Study on Response Mechanism and Brittle Evaluation of RockFracture Acoustic Emission Signals Based on Wavelet Packet Decomposition
Rock brittleness is a key indicator controlling rock fracturing,determining the formation of an effective fracture network during fracturing.Studying the characteristics of rock brittleness and fracturing behavior through a-coustic emission signals can directly reveal the relationship between rock fracturing and brittleness.However,the relationship between acoustic emission signal characteristics and rock fracturing patterns has not yet been estab-lished,making it difficult to accurately determine the brittleness characteristics of rocks.Therefore,based on the wavelet packet decomposition method,this study divides rock acoustic emission signals by energy frequency bands and builds the relations between different brittle rock fracturing patterns and the energy distribution of acoustic emis-sion signals.Through the analysis of the three-dimensional spatial distribution characteristics of acoustic emission signals,a rock brittleness index evaluation method based on the energy distribution of acoustic emission signals is proposed.The study shows that the energy characteristics of acoustic emission signals are related to rock brittleness,with the main frequency of energy distribution mostly below 750 kHz.The higher the content of brittle minerals in the rock,the larger the proportion of energy signals,the more concentrated the energy distribution of rock fracturing acoustic emission signals,the stronger the mutability of rock fracturing,the more apparent the transition between fracture tension,shearing,and mixed evolutionary expansion modes,and the greater the brittleness index.The re-sults can provide reference and guidance for research on rock fracturing warning and other related aspects.
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