碾压混凝土大坝全断面准三级配施工方法

Construction of Full-section Three-graded Concrete of RCC Dam

碾压混凝土坝上下游防渗区一般采用二级配混凝土,中部采用三级配混凝土。施工过程,混凝土种类繁多易造成铺料错误,影响施工质量,仓号内出现不同级配碾压混凝土、常态混凝土、砂浆等多达5~6种,工艺复杂,导致无法快速施工。下凯富峡水电站对碾压混凝土设计和施工新理念、新技术、新工艺进行系统的提炼和总结,对大坝结构进行设计优化,整个坝体采用同一级配的准三级配(最大骨料粒径为63 mm)碾压混凝土,上下游防渗区也采用同种碾压混凝土,通过底部加浆、振捣形成变态混凝土。

Two-graded concrete is normally used in the upstream and downstream for the seepage control of rolled dam,while three-graded concrete is used in the dam body itself.In the construction,different kind of concrete mignt be mixed in placement in same block,affecting the construction quality.Placement of roller compacted concrete,normal concrete and mortar in the same block will affect construction progress.In the Kafue Gorge Lower Hydropower Station construction,the dam structure design was optimized based on the analysis and study of new concept,technology and processes of RCC design and construction,and quasi three-graded roller compacted concrete(max aggregate size of 63 mm)was used in the dam body,while in the upstream and downstream of the dam the roller compacted conrete was transformed into enrich-vibrated Rcc by adding sllury from the bottom and vibrating.