海沧大桥大体积混凝土锚碇温度场有限元分析

Finite Element Analysis on the Temperature Field of the Massive Concrete Anchorage of Haicang Bridge

结合厦门海沧大桥大体积混凝土锚碇分层浇筑动态施工过程,基于瞬态温度场三维有限元分析方法,应用大型通用商业软件ANSYS,考虑外界气温的周期变化、太阳辐射、水化生热、浇筑温度、分层厚度、边界条件随龄期变化及分层浇筑动态施工过程等因素,对大体积混凝土施工期和运行期的温度场进行仿真分析。分析结果表明:锚碇混凝土温度的变化过程可分为温升期、降温期和稳定期3个阶段,施工期和运行期影响混凝土锚碇温度的主要因素分别是水泥水化热和环境温度;水泥水化热是混凝土温升最根本、最直接的原因,采用低热水泥、降低水泥用量是降低水化热温升的直接手段;温度场中靠近外表面的温度梯度比较大,而内部温度梯度相对较小,应特别注意混凝土早期的内部降温、外部保温和养护。

Associated with the dynamic construction process of the layer pouring for the massive concrete anchorage of Haicang Bridge in Xiamen,based on transient temperature field three-dimensional finite element analysis method,the temperature field during both the construction and operation periods of the massive concrete was simulated by large-scale commercial software ANSYS considering such factors as the periodic variation of atmospheric temperature,solar radiation,hydration heat of cement,concrete constructing temperature, layer thickness, variation of boundary conditions with time, and the dynamic state process of constructing in layers. Analysis results show that the temperature change process of the anchorage concrete can be divided into three stages, temperature rise stage, temperature drop stage and stable stage. The key influencing factor of the concrete anchorage temperature during the construction period is the hydration heat of cement, but in operation period the atmospheric temperature is a decisive factor. Hydration heat of cement is the most ultimate and direct factor which affects the temperature rise of concrete.The direct way to reduce temperature rise of hydration heat is to use low-heat cement and reduce the amount of cement. The temperature gradient is relatively greater near the exterior of the surface and smaller interior in the temperature field of the massive concrete. Therefore, interior cooling, exterior thermal retardation and maintenance of concrete should be pay attention to in early time.