【摘要】 多年冻土区公路路基大多属高温冻土、极易受工程的影响产生融化下沉,多年冻土区宽幅公路聚热效应尤明显,路基宽度的增加会导致路基病害加重,路基稳定性问题已成为青藏道路工程建设亟待解决的关键问题。透壁式通风管-块石复合路基是一种主动降温措施。为研究其在宽幅公路的冷却效果及路基宽度的变化对路基降温效应的影响,基于块石层和通风管中空气的流速场和多孔介质传热的温度场的特征,采用两相物理场耦合关系,在考虑全球气候变暖以及路基两侧阴阳坡的条件下对宽幅公路透壁式通风管-块石复合路基的温度场进行数值模拟,分析路基施工后10年间的降温效应。研究结果表明:相较于素土路基,透壁式通风管-块石复合路基在路基下侧形成稳定冰核,对宽幅公路的冷却效果更为显著,宽度对路基的风速场和温度场影响明显。路基宽度增大,透壁式通风管风速减小,块石层风速增加,冰核面积及其下移深度增长速率变小,路基稳定时间加长,透壁式通风管-块石复合路基的降温效应逐渐减弱。当路基宽度大于32 m时,块石层风速增长速率明显放缓,低温区域面积增长速率及边缘深度下移增长速率下降,路基稳定时间延长,零温线上升高度减小。更多还原

【Abstract】 The roadbeds in permafrost regions are mostly high-temperature frozen soils, which are highly susceptible to melting by engineering. The wide-area highways in permafrost regions have obvious heat-collecting effect, the increase of roadbed width will lead to aggravation of roadbed diseases. The stability of subgrade has become a key problem to be solved in the construction of Qinghai-Tibet road project. The composite roadbed which is composed of perforated ventilation ducts and crushed-rock layers is an active cooling measure. To study the cooling effect of wide highway and the influence of roadbed width on the cooling effect of roadbed, based on the characteristics of velocity filed of air flow in the crushed-rock layer and the ventilation duct as well as temperature field in heat transfer of porous media, adopting the two-phase physical field coupling relations, the numerical analysis on the temperature field of the composite roadbed with ventilated crashed rock layer of wide highway is carried out under sunny-shady slope boundaries and global warming condition to analyze the cooling effect of the roadbed after 10 years of construction. The result shows that(1) compared with the plain soil roadbed, the abovementioned composite roadbed forms a stable ice core on the lower side of the roadbed, the cooling effect on the wide highway is more significant, and the width has an obvious effect on the wind speed field and temperature field of the roadbed;(2) as the width increases, the wind speed in perforated ventilation duct decreases, the wind speed in crushed-rock layer increases,the growth rates of ice core area and its depth become slower, the stabilization time of roadbed becomes longer, and the cooling effect of the composite roadbed is gradually weakened;(3) when the roadbed width is greater than 32 m, the wind speed growth rate of crushed-rock layer is obviously slowed down, the growth rates of the low temperature area and the edge depth decrease, the roadbed stabilization time is prolonged, and the 0 ℃ line rise height is reduced.更多还原