青藏高原多年冻土路基温度场公路空间效应的非线性分析

Nonlinear analysis for dimensional effects of temperature field of highway embankment in permafrost regions on Qinghai-Tibet plateau

多年冻土路基温度场的公路空间效应包括路基尺度效应与路面结构效应。利用考虑冰水相变与水分迁移的热流传导等效参数模型,数值模拟公路路基不同高度、不同宽度、不同边坡坡度的尺度效应与公路沥青路面、水泥混凝土路面、砂砾路面的结构效应,分析高原多年冻土路基温度场的变化。结果表明,青藏高原多年冻土对公路空间效应反映敏感,路基尺度直接影响地基温度场的变化,路基高度、边坡坡度与地基吸热量呈负相关性,路基宽度与吸热量呈正相关性;在高原强太阳辐射环境下,沥青路面吸热对冻土地基温度场影响剧烈,沥青路面吸热量是砂砾路面的1.7倍左右。研究认为,与其它线状工程相比,公路宽幅路基、沥青路面热效应是多年冻土路基温度场改变的关键因素,未来青藏高原多年冻土区高速公路建设必须妥善处理因公路空间效应引起多年冻土地基升温融化而导致的工程稳定与安全运营问题。

The dimensional effect of temperature field in permafrost embankment was a general term for size effect of embankment and structural effect of pavement. Based on the equivalent parameter model of heat-transfer considering phase change of ice and water and moisture transfer, the size effect of embankment with different heights, widths and side slope angles and the structural effect of asphalt pavement, cement concrete pavement and gravel pavement were simulated to analyze variation of embankment temperature field in permafrost regions on the plateau. It was shown that the permafrost was sensitive to dimensional effect of the highway on the Qinghai-Tibet Plateau and the variation of temperature field of embankment was directly influenced by the embankment size. The heat absorption of frozen foundation was negatively dependent on embankment height and side slope, but positively dependent on the embankment width. The influence of heat absorption of asphat parement on the temperature field was about 1.7 times that of gravel parement. According to the research, it could be concluded that the wide embankment and thermal effect of asphalt pavement were the two key factors for the variation of temperature field of frozen soil embankmentcompared with other projects. Therefore, it was necessary to emphasize the engineering stabilization and security problems from the dimensional effect of highway on permafrost foundation in expressway construction on Qinghai-Tibet Plateau in the future.