“边浇边灌”快速施工条件下拱坝温控防裂研究

Research on Prevention of Cracks by Temperature Control in Arch Dam under the Condition of“Simultaneous Pouring and Grouting”Rapid Construction

混凝土拱坝建设周期较长,温控要求严格;但有时为缩短工期,会采用“边浇边灌”方式,即上部浇筑新坝块的同时,下部老坝块进行灌浆封拱。由此产生的难题是上部一期冷却和下部二期冷却同步进行,温度梯度控制难度更大。为研究此工况下合理的温控方法,以在建拱坝为依托,建立三维有限元计算模型,对比分析浇完再灌方案和不同边浇边灌方案下坝体的温度及应力情况。结果表明,边浇边灌工况需要更为严格且精细的温控措施才能确保拱坝防裂安全,通过采用长时间缓慢的一期冷却、尽早开展缓慢的二期冷却、增设第三期冷却形成合理的温度梯度,以及加强表面保温等措施,可有效控制坝体拉应力。研究结果适用于拱坝快速施工。

The construction period of concrete arch dam is long and the temperature control requirement is strict.However,in order to shorten the construction period,a method called“Simultaneous Pouring and Grouting”will be applied in some circumstances.The first-stage cooling of the upper newly-built block and the second-stage cooling of the lower already-built block are performed simultaneously,which makes it difficult to control the temperature gradient.In order to analyze the temperature control method under such condition,a three-dimensional finite element model of an arch dam is established.The dam concrete temperature and stress simulated results under traditional arch construction and multiple“Simultaneous Pouring and Grouting”rapid construction cases are compared.The results show that stricter and more precise temperature control measures are needed to ensure the safety of arch dam under the condition of“Simultaneous Pouring and Grouting”.The measures including a longer time slow first-stage cooling,an earlier and slower second-stage cooling,providing a third-stage cooling,a more reasonable temperature gradient,enhancing surface insulation,will be effective in controlling the dam tensile stress.The research results may provide reference for the rapid construction of similar arch dams.