硫酸盐渍土热-质迁移试验与耦合模型

为研究西部寒旱区盐渍土传热传质行为,首先,在无压补给条件下进行非饱和硫酸盐渍土的单向冻结试验;其次,考虑结晶潜热、结晶阻抗及结晶消耗等因素,建立非饱和硫酸盐渍土水-热-盐三场耦合模型;最后,采用COMSOL Multi-physics对耦合模型进行数值模拟,将模拟结果与试验数据进行对比分析.研究结果表明：盐渍土内温度随冻结时长呈三阶段发展,逐步形成上冷下暖的温度梯度;在温度梯度和基质吸力双重驱动下,水、盐向冻结锋位置迁移,冻结锋位置水、盐含量出现峰值,峰值含水率、含盐量相较初始值分别增加2.16%和0.28%;冻结锋沿冻结温度线移动,形成冻结锋面;土柱最大冻结深度约为15.5 cm.

Heat-Mass Transfer Test and Coupling Model of Sulfate Saline Soil

In order to study the heat and mass transfer behavior of saline soil in western cold-arid regions, firstly unsaturated sulfate saline soil experienced unidirectional freezing tests with no pressure recharge. In addition, while the latent heat of crystallization, crystallization impedance and crystallization consumption are considered, a three-field coupling model of water-heat-salt for unsaturated sulfate saline soil is established. Finally, COMSOL Multi-physics is used to simulate the coupling model, the simulation results of which are then compared with the experimental data for analysis. The results show that the internal temperature of saline soils develops in three stages with the freezing time, gradually forming a temperature gradient of cold at the top and warm at the bottom. Driven by both temperature gradient and matrix suction, water and salt migrate to the freezing front position, and the water and salt contents reach peaks at the freezing front position, and compared with the initial values, the peak water content and salt content increase by 2.16% and 0.28%, respectively. The freezing front moves along the frozen temperature line, and forms a freezing front. The maximum freezing depth of soil column is about 15.5 cm.