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连续观测了青藏高原多年冻土区道路结构不同层位和天然大地不同深度处温度,分析了不同层位日均温度的时空变化趋势、实时温度的频率分布特性与不同结构层材料的冻融特性。分析结果表明:空气、面层、基层、路基和天然大地温度年度变化趋势均呈现明显的热季与冷季之分,转换时间分别是4月份和9月份;观测周期年内,沥青混凝土路面路表日平均温度为-17℃~40℃,水泥混凝土路面路表温度为-18℃~17℃,沥青混凝土路面下的路基顶面以下0.8m处温度波动范围为-2.8℃~6.3℃,水泥混凝土路面下的路基顶面下0.7m处温度波动范围为-3.4℃~5.4℃;空气、沥青混凝土面层、水泥混凝土面层的温度和温度梯度频率分布均呈现出明显的单峰形态,且峰值对应的温度或温度梯度与相应的年均值存在偏差;基层、垫层和路基的温度频率分布均呈现多峰并存的形态,分别与冷季、热季、冷热季转换期相对应;分析周期年内沥青混凝土路面和水泥混凝土路面的路表冻融次数分别为182、178;沥青混凝土与水泥混凝土冻结融化持续时间频率分布均呈现主峰+多副峰的形态,主峰对应的持续时间分别为0~2h和18~20h。可见,在多年冻土区,可优先选择水泥混凝土路面,以利于冻土的保护,沥青混凝土与水泥混凝土配合比设计均应验证抗冻融耐久性能。
The temperature in different layers of road structure and natural earth in permafrost region of Qinghai-Tibet Plateau was continuously observed. The temporal and spatial variation trend of daily average temperature in different layers was analyzed. The frequency distribution of real-time temperature and the freeze-thaw characteristics of different structural layers . The results show that the annual trend of air temperature, surface temperature, grassroots level, subgrade and natural ground temperature show obvious hot season and cold season, the conversion time is April and September, respectively. During the observation period, the asphalt pavement road surface The average temperature is -17 ℃ ~ 40 ℃. The temperature of the cement concrete pavement is -18 ℃ ~ 17 ℃. The temperature fluctuation range of 0.8m below the asphalt pavement under the subgrade surface is -2.8 ℃ ~ 6.3 ℃. The cement concrete pavement The temperature fluctuation range of 0.7m below the top surface of embankment is -3.4 ℃ ~ 5.4 ℃. The temperature and temperature gradient distribution of air, asphalt concrete surface and cement concrete surface all show obvious unimodal morphology with peak corresponding Temperature and temperature gradients deviated from the corresponding annual average values. The temperature and frequency distributions of grass-roots, cushion and subgrade all showed multi-peak coexistence patterns, corresponding to cold season, hot season and cold-hot season conversion period respectively. During the analysis period The numbers of road surface freezing and thawing of asphalt concrete pavement and cement concrete pavement are respectively 182 and 178. The frequency distribution of the duration of freezing and thawing of asphalt concrete and cement concrete shows the shape of main peak + State, the main peak corresponds to the duration of 0 ~ 2h and 18 ~ 20h. It can be seen that in the permafrost regions, the cement concrete pavement can be preferentially selected to facilitate the protection of frozen soil. The mix design of asphalt concrete and cement concrete should verify the anti-freeze-thaw durability performance.