Abstract:

In Keelung River Yuanshantz Flood Diversion project, the inlet structure of diversion tunnel is located at a high and steep mountainside. A cutandcover structure was originally planned, but, from the viewpoint of environmental impact, cost effectiveness and time schedule, the tunnel structure is reconsidered. By the experience from locks excavation of Yangtze River Three Gorges project, an open channel and deepcut method was adopted finally. Piles and anchors are used as primary supports in the upper soil layer. Rock layer excavation is supported by semirigid elements, such as rock mass, shotcrete and bolts. Both FEM analysis and site monitoring are implemented in this project. Lining wall design concept is applied in channel structure. Piles and rock mass are incorporated with the final structures, and a drainage system is provided. By the design concept, earth and water pressure is greatly diminished.

Key words: Yuanshantz flood diversion tunnel, deep cut, lining wall