基于光纤测温的混凝土坝上下游表面苯板保温效果反馈

摘要

In order to prevent cracking on concrete dam surface during construction period,the polystyrene board is usually pasted on dam upstream and downstream surfaces for heat insulation.Taking a concrete arch dam under construction in Southwest as a study case,the feedback on polystyrene board insulation effects are analyzed from the measured temperatures of daily average and daily variation respectively,in which,the real-time and online monitoring of temperatures in different depth near upstream and downstream surfaces of typical concrete pouring lift are carried out by optical fiber sensing technology.The feedback analyses show that the surface heat transfer coefficients of upstream and downstream surface are 3.4824 kJ/(m2·h·℃) and 8.5847 kJ/(m2· h· ℃) respectively when the upstream and downstream surface paste polystyrene board with a thickness of 5 cm and 3 cm respectively.The surface heat transfer coefficients are greater than estimated value based on polystyrene board material thermal resistance.%为防止混凝土坝在施工期产生表面裂缝,经常在坝体上下游混凝土表面粘贴聚苯乙烯泡沫塑料板进行保温.结合西南某建设中的混凝土拱坝,采用分布式光纤传感技术,实时在线监测典型混凝土浇筑仓上下游表面附近不同深度的温度状况,分别采用日变化和日平均实测温度反馈苯板保温效果.分析表明,上下游表面分别粘贴厚5 cm和3 cm苯板后,上下游面表面放热系数反演值分别为3.482 4、8.584 7 kJ/(m2·h·℃),均大于由材料热阻估计的苯板等效放热系数.