松嫩平原分散土成因机制及水热盐耦合离子迁移模型研究

Dispersive soil is a kind of emerging special soil, which could be dispersed and fell apart when it reacts with water, but it haven't been taken seriously by many scholars because of it's limited distribution. The dispersive soil which is distributed widely on Songnen Plain located in cold and drought region of the western area of the Jilin Province, is the ecologically extremely fragile and sensitive ecotone. With the large-scaled implementation of the Water Supply Project from Nenjiang River to Baicheng City, new freeing surfaces appeared resulting in the transformations of seepage, evaporation, freeze-thaw and material migration pattern and thereby it leaded to the time response problem of negative environmental effect, such as secondary salinization, etc. Thus, the theoretical research of dispersive soil has a great significance of the restoration and reconstruction of agriculture ecological environment. This project will choose four locations of the Jilin Province and that are Nong'an, Qian'an, Da'an and Baicheng. The project will carry out research around the three problems which included seepage, evaporation, freeze-thaw of dispersive saline soil: 1.The long-term monitoring of changing rules of engineering geological properties of the dispersion saline soil under the superimposed conditions of temperature, moisture and time; 2.The simulation tests which taken by self-developing equipment about material migration and transformation law in soil in the natural conditions superimposed human activities; 3.The mechanism of material migration and the formation mechanism of dispersive soil which analysed by researching the material composition and microstructure of dispersive soil;4.Clear the definition of dispersive soil, establish the coupling model of water-heat-salt migration and provide the suggestion of formulating engineering code standard of dispersive soil.

分散土是一种新兴的特殊土体，由于它分布局限，虽然具有遇水分散解体的极坏工程特性，也不为广大学者所重视，位于吉林省西部寒旱区松嫩平原上广泛分布的这种分散土，是生态极其脆弱且敏感的地带，随着大规模引嫩入白农业工程的实施，导致渗流、蒸发、冻融及物质迁移方式发生变化、从而引发次生盐渍化等环境负效应的时间响应问题。因此，该研究对分散土的理论研究、保证生态环境的恢复与重建具有重大意义。 本项目将选择吉林省4 个地点，即农安、乾安、大安、白城，围绕分散性盐渍土渗流、蒸发、冻融3方面开展研究：1、长期监测分散性盐渍土体在温度、干湿、时间的叠加条件下土的工程地质性质变化规律；2、研制仪器在室内物理模拟自然条件叠加人类活动情况下土体中的物质迁移与转化规律；3、从物质组成和微观结构特征上进行分散土物质迁移的机理及成因机制研究；4、明确进行分散土的定义、建立水热盐的迁移耦合模型，为制定分散土的规范标准提供建议。

分散土是一种新兴的特殊土体，由于它分布局限，虽然具有遇水分散解体的极坏工程特性 ，也不为广大学者所重视，位于吉林省西部寒旱区松嫩平原上广泛分布的这种分散土，是 生态极其脆弱且敏感的地带，随着大规模引嫩入白农业工程的实施，导致渗流、蒸发、冻 融及物质迁移方式发生变化、从而引发次生盐渍化等环境负效应的时间响应问题。因此， 该研究对分散土的理论研究、保证生态环境的恢复与重建具有重大意义。  本项目将选择 吉林省4 个地点，即农安、乾安、大安、白城，围绕分散性盐渍土渗流、蒸发、冻融3方 面开展研究：1、长期监测分散性盐渍土体在温度、干湿、时间的叠加条件下土的工程地 质性质变化规律；2、研制仪器在室内物理模拟自然条件叠加人类活动情况下土体中的物 质迁移与转化规律；3、从物质组成和微观结构特征上进行分散土物质迁移的机理及成因 机制研究；4、明确进行分散土的定义、建立水热盐的迁移耦合模型，为制定分散土的规 范标准提供建议。5、建立吉林西部盐渍土室内封闭系统冻胀试验三维颗粒流数值模拟模型，反应大安及镇赉两地土样在侧壁及底面受限情况下冻胀过程，并对两地土样在冻胀过程中的颗粒运移、孔隙特征以及内部应力的变化规律进行讨论；6、在对研究区土样进行基本物理化学性质以及水热盐参数测定的基础上结合水分、热量、盐分的基本运移方程、质量连续性方程、能量守恒方程、平衡微分方程等相关理论建立了吉林西部盐渍土水热盐力（HTSM）耦合数学模型。利用COMSOL Multiphyscis数学模块中的PDE方程接口建立物理场对吉林西部盐渍土水热盐力（HTSM）耦合数学模型进行求解，并与室内水盐迁移试验结果进行对比，验证了模型的有效性。同时适当简化边界条件，设计了开放系统条件下饱和正冻土水盐迁移与相应的伴生现象的算例，并对土体内部水盐迁移的机理进行了分析。