块石基底路基中局部非热平衡效应研究  

Research on local thermal non-equilibrium effect in crushed rock based embankment

作　　者：侯彦东 王凯歌 雷文远 梁澍豪 唐东昌 HOU Yandong;WANG Kaige;LEI Wenyuan;LIANG Shuhao;TANG Dongchang(College of Civil Engineering,Lanzhou University of Technology,Lanzhou 730050,China)

机构地区：[1]兰州理工大学土木工程学院,甘肃兰州730050

出　　处：《冰川冻土》2023年第3期993-1005,共13页Journal of Glaciology and Geocryology

基　　金：国家自然科学基金项目(41861010);中国科学院西部之光“西部青年学者”项目;甘肃省基础研究创新群体(20JR5RA478)资助。

摘　　要：块石作为一种高孔隙率、大粒径的多孔介质,因其可通过调节内部冷暖季节对流方式实现多年冻土路基降温,而被广泛应用于青藏铁路工程以减弱气候变暖及工程扰动对多年冻土路基的影响。因此,精准描述块石路基结构换热机理并模拟其长期热防护效应十分重要。在一些领域内,已经证明使用局部非热平衡(LTNE)可以提升多孔介质的计算精度,但在块石结构孔隙尺度下的传热效能计算中仍较少使用。其中,多孔介质内部流固换热系数(hsf)是LTNE能量方程中重要的参数,该系数如何选取也决定着模型计算的准确性。本文以块石基底路基为例,通过数值模拟方法,将传统路基使用的局部热平衡(LTE)模型与LTNE模型的模拟结果与实测数据进行对比,并分析了不同经典hsf对块石结构换热的影响。研究结果表明,块石基底路基局部非热平衡效应明显:模拟结果显示LTNE模型中,同一时间内块石与空气温度不相等,空气与块石在夏季和冬季的最大温差高达1.54℃和0.80℃;LTNE的模拟结果与实测数据更为接近,且LTE模型的降温幅度略高于预期,二者在2 m、5 m、10 m处的年平均误差百分数分别相差6%、1%和8%;不同研究者(Achenbach、Wakao、Dixon等、Pallares等)得出的hsf在块石路基中变化趋势相近,峰值差异明显,但对块石路基下部土体温度的影响较小。As a porous medium with high porosity and large particle size,crushed rock is widely used in Qing⁃hai-Tibet Railway project to reduce the impact of climate warming and engineering disturbance on permafrost foundation because it can cool the permafrost foundation by auto-adjusting its internal convection seasonally.Therefore,it is very important to accurately describe the heat transfer mechanism of the crushed rock embank⁃ment and simulate its long-term thermal protection effect.In some fields,it has been proven that can improve the calculation accuracy of porous media by using of local thermal non-equilibrium(LTNE),but it is still sel⁃dom used in the calculation of heat transfer efficiency at the pore scale as large as crushed rock skeleton.The heat transfer coefficient(hsf)among the fluid and solid in the porous medium is a key parameter in the LTNE en⁃ergy equation,and rationality of the selection for this coefficient also determines the accuracy of the calculating result.In this paper,taking the crushed rock based embankment as an example,the numerical simulation results of the traditional used local thermal equilibrium(LTE)model and the LTNE model are validated with the mea⁃sured data.Besides,the influence of different classical hsf on the heat transfer of the crushed rock embankment are also analyzed.The results show that LTNE effects in the crushed rock embankment is apparent.For exam⁃ple,temperature of the crushed rock skeleton and the air are not equal at the same time,and the maximum tem⁃perature differences between the air and the rock is as large as 1.54℃and 0.80℃in summer and winter,re⁃spectively.What’s more,simulation results of the LTNE model are closer to the monitored data,while cooling rate of the LTE model is slightly higher than expected.Difference for the averaged annual error percentages of the two models at 2 m,5 m and 10 m researched by 6%,1%,and 8%,respectively.Calculating result of hsf ob⁃tained by different researchers(Achenbach,Wakao,Dixon et al.,Pallares Dixon e

关 键 词：块石路基 多孔介质 局部非热平衡 换热系数 多年冻土 

分 类 号：U416.168[交通运输工程—道路与铁道工程] P642.14[天文地球—工程地质学]