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.
- A Clean Solution for Renewable Energy: Small Diameter Hydro Tunnels
- Non-Circular Tunnel Boring for Underground Mine Development
- Unprecedented In-Tunnel Diameter Conversion of the Largest Hard Rock TBM in the U.S.
- Hard Rock Tunnel Boring at the Jefferson Barracks Tunnel
- The Next Generation of Mixed Ground Tunnel Boring Machines