Influence of boundary conditions on the thermal stability of expressway constructed with an integral and two separated embankments in permafrost zones [边界条件对多年冻土区高速公路整体式和分离式路基热稳定性的影响]

作者：Li X.; Ma W.^*; Mu Y.; Niu Y.; Huang Y.; Chai M.

来源：Journal of Central South University(Science and Technology), 2020, 51(2): 420-432.

DOI：10.11817/j.issn.1672-7207.2020.02.016

• Annual mean ground temperature
• Integral embankment
• Permafrost zones
• Separated embankment
• Separating strip width
• The Qinghai-Tibet expressway

Based on the adherent layer theory and the long-term monitoring data of different permafrost regions in the Qinghai-Tibet Plateau, numerical models with an integral and two separated embankments were proposed and the influences of climate warming and embankments construction on permafrost were analyzed. Considering the use of two separated embankments to weaken the gathered heat effect of an integral embankment, the influence of separated embankments on permafrost zones was analyzed under the condition of different annual mean ground temperatures and separating strip widths. The results show that compared with the narrow embankment, the wide embankment has a strong heat absorption, which leads to serious permafrost degradation beneath the wide embankment. After 50 years of embankment construction on permafrost zones with annual mean ground temperature of -0.5, -1.0, -1.5 and -2.0 ℃, permafrost tables beneath the centerline of wide embankment are 2.73, 3.66, 3.67 and 2.60 m lower than those of narrow embankment, and ground temperatures of permafrost beneath the 6 m depth of wide embankment are 0.61, 0.87, 0.82 and 0.48 ℃ warmer than those of narrow embankment, respectively. The mutual thermal disturbance between two separated embankments leads to the asymmetry of temperature fields beneath both sides of separated embankment. The asymmetrical distribution gradually decreases with the decrease of annual mean ground temperature and the increase of separating strip width, which means the mutual thermal disturbance between two separated embankments weakens. Thus, it is suggested that the Qinghai-Tibet expressway should be constructed with two separated embankments rather than an integral embankment, and the annual mean ground temperature and separating strip width are important factors to be considered for the construction of two separated embankments.

• 单位
  冻土工程国家重点实验室; 中国科学院大学