关键词: 声发射信号, 小波包分解, 岩石破裂, 脆性评价

Abstract: 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 acoustic 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 established, 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 emission 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 results can provide reference and guidance for research on rock fracturing warning and other related aspects.

Key words: acoustic emission signals, wavelet packet decomposition, rock fracturing, brittleness evaluation