CASE STUDIES

PROJECT SUMMARY

The Tunneling Company was engaged to install a 1524 mm (60 in) steel culvert under its rail line and a four-lane highway divided by a median. Based on the information provided, we began drilling using a tunnel boring machine (TBM).

With rich clay soil throughout most of the province, Saskatchewan is considered to have ideal ground condition for trenchless construction. Anticipating this would hold true along a section of track southeast of North Battleford, no Geotechnical Study was prepared for this crossing.

KEY CHALLENGES

Early into drilling, we encountered unexpectedly challenging ground conditions, hitting several large boulders. As we approached the 3 m (11 ft) mark, we were faced with a million dollar decision: to stop drilling or to continue on and risk losing this expensive piece of equipment with no chance of recovery.

The Tunneling Company decided to pull out the TBM and complete the project by hand tunneling. Two crew members worked in the pipe. One did the tunneling using an air pick capable of pulverizing the boulders, while a “mucker” loaded the material into a cart on rails. Every couple of feet the pipe would be hydraulically pushed into the void.

The skill and experience of our crew allowed us to excavate at an impressive rate of 3 to 4 m/ day (vs. 6 m/day for the TBM). The client was pleased with our ability to adapt to the unexpected conditions and safely complete the project in a timely manner.

SERVICES PROVIDED

TUNNEL BORING MACHINE AND HAND TUNNELING