混凝土早期温度回升对高拱坝应力的影响

Impact of early age temperature rising again on high arch dam stress

高拱坝在建设过程中,大体积混凝土经过初期冷却通水后,混凝土温度会发生不同程度的回升,区别于后期通水结束后的混凝土温度回升,早期混凝土弹模发展较快,温度开始回升到再次降至该温度值时,高拱坝会产生温升残余应力从而提高了坝体应力水平.采用热流耦合管单元真实反映水管附近及远离水管部位温度变化规律,分别考虑了温升幅值、温升时刻、温升历时三个因素对坝体应力的影响.仿真模拟结果表明:温升幅值越大,温升开始时间越早,温升历时越长,温升残余应力越大,坝体后期应力水平越高,且温升后采取通水冷却时水管附近会产生极大的拉应力,对大体积混凝土温控防裂较为不利.

During the construction of high arch dam, the temperature of mass concrete rising again to dif- ferent extent after initial cooling, which is different from that after later cooling, because modulus o{ elas- ticity grows fast in the early period. A residual stress will be produced which will increase the stress level of high arch dam when temperature rising again and then falls again. Using coupled thermal-fluid pipe which is able to accurately reflect temperature change laws of the position near and far from pipe to simu- late temperature rising again for researching the stress of dam considering effect of temperature rising again amplitude, temperature rising again moment, temperature rising again duration respectively. The simula- tion results show that the larger temperature rising again amplitude, the earlier temperature rising again be- gins; the longer temperature rising again lasts, and the larger the residual stress, the higher stress level will be. A great tensile stress would occur when pipe cooling start after temperature rising again, which is not conducive to temperature control and crack prevention of mass concrete.