摘要
冻土层的变化与地 气交接面的能量交换过程有直接的联系.地 气交接面的能量交换过程包含了辐射、对流、热传导三种最基本的热物理过程.利用以此为基础建立的青藏铁路沿线地表和路基表面热力学数值模式(RSTM),将安多站的实测资料作为模式输入,针对梯形路基与边坡朝向和坡度有关的坡面温度变化及两侧坡面温差变化的问题,对无云大气条件下不同坡度和坡向的表面温度变化特征进行了模拟分析.结果表明,对于就地取土修筑的路基而言,安多段路基上表面温度在各季节都高于气温,在夏季具有明显的高表面温度值,尽管在夏季任何坡度和坡向的路基坡面都具有冷却效应,但路基仍处于高温状态;冬季路基上表面温度虽略低于0℃,但路基偏南方向坡面的强烈增温效应,使南坡表面温度远远超过冻土融化温度的临界状态,而路基两侧坡面热效应的相反作用,通过影响冻土层的冻融过程,可能引起路基纵向裂缝的发生.因此,对冻土路基采取有效的防护措施是非常必要的.用实测资料进行的检验表明,RSTM具有良好的模拟性能,对不同防护措施下青藏铁路路基热状况的预测具有良好的应用前景.
Variations of frozen soil layer have direct relation with the energy exchange between the ground and atmosphere. The energy exchange contains three basic physical processes: radiation, convection and heat conduction. In this paper, a thermodynamics model of ground surface and embankment surface (RSTM) along the Qinghai-Tibet Railway constituted on the above physical processes is used, with observation from Amdo Station as the model input, aiming at the slope surface temperature changes and temperature differences between two slope surfaces on both sides of an embankment, which relate to the direction and gradient of the slope surface, to simulate the characteristics of the surface temperature of the embankment changing with direction and gradient of the slope under cloud-free condition. The results show that, for the embankment built on the spot in Amdo, the embankment top temperature is always higher than the air temperature and has a obvious high value in summer, despite a cooling effect on the slopes in any direction and gradients; In winter, although embankment top temperature is lower than 0 ℃, a strong heating effect on the southward slope causes the surface temperature increasing over the critical state of thawing frozen-in soil, and the opposite heating effect on different sides of the embankment via changing the freezing and thawing course can cause lengthways fissure on the embankment. Therefore, effective safety measure is necessary for the frozen soil embankment. A test by observation data shows that the RSTM has a good simulating performance and an important significance for forecasting the embankment heating status of the Qinghai-Tibet Railway.
出处
《冰川冻土》
CSCD
北大核心
2004年第2期171-176,共6页
Journal of Glaciology and Geocryology
基金
中国科学院知识创新工程重大项目(KZCX1 SW 04)资助
关键词
冻土层
能量交换
热力学
坡面温度
路基表面
青藏铁路
slope surface temperature
embankment surface
thermodynamics model
Qinghai-Tibet Railway
