施工因素对地铁车站侧墙混凝土早期裂缝影响监测分析

Monitoring Analysis of Influence of Construction Factors on Early Age Cracking of Sidewall Concrete in Metro Station Engineering

监测了不同施工季节、模板材质和拆模时间等工况下某地铁车站主体结构侧墙混凝土温度、应变历程,分析了其对混凝土早期收缩开裂的影响。结果表明,施工时气温越高,侧墙混凝土温升、温降、温降速率以及温降收缩越大,开裂风险也显著上升。使用钢模板有利于早期散热,可显著降低侧墙混凝土的温升与温度峰值,降低其开裂风险。延长木模板拆模时间可减小侧墙混凝土的温降速率,利用混凝土的徐变效应抑制开裂风险。上述施工因素变化过程中,侧墙混凝土的里表温差及其引起的开裂风险总体较小。

The temperature and strain history of sidewall concrete of a metro station main structure were monitored under conditions including different construction seasons,form materials and its removal time,based on which the effects of these conditions on the early age cracking of sidewall concrete were analyzed furtherly.The results show that the temperature rise,temperature drop,temperature drop rate and shrinkage deformation at temperature drop stage of sidewall concrete increase with the increase of air temperature during construction,and the cracking risk of sidewall concrete also rises obviously.The application of steel form helps hydration heat dissipation and decreases the temperature rise and peak of sidewall concrete significantly,as well as the cracking risk.Removing wood form later decreases the temperature drop rate and cracking risk of sidewall concrete because of creep effect.The temperature difference between center and surface of sidewall concrete and the cracking risk caused by it are always small under the above variable construction conditions.