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利用块石层调控路基地温是冻土工程主动冷却路基的一种重要措施,有关块石层的降温性能和对流换热过程是冻土工程应用研究的重要内容之一。试验基于块石层的对流换热机理以及影响块石降温性能和对流过程的因素,提出一种新型的空心块石路基结构,通过室内模型试验对空心块石层的对流过程、温度特性及降温影响因素进行研究,并通过高精度微风速探测,首次获得封闭条件下空心块石层的对流特征和温度特性的关系,实测证实对流换热过程的存在。研究发现,换热过程和换热强度的差异导致温度曲线的非对称性,对流换热是空心块石层降温的根本原因;空心块石层上下表面温差和对流速度大小存在一定的联系,对流速度和对流时间的长短直接影响降温效果;空心块石层降温效果相当显著,并且垂直堆放方式和大尺寸空心块因具有较畅通的对流通道,降温速度更快且效率高,对流放热时间明显延长。该试验研究成果将对该种新型工程措施机理的进一步认识和改进,以及在冻土区高速公路等重大工程建设中的应用都具有指导意义。
It is an important measure to control the subgrade temperature by using block rock to control active subgrade cooling. The cooling performance and convection heat transfer of block rock are one of the important contents in the research of permafrost application. Based on the convective heat transfer mechanism of block rock and the factors that affect the cooling performance and convection process, a new type of hollow block stone subgrade is proposed. The convection process, temperature characteristics and cooling of hollow block rock are studied by indoor model tests. And the relationship between the convection characteristics and the temperature characteristics of the hollow block rock under the closed condition was obtained for the first time through the high-precision micro-wind velocity detection. The existence of the convective heat transfer process was confirmed. It is found that the difference between the heat transfer process and the heat transfer intensity leads to the asymmetry of the temperature curve. Convection heat transfer is the fundamental reason for the cooling of the hollow block. The temperature difference between the upper and lower surfaces of the hollow block has a certain relationship with the convection velocity. The velocity and convection time have a direct effect on the cooling effect. The cooling effect of hollow block rock is quite remarkable. Vertical stacking mode and large hollow block have faster cooling and high efficiency because of the convection channel with smooth flow. Convection exothermic time Significantly longer. The results of this pilot study will be instructive for further understanding and improvement of this new type of engineering measures, as well as for the construction of major projects such as expressways in permafrost regions.