高原公路,拔海高,气候严寒,空气稀薄,冬季期从每年10月起至次年5月底,长达八个月之久。笔者就自己的体会谈谈高原公路在设计与施工中应注意的几个问题。 1.永冻地带。在拔海4000米以上,土壤处于永冻状态。在永冻层表面有一层厚达80～100厘米的覆盖层。这层覆盖层在气温下降时冻结,上升时溶化,即冬季冻结,夏季溶化,夜晚冻结,白天溶化。无论冻结或溶化,对永冻层来说,均起着保护作用。在施工过程中,如果破坏了这层覆盖层,永冻层在气温升高时就开始溶化。由于永冻层含水量较覆盖层为高,溶 Plateau highways, pulling sea high, cold climate, thin air, the winter period from October each year until the end of May next year, up to eight months. The author on his own experience to talk about the design and construction of highland highway should pay attention to several issues. 1. Never frost zone 4000 meters above sea level, the soil is in the state of permafrost. In the surface layer of permafrost has a thickness of 80 to 100 cm cover. This layer of cover when the temperature drops in the freeze, melting when the rise, that is frozen in winter, melting in summer, night freeze, melt during the day. Both freeze and thaw protect the permafrost. During construction, if the overburden is destroyed, the permafrost begins to melt as the temperature rises. As permafrost moisture content than the overburden is high, soluble