Achieving Fast EPB Advance in Mixed Ground: A Study of Contributing Factors
Earth Pressure Balance (EPB) tunneling in mixed ground conditions is a challenging prospect, as it often includes excavation in boulder fields, sections of rock, and/or sticky clay, under high water pressure or changing water pressure. Maintaining a rapid advance rate in such conditions is a function of many factors—from adequate cutting tools to cutterhead design, pre-planning and execution of an appropriate ground conditioning regime as well as proper maintenance and operation of the TBM. This paper will analyze recent record-breaking and high-performing projects seeking to identify factors that contribute to fast machine advance. These factors will then be discussed and an effort made to form simple, high level guidelines for optimal TBM excavation in mixed ground conditions.
- Use of a Tunnel Boring Machine on Nepal’s First and Second TBM-Driven Tunnels
- Record-Setting Large Diameter Mixed Ground Tunneling in Turkey: The Eşme-Salihli Railway Tunnel
- Lessons Learned During Excavation of the Incredibly Challenging Yin Han Ji Wei Water Diversion Tunnel
- Record-Setting Tunnel Boring Below Lake Ontario at the Ashbridges Bay Outfall Tunnel
- Enhanced Probe Drilling & Pre-Grouting on Hard Rock TBMs