小温差冷却对大体积混凝土温度应力的影响效应

Effects of small temperature difference cooling on temperature stress of mass concrete

提出了大体积混凝土采用小温差冷却的方式,以有效降低水管周边混凝土温度梯度,减小温度应力,防止水管周边混凝土早期温度裂缝的产生。为验证小温差冷却的影响效应,本文采用三维有限元热流耦合算法,对传统低温通水冷却和小温差变温通水冷却分别进行了研究。结果表明:传统低温通水冷却水管周边混凝土温度梯度大、温降速率快,混凝土浇筑早期温度应力易超过同期的允许应力;小温差变温通水冷却水管周边混凝土温度梯度小、温降速率慢,改善了水管周边混凝土早期温度应力,避免混凝土因遭受冷却水的冷击而形成早期裂缝。小温差变温通水冷却方式将成为大体积混凝土通水冷却的发展趋势。

It is proposed that mass concrete should be cooled by small temperature difference to effectively reduce the temperature gradient of concrete around water pipes, reduce the temperature stress and prevent the early temperature cracks of concrete around water pipes. In this paper, in order to verify the influence effects of small temperature difference cooling, a three-dimensional finite element heat flow coupling algorithm is used to study the traditional low-temperature water cooling and water cooling with small temperature difference and variable temperature, the results show that the concrete around the water pipe has a larger temperature gradient and faster temperature drop rate in the traditional low-temperature water cooling mode, so the temperature stress at the early stage of concrete pouring is easy to exceed the allowable stress during the same period. And it also shows that under the water cooling with small temperature difference and variable temperature mode, the temperature gradient of the concrete around the water pipe is smaller and the temperature drop rate is slower, which improves the early temperature stress of the concrete around the water pipe, and avoids the early cracks of the concrete due to the rapid temperature drop of the cooling water. Water cooling with small temperature difference and variable temperature mode will become the trend of mass concrete water cooling.