三峡大坝采用碾压混凝土的施工方案初步研究

Study on construction schemes of Three Gorges RCC dam

三峡工程技术设计阶段进一步研究了三峡大坝部分采用ＲＣＣ碾压混凝土的方案，经分析比较，工期可较初设推荐方案缩短３个月和提前４个月将坝体浇筑至坝顶。但枢纽最高年混凝土浇筑强度将由常态混凝土方案的４１０万立方米增大到４８３万立方米，最高月强度由４６万立方米增大到５３．９万立方米，且高峰提前，施工不均匀性增大。部分采用碾压混凝土方案的施工，初步研究了４个浇筑方案，推荐高程１２０米以下用美国洛泰克塔带机成套设备、高程１２０米以上用高架门机浇筑的方案和高程５３米以下用大型塔机吊皮带机（或自卸汽车直接入仓）、５３米以上用大型塔机浇筑两个方案。为慎重起见，建议上述两个方案的关键设备，即专用塔带机和大型塔机用于三峡大坝浇筑混凝土之前，必须先在一期工程先进行生产性使用。由于强度的增加，大坝部分采用碾压混凝土后，拌和楼配置的容量需增大，冷冻容量则仍与常态混凝土方案相当。

Study is further carried out on construction schemes of partial dam body of Three Gorges Project to adopt RCC during technical design stage.Analysis and comparisons show that with adopting RCC,the total construction time taken may be 3 months shorter than preliminary design stage,and the time of concrete placing to the top of the dam may be 4 months ahead of schedule. However,the annual peak intensity of concrete placement would increase from 4.1 million m3 of conventional concrete to present 4. 83 million m3,and monthly peak intensity from 460 thousand m3 to 539 thousand m3. The occurrence time of peak intensity will be ahead of the original target date. The construction of C'Oncrete will become more unbalanced.For adopting RCC in construction of partial Three Gorges dam body,four RCC placement schemes are studied preliminarily, of which two schemes ate recommended:the one is that the dam body below elevation of 120 m will be placed by using U. S.Rotec tower crane infullset,above elevation of 120 m using high-framed portal cranes;the another is that the dam body below elevation of 53m will be placed by using heavy creter cranes(or dump trucks directly to the placing area),above elevation of 53 m using heavy tower cranes.For cautiousness,it is suggested that the key equipments of above two schemes,i. e.specific tower crane,and heavy creter crane 4 must be productively used in first-stage works before they will be used in concrete placement of Three Gorges dam' With partial dam body to adopt RCC,because of increment of concrete placement intensity,the capacity of mixer plant must be also increased,while the capacity of cooling plant is still equivalent to one of conventional concrete scheme.