Microscopic analysis of deformation and water-salt transport in chlorine saline soils under unidirectional freezing in cold and arid zones  

作　　者：Chenxi Dong Xin Chen Yanhu Mu Zhao Duan Qiang Xue Chuanbo Sun Jiangshan Li 

机构地区：[1]State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,430071,China [2]College of Geology and Environment,Xi'an University of Science and Technology,Xi'an,710054,China [3]State Key Laboratory of Frozen Soil Engineering,Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou,730000,China [4]School of Civil Engineering,Liaoning Technical University,Fuxin,123000,China

出　　处：《Journal of Rock Mechanics and Geotechnical Engineering》2025年第4期2445-2460,共16页岩石力学与岩土工程学报(英文)

基　　金：supported by the Open Fund of State Key Laboratory of Frozen Soil Engineering (Grant No.SKLFSE201806);the National Natural Science Foundation of China (Grant No.42177155).

摘　　要：Sudden temperature drops cause soils in natural environments to freeze unidirectionally,resulting in soil expansion and deformation that can lead to damage to engineering structures.The impact of temperature-induced freezing on deformation and solute migration in saline soils,especially under extended freezing,is not well understood due to the lack of knowledge regarding the microscopic mechanisms involved.This study investigated the expansion,deformation,and water-salt migration in chlorinated saline soils,materials commonly used for canal foundations in cold and arid regions,under different roof temperatures and soil compaction levels through unidirectional freezing experiments.The microscopic structures of saline soils were observed using scanning electron microscopy(SEM)and optical microscopy.A quantitative analysis of the microstructural data was conducted before and after freezing to elucidate the microscopic mechanisms of water-salt migration and deformation.The results indicate that soil swelling is enhanced by elevated roof temperatures approaching the soil's freezing point and soil compaction,which prolongs the duration and accelerates the rate of water-salt migration.The unidirectional freezing altered the microstructure of saline soils due to the continuous temperature gradients,leading to four distinct zones:natural frozen zone,peak frozen zone,gradual frozen zone,and unfrozen zone,each exhibiting significant changes in pore types and fractal dimensions.Vacuum suction at the colder end of the soil structure facilitates the upward migration of salt and water,which subsequently undergoes crystallization.This process expands the internal pore structure and causes swelling.The findings provide a theoretical basis for understanding the evolution of soil microstructure in cold and arid regions and for the management of saline soil engineering.

关 键 词：Chlorine saline soils MICROSTRUCTURE Unidirectional freezing Water-salt transport DEFORMATION 

分 类 号：TU448[建筑科学—岩土工程] TU443[建筑科学—土工工程]