Research On Acoustic Emission Source Mechanisms Of Rock Failure Based On Moment Tensor Theory

Rocks are typical brittle materials with non-uniformity, rich in various internal defects (cracks, pores, cracks and other joints). Rock deformation and failure process is the essence of rock crack initiation, propagation and interaction through the process. To carry out research of acoustic emission testing, observation and space rock evolution of micro-cracks has great significance for studying rock unstable failure mechanism and forecasting mine disaster ground pressure. For researching the rock failure mechanism, temporal and spatial distribution of micro-cracks is not enough. It’s also need to know the type and direction of slip and its temporal evolution, so as to a deeply understand of the interaction between micro-cracks and expansion through mechanism. The moment tensor theory research in these areas has a huge advantage. The main research contents are as follows:(1) Using the Auto-regression model and AIC criterion theory to pick AE signals arrival time, rational arrangement of AE sensors array to meet the requirements of location accuracy; based on CAD Lisp to achieve the visual display of AE events location and the source parameters.(2) The methods of researching focal mechanism are summarized, focusing on moment tensor methods, which can get both types and the surface direction of normal and motion during rock fracture. Based on elastic wave theory and the moment tensor theory, through picking first motion of AE signal, study on the focal mechanism of AE events, and then get rupture direction, size, slip direction and other parameters of rock micro-cracks. The process of moment tensor solution is given based on AE data, compile the related data analysis procedures using Matlab software.(3) A three-point bending test and "Z"-type shear test are designed, the application of the moment tensor analysis program for micro-cracks to determine the type of fracture, and also checking the reliability of moment tensor analysis procedures in the study of rock cracks and expansion mechanism.(4) Uniaxial loading tests using rocks with a circular, arched and bore holes are experimented, to research the failure mechanism in tunnels, roadways and stopes. Based on moment tensor analysis and AE focal mechanism to research evolution process of micro-crack initiation, propagation, until the rock failure; the number of different types of micro-cracks, the cluster level, slip direction and other parameters on the final rupture surface are analyzed, the relations between the focal pattern of micro-cracks and macro cracks penetrating mechanism are studied.