小浪底孔板泄洪洞的施工

小浪底水利枢纽布设的３条导流洞完成导流任务后，陆续改建成永久孔板泄洪洞。孔板洞改建成泄洪洞不仅节省投资，而且可以控制泄洪洞内水流流速，延长泄洪建筑物，但其改建工程是泄洪系统中施工难度最大的关键项目，而其成败的关键在于解决高水头、高流速、高含沙量对孔板洞流道的磨损。

Construction of the hole plate spillway tunnel of the Xiaolangdi Multipurpose Project

After the three diversion tunnels for the Xiaolangdi Multipurpose Project end its diversion tasks, they are reconstructed into the permanent hole plate spillway tunnel one after another Such reconstruction not only can save the investment but also can control the water velocity in the spillway tunnel to prolong its service life But such reconstruction project is key to the flood releasing system because it is the most difficult to construct The key of success or failure is to solve the abrasion of the hole plate tunnel by the water flow with high head, high velocity and high sediment content On the basis of a number of theoretical analysis and model tests, the method of placing three stage hole plate ring in the tunnel was adopted Such method can use the rotation and rolling of water flow when passing the narrow and then wide channel in the position of hole plate ring to produce the friction and collision inside the water flow and then to dissipate a lot of energy, and finally to reduce the water pressure, lower the velocity and avoid the abrasion to the tunnel This is a pioneering method in the world