Tunneling in Mixed Face Conditions: An Enduring Challenge for EPB TBM Excavation
EPB TBM tunneling in mixed face conditions—partially in both rock and soil—is inherently problematic for even the most experienced crews. Over-excavation, excessive damage to cutter tools and regular cutterhead interventions are major challenges when negotiating mixed face geology. This paper draws from real field experiences, including successful bores in abrasive rock and soil at India’s Chennai and Bangalore metro projects, to determine the optimal operational parameters for TBMs in such conditions. It also addresses reduction of air losses to facilitate cutterhead interventions under hyperbaric conditions when installation of safe-haven grout blocks is not an option due to surface structures.
- Rock Tunnels at High Water Pressure: Non-Continuous Pressurized TBMs vs. Slurry
- Hybrid TBM Excavation in Challenging Mixed Ground Conditions at the Mumbai Metro
- TBM Excavation in Himalayan Geology: Over 1,200 Meters per Month at the Bheri Babai Diversion Multipurpose Project
- Tunneling through 48 Fault Zones and High Water Pressures on Turkey’s Gerede Water Transmission Tunnel
- Overcoming Multiple Caverns: Successful TBM Tunneling in Karst Geology at Galerie des Janots