淤泥质盐渍土冻胀特性试验研究与数值模拟  

Experimental research and numerical simulation on frost heave characteristics of silty saline soil

作　　者：朱杰[1] 戚珊珊 罗阳 ZHU Jie;QI Shanshan;LUO Yang(School of Civil Engineering and Architecture,Anhui University of Science and Technology,Huainan 232001,Anhui,China)

机构地区：[1]安徽理工大学土木建筑学院,安徽淮南232001

出　　处：《冰川冻土》2024年第4期1259-1270,共12页Journal of Glaciology and Geocryology

摘　　要：针对开放系统下淤泥质盐渍土在单向冻结过程中的水盐迁移和冻胀特性开展了试验和理论研究。为了研究淤泥质盐渍土在单向冻结条件下冻胀力随冷端温度、初始含水量、含盐量和上覆荷载变化的规律,通过配制含有硫酸盐的淤泥质盐渍土土样作为试样进行了单向冻结条件下的冻胀试验。基于非饱和土渗流和热传导理论和水动力学模型,遵循质量守恒和能量守恒定律,考虑水盐迁移、相变的影响,从盐胀和冻胀机理出发简化应力场方程,建立了适用于淤泥质盐渍土的三维水、热、盐、力多场耦合方程。通过COMSOL Multiphysics软件PDE模块对室内非饱和土体建立耦合模型并进行数值计算。通过比较不同深度处测点的温度、含水量、含盐量以及土体冻胀力的数值模拟计算值和试验结果,验证了模型的有效性。结果表明:降低冷端温度和增加初始含水量有助于促进土体的冻胀力产生,而上覆荷载和土体含盐率的增加对土体的冻胀力产生抑制作用。淤泥质软土的冻胀力稳定值(即最终冻胀力稳定数值)与冻结温度呈线性关系,与土体初始含水量、上覆荷载以及含盐率呈二次抛物线关系。In cold and saline soil environments,water-salt wetting-drying cycles and salt-freeze-thaw cycles can cause damage and failure to rock and soil structures.The complex coupling of heat and mass transfer with saltsoil frost heaving characteristics presents significant challenges.Understanding the frost heaving and salt expansion characteristics of sulfate saline soil under freezing conditions is essential for engineering projects and underground structures in saline soil areas.This study investigates the water-salt migration and frost heaving characteristics of silty saline soil under unidirectional freezing in an open system through experimental and theoretical research.Saline soil is a multiphase continuous porous medium composed of solid,liquid,and gas phases.Changes in water-salt content in the soil occur with temperature variations,leading to water-ice phase changes and salt-crystal phase changes,resulting in frost and salt expansion,thus generating frost heave force.The variation of frost heaving force in silty saline soil under unidirectional freezing conditions with changes in lower-end temperature,initial moisture content,salt content,and overlying load is examined,providing insights into the soil's structure and properties.We prepared silty saline soil samples containing sulfate and conducted tests using a self-developed frost heave experimental setup under unidirectional freezing conditions.Waterproof temperature sensors and pressure sensors were used to monitor temperature and frost heave force,respectively.To delve deeper into the frost heave mechanism of silty saline soil,a three-dimensional equation for water,heat,and salt forces suitable for this soil type was established.The coupled equation was based on unsaturated soil seepage,heat conduction theory,and hydrodynamic models,following the laws of mass and energy conservation,considering the effects of salt-water migration and phase change.The stress field equation was simplified from the salt expansion and frost heaving mechanisms.The PDE module of

关 键 词：淤泥质盐渍土 人工单向冻结 冻胀力 耦合方程 数值模拟 

分 类 号：P642.14[天文地球—工程地质学]