考虑冷却措施的高混凝土坝施工过程温度场分析研究

Analysis of temperature field of high concrete dams with cooling measures during construction

为充分开发利用我国蕴藏的丰富水能,一批高混凝土坝正在规划建设之中。在高混凝土坝施工过程中,由于温度处理不当而导致坝体开裂甚至危及坝体安全的事例较为多见,温度控制问题已成为影响坝体施工速度和坝体安全的关键因素。埋设冷却水管是混凝土坝人工冷却的一个有效手段,可以实现削减初期温度峰值、减少混凝土温度降至稳定温度的时间的作用。因此,研究冷却水管对高混凝土坝施工过程温度场的影响具有十分重要的工程意义。本文在前人研究的基础上,以ANSYS为平台,以APDL开发语言为工具自行编制了混凝土浇筑过程非稳定温度场的计算程序,验证了程序的准确性,进而以该程序为工具,以龙滩碾压混凝土重力坝浇筑过程为实例,针对天然冷却和有人工冷却措施两种工况进行了温度仿真分析,并研究了大坝浇注完毕后坝体温度场与正常蓄水位下的水荷载耦合作用的应力场分布规律,通过两种工况研究结果对比,分析了人工冷却措施对大坝安全性的影响,得出了一些有益的结论。

To further develop the rich hydropower resources,a number of high concrete dams are under construction in China.The cracking of these dams caused by improper temperature control during the construction period is prevalent,and it can be a threat to dam safety.Temperature control becomes a determining factor of the dam safety and construction speed,and artificial cooling in the construction period is often necessary.Lying cooling pipes is an effective measure that is commonly adopted to lower the peak temperature and shorten the period of temperature dropping to its stable value.Study of the thermal stress field under this measure is of great significance.In this paper,a code in ANSYS parametric design language（APDL）is developed on the basis of the previous studies and verified to simulate the unsteady temperature field during concrete placing.In a case study of the Longtan RCC gravity dam,this model is applied to the artificial cooling case and the case without artificial cooling,and the behaviors of temperature and stress fields upon the completion of concrete placing under the normal stage water pressure are examined.The effects of artificial cooling on dam safety are analyzed through a comparison of the two cases,and some useful conclusions are derived.