Analysis of property changes and strength degradation of basalt induced by microwave irradiation

Ji Hye Hwang; Tae Young Ko

doi:10.9711/KTAJ.2025.27.2.157

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2025 Vol.27, Issue 2 Preview Page

Research Paper

Analysis of property changes and strength degradation of basalt induced by microwave irradiation 현무암의 마이크로파 조사에 따른 물성 변화 및 강도 저하 특성 분석

31 March 2025. pp. 157-168

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Abstract

This study investigates the effect of microwave irradiation on the mechanical properties of basalt through controlled laboratory experiments. Cylindrical basalt specimens from two different sources (Cheorwon and Vietnam) were exposed to 1,000 W microwave energy for durations of 1, 3, and 5 minutes. Physical and mechanical properties such as P-wave velocity, Schmidt hammer rebound hardness, Leeb hardness, and uniaxial compressive strength (UCS) were measured before and after microwave exposure. Results indicate that increasing microwave exposure time induces microcracking within the basalt, leading to significant reductions in P-wave velocity and UCS. Notably, after 5 minutes of exposure, the Cheorwon basalt showed approximately 14% decrease in UCS and 10% decrease in P-wave velocity, while Vietnamese basalt exhibited 6% reductions in both properties. Surface hardness measurements showed varying degrees of reduction depending on the initial rock strength and composition. Interestingly, no significant changes in density were observed for either rock type. These findings demonstrate the potential of microwave pretreatment to effectively weaken basalt and improve mechanical excavation efficiency. The results also suggest that rock mineral composition influences microwave reactivity, emphasizing the importance of optimizing exposure conditions for specific rock types.

Keywords

Microwave irradiation

Basalt

Strength reduction

P-wave velocity

Uniaxial compressive strength

본 연구는 마이크로파 조사가 현무암의 물리적 ‧ 역학적 특성에 미치는 영향을 실험적으로 분석하였다. 원통형 현무암 시편에 대해 1,000 W의 마이크로파를 각각 1, 3, 5분간 조사하였으며, 조사 전후 P파 속도, 슈미트 반발경도, Leeb 경도, 일축압축강도(uniaxial compressive strength, UCS) 등을 측정하였다. 실험 결과, 조사 시간이 증가할수록 시편 내부에 미세균열이 발생하여 P파 속도와 일축압축강도가 유의미하게 감소하는 경향을 보였다. 특히 5분 조사 시 철원 현무암의 일축압축강도는 약 14%, P파 속도는 약 10% 감소하였으며, 베트남 현무암은 일축압축강도 약 6%, P파 속도 약 6% 감소를 나타냈다. 표면 경도의 경우, 암석의 초기 강도에 따라 슈미트 반발경도와 Leeb 경도 측정값에서 각기 다른 정도의 감소가 관찰되었다. 한편 밀도는 두 암석 모두 유의미한 변화가 관찰되지 않았다. 이러한 결과는 마이크로파 전처리를 통해 현무암을 효과적으로 약화시켜 기계 굴착 효율을 향상시킬 수 있음을 시사하며, 암석의 광물 조성에 따라 마이크로파 반응성에 차이가 있어 적정 조사 시간 설정의 중요성을 보여준다.

키워드

마이크로파 조사

현무암

강도 저하

P파 속도

일축압축강도

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Information

Publisher :Korean Tunneling and Underground Space Association
Publisher(Ko) :한국터널지하공간학회
Journal Title :Journal of Korean Tunnelling and Underground Space Association
Journal Title(Ko) :한국터널지하공간학회 논문집
Volume : 27
No :2
Pages :157-168
Received Date : 2025-03-04
Revised Date : 2025-03-21
Accepted Date : 2025-03-21
DOI :https://doi.org/10.9711/KTAJ.2025.27.2.157

Journal of Korean Tunnelling and Underground Space Association ISSN:2233-8292(Print) 2287-4747(Online) 한국터널지하공간학회 논문집

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