零号箱梁水化热温度应变场分析

Analysis of hydration heat temperature and strain field in the zero block

为研究混凝土箱梁零号块的水化热温度效应,找到合理的温控措施,基于某大跨度连续梁桥两处零号箱梁浇筑后的实测数据,运用有限元分析软件模拟箱梁浇筑后的水化热温度场,分析了外部温度对水化热温度场的影响,提出了用竖向筋波纹管充当冷却管的温控方案.试验研究表明:混凝土箱梁的温度实测值与计算值符合较好,说明有限元分析模型能有效模拟水化热温度场;水化热产生的顶底板温度梯度与外部温度有关,夏季施工比冬季施工时达到的顶底板温差更大;应变场与温度场呈负相关状态,且应变变化滞后于温度变化,应变先压后拉.因此,零号箱梁的浇筑宜在温度较低时进行,浇筑完成后,应当根据水化热温度效应的特点,对重要部位进行针对性养护,并采用适当温控方案,以降低混凝土内部最高温度及顶底板温度梯度.

In order to study the hydration heat temperature effect of zero block and find appropriate temperature control measures,based on the measured date of two zero blocks on a long-span continuous beam bridge,the simulation analysis of hydrated heat temperature field after the depositing period of zero block is made by the help of software of finite element analysis.This paper analysis the effect of ambient temperature on the hydration heat temperature field,and a temperature control scheme by which vertical corrugate pipe acts as cooling pipe is proposed.The results indicate that the simulation results coincide with the measured data,which prove that the finite element analysis model can effectively simulate the hydration heat temperature field;the temperature differences generated by hydration heat between upper and bottom plate are influenced by ambient temperature,it is greater when constructed in summer than in winter;the stress field is negatively correlated with the temperature field,and the strain variation lags behind the temperature variation,the strain changes from pressure to tension.Thus,the depositing of zero block should be carried out under low temperature,and after it is completed the maintenance of important parts should be kept targeted in accordance with the characteristics of hydration heat temperature field.And appropriate temperature control scheme should be adopted to reduce the maximum temperature of inner concrete and the temperature differences between upper and bottom plate.