钢砂沥青混凝土感应加热简化模型构建及仿真分析

Construction and Simulation Analysis of Simplified Model of Induction Heating of Steel Sand Asphalt Concrete

为研究沥青混凝土自愈合性能,为沥青路面养护技术中的自愈合方向提供理论及数据支撑。基于有限元方法,分别考虑了感应加热系统模型及感应加热数值计算模型,构建了多物理场下的钢砂沥青混凝土感应加热有限元简化模型,针对其感应加热自愈合过程进行了仿真分析,分别研究了电流强度、钢砂掺量及加热方式对感应加热的影响特性与能量分析,探究了不同情况下感应加热的机理及规律,并对耗散功率、耗散能以及能源利用率做分析。定义了两个新参数:有效愈合深度指数E1与感应加热时间指数E2,并结合有效愈合深度,联合评价感应加热的综合效益以优化参数配置。结果表明:电流强度越大或试件的钢砂掺量越大时,感应加热速率越快,由此形成的层间温度梯度越大,而钢砂产生的耗散能却会减小;感应加热停止时,有效愈合深度随加热时的电流强度与试件钢砂掺量的降低而减小,感应加热效果变差;处于自然散热阶段的试件的温度场在横向上呈现“翘曲分布”现象,即试件温度中心高而边缘低,层间温度梯度向着趋于零的趋势逐渐减小;可通过增大感应加热电流强度或钢砂掺量,采用较大循环加热时间、较短加热间隔的间歇式加热提高感应加热的综合效益。

In order to study the self-healing performance of asphalt concrete and provide theoretical and data support for the self-healing direction in asphalt pavement maintenance technology,based on the finite element method,the induction heating system model and the induction heating numerical calculation model are considered respectively,and the induction heating finite element model of steel sand asphalt concrete under multiple physical fields is constructed.The simulation analysis of its induction heating selfhealing process is carried out,and the influence characteristics and energy analysis of current intensity,steel sand content and heating mode on induction heating are studied respectively,the mechanism and law of induction heating under different conditions are explored,and the dissipated power,dissipated energy and energy utilization are analyzed.At the same time,two new parameters,effective healing depth index E,and induction heating time index Ez,are defined.Combined with effective healing depth,the comprehensive benefits of induction heating are jointly evaluated to optimize parameter configuration.The results show that,the higher the current intensity or the greater the amount of steel sand in the specimen,the faster the induction heating rate,the greater the interlayer temperature gradient,and the dissipated energy produced by steel sand will decrease.When the induction heating stops,the effective healing depth decreases with the decrease of the current intensity and the content of steel sand,and the effect of induction heating becomes worse.The temperature field of the specimen in the natural heat dissipation stage presents the phenomenon of“warping distribution”in the transverse direction,that is,the temperature at center of the specimen is high and at the edge is low,and the interlayer temperature gradient gradually decreases towards zero.The comprehensive benefit of induction heating can be improved by increasing the intensity of induction heating current or the content of steel sand,and adopting intermittent heating with larger cycle heating time and shorter heating interval.