Design aspects of the Bangkok Blue Line Extension

摘要

The Bangkok Blue Line Extension is the second phase of the subway system in Bangkok implemented to mitigate traffic problem in the Metropolitan area. The tunnel will be excavated underneath the old Chinatown, a densely populated urban district, historical areas, and cross underneath the major river in Bangkok. Since, there are very limited working spaces on the ground level, design and construction methods will be optimized to reduce effects of the construction on ground surface and existing structures. A large dual-track tunnel with 11 meter in outer-diameter and twin tunnels with 6.3 meter in outer-diameter are considered. Selecting a suitable type of tunnel boring machines is also crucial since the machine must be capable of excavating a tunnel throughout various geological conditions including soft to stiff clay layer, dense sand layer, and sand layer with high water pressure without inducing large ground movements.