Diaphragm Walls, DPT

Dublin Port Tunnel is a 4.6 km twin bore tunnel and 1.1 km of new surface roadway in Dublin city centre linking Dublin Port to the national road network. It is a dedicated route for heavy goods vehicles and it is anticipated that it will remove over 9,000 trucks from Dublin city streets.

Carillion Piling in joint venture with Intrafor, undertook the geotechnical works which had a total value of £25m.

The largest shaft, WA2, was a launch/reception shaft for tunnel boring machines. It has a shaft diameter of 55m, a depth of 34m and wall thickness 1.5m.

The diaphragm walls were constructed using a combination of rope grabs and hydraulic milling machines. The complex nature of the site required careful planning and skillful construction to overcome many live services that remained on the site.

In addition to the diaphragm wall work on this project the joint venture undertook CFA and rotary piling, soil nailing and rock anchoring.

Equipment used:

• Bauer diaphragm wall mill.

• Rope suspended diaphragm wall grabs.