Effect point and predicting fracture point. In this experiment, the predicting fracture time corresponding with predicting fracture strain point of 3 limestone samples was advanced 4, 5 and 5 seconds than actual fracture time respectively, and the predicting error is in the range of 6%-10%.From surveying the horizontal initial stress of horizontal west roadway of Tangkou Colliery at -1000m with Kaiser Effect method and stress relief method, the results of two methods was contra contrastive analyzed, obtained that, the ratio of maximum principle stress is 1.07, that of intermediate principal stress is 0.83, and that of least principle stress is 0.75, so, the results of two methods was close to each other. So, initial stress of rock mass surveyed through Kaiser Effect method is credible, and it can satisfy the engineering need generally.