温度及约束对地下长墙应变分布的影响

Study on Effects of Temperature and Restraint Coefficient for Strain Distribution in the Basement Wallboard

通过实际工程地下室墙体的原位试验,明确了墙体混凝土的应变随混凝土水化温度发展的变化规律。在全面分析对比不同厚度墙板温度曲线的基础上,提出由于厚度不大的地下室墙板达到温度峰值的时间较早、温差较大且降温段较陡,应重视提早进行养护。将约束系数现有公式的计算值与试验值进行对比,分析了产生差异的原因,主要是混凝土弹性模量增长趋势发生变化所致。混凝土弹性模量早期快速增长使墙板的约束系数迅速增大,现有公式的计算值无法反映出早期墙板中较高的约束系数。同时,根据试验结果提出了有益的防裂措施建议。

According to test results of basement wall in a practical project,it is clear about the relationship between the development of concrete strain and the diversification of cement hydration temperature in concrete wall.Based on the comprehensive analysis of temperature curves of wallboard with different thickness,it is suggested that the curing of wallboard should be remarkably ahead due to that the peak value of hydration heat appears earlier,the maximum temperature rise-up is more,and the fall of segment temperature is steep. A variance about restraint coefficient between the results of the calculating formula and the experimental data is caused by the change of the grow - up law in elastic modulus of concrete in the early age. The restraint coefficient of wallboard rises up rapidly with elastic modulus of concrete in the early age, and the existing formula of restraint coefficient could not be entirely applicable. Besides, some suggestions about crack prevention are given.