特高拱坝封拱后温度回升及其原因分析

Temperature Rise in Super High Arch Dam after Arch Closure and its Cause Analysis

利用小湾拱坝工程的温度观测资料，运用仿真计算和回归分析相结合的方法来研究拱坝封拱后温度回升这一问题。小湾观测资料表明，坝体内距上、下游位置相近处，温度沿高程分布基本相同。封拱后坝体中心断面总体温升约6～8℃。研究表明，特高拱坝后期温度回升的主要原因是边界热量内传和坝体混凝土的残余水化发热，其中后期水化发热是主要原因，会使坝体内部温度高于稳定温度。后期水化发热的原因是早龄期低温温控抑制了胶凝材料早期水化和高掺粉煤灰的后期水化发热。封拱后的温度上升和回落会在坝体内部留下残余应力，且会增大拱座推力，给大坝和基础带来不利荷载增量，因此有必要进一步研究特高拱坝封拱后温度回升对坝体应力的影响。

Based on the monitoring data of Xiaowan arch darn, the phenomena of concrete temperature rise after arch closure of arch clam is studied by using FE simulation and regression analysis method. According to the monitoring data of Xiaowan arch dam, the temperature is almost the same where it has the same distance to dam surfaces, and the average temperature rise is about 6-8 ℃ in the center of dam. This study shows the temperature rise of super high arch dam after arch closure is the result of the thermal conductivity from boundary to dam internal and the residual hydration heat generating inside dam, and the residual hydration heat is main cause. The residual hydration heat will lead to the temperature inside dam being higher than stable temperature. There are two reasons for so large residual hydration heat： one is the delayed hydration of the binding material owing to the low temperature control at early age, and the other is the hydration of fly ash at mature age. Due to the creep effect of concrete, the temperature rise and fall in dam after arch closure will induce residual stress in dam body and additional force in arch support, i.e. it will lead to disadvantage load increment to dam and foundation. Therefore, it is necessary to study the effect of temperature rise in super high arch dam after arch closure on clam stress state in future.