Infrasonic wave response characteristics of coal samples in fracture process under low confining pressure

doi:10.16265/j.cnki.issn1003-3033.2020.02.003

Abstract

Abstract: In order to monitor underground geological disasters in mines by using infrasound, creep-seepage loading system, acoustic emission acquisition system and infrasound wave acquisition system were used to monitor fracture and destabilization of coal samples under low confining pressure. Then, contrastive analyses were conducted between first channel infrasound signal coupled with oil body in confining pressure cylinder and second channel infrasound signal coupled with air outside the cylinder. The first signal had obvious response characteristics before fracture and conformed fairly well with stress-strain curve and acoustic emission signal with no significant changes before elastic stage. It was superior to the second signal and witnessed abnormal signals at late plastic stage, and its sound pressure gradually increased. The results show that coal sample failure causes wide-band phenomenon, and signal strength is larger as frequency is lower, with maximum strength at 1 Hz. Characteristics of abnormal infrasound waves can be regarded as one of the bases for coal failure determination.

Key words: low confining pressure, two-way monitoring, infrasonic wave, time-frequency analysis, response characteristics

CLC Number:

X936

WANG Yungang, DENG Wanjiu, ZHANG Hongtu, WEI Jianping, XU Yanru. Infrasonic wave response characteristics of coal samples in fracture process under low confining pressure[J]. China Safety Science Journal, 2020, 30(2): 14-20.

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