大型坝体基础结构新施工方案的综合研究

Comprehensive study of the new construction scheme for large-scale dam body foundation structure

鉴于坝基结构施工传统沉井方案在大型坝体应用中的局限性,设计采用地下连续墙处理坝基深厚覆盖层、兼具挡土与坝体基础双重作用的新施工方案.分别从结构受力、施工技术以及工程造价的角度对此方案进行了综合研究:依据水工规范,在进行坝体整体结构核算的基础上,采用三维有限元方法,分析坝体整体结构及地下连续墙复合挡土墙体系在最不利工况下的受力变形与稳定特性;并作出方案的技术经济评价.结果表明,结构的受力状况满足规范要求且安全储备较大,地下连续墙技术能够胜任大型坝基施工,新方案与原沉井方案造价约相差5.5%.综合分析验证了新方案的可行性,并针对结构特点提出一些施工建议,为同类大型工程设计施工提供参考.

Considering the limitation of the traditional open caisson scheme for construction of dam body foundation structures when it is applied to a large-scale dam body project, a new construction scheme where the underground diaphragm wall plays double parts in both retaining wall and dam body foundation is designed to deal with the deep overburden layer of the dam foundation. The comprehensive study of this scheme is carried out from the aspects of structure stress, construction technology and engineering cost. According to specifications for water conservancy and hydropower engineering,after the checking computations of the overall structure of the dam body have been done, the three-dimensional finite element method is employed to analyze the stress, deformation and stabilization characteristic of the overall structure of the dam body and the composite retaining wall of diaphragm wall under worst operating modes. In addition, a technical and economical evaluetion of the scheme is provided. The results of these previous researches indicate that, the stress status of structure meets the demand of specifications very well; underground diaphragm wall technology is competent for the con- struction of the large-scale dam body foundation; the cost of the new scheme is 5. 5% higher than the old one. The feasibility of the new scheme is verified by the comprehensive analysis, of which the function is not only to table some proposals for construction in the light of design features, but also to provide reference for like large-scale engineering.