BRIGHTWATER CONVEYANCE SYSTEM, CENTRAL CONTRACT: OVERCOMING THE CHALLENGES OF INSTALLING PIPE AND FINAL LININGS IN LONG BORE TUNNELS

摘要

The Brightwater Central Contract is comprised of two tunnel sections, BT-2 and BT-3. The BT-2 tunnel is 3,536m (11,600 ft) long with the final lining consisting of three separate pipelines that run the tunnel’s entire length. The BT-3 tunnel is 6,127m (20,100 ft) with the final lining being a 3.22m (10.58 ft) steel pipe running the first 1,400m (4600 ft) from the North Kenmore Portal. The piping in both tunnels is backfilled with low density cellular concrete (LDCC). In BT-2 the backfill concrete is capped with a structural slab that slopes towards the pump station shaft. In BT-3 the backfill concrete fills there entire annulus between the steel pipe liner and the tunnel segmented liner. Challenges common to both tunnels were placing straight pipe sections in curves, maintaining specified clearances between the tunnel liner and pipe, and conveying the LDCC long distances from the surface batch plant. Each tunnel had specific challenges due to their configuration also. This paper will review the methods used to overcome these common and specific challenges to successfully complete the Brightwater Central Project.