那曲-羊八井季节性冻土区高速公路路基温度场变化规律研究  

Temperature Field Change Law of Highway Subgrade in Naqu-Yangbaj ing Seasonal Frozen Soil Area

作　　者：何先志[1] 曾超[1] 高智清 张卫[2] 万豪杰 张茹星 HE Xianzhi;ZENG Chao;GAO Zhiqing;ZHANG Wei;WAN Haojie;ZHANG Ruxing(CCCC Second Highway Survey,Design and Research Institute Co.,Ltd.,Wuhan 430100,China;Three Gorges Research Center for Geo-hazard of Ministry of Education,China University of Geosciences(Wuhan),Wuhan 430074,China;Shandong Zhenyuan Constr uction EngineeringCo.,Ltd.,Jinan 250101,China)

机构地区：[1]中交第二公路勘察设计研究院有限公司,湖北武汉430100 [2]中国地质大学(武汉)教育部长江三峡库区地质灾害研究中心,湖北武汉430074 [3]山东正元建设工程有限责任公司,山东济南250101

出　　处：《安全与环境工程》2023年第2期92-100,共9页Safety and Environmental Engineering

基　　金：中交第二公路勘察设计研究院有限公司科技研发项目(KJFZ-2018-049)。

摘　　要：季节性冻土在温度的正负变化下会给公路路基的稳定性带来安全隐患。西藏那曲地区季节性冻土分布广泛,那曲-羊八井段高速公路贯穿季节性冻土区,为明确该路段的温度场分布变化特征,通过对那曲-羊八井段典型路基断面展开温度、含水率现场监测,依据2020年的地温资料进行回归分析,并结合室内试验对监测断面地温振幅、滞后时间和土体热扩散系数等进行分析。结果表明:监测断面地温整体在外界气温的波动下大致呈正弦曲线状变化,地温振幅随深度的增加而减小,并且伴随着滞后时间的顺延,路基在0~4.7 m深度处的每米滞后时间约为24 d/m,路基在0~5.4 m深度处的每米滞后时间约为30.8 d/m;监测断面不同位置土体热扩散系数的不同导致地温对气温的响应程度不同,路基土体的热扩散系数为0.0414~0.0628 m^(2)/d,对气温的响应最明显,地基土体的热扩散系数为0.0223~0.0379 m^(2)/d,对气温的响应较弱;路基的修建增加了对热量的吸收,在路基中形成一个高温区,通过两侧边坡和坡脚向外散热;路基内部土体含水率较低,且不存在明显的水分迁移;对称式的路基结构不存在明显的阴阳坡效应。据此可以判定该路基监测断面整体不存在因冻胀产生不均匀变形引发路基失稳的安全隐患。Seasonal frozen soil is widely distributed in Naqu,Tibet,which brings hidden dangers to the sta-bility of highway subgrade under the positive and negative changes of temperature.Naqu-Yangbajing high-way passes through the seasonal frozen soil area.To clarify the characteristics of the temperature field dis-tribution in the section,the temperature and moisture content of the typical subgrade section of Naqu-Yangbajing section were monitored on site,and the regression analysis was carried out based on the ground temperature data in 2020 in combination with the indoor test.The results are as follows:the overall ground temperature of the monitoring section changes sinusoidally under the fluctuation of external air tempera-ture,and the amplitude decreases with the increase of depth.With the change of delay time,the subgrade lag time is about 24 d/m in the depth of 0-4.7 m,and that of foundation is about 30.8 d/m in the depth of 0-5.4 m;the different thermal diffusivity at varying positions of the section leads to other response de-grees of ground temperature to air temperature.The thermal diffusivity of the subgrade is about 0.0414-0.0628 m^(2)/d,corresponding to the most obvious response to air temperature.The thermal diffusivity of subgrade is about 0.0223-0.0379^(2)/d,and its response to air temperature is weak;the construction of subgrade increases the absorption of heat,forming a high temperature zone,which dissipates heat through both sides of slope and the slope toe;the moisture content in the subgrade is low,and there is no obvious water migration;the symmetrical subgrade structure has no noticeable sunny-shady slope effect;there is no hidden danger of subgrade instability due to uneven deformation caused by frost heave in the whole monito-ring section of the subgrade.

关 键 词：季节性冻土 温度场 滞后时间 热扩散系数 路基稳定性 那曲-羊八井段高速公路 

分 类 号：X951[环境科学与工程—安全科学]