The Optimized Design of the Diversion Tunnel Intake Transition Section for Construction of the Longma Hydropower Project

The structural configuration of the transition section of the diversion tunnel for construction of the Longma hydropower project was readjusted and changed into an open cut tunnel from a deeply buried tunnel after optimization in view of its restricted construction conditions,construction schedule and structural safety,which created favorable conditions for successful completion and commercial operation of the project on schedule,thus bringing about significant economic benefits.The transition structure proved safe and reliable and neither damage nor leakage was found under direct action of an external water head as high as 93m during gate closing and plugging of the tunnel in March,2003.