硫酸盐渍土路基盐冻胀变形理论修正及应用

发布时间：2018-06-29 17:47

本文选题：硫酸盐渍土路基 + 四场耦合理论　；参考：《北京交通大学》2015年硕士论文

【摘要】：硫酸盐渍土路基受水、盐、热、力的交互影响,会引起路面盐胀开裂、加剧翻浆、侵蚀路面。目前关于硫酸盐渍土四场耦合理论不够完善,硫酸盐渍土路基盐冻胀变形量的数值计算仍没有实现。因此,有必要深入研究硫酸盐渍土地区公路路基盐胀机理及规律,为硫酸盐渍土地区公路建设及病害防治提供依据。为了准确计算硫酸盐渍土盐冻胀变形量,本文从盐冻胀机理出发,首先对硫酸盐渍土盐冻胀变形量计算的四场耦合理论进行修正,并将修正后的理论接入Comsol Multiphysics有限元软件中,利用修正后的理论计算新疆焉耆农二师21团-24团公路盐渍土路基的盐冻胀变形量,并与实测结果进行对比分析,主要研究内容和结论如下： (1)基于水动力学模型和质量守恒定律,在水分场方程和盐分场方程中分别引入修正等效含水量和等效含盐量的概念,以此为耦合因子建立水-盐-热耦合模型。在盐分场中不仅考虑了溶质扩散及水动力弥散的作用,还考虑了溶质化学反应的作用。根据能量守恒定律,增加结晶盐的相变潜热,使温度场方程更符合工程实际情况。 (2)在建立应力场方程时,将冻胀与盐胀统一考虑,以芒硝的化学反应速率简化模型,实现硫酸盐渍土路基的盐冻胀变形计算。 (3)选取新疆硫酸盐渍土路基现场试验段,长期监测当地气温与路基地温变化情况,检测含水量和易溶盐分布规律及路基盐冻胀变形规律,分析现场温度监测、易溶盐检测及盐冻胀变形数据,并得出硫酸盐渍土路基的盐冻胀变形规律。 (4)将修正后的理论接入Comsol Multiphysics有限元软件中,修正部分主要包括：盐分运移方程采用多孔介质稀物质传递模块并添加反应过程：温度场运用多孔介质传热方程,设置了土质、冰与芒硝三种固体材料,增加芒硝的相变潜热；在固体力学方程中不仅考虑线弹性材料即弹性模量及泊松比对变形场的影响,同时考虑冰体积膨胀与芒硝体积膨胀对变形场的影响。 (5)结合新疆地区现场取样试验数据,对比分析模拟结果与工程实际监测数据,为模型的有效性验证提供依据。本文的研究成果可以为硫酸盐渍土路基盐冻胀变形量的计算提供依据。
[Abstract]:The influence of water, salt, heat and force on the subgrade of sulphate saline soil will lead to salt swelling and cracking of road surface, aggravation of churning and erosion of road surface. At present, the four-field coupling theory of sulphate saline soil is not perfect, and the numerical calculation of frost heave deformation of sulfate saline soil subgrade has not been realized. Therefore, it is necessary to study the salt expansion mechanism and law of highway roadbed in sulphuric acid saline soil area, so as to provide the basis for highway construction and disease prevention in sulphuric acid soil area. In order to accurately calculate the frost heave deformation of sulfate soil salt, this paper, based on the mechanism of salt frost heaving, first modifies the four-field coupling theory for calculating the frost heave deformation of sulfate salt soil, and applies the modified theory into Comsol Multiphysics finite element software. Based on the revised theory, the salt frost deformation of the saline soil subgrade of the 21tuan-24th regiment of Yanqi second Division in Xinjiang is calculated, and the results are compared with the measured results. The main contents and conclusions are as follows: (1) based on the hydrodynamic model and the law of conservation of mass, the concepts of modified equivalent water content and equivalent salt content are introduced into the water field equation and salt field equation, respectively. The water-salt-thermal coupling model is established by using this model as a coupling factor. The solute diffusion and hydrodynamic dispersion are not only considered in the salt field, but also the solute chemical reaction is considered. According to the law of conservation of energy, the latent heat of phase transition of crystalline salt is increased to make the equation of temperature field more accord with the actual engineering situation. (2) when establishing the stress field equation, the frost heave and salt heaving are taken into account, and the model is simplified by the chemical reaction rate of glauber. To realize the calculation of salt frost deformation of sulphate soil subgrade. (3) select the field test section of Xinjiang sulfate saline soil roadbed, and monitor the variation of local temperature and subgrade ground temperature for a long time. The distribution law of water content and soluble salt and the rule of salt frost heave deformation of roadbed were detected, and the data of field temperature monitoring, soluble salt detection and salt frost heave deformation were analyzed. The law of salt frost deformation of sulfate soil subgrade is obtained. (4) the modified theory is applied to Comsol Multiphysics finite element software. The correction part mainly includes: the salt transport equation adopts the porous medium dilute material transfer module and adds the reaction process: the temperature field uses the porous medium heat transfer equation, has set up the soil quality, the ice and the mirabilite three kinds of solid materials, increases the phase change latent heat of the mirabilite; In the equation of solid mechanics, not only the influence of elastic material, that is, elastic modulus and Poisson ratio, but also the deformation field are considered. At the same time, the effect of ice volume expansion and glauber volume expansion on deformation field is considered. (5) combined with the field sampling test data in Xinjiang, the simulation results and the engineering actual monitoring data are compared and analyzed, which provides the basis for the validation of the model. The research results of this paper can provide the basis for calculating the frost heaving deformation of the subgrade of sulphuric acid saline soil.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U416.1

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