钢桥面浇注式沥青混合料施工过程温度场分析

Temperature Field during the Construction of Gussasphalt onSteel Bridge Deck

摊铺工艺和环境对钢桥面浇注式沥青混合料施工温度场影响较大。为优化摊铺工艺,减小温度变形对钢桥面系结构的损伤,以武汉沌口长江大桥为依托,采用Abaqus软件建立了三维有限元模型,基于生死单元控制技术模拟了浇注式沥青混合料在不同风速和摊铺速度下的温度场;并基于实桥监测数据进行了对比分析。研究结果表明:浇注式沥青混合料在摊铺完成后,铺装层表面温度呈“三阶段”变化趋势,即急剧下降阶段、快速下降阶段和缓慢下降阶段;在浇注式沥青混合料摊铺完成30 min后,钢桥面顶板实测最高温度为103℃(比摊铺温度低138.6℃),该温度持续时间较短,约为8 min;由于MMA防水黏结层的吸热及阻热效应,最高温度出现的时间比有限元模拟的时间滞后约13 min;为避免钢桥面系在摊铺过程中出现温度应力集中,浇注式沥青混合料摊铺速度宜控制在2.5~3.0 m/min之间;当风速大于3 m/s时,浇注式沥青混合料温度散失较为明显,为了降低温度散失对施工和易性的影响,混合料卸料点应尽可能地接近摊铺机,距离宜控制在0.5~1.5 m。

The paving technics and environment have a great influence on the construction temperature field of gussasphalt on steel bridge deck.In order to optimize the paving technics and reduce the damage to the steel bridge deck structure caused by temperature deformation,based on the project of Wuhan Zhuankou Yangtze River Bridge,a three-dimensional finite element model was established with Abaqus software.And the temperature field of gussasphalt under different wind speeds and paving speeds was simulated based on the life-and-death unit control technology.And comparative analysis was conducted based on the monitoring data of the actual bridge.The research results show that:after the gussasphalt is paved,the surface temperature of the pavement layer shows a“three stage”trend of change,namely a sharp decline stage,a rapid decline stage and a slow decline stage.After 30 minutes of gussasphalt paving,the measured maximum temperature of the top plate of steel bridge deck is 103°C(138.6°C lower than the paving temperature),and the duration of this temperature is relatively short,approximately 8 minutes.Due to the heat absorption and heat resistance effects of the MMA waterproof-bonding layer,the time when the highest temperature occurs is about 13 minutes later than the time simulated by finite element analysis.In order to avoid the concentration of temperature stress on the steel bridge deck during paving,the paving speed of gussasphalt should be controlled between 2.5 m/min and 3.0 m/min.When the wind speed is greater than 3 m/s,the temperature loss of gussasphalt is more obvious.In order to reduce the influence of temperature loss on the workability of construction,the unloading point of gussasphalt should be as close to the paver as possible,and the distance should be controlled between 0.5 m and 1.5 m.