Title: DESIGN AND CONTRACTING STRATEGY FOR A SHORT TUNNEL IN MIXED GROUND CONDITIONS
Abstract: One of the key decisions in the planning and implementation of a tunnel project is the selection of the most appropriate tunnelling technology. Decision factoring tunnel projects often include: subsurface conditions; groundwater; tunnel size and spacing; depth below grade; proximity to buildings and facilities; local contractor capability and availability; risks due to ground loss; schedule; and, of course, costs. Approximately 40% of the City of Edmonton Light Rail Transit system's 12.3 km consists of underground works successfully constructed using Tunnel Boring Machine (TBM), Sequential Excavation Method (SEM) tunnelling and cut-and-cover techniques. The latest LRT extension consists of twin tunnels of complex geometry only 300 meters long, which pass under existing buildings and utilities and through a number of geological units. Due to this relatively short length of tunnel, the difficult ground conditions and the lack of local tunnel construction experience, the decision regarding the most appropriate tunnelling technology was perhaps more challenging than for any of the City's previous tunnel projects. This paper presents the design and contracting strategies implemented to mitigate tunnelling risks and to maximize interest and competition for the project.
Publication Year: 2004
Publication Date: 2004-01-01
Language: en
Type: article
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