东庄高拱坝温控措施敏感性分析

Sensitivity Analysis of Temperature Control Measures for Dongzhuang High Arch Dam

为了提高混凝土高拱坝温控防裂安全性,结合泾河东庄230 m超高拱坝工程特点,采用三维有限元法考虑混凝土浇筑温度、冷却水管间距、水温及流量等影响因素条件下对结构应力进行计算,分析不同温控措施条件对坝体温度及温度应力的影响程度。结果表明:混凝土浇筑温度每提高2℃,坝体混凝土最高温度增加约0.8℃~1.2℃,最大拉应力增加0.2 MPa~0.3 MPa左右,混凝土开裂风险有所增加;冷却水管间距从3.0 m~1.5 m变化,可以降低内部最高温度近4℃,大幅降低了混凝土早期最高温度;冷却水水温对最高温度和通水降温速率有较大影响,通水水温降低2℃,最高温度降低约0.5℃~0.7℃左右,初冷阶段适当降低冷却水温对控制最高温度较为有利;通水流量的影响主要体现在混凝土早期最高温度和各时期通水时间方面,而对坝体内部的温度应力影响则不明显。浇筑温度、初期冷却水温是温控敏感性较大的因素。

In order to improve the temperature control and crack prevention safety of concrete high arch dams, combined with the characteristics of the Jinghe Dongzhuang 230 meter ultra high arch dam project, a three-dimensional finite element method was used to analyze the influence of four key temperature control factors, namely concrete pouring temperature, cooling water pipe spacing, cooling water temperature, and water flow rate, on temperature stress. The degree of influence of different temperature control measures on the temperature and temperature stress of the dam body was elucidated. The results are as follows. For every 2°C increasing in concrete pouring temperature, the maximum temperature of the dam concrete was elevated about 0.8℃~1.2℃, and the maximum tensile stress increased about 0.2 MPa~0.3 MPa, rising the risk of concrete cracking;The spacing between cooling water pipes varies from 3.0 to 1.5 meters, which can reduce the internal maximum temperature by nearly 4℃ and significantly lower the early maximum temperature of concrete;The cooling water temperature had a significant impact on the maximum temperature and the water cooling rate, and for every 2℃ decrease in the water temperature, the maximum temperature decreased by about 0.1℃~0.4℃. Therefore, it was more beneficial to control the maximum temperature by appropriately lowering the cooling water temperature at the initial cooling stage;The influence of water flow rate was mainly reflected in the maximum temperature of concrete at early stage and the water flow time of each stage, while the influence on the temperature stress inside the dam body was not obvious. In summary, the pouring temperature and the initial cooling water temperature were determined as the factors with high temperature control sensitivity. This research provides a theoretical basis for recommending temperature control measurements and improving the crack resistance safety of the dam concrete.