Journal of Korean Society of Disaster and Security (한국방재안전학회논문집)

Korean Society of Disaster & Security (한국방재안전학회)
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Experimental and Numerical Study on the Dynamic Fracture Processes of PMMA Block by NRC Vapor Pressure Fracture Agent

NRC 증기압 암석 파쇄제에 의한 PMMA 블록의 동적 파괴 과정에 관한 실험 및 수치해석적 연구

  • Gyeongjo Min (Department of Mineral Resources and Energy Engineering, Jeonbuk National University)
  • 민경조 (전북대학교 자원.에너지공학과)
  • Received : 2023.03.15
  • Accepted : 2023.03.30
  • Published : 2023.03.31
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Abstract

This study aims to investigate the dynamic fracture characteristics of rocks and rock-like materials subjected to the Nonex Rock Cracker (NRC), a vapor pressure crushing agent that produces vapor pressure by instantaneously vaporizing a liquid mixture crystallized through the thermite reaction. Furthermore, the study seeks to develop an analytical technique for predicting the fracture pattern. A dynamic fracture test was performed on a PMMA block, an artificial brittle material, using the NRC. High-speed cameras and dynamic pressure gauges were employed to capture the moment of vapor pressure generation and measure the vapor pressure-time history, respectively. The 2-dimensional Dynamic Fracture Process Analysis (2D DFPA) was used to simulate the fracture process caused by the vapor pressure, with the applied pressure determined based on the vapor pressure-time history. The proposed analytical method was used to examine various fracture patterns with respect to granite material and high-performance explosives.

본 연구의 목적은 테르밋 반응으로 결정화된 액체혼합물을 순간적으로 기화시켜, 이에 따라 발생되는 증기압을 이용하여 암석 및 콘크리트를 파쇄시키는 Nonex Rock Cracker(NRC) 암석 파쇄제의 동적 파괴 특성을 분석하고 파괴패턴을 예측할 수 있는 해석기법을 개발하기 위함이다. NRC 암석 파쇄제의 순간적의 증기압 발생 특성을 분석하기 위하여 인공취성재료로 알려진 Polymethyl methacrylate(PMMA) 블록을 대상으로 NRC를 장전하여 파쇄시험을 수행하였다. NRC의 증기압 발생순간을 촬영하기 위하여 초고속 카메라를 활용하였으며, 장약실과 연결된 관측공에 동적압력게이지를 부착하여 장약공 압력-시간이력을 계측하였다. 증기압 암석 파쇄제에 의한 PMMA 블록의 파괴패턴을 모사하기 위하여 2차원 동적 파괴 과정 해석 기법인 2D Dynamic Fracture Process Analysis(2DDFPA)가 활용되었으며, 계측된 장약공 압력-시간이력을 고려한 입사압력함수를 결정하였다. 제안된 해석조건을 활용하여 화강암재료와 고성능 폭약에 의하여 발생될 수 있는 파괴패턴에 대하여 고찰하였다.

Keywords

Acknowledgement

The author would like to thank Prof. Sangho Cho at Jeonbuk National University in South Korea and Prof. Daisuke Fukuda at Hokkaido University in Japan for their valuable guidance and support throughout this research. The author also appreciates the assistance provided by Mr. Gyeonggyu Kim at Jeonbuk National University, during the experimental phase. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2020R1I1A3074451).

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