A method for inversion of rock fracture mechanism and instability prediction using microseismic monitoring data

Abstract

The invention discloses a rock fracture mechanism inversion and instability prediction method using microseismic monitoring data. According to the characteristics of the microseismic waveform, the first arrival amplitude and first arrival time of the microseismic waveform are determined; based on the first arrival time of the microseismic waveform, the construction The new positioning objective function solves the coordinates of the rupture source, and eliminates the positioning points that do not meet the requirements by considering the number of microseismic waveforms and the standard deviation of the difference between the first arrival time and the back-calculated first arrival time; calculates the theoretical normal direction of the microseismic waveform Displacement value, through the difference expression between the theoretical normal displacement value and the measured displacement value, the fracture source moment tensor is solved and regularized, and the rock fracture mechanism is directly judged by the nature of the fracture surface; on this basis, the rock fracture The instability prediction index predicts the risk of rock fracture instability according to the risk evaluation level, and provides monitoring and early warning for disasters such as rock burst, rock burst, coal and gas outburst, water inrush, collapse, and landslide.

Description

technical field [0001] The invention relates to the technical field of rock mass deformation and fracture monitoring and evaluation, in particular to a rock fracture mechanism inversion and instability prediction method using microseismic monitoring data. Background technique [0002] With the gradual depletion of near-surface coal resources, deep mining has become an inevitable trend. Under deep conditions, coal rocks are affected by high ground stress, high gas and mining at the working face, and coal rock dynamic disasters are becoming more and more serious and complex, seriously affecting the production capacity of coal mines and threatening the safe and efficient production of coal mines. Accurate monitoring and early warning is the premise and basis for effective prevention and control of coal-rock dynamic disasters. At present, microseismic monitoring technology is widely used because of its simple and convenient installation, no damage to the monitored object, large...

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Problems solved by technology

The most widely used is the seismic moment tensor theory. For example, Chinese patent application CN112964787A discloses a method for detecting cracks in brittle materials based on acoustic emission. Determine the type of source rupture; Chinese patent application CN113218766A discloses a rock crack initiation stress and damage stress identification method based on moment tensor analysis, and Chinese patent application CN113050159A discloses a coal-rock hydraulic fracturing fracture microseismic location and expansion mechanism monitoring method , both use the proportion of the pure shear part after the moment tensor decomposition to judge the rock fracture mechanism, and do not take into account the unclear meaning of the nonlinear dipole CLVD in the decomposition part, which makes the source fracture type judgment result questionable.

In addition, the local AIC method is used for the first arrival time and the amplitude picking direction, which is prone to multiple local minima, resulting in inaccurate picking results

Chinese patent application CN106154307A discloses a microseismic identification method for coal-rock impact instability mode, which uses source moment tensor analysis to obtain the occurrence of the fracture surface, but does not make any discussion on the coal-rock impact instability mode

The above-mentioned literatures all mentioned how to solve the moment tensor, but the method used is single, all adopt the simplified moment tensor inversion method and aim at the rock fracture mechanism but only stay in the theory and experiment, and do not make reasonable use of it. Guidance on rock fracture instability

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