Study On The Lay And Foundation Design Of Cable Crane For Xiaowan Hydropower Station

The Xiaowan hydropower station is a huge project, whose double-curvature arch dam is a height of 292m, a width of 12m on the crest and a maximum width of 72.912m on the bottom. The arch dam is composed of 43 monoliths and the total amount of concrete is approximately 837.351×104m3.The cable crane is the unique economical and feasible means in the process of dam concrete pouring. Because of the steep cliff and topographical asymmetry in the position of the dam abutment where is a talus slide in the Yinshui ditch on the left bank and a talus slide in the Da Chunshu ditch on the right bank, layout of the cable crane is difficult. After multi-variant argumentation in four stages, the scheme of the cable cranes layout that the five cable cranes are laid out in double layers, 2 cable cranes on the upper layers and 3 on the lower layers, was determined.Taking account of importance of the cable crane foundation to the project, its stability, safety and credibility is key. After multi-variant argumentation, a more perfect scheme of the foundation of the cable cranes on the left and right banks whose structure is simpler, distortion is satisfied with control request, construction is easier and scheduled investment is more ideal was determined.During the course of the cable cranes foundation design, deposit dispose, slope stability and deep level antiskid should be considered, in addition, the cable cranes foundation distortion, safety and stability of the cable cranes foundation and its upper structures should be considered too.According to different topographic and geologic conditions, foundation structure of the cable cranes should be satisfied with the request of intensity, stability, distortion and differential settlement and so on and it will be designed into different forms in sections in different positions in order to appeal to different places'geologic conditions.In addition to satisfying the foundation structure own demands, control to horizontal displacement of cable cranes foundation crest should be met the deflection demand in the course of operation of the cable cranes.Base on local geologic and construction conditions, the cable cranes foundation structures in the sections across the Yinshui ditch on the left bank and the Da Chunshu ditch on the right bank are changed into arched structures.Monitoring design of the cable cranes safe operation, material and temperature control design of foundational concrete pouring is carried out.