【摘要】 为研究路堤块石在边界温度周期波动条件下的自然对流发生机理及降温效应的表征参数,采用室内模拟方法对50×50×65cm3尺寸的不同块石试样进行了试验和理论分析,结果表明:平均RAYLEIGH数能描述块石层自然对流的发生情况,不同厚度的块石层将产生不同的对流模式,厚度大的块石层所产生的自然对流降温效应也较大,上层砂砾加下层块石的结构自然对流效应最弱。块石层降温效果取决于块石粒径、层厚及铺筑在路堤中的位置,这一结论对多年冻土地区路堤设计、施工,合理确定块石铺筑层厚、铺筑层位具有现实指导意义。更多还原

【Abstract】 In order to study the natural convection mechanism of embankment ballast and the token parameter influenced by lowering temperature during cyclical fluctuations of verge temperature,various ballast samples with dimensions of 50×50×65 cm~3 have been tested and studied theoretically. The results show that the mean RAYLEIGH number can effectively represent the conditions of natural convection of the ballast layers. The ballast layers with different depth will have various convection mechanism. The cooling effect of natural convection in ballast layer will increase with the ballast layer depth increasing. The effect of natural convection in the roadbed composition of sand-gravel layer with ballast layer is very poor. The effect resulting from lowering temperature of ballast layer will depend on the gravel diameter. The conclusion of ballast layer depth and its position in embankment can be used effectively for the design of ballast embankment in cold regions and determining the ballast layer depth and its location during construction.更多还原