【作者】 王峰；

【导师】 原俊红； 赵海飞；

【作者基本信息】 内蒙古大学 ， 交通运输（专业学位）， 2025， 硕士

【摘要】 土体热物性参数直接影响地铁隧道、地下管廊等地下结构的热稳定性设计。同时,也与地热能的开发利用密切相关。在热物性参数中,以导热系数、比热容及热扩散系数为主,特别是导热系数,是反映土体热传导能力的重要指标。目前,虽然国内外学者对土体热物理性质开展了大量的研究,但针对呼和浩特市和林格尔新区浅层土体的研究较少,尤其是围绕导热系数与电阻率相关联的研究更为匮乏。本文通过五类试验方法进行了研究,具体包括:(1)对原状土进行测试,获取了热物性参数与电阻率的总体数值范围,并分析了二者随深度、含水率和干密度的变化规律;(2)基于重塑土试验,研究了热物性参数及电阻率的变化规律,揭示了二者的内在变化机理,并探讨了导热系数与电阻率的相关性;(3)结合温度梯度试验,分析了温度对热物性参数及电阻率的影响,得到了不同温度区间内导热系数随电阻率的变化规律;(4)通过微观试验,从微观角度分析了宏观导热系数与电阻率的内在变化机理;(5)将现场测试与室内测试相结合,分析了土体综合导热系数与视电阻率的相关性,并对室内外测试结果进行了对比分析。经研究得到以下主要结论:(1)原状土的导热系数与比热容范围基本在0.5～1.1W/(m·K)和1.4～3.0MJ/(m~3·K)之间,且整体上随含水率、干密度及深度增加而增大。电阻率多在10～160Ω·m之间,与上述变化呈相反趋势。热扩散系数多在0.3～0.5mm~2/s之间,整体上随深度递减,在含水率低于15%时随含水率增加而增加,但对干密度变化不敏感。(2)室内试验结果表明,重塑土的热物性参数和电阻率受含水率及干密度的影响较大。导热系数和比热容均随含水率和干密度的增大而提高,电阻率则随两者增大而降低。但热扩散系数随含水率的增加,呈现先增大后减小的变化趋势,且在不同含水率条件下,其随干密度的变化趋势也不同。此外,导热系数随电阻率的增加呈现先剧烈减小,而后趋于平缓的变化特征。(3)温度对土体热物性参数及电阻率的影响研究表明:在低温区(≤0℃),导热系数和热扩散系数随温度降低而增大,其中0～-5℃区间增速最快,低于-10℃后趋于稳定,同时,比热容减小而电阻率增大;在正温区(≥25℃),导热系数和比热容随温度升高略微增加,热扩散系数基本保持稳定,而电阻率则减小。此外,导热系数与电阻率的关系在低温区呈正相关,在正温区则表现为负相关。(4)通过微观试验发现:整体上,导热系数随概率熵和分形维数的增大而减小,随区域概率分布指数的增大而增加;电阻率的变化规律则与导热系数相反。(5)现场测试得到的综合导热系数、视电阻率增大时,室内测试结果同步增加,反之亦然,同时发现土体综合导热系数随视电阻率的增大而减小。更多还原

【Abstract】 The thermal physical parameters of soil directly affect the thermal stability design of underground structures such as subway tunnels and underground pipe galleries.At the same time,it is also closely related to the development and utilization of geothermal energy.Among the thermophysical parameters,thermal conductivity,specific heat capacity and thermal diffusion coefficient are the main ones,especially thermal conductivity,which is an important index to reflect the thermal conductivity of soil.At present,although scholars at home and abroad have carried out a lot of research on the thermophysical properties of soil,there are few studies on the shallow soil in Hohhot Helingeer New Area,especially on the correlation between thermal conductivity and resistivity.In this paper,five kinds of test methods were studied,including:(1)The undisturbed soil was tested to obtain the overall numerical range of thermal physical parameters and resistivity,and the variation of the two with depth,moisture content and dry density was analyzed;(2)Based on the remolded soil test,the variation law of thermal physical parameters and resistivity was studied,the internal change mechanism of the two was revealed,and the correlation between thermal conductivity and resistivity was discussed;(3)Combined with the temperature gradient test,the influence of temperature on the thermal physical parameters and resistivity was analyzed,and the variation of thermal conductivity with resistivity in different temperature ranges was obtained;(4)Through microscopic experiments,the internal change mechanism of macroscopic thermal conductivity and resistivity is analyzed from the microscopic point of view;(5)The correlation between the comprehensive thermal conductivity and the apparent resistivity of the soil was analyzed by combining the field test with the indoor test,and the indoor and outdoor test results were compared and analyzed.The main conclusions drawn from the research are as follows:(1)The thermal conductivity and specific heat capacity of undisturbed soil are basically in the range of 0.5～1.1W/(m·K)and 1.4～3.0MJ/(m~3·K),and increase with the increase of water content,dry density and depth.The resistivity is mostly between 10～160Ω·m,which is opposite to the above change.The thermal diffusion coefficient is mostly between 0.3～0.5mm~2/s,which decreases with depth as a whole,and increases with the increase of water content when the water content is less than15%,but it is not sensitive to the change of dry density.(2)The results of laboratory tests show that the thermal physical parameters and resistivity of remolded soil are greatly affected by water content and dry density.The thermal conductivity and specific heat capacity increase with the increase of water content and dry density,while the resistivity decreases with the increase of both.However,with the increase of water content,the thermal diffusion coefficient increases first and then decreases,and under different water content conditions,its change trend with dry density is also different.In addition,the thermal conductivity decreases sharply with the increase of resistivity,and then tends to be gentle.(3)The influence of temperature on the thermal physical parameters and resistivity of soil shows that in the low temperature region(≤0°C),the thermal conductivity and thermal diffusion coefficient increase with the decrease of temperature,and the growth rate is the fastest in the range of 0～-5°C,and tends to be stable below-10°C.At the same time,the specific heat capacity decreases and the resistivity increases.In the positive temperature region(≥25°C),the thermal conductivity and specific heat capacity increase slightly with the increase of temperature,the thermal diffusion coefficient remains basically stable,while the resistivity decreases.In addition,the relationship between thermal conductivity and resistivity is positively correlated in the low temperature region and negatively correlated in the positive temperature region.(4)Through microscopic experiments,it is found that:on the whole,the thermal conductivity decreases with the increase of probability entropy and fractal dimension,and increases with the increase of regional probability distribution index;the change law of resistivity is opposite to that of thermal conductivity.(5)When the comprehensive thermal conductivity and apparent resistivity obtained by field test increase,the indoor test results increase synchronously,and vice versa.At the same time,it is found that the comprehensive thermal conductivity of soil decreases with the increase of apparent resistivity.更多还原