Tunnel Boring

Tunnel Boring

Tunnel boring is a construction method used to install utility tunnels through the ground. Mechanical excavation of the ground is done by a cutterhead that is pre-selected based on the soil conditions prior to launching the machine. An operator located inside of the TBM controls all TBM functions including cutterhead rotation, spoil conveyance, and steering for line and grade accuracy. Excavated material from the cutterhead is conveyed to an electrically driven haul unit that transfers material to the launch shaft when full.

Pipe Jacking Mode

The TBM is advanced from the launch to reception shaft by thrust forces transmitted through the product pipe by a main jacking unit located at the launch shaft.

Two-Pass Mode

The TBM is advanced by propulsion cylinders located inside a secondary shield at the machine. Thrust forces are transmitted to a liner that is hauled into the TBM and erected at the tail section of the shield.

Case Studies

Blacks Run Interceptor Division 1B Replacement

The Blacks Run Interceptor – Division 1B –Replacement project scope included 3,700-lf. of 48-in. sanitary sewer installed by open-cut and trenchless methods.

A 200-lf. section that crossed under Stone Spring Road requiring a tunnel boring machine to maintain traffic on a busy arterial roadway.

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