截流龙口河床精确抛投护底施工技术研究

Study on Construction Technology of Accurate Riprap Protection for the Riverbed at Closure Gap

截流是水利水电工程施工中的关键项目,其成败直接影响工程进度和施工安全。拉哇水电站是在高寒高海拔地区建设的250 m级特高面板堆石坝,枢纽区覆盖层深厚,地形地质条件复杂。因河床覆盖层抗冲能力差和龙口水力学条件复杂,截流戗堤进占期间受到高速水流冲刷,截流戗堤易坍塌、河床易冲蚀、抛投料损失大,只有对河床精确抛投护底,才能顺利实现截流目标。本文通过对拉哇水电站截流龙口河床精确抛投护底施工技术进行研究,以供类似工程参考和借鉴。

River closure is a key task in construction of water conservancy and hydropower projects,and it directly affects the project progress and construction safety.Lawa Hydropower Station is built in alpine and high-altitude region with a concrete faced rock-filled dam which has a height of 250m.Overburden layer at the areas of main structures of the project is deep,and the topographic and geological conditions are complicated.Due to poor anti-scour ability of overburden layer at riverbed,the complex hydraulic conditions at the closure gap,and the high-speed water flow,the closure embankment is easy to collapse,the riverbed is easy to be eroded,and the loss of riprap is in a big amount during occupation of the embankment,thus only when riprap is casted accurately into the bottom of the riverbed,can closure of the river be realized smoothly.This paper studies the construction technology of accurate riprap protection for riverbed at the closure gap of Lawa Hydropower Station for further reference by similar projects.