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温度作用下膨胀土的胀缩特性及微观机理 被引量:3

Experimental Study on Temperature Effect on Swelling-shrinking Behaviours of Expansive Soil
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摘要 温度场作为外部环境要素场之一,对膨胀土的水-力学性质具有显著影响。为研究温度对膨胀土胀缩特性的影响规律及微观机理,以南宁膨胀土为对象,开展了不同温度(5~45℃)下膨胀土的浸水膨胀和失水收缩试验,结果表明膨胀土的胀缩特性具有显著的温度效应,其膨胀率随温度升高而增大,温度越高其增大效果越明显;收缩率随温度升高则呈现出先增大后减小的变化规律,存在临界温度“T_(c)=35℃”。在此基础上,基于不同温度(5~45℃)下的吸附结合水试验,从土-水作用角度阐释了膨胀土胀缩特性温度效应的微观机理;随着温度的升高,土中结合水量减小,水膜厚度变薄,从而引起两方面的结果:①土颗粒间的吸力减弱而斥力增加,宏观表现为土体的膨胀性增加;②土颗粒间距变小,促进了土颗粒骨架由松散状态向紧密状态转化,颗粒排列更紧密,收缩性增加,而达到一定温度后,水分蒸发时间较短,土-水作用加剧使得土体骨架没有充足的时间向紧密状态转化,是造成土体收缩性减小的主要原因。 Temperature is one of the most important external environmental elements,which has a significant influence on hydro-physical properties of expansive soils.Taking one typical Nanning expansive soil as the research object,swelling and shrinkage tests were carried out at the temperature of 5~45℃.The results show that the swell-shrinking characteristics of the expansive soil are significantly affected by temperature.The swelling ratios increase with the increase of temperature.The shrinkage ratio increases first and then decreases with rising temperature,and there is a critical temperature T_(c)=35℃.Furthermore the mechanism of temperature effects on the swell-shrinking characteristics of the expansive soils was explained based on the adsorptive bound water tests at different temperatures(5~45℃).With the increase of temperature,the amount of bound water decreases,and the thickness of the water film becomes thinner.The change of soil microstructure has caused two results:①The suction between the soil particles weakens and the repulsive force increases during the process of soil water absorption and expansion.Macroscopically,it is an increase of soil swelling;②For the loss of wa-ter shrinkage,the decrease of the water film thickness makes the reduction of the distance between soil particles and promotes the transformation of the soil particle framework from a loose state to a compact state,the shrinkage increase.After reaching a certain temperature,the water evaporation time is shorter,and the soil-water interaction is intensified.The soil skeleton have no sufficient time to transform into a compact state,which is the main reason for the decrease in shrinkage deformation.
作者 曾召田 潘斌 莫红艳 梁珍 王平 张瀚彬 ZENG Zhaotian;PAN Bin;MO Hongyan;LIANG Zhen;WANG Ping;ZHANG Hanbin(College of Civil Engineering and Architecture,Guilin University of Technology,Guilin 541004,China;Guangxi Key Laboratory of Geomechanics and Engineering,Guilin University of Technology,Guilin 541004,China;The Third Institute of Geology and Minerals Exploration,Gansu Provincial Bureau of Geology and Minerals Exploration and Development,Lanzhou 730050,China)
出处 《防灾减灾工程学报》 CSCD 北大核心 2022年第5期1053-1060,共8页 Journal of Disaster Prevention and Mitigation Engineering
基金 国家自然科学基金(41962014、42167020)资助。
关键词 膨胀土 胀缩特性 温度作用 结合水 微观机理 expansive soil swell-shrinking properties temperature effect bound water micro-mechanism
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