近相变区细砂土导热系数试验及预测模型研究  

Study on thermal conductivity testing and prediction model of fine sandy soil in near phase transition zone

作　　者：刘志云[1] 张亚星 崔福庆[1,2] 袁堃[2,3] 黄川 LIU Zhiyun;ZHANG Yaxing;CUI Fuqing;YUAN Kun;HUANG Chuan(College of Geology Engineering and Geomatics,Chang’an University,Xi’an 710054,China;State Key Laboratory of Road Engineering Safety and Health in Cold and High-Altitude Regions,CCCC First Highway Consultants Co.,Ltd.,Xi’an 710075,China;Qinghai Huashixia Permafrost Highway Engineering Safety National Observation and Research Station,Madoi 813500,Qinghai,China;Chongqing Branch of Sichuan Zhide Geotechnical Engineering Co.,Ltd.,Chongqing 400025,China)

机构地区：[1]长安大学地质工程与测绘学院,陕西西安710054 [2]中交第一公路勘察设计研究院有限公司高寒高海拔地区道路工程安全与健康国家重点实验室,陕西西安710075 [3]青海花石峡冻土公路工程安全国家野外科学观测研究站,青海玛多813500 [4]四川志德岩土工程有限责任公司重庆分公司,重庆400025

出　　处：《冰川冻土》2023年第3期865-875,共11页Journal of Glaciology and Geocryology

基　　金：陕西省自然科学基金项目(2022JM143);中国交建科技研发项目(2020-ZJKJ-PTJS04,2020-ZJKJ-QNCX09);第二次青藏高原综合科学考察研究项目(2019QZKK0905);长安大学中央高校基本科研业务费专项资金项目(300102262104)资助。

摘　　要：近相变区冻土导热系数是影响寒区岩土工程热稳定性的关键物性参数,针对该温度区间冻土导热系数难以精确测量的问题,提出了一种稳态热流计法试验获得导热系数、量子粒子群寻优算法近似回归定性温度的近相变区冻土导热系数测试方法,采用核磁共振技术对细砂土近相变区未冻水含量进行测试并探究了其与导热系数的关系,分析了负温区细砂土导热系数的分布特征和参数影响规律,建立了不同温度区间的导热系数预测模型。结果表明:负温区细砂土未冻水含量变化曲线与其导热系数呈现出极为相似的变化规律,温度-导热系数曲线可划分为-3.2℃为界的近相变区和稳定相变区;冻结细砂土导热系数的增幅区间主要发生在近相变区,增长幅度约占整个负温区导热系数总增幅的50%,且随温度降低,导热系数的增幅逐渐减小;预测模型平均相对误差为4.14%,±10%误差内占比为94.7%,稳定相变区确定系数R2为0.892,近相变区确定系数R2为0.883,证明了该模型具有较好的准确性。研究成果可为寒区工程温度场的计算与分析提供基础参数,亦可为寒区重大基础设施精细化设计和冻土风险精细化防控提供数据支持。Thermal conductivity of frozen soil near transition point is a key physical parameter which affects the thermal stability of geotechnical engineering in cold regions.To accurately measure the thermal conductivity of frozen soil in this temperature range,a testing method for obtaining thermal conductivity by steady-state heat flux method and approximating the qualitative temperature by quantum particle swarm optimization algorithm was proposed in present work.Nuclear magnetic resonance(NMR)technology was used to determine unfrozen water content of fine sandy soil near transition point and its relationship with thermal conductivity was analyzed.Based on the testing results,distribution characteristics and parameter influence laws of thermal conductivity of fine sandy soil in the negative temperature zone were investigated,and corresponding thermal conductivity pre⁃diction models of different temperature zones were also established.The results show that:Variation curve of unfrozen water content and thermal conductivity of fine sandy soil in the negative temperature region exhibits a similar pattern,and temperature-thermal conductivity curve can be divided into near phase transition zone and stable phase transition zone with the limit of-3.2℃.The increase of thermal conductivity mainly occurs in near phase transition zone,and the increment accounts for about 50%of total thermal conductivity increase in the en⁃tire negative temperature zone.Meanwhile,the increment of thermal conductivity decreases gradually with tem⁃perature decrease.The average error and relative error within±10%of predict results are 4.14%and 94.7%,and coefficients of determination(R2)in stable and near phase transition zone are 0.892 and 0.883 respectively,which proves the reliability of proposed model.The research results can provide basic physical properties for temperature field calculation and analysis of engineering in cold regions,and also offer data support for major in⁃frastructure refined design and frozen soil risks prevention

关 键 词：细砂土 近相变区 导热系数 稳态热流计法 预测模型 

分 类 号：P642.14[天文地球—工程地质学]