Abstract: There were great differences of ground temperature circumstance on both slope sides of subgrade and the underlying soil layers because of the highway direction in island-shaped permafrost areas, which caused the inhomogeneous thermal deformation of subgrade structure and brought about a series of serious subgrade diseases such as longitudinal cracking, thermal thawing, which threatened the driving safety directly. Mastering the slope-oriented difference characteristics was the premise of improving design quality and enhancing thermo-stability for permafrost subgrade. Therefore, based on the practical project, the slope-oriented thermal effect of island-shaped permafrost subgrade in high latitude and high cold regions was studied by using finite element numerical simulation method and applying different heat flux densities on both slope sides of subgrade. The research results show that the uneven change of subgrade thermal stability will become more obvious with the increasing temperature difference both of subgrade slopes. Based on the thermal response of subgrade displacement field with different heat flux conditions, the characteristics of slope-oriented thermal deformation and the possible diseases for island-shaped permafrost subgrade in different states are revealed.

Key words: highway engineering, island-shaped permafrost subgrade, slope orientation, temperature field, displacement field, numerical simulation

摘要： 在多年岛状冻土区，公路的走向会使路基两侧坡面及其下伏土层的地温环境存在较大差异，从而导致路基结构发生不均匀热变形，继而引发纵向开裂、热融沉等严重的路基病害，直接威胁行车安全。掌握该类路基坡向性差异特征是提高公路设计质量，改善路基热稳定性的前提，因此，以实际工程为载体，采用有限元数值模拟方法，通过在路基两侧坡面施加差异性热流密度，对高纬高寒地区多年岛状冻土路基的坡向性热效应展开研究，研究结果表明：路基热稳定性会随着坡面热差异的增大而发生不均衡性变化，依据差异性热流密度条件下的路基位移场热响应情况，揭示了多年岛状冻土路基在不同状态下的坡向性热变形特征及可能诱发的路基病害。

关键词: 道路工程, 多年岛状冻土路基, 坡向性, 温度场, 位移场, 数值模拟