高温冻土区高速公路特殊结构路基地温分布特征及降温效果分析

Analysis on distribution characteristics of ground temperature and cooling effect of special-structured subgrade of the expressway in warm permafrost region

根据青海省共(和)玉(树)高速公路特殊结构路基的地温监测资料,对3种路基(XPS保温板路基,碎石路基和通风管路基)填土与地基土的地温变化情况及冻土人为上限变化与天然上限附近热流密度状况以及路基温度场的非对称性进行对比分析,研究3种路基的地温分布特征及降温效果。测试结果表明:(1)3种路基在左、右路肩的不同深度处均呈现出明显的升温趋势,观测期内,XPS板路基升温幅度最大;碎石路基次之,通风管路基最小;(2)路基修筑完成初期,3种路基的多年冻土人为上限均存在不同程度抬升;到第3年,3种路基下多年冻土人为上限均下降;(3)3种路基的冻土上限附近热量收支均呈吸热状态,吸热量大小顺序为XPS板路基>碎石路基>通风管路基;(4)3种路基内部温度均呈左高右低的不对称分布。综上研究结果,建议在今后高温冻土区的高速公路建设中优先采用通风管路基。同时,为减小地温不均匀分布造成的路基纵向裂缝等病害,路基的横断面应采取差异化设计的原则。

Based on the monitored ground temperature data of special-structured subgrade of Gonghe-Yushu expressway in Qinghai province, this article analyzed ground temperature variations of foundation soil and subgrade fillings of three kinds of subgrades（XPS insulation board subgrade, crushed rock subgrade and ventilated subgrade）, the changes of artificial permafrost table, the heat flux density near the permafrost table and the asymmetry of subgrade temperature distribution in a comparative way, aiming to study distribution characteristics of ground temperature and cooling effects of three kinds of subgrades. The results indicate that： （1） the temperatures at left and right shoulders of all three kinds of subgrades present a significant increasing trend at different depths. During the observation period, the temperature of XPS insulation board subgrade increases by the largest extent, followed by the crushed rock subgrade and ventilated subgrade. （2） During the initial period after construction, the artificial permafrost tables of three kinds of subgrade rise in different degree, yet declined in the third year. （3） The heat budget of three kinds of subgrade near permafrost table remains a heat absorbing state, the relationship of absorbed heat amount can be listed as： XPS insulation board subgrade〉crushed rock subgrade〉 ventilated subgrade. （4） The internal temperature of three kinds of subgrade distributes asymmetrically, featured by high on the left side and low on the right. According to the results, ventilated subgrade is recommended in the construction of expressway in warm permafrost regions. At the same time, we should stick to the principle of differentiated design to reduce the longitudinal cracks and other diseases caused by uneven distribution of ground temperature.