天生桥一级水电站土石过水围堰设计

Design of the earth rock overflow cofferdam in Tianshengqiao First cascade Hydropower Station

天生桥一级水电站土石过水围堰在二级水电站库区修建，具有轴线长、基础复杂、深水填筑等特点，在设计、施工过程中，通过堰型选择，采用高喷板墙、振冲碎石桩、混凝土楔型体护面等新技术，较好地解决了防渗、堰基稳定和度汛保护的难题。由于标书提供的水位流量关系指标较实际运行值相差较大，且受到已建二级水电站运行水位制约，１９９５年单洞度汛中，下游围堰堰脚局部遭到淘刷，但上、下游围堰安全度汛，保护了截流成果和大坝基坑。维修加固后，１９９６年汛期双洞导流，围堰和坝面７次过水完好无损，保护了大坝填筑体的度汛安全。证明天生桥一级水电站土石过水围堰设计是成功的。

The earth rock overflow cofferdam for Tianshengqiao First cascade Hydropower Station is built in the reservoir area of Tianshengqiao Second cascade Hydropower Station,with long dam axis,complex foundation and filling in deep water.In the design and construction,some new technologies of high shotcrete sheet wall,vibroflotation crushed stone pile and concrete wedge block facing have been used so that the difficulties of seepage control,stability of weir foundation and protection in flood season have been solved.Due to the big difference between the stage discharge relation provided in the bidding document and its actual values and the restriction of the operation water level of the completed second cascade hydropower station,local parts of weir toe of the downstream cofferdam were eroded in 1995.After the repair and reinforcement,it passed 7 floods without erosion during flood season in 1996 so that it made the dam pass the flood season safely.It shows that the design of earth rock overflow cofferdam for Tianshengqiao First cascade Hydropower Station is successful.