大体积混凝土水化热冷-孔混合温控方案研究

Study on Temperature Control Scheme of Mixing Cooling Pipes and Prestressed Ducts for Hydration Heat of Mass Concrete

摘要:

大体积混凝土在浇筑过程中易因水化热积聚而引发温度裂缝。为避免冷水管与预应力孔道的空间布置冲突问题，以新建珠海至肇庆高铁某特大桥为研究对象，创新性提出了冷-孔（冷水管-预应力筋孔道）混合温控方案，即利用0#块上层加宽截面的预应力孔道作为通水冷却通道，联合内部冷水管协同温控。基于MIDAS FEA NX 2022软件建立了三维水化热有限元模型，系统分析了冷水管关键参数及预应力孔道通水数量对温控效果的影响规律，并确定了最优参数。与无温控方案相比，采用混合温控方案可使核心最大温度降低22%、温效主拉应力降低50%。该桥现场温度监测数据验证了有限元分析模型的正确性和提出的冷-孔混合温控方案的有效性。

Abstract:

Mass concrete is prone to thermal cracking during the pouring process due to the accumulation of hydration heat. To avoid the spatial layout conflicts between cooling pipes and prestressed ducts, taking a specific large bridge on the newly constructed Zhuhai - Zhaoqing High-speed Railway as the research subject, a mixed temperature control scheme of Cooling-Duct (cooling pipe - prestressed tendon duct) is innovatively proposed, which is to use the prestressed ducts in the widened upper section of the 0# block as water-cooling channels, jointing the internal cooling pipes for collaborative temperature control. Based on MIDAS FEA NX 2022 software, a three-dimensional hydration heat finite element model is established to systematically analyze the influence of key parameters of cooling pipes and the amount of water flowing through prestressed ducts on temperature control effects, and the optimal parameters are determined accordingly. Compared with the no-temperature-control scheme, the use of mixed temperature control scheme can reduce the maximum core temperature by 22% and the principal tensile stress induced by temperature effects by 50%. The on-site temperature monitoring data from the bridge validate the accuracy of the finite element analysis model and confirm the effectiveness of the proposed Cooling-Duct mixed temperature control scheme.