Mechanism of salt-frost heave in sulfate-affected soils: Unveiling the dynamics of moisture-vapour-salt transfer and crystallization-induced deformation

IF 3.8 2区工程技术 Q1 ENGINEERING, CIVIL

Cold Regions Science and Technology Pub Date : 2025-09-22 DOI:10.1016/j.coldregions.2025.104698

Yibo Zhang , Yuanming Lai , Jing Zhang , Mingyi Zhang , Zhimin Chen , Ruiqiang Bai

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引用次数: 0

Abstract

The moisture-vapour-salt (MVS) transfer is the key mechanism driving moisture and salt accumulation beneath impermeable layers in saline soils of cold regions. This process initiates salt-frost heave (SFH), posing serious risks to the safety and stability of roads, hydraulic structures, and power transmission facilities. Through theoretical analysis, the critical factors controlling ice-water phase transition and salt crystallization during freezing in sulfate-affected soils were identified. The dominant influencing parameters were determined, and corresponding calculation methods were proposed. A unidirectional stepwise freezing experiment was conducted on unsaturated sulfate-affected soils to investigate the MVS transfer and spatial redistribution. The mechanisms by which vapour-moisture-ice transitions and salt crystallization contribute to the SFH were clarified. Results show that under stepwise freezing, volumetric unfrozen water content (VWC) and pore solution concentration decrease in distinct stages. In the initial cooling phase, rapid freezing occurs at the cold end, with limited moisture and salt migration. Vapour migrates upward and condenses into a thin ice layer at the surface. As stepwise freezing progresses, continuous MVS transfer toward the freezing front leads to the formation of three distinct freezing regions, each showing peak moisture and salt concentrations near the front. In the unfrozen zone, upward migration of moisture and salt persists until the water content drops below a critical threshold, disrupting capillary continuity. At this point, moisture transport weakens, and soil deformation gradually stabilizes. The SFH is closely associated with the MVS migration, multiphase transitions among air, water, and ice, and salt crystallization. These coupled processes lead to dynamic redistribution and ultimately trigger cascading failures through crystallization-induced deformation. This study reveals the multiphase-multifield coupling mechanism in unsaturated saline soils, providing a theoretical basis for controlling the MVS transfer and preventing SFH in engineering projects in cold and arid regions.

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硫酸盐影响下土壤盐冻胀的机理：揭示湿-气-盐传递和结晶变形的动力学

湿-气-盐（MVS）传递是寒区盐渍土不透水层下湿盐积累的关键机制。这一过程引发了盐冻胀（SFH），对道路、水工结构和输电设施的安全和稳定构成严重威胁。通过理论分析，确定了硫酸盐侵蚀土壤冻结过程中控制冰-水相变和盐结晶的关键因素。确定了主要影响参数，并提出了相应的计算方法。对非饱和硫酸盐影响下的土壤进行了单向逐步冻结试验，研究了MVS的迁移和空间再分布。澄清了蒸汽-水分-冰转变和盐结晶对SFH的作用机制。结果表明，在逐级冻结条件下，试样的体积未冻水含量（VWC）和孔隙溶液浓度呈不同阶段下降；在初始冷却阶段，冷端发生快速冻结，水分和盐的迁移有限。水蒸气向上迁移，在表面凝结成一层薄薄的冰层。随着冻结的逐步进行，MVS不断向冻结锋转移，形成了三个不同的冻结区，每个冻结区都在冻结锋附近显示出峰值的水分和盐浓度。在未冻结区，水分和盐的向上迁移持续，直到含水量降至临界阈值以下，破坏毛细连续性。此时，水分输送减弱，土壤变形逐渐稳定。SFH与MVS迁移、空气、水和冰之间的多相转变以及盐结晶密切相关。这些耦合过程导致动态再分配，并最终通过结晶引起的变形引发级联破坏。本研究揭示了非饱和盐渍化土的多相多场耦合机理，为寒旱区工程项目控制MVS转移和防治SFH提供了理论依据。

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来源期刊

Cold Regions Science and Technology 工程技术-地球科学综合

CiteScore

7.40

自引率

12.20%

发文量

209

审稿时长

4.9 months

期刊介绍： Cold Regions Science and Technology is an international journal dealing with the science and technical problems of cold environments in both the polar regions and more temperate locations. It includes fundamental aspects of cryospheric sciences which have applications for cold regions problems as well as engineering topics which relate to the cryosphere. Emphasis is given to applied science with broad coverage of the physical and mechanical aspects of ice (including glaciers and sea ice), snow and snow avalanches, ice-water systems, ice-bonded soils and permafrost. Relevant aspects of Earth science, materials science, offshore and river ice engineering are also of primary interest. These include icing of ships and structures as well as trafficability in cold environments. Technological advances for cold regions in research, development, and engineering practice are relevant to the journal. Theoretical papers must include a detailed discussion of the potential application of the theory to address cold regions problems. The journal serves a wide range of specialists, providing a medium for interdisciplinary communication and a convenient source of reference.