• Tunnel and Underground Space
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• v.34 no.5
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• pp.599-618
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• 2024

This study investigated the effects of microwave irradiation on the physical properties of basalt to explore its potential as an efficient technique for lunar surface and deep excavation. Experiments were conducted to measure changes in P-wave velocity, Leeb hardness, Schmidt hammer rebound hardness, Cerchar Abrasivity Index (CAI), Uniaxial compressive strength (UCS), Young's modulus, and temperature of basalt specimens according to microwave irradiation time. Results showed that microwave irradiation induced microcracks in basalt and reduced its physical strength. Notably, after 5 minutes of microwave irradiation, UCS and Young's modulus decreased significantly. P-wave velocity also decreased markedly with increased irradiation time, indicating internal structural weakening of the rock. This is primarily attributed to thermal stress induced by microwave penetration into the rock and crack propagation due to differential thermal expansion between minerals. By confirming the rock weakening effect of microwave irradiation under conditions similar to the lunar environment, this study suggests the possibility of greatly improving the efficiency of lunar surface and deep excavation operations.