春融作用对寒区机场土面区工作性能的影响

Influences of spring thaw on working performance of airport soil field surface in cold region

为研究春融期间温升效应影响下寒区机场升降带土面区导热性能及剪切强度变化规律,通过预埋温度传感器、稳态平板法和快速直剪法,制备了含水率分别为15%、17%、19%和21%,压实度分别为90%、95%和98%的冻土试样,分析了内部温度场变化、导热系数变化和快速直剪实验结果,得到了冻土试样导热性能及力学性质的变化特征,总结了春融过程对土面区工作性能的影响.结果表明,冻土试样内部温度场在温升过程中发生了剧烈变化,冻结核的存在使其融化过程呈现4个阶段,包括快速升温期、缓和融化期、加速融化期和已融化期.通过对12组冻土试样的导热系数变化规律分析,发现温升过程中导热系数整体下降但仍存在波动变化,与内部温度场变化规律一致.通过分析60组冻土试样分别在环境温度为-5、-1、3、7和11℃时的快速直剪实验结果发现,在温升过程中压实度提高使抗剪强度变大,含水率增加使抗剪强度减小.

By considering the temperature-rising effect during spring-thawing period,the frozen soil samples with water content of 15%,17%,19%and 21%and compaction degrees of 90%,95%and 98%are prepared to investigate the variation characteristics of thermal conductivity and shear strength in the soil field surface of airport lifting zone in cold region by pre-embedded temperature sensor,steady plate method and fast direct shear method.Laboratory experiments on the frozen soil samples are conducted to achieve internal temperature changes,thermal conductivity variations and fast direct shear strengths.The characteristics of thermal conductivity and mechanical properties of the frozen soil samples are obtained and the influences of the spring-thawing effect on the working performance of airport soil field were summarized.The results show that,there are significant internal temperature variations in the frozen soil samples during the process of temperature rise.The existence of frozen core makes its melting process present four stages,including rapid heating period,moderate melting variation period,accelerated melting variation period and melted period.By analyzing the thermal conductivity variation curves of twelve sets of frozen soil samples,it is found that the thermal conductivity of frozen soil samples decreases as a whole,but still fluctuates,during the temperature rising process,which is also consistent with the internal temperature field.By analyzing the results of fast direct shear tests on sixty sets of the frozen soil samples at ambient temperatures of-5,-1,3,7 and 11℃,it is proved that the shearing strength increases with the increase of compaction degree and decreases with the decrease of water content significantly during the temperature rising process.