Exploring the effects of temperature on intrinsic permeability and void ratio alteration through temperature-controlled experiments
Exploring the effects of temperature on intrinsic permeability and void ratio alteration through temperature-controlled experiments
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DOI：
10.1016/j.enggeo.2021.106299
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发表时间：
2021-11
影响因子：
7.4
通讯作者：
M. Joshaghani;Omid Ghasemi-Fare
中科院分区：
文献类型：
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作者：
M. Joshaghani;Omid Ghasemi-Fare
温度的升高改变了地下水的密度和粘度，因此，预计土壤导水率随温度而变化。超过这一点，热负荷引起砂和粘土的体积变化，并可能改变土壤结构。这些变化可能会增加或减少土壤的固有渗透性。在这项研究中使用了一个改进的温控三轴渗透池，将土壤温度从20 ° C升高到80 ° C。此外，该装置被设计成控制注入到试样中的渗透水的温度和压力。测定了渥太华砂和高岭土在不同围压（69~690 kPa）下的导水率。然后，考虑水的性质随温度的变化，计算固有渗透率。结果表明，尽管渥太华砂和高岭土的导水率随温度升高而增加，但当温度从20 ° C升高到80 ° C时，渥太华砂的固有渗透率降低了50%，而高岭土的固有渗透率略有降低。尽管如此，分析体积变化和孔隙比变化的两种选定的土壤类型显示孔隙比随温度的降低。孔隙比的降低可以解释渥太华砂在高温下固有渗透率较低的原因，然而，在高岭土中，尽管孔隙比降低较高，但另一种机制是结构内的一部分非移动的水退化为移动的水起着重要作用。
An increase in temperature changes the groundwater density and viscosity, therefore, it is expected that the soil hydraulic conductivity varies with temperature. Beyond this point, thermal loading induces volumetric changes for both sand and clay and may alter soil fabric. These variations might increase or decrease the intrinsic permeability of the soil. A modified temperature-controlled triaxial permeameter cell was used in this study to elevate soil temperature from 20 °C to 80 °C. Moreover, the setup was designed to control the temperature and pressure of the permeant water injected into the specimen. The hydraulic conductivity of both Ottawa sand and Kaolin clay under different confinement stresses (69 kPa to 690 kPa) was measured. Then, intrinsic permeability was calculated considering water properties variation with temperature. The results determined that, although hydraulic conductivity increases with temperature for both Ottawa sand and Kaolin clay, the intrinsic permeability of Ottawa sand reduces by 50%, while in Kaolin clay it slightly reduces when the temperature rises from 20 °C to 80 °C. Nonetheless, analyzing volumetric changes and void ratio variations for both selected soil types show a reduction in void ratio with temperature. Reduction in the void ratio can explain the lower intrinsic permeability in Ottawa sand at the elevated temperature, however in Kaolin clay despite the higher void ratio reduction, another mechanism which is the degeneration of a part of the immobile water within the structure into the mobile water plays an important role.