三峡大坝应用碾压混凝土的研究

Study on the application of RCC to Three Gorges dam

三峡工程具有工程量大、工期长的特点。为加快施工进度、缩短工期、节约水泥用量，拟在大坝的部分部位采用碾压混凝土（ＲＣＣ）。根据研究，考虑到坝体结构布置、构造要求、ＲＣＣ施工方法等因素，各坝段采用ＲＣＣ的部位将有所不同，总的采用原则是在坝体多钢筋的大孔。以下和结构布置简单而较规则的部位应用ＲＣＣ，但在基岩面上仍铺设１．０～１．５米厚的常态混凝土垫层。按上述原则，各坝段应用ＲＣＣ混凝土的总量约占大坝总混凝土量的１／３。采用ＲＣＣ的坝体断面，其迎水面用一定厚度的常态混凝土作防渗结构，即所谓“金包银”型式。采用ＲＣＣ后，对于控制工期的泄洪坝段，工期可缩短３～４个月，右岸厂房坝段可提前约４个月、研究结果表明，三峡大坝部分采用ＲＣＣ是可行的。但必须严格施工管理，以确保ＲＣＣ的施工质量，特别是保证层面结合良好和迎水面防渗层的防渗效果可靠。

Three Gorges Project has f6atures of large volume of works and long construction time. In order to speed the construction progress, shorten the construction time and save the cement, the applicaion of RCC to partial position of Three Gorges dam body is proposed. From study, because of constraint of structural layout and constitutional requirement of dam body and RCC construction method,etc, for different dam sections, the positions which are made up of RCC will be different from each other. The general principle for its adoption is that at positions below the large openings reinforced with many steel bars, and at positions of simply and regularly structural layout, RCC may be used to construct the dam body, but on the base rock surface a conventional concrete layer 1. 0-1. 5 m thick should be used as a cushion. Following above principle,the total RCC volume of various dam sections amounts to 4. 6 million m3 plUs, about one third of whole dam concrete volume. On the upstream surface of RCC dam body,a conventional concrete layer is laid for seepage control, i. e. so called n silver enclosed in gold' type. With adoption of RCC, the construction time of spillway dam section which controls total construction time of Three Gorges Project may be shortened by 3-4 months ; and the powerplant dam secton may be completed some 4 months ahead of schedule. The study result shows that it is feasible to apply RCC to partial position of Three Gorges dam body. However,consturction management must be strengthened to ensure good quality of RCC construction .especially good bonding of lin joints and reliable upstream facing of conventional concrete.