Hyperbaric Interventions

Chesapeake Bridge Bay Tunnel (CBBT)

SUMMARY

For the Hyperbaric Intervention procedure, it has ins- pected the excavation, pre intervention, intervention, and restart of mining activities phases.

Interve Tunnel Boring Machine (TBM):
Name: Mary
Diameter: 46 ft

The Parallel Thimble Shoal Tunnel will form part of the parallel Chesapeake Bay Bridge-Tunnel Crossing, which connects Virginia Beach with Northampton County, VA. The new tunnel will carry two lanes of traffic southbound, while the existing parallel tunnel will be converted from bi- directional flow to one directional two lanes northbound flow.

The tunnel will have a length of approximatively 1.2 miles (1.9 km), a finished internal diameter of 39 feet (11.88 m) and will be excavated by using an EPB machine with an excavation diameter of 43.5 feet (13.2 m) designed to cope with an external water pressure of up to 5.5 bar.

The CTJV engaged Azierta, for the planning of the hyperbaric interventions. Due to the length of the tunnel, hyperbaric interventions were needed in order inspect and maintain the cutter head. The combination of soft ground and low tunnel overburden, made the risk of face instability.