Experimental study on rock breaking using a microwave-assisted tunnel boring machine cutter

• Published in: Bulletin of engineering geology and the environment 2024-04, Vol.83 (4), p.114, Article 114
• Main Authors: Ning, Bo, Liu, Fengzhou, Liu, Hao, Xia, YiMin
• Format: Article
• Language: English
• Subjects: Basalt; Boring machines; Boring tools; Breaking; Construction; Cutting; Cutting force; Cutting parameters; Dielectric properties; Dredging; Drilling & boring machinery; Earth and Environmental Science; Earth Sciences; Efficiency; Energy; Energy consumption; Engineering; Excavation; Experiments; Foundations; Geoecology/Natural Processes; Geoengineering; Geotechnical Engineering & Applied Earth Sciences; Hydraulics; Irradiation; Load; Microwave heating; Microwave radiation; Microwaves; Nature Conservation; Original Paper; Radiation; Rock; Rocks; Specific energy; Tunnel construction; Tunnels
• ISSN: 1435-9529; 1435-9537
• DOI: 10.1007/s10064-024-03632-x

Tunnel boring machines (TBMs), excavation tools for tunnel construction, often struggle to penetrate extremely hard rock formations. This study proposes an innovative solution to enhance the construction efficiency of TBMs in such environments: a microwave-assisted TBM cutter. In our experiments, we irradiated basalt samples with 3 kW microwaves for varying durations. We conducted a full-scale rock-breaking experiment using the multifunctional rock-breaking platform at Central South University, China. We then compared the cutting force, cutting coefficient, and specific energy consumption of the cutter at different processing times. Our results indicate that microwave pretreatment can effectively reduce both the cutting force and specific energy consumption of rock. Furthermore, under certain cutting force conditions, the quantity of rock broken can be significantly increased with extended microwave irradiation. However, we found a critical threshold for the processing time of 3 kW microwave-assisted rock breaking. Beyond this threshold, the specific energy consumption of rock breaking is not significantly reduced. For a microwave processing time of 16 min, the optimal ratio of cutter spacing to penetration ( s/p) is 16.7. The findings of this study offer valuable insights and guidance for TBM construction operations in extremely hard-rock environments.