Experimental study on characteristics of strain and acoustic emission in the process of coal rock expansion and fracture
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摘要: 针对目标对煤岩膨胀破裂过程中的声发射特征研究较少的问题，开展了煤岩膨胀破裂实验，分析了煤岩膨胀破裂全过程应变与声发射信号的变化规律。结果表明：① 煤岩膨胀破裂过程可划分为微破裂阶段(Ⅰ)、宏观裂纹生成及扩展阶段(Ⅱ)和劈裂阶段(Ⅲ)。② 煤、岩试样膨胀过程应变演化具有一致性，均呈现“缓变→加速→极值”变化趋势，但两者各阶段声发射信号差异较大。③ 煤样在第Ⅰ、Ⅱ阶段声发射振铃计数较为丰富，在临近第Ⅲ阶段累计振铃计数呈指数型递增；而砂岩在第Ⅰ、Ⅱ阶段声发射振铃计数较少，在临近第Ⅲ阶段累计振铃计数表现出 “突增→平静”趋势。④ 煤岩膨胀破裂过程均存在变形局部化现象，应变变异系数的突变和声发射峰值频率段增多现象可作为煤岩胀裂失稳破坏的前兆特征。研究结果可为煤岩致裂等工程的监测预警提供依据。Abstract: In order to solve the problem that there are few researches on the acoustic emission characteristics in the process of coal rock expansion and fracture, experiments on coal rock expansion and fracture are carried out to analyze the change law of strain and acoustic emission signals during the whole process of coal rock expansion and fracture. The results show that: ① the coal-rock expansion and fracture process can be divided into micro-fracture stage (Ⅰ), macro-fracture generation and expansion stage (Ⅱ) and splitting stage (Ⅲ). ② the strain evolution of coal and rock samples in the expansion process is consistent, showing the trend of 'slow change→acceleration→extreme value'. However, the acoustic emission signals of the two samples at each stage are quite different. ③ the acoustic emission ringing counts are more abundant in the coal samples at stages Ⅰ and Ⅱ, and the cumulative ringing counts increase exponentially near stage Ⅲ; while the acoustic emission ringing counts are less in the rock samples at stages Ⅰ and Ⅱ, and the cumulative ringing counts show a 'sudden increase - calm' trend near stage Ⅲ. ④ there is deformation localization in the process of both coal and rock expansion and fracture. The sudden change of strain variation coefficient and the increase of acoustic emission peak frequency range can be used as the precursor characteristics of coal rock expansion,fracture and instability. The research results can provide a basis for monitoring and early warning of coal rock fractures and other projects.
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期刊类型引用(6)
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