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Analysis of acoustic emission parameters according to failure of rock specimens

암석시편 파괴에 따른 acoustic emission 특성인자 분석

  • Lee, Jong-Won (Multi Disaster Countermeasure Organization (MDCO), Korea Institute of Geoscience and Mineral Resources (KIGAM)) ;
  • Oh, Tae-Min (Department of Civil and Environmental Engineering, Pusan National University (PNU)) ;
  • Kim, Hyunwoo (Multi Disaster Countermeasure Organization (MDCO), Korea Institute of Geoscience and Mineral Resources (KIGAM)) ;
  • Kim, Min-Jun (Multi Disaster Countermeasure Organization (MDCO), Korea Institute of Geoscience and Mineral Resources (KIGAM)) ;
  • Song, Ki-Il (Department of Civil Engineering, Inha University)
  • 이종원 (한국지질자원연구원 복합재난대응연구단) ;
  • 오태민 (부산대학교 사회환경시스템공학과) ;
  • 김현우 (한국지질자원연구원 복합재난대응연구단) ;
  • 김민준 (한국지질자원연구원 복합재난대응연구단) ;
  • 송기일 (인하대학교 사회인프라공학과)
  • Received : 2019.06.24
  • Accepted : 2019.08.29
  • Published : 2019.09.30

Abstract

A monitoring method based on acoustic emission (AE) sensor has been widely used to evaluate the damage of structures in underground rock. The acoustic emission signal generated from cracking in material is analyzed as various acoustic emission parameters in time and frequency domain. To investigate from initial crack generation to final failure of rock material, it is important to understand the characteristics of acoustic emission parameters according to the stress ratio and rock strength. In this study, uniaxial compression tests were performed using very strong and weak rock specimen in order to investigate the acoustic emission parameters when the failure of specimen occurred. In the results of experimental tests, the event, root-mean-square (RMS) voltage, amplitude, and absolute energy of very strong rock specimen were larger than those of the weak rock specimen with an increase of stress ratio. In addition, the acoustic emission parameters related in frequency were more affected by specification (e.g., operation and resonant frequency) of sensors than the stress ratio or rock strength. It is expected that this study may be meaningful for evaluating the damage of underground rock when the health monitoring based on the acoustic emission technique will be performed.

최근 음향방출(Acoustic Emission, AE) 센서를 이용하여 지하 암반 내 구조물의 손상을 평가하는 기법이 활발하게 사용되고 있다. 암반 손상 시 발생되는 미소파괴음은 시간 및 주파수 영역에서 다양한 음향방출 특성인자로 분석된다. 암반 내 초기 균열 발생부터 최종 파괴까지의 특징을 파악하기 위해서는 외부응력 수준과 암반 강도에 따른 음향방출 특성인자 발생 양상을 이해하는 것이 중요하다. 본 연구에서는 경암과 연암 강도를 가진 화강암 시편을 이용하여 일축 압축시험을 수행하여, 암석 시편 파괴 시 발생하는 음향방출 특성인자를 분석하였다. 실험결과, 응력 비율이 증가할수록 이벤트 횟수, 실효값, 최대 진폭, 절대 에너지가 경암 시편에서 연암 시편 보다 높은 경향을 보였다. 또한, 주파수 관련 특성인자는 응력 비율 증가나 시편의 물성특성에 대해 민감도가 낮은 것으로 분석되었다. 본 연구에서 암석 시편 파괴에 따른 음향방출 특성인자 분석 결과, 실효값(RMS)이 가장 민감한 인자로 평가되었다. 본 연구의 결과는 음향방출 기반 모니터링 수행 시 암반 손상 정도 평가를 위하여 유용하게 활용될 수 있을 것으로 기대된다.

Keywords

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