上海市前卫泵站流道结构精细化温控仿真

Simulation study on refined temperature control of passagewaysstructure in Qianwei Pumping Station

泵站的进出口流道结构在温度荷载的作用下容易开裂,结构内埋设冷却水管是主要的大体积混凝土温控措施。为对采用预埋冷却水管的流道结构进行精细化仿真分析,结合前卫泵闸实际工程,采用热流耦合算法分析了预埋水管的流道混凝土内部温度场及应力场分布特征,比较了等效算法与热流耦合算法顺河向最大应力,对冷却水通水流量及通水温度进行了参数敏感性分析。结果表明:热流耦合精细算法相较于其他算法,考虑了水管附近温度梯度,计算应力值更大;加大通水流量对削减水化温升效果不显著;降低水温能有效削减水化温升,但加大了水管附近的温度梯度与通水期间温降速率,增大拉应力,增加早龄期混凝土开裂风险。建议夏季浇筑时进行一期通水冷却,冷却水流量0.5~1.5 m~3/h,水温15~20℃。流道与底板结合部位是防裂重点关注区域,需控制通水强度。研究结果可为类似工程中的泵站流道温控工作提供参考。

The inlet and outlet passageways of the pump station were easy to crack under temperature loads and the buring cooling-water pipes in the structure was the main temperature-control measure for mass concrete.In order to make a fine simulation analysis of the passageway structure with embedded cooling water pipes,combined with the practical project of the Qianwei pumping station,the heat flow coupling algorithm was used to analyze in detail the distribution characteristics of the temperature field and stress field in the passageways concrete with embedded water pipes.Comparing the equivalent algorithm with the heat-flow coupling algorithm for downriver maximum stress,the parameter sensitivity analysis of cooling-water flow and water temperature was conducted.It was showed that the heat-flow coupling fine algorithm,compared with other algorithms,can take into account the temperature gradient near the water pipe,and the calculated stress value was larger than other algorithms.The increasing of the through-water flow rate didn’t have a significant effect on cutting down the hydration temperature rise.The lowering water temperature can effectively cut down the hydration temperature rise,but would increase the temperature gradient near the water pipe and the temperature drop rate during the through-watering period,which increased the tensile stress and the risk of cracking of the concrete at early age.The suggestions were as following:the phase of water passage cooling was carried out during the summer pouring,with a cooling water flow rate from 0.5 m 3/h to 1.5 m 3/h and the water temperature from 15℃to 20℃.The combined area of runner and bottom plate was the key concern area for the crack prevention,and the intensity of water passage needed to be controlled.The results of the study can provide a reference for temperature-control measures of pump station passageways in similar projects.