大体积承台水化热计算分析研究

Calculation, Analysis and Study on Hydration Heat of Mass Base Slab

摘要:

为研究大体积承台浇筑过程中水化热对结构抗裂性能的影响，以主跨148 m的某大桥Y墩变截面连续刚构桥为工程依托，从水化热计算分析涉及到的各个力学与物理特性参数出发，建立其有限元模型模拟浇筑过程中的温度场和应力场，利用规范对计算模拟结果进行判断，从而得到指导实际浇筑过程的温控措施，提高施工质量和效率。结果表明：内部最高温度出现在2~3 d时间段，在实际浇筑过程中应着重关注早期的温度骤增情况对结构的不利影响；混凝土结构里表温差最大出现在2~3 d时间段，拉应力最大出现在28 d时间段，说明浇筑后水化热前期对结构应力影响较小，后期由于混凝土收缩徐变导致拉应力增大；混凝土最大主拉应力为2.8 MPa，发生在第28 d时刻，需采取有效的保温保湿措施以确保结构抗裂性能。

Abstract:

In order to study the influence of hydration heat on the structural crack resistance during the pouring of mass base slab, taking a Y-pier variable cross-section continuous rigid-frame bridge with the main span of 148 m as the engineering background, starting from various mechanical and physical characteristic parameters involved in the calculation and analysis of hydration heat, its finite element model is established to simulate the temperature field and stress field during the pouring process. The code is used to judge the calculation and simulation results so as to obtain the temperature control measures to guide the actual pouring process and improve the construction quality and efficiency. The results show that the maximum internal temperature occurs in the period of 2~3 d. In the actual pouring process, the attention should be paid to the adverse impact of the early temperature surge on the structure; The maximum inner surface temperature difference of concrete structure occurs in the period of 2~3 d, and the maximum tensile stress occurs in the period of 28 d, indicating that the hydration heat after pouring has little effect on the structural stress in the early stage, and the tensile stress increases due to the shrinkage and creep of concrete in the later stage. The maximum principal tensile stress of concrete is 2.8 MPa, which occurs at the 28 th day. The effective thermal insulation and moisturizing measures shall be taken to ensure the crack resistance of the structure.