Heat-Mass Transfer Test and Coupling Model of Sulfate Saline Soil
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摘要:
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.
Abstract: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.
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图 1设备装置
a.冷浴；b.温控箱；c.数据采集仪；d.计算机系统；e.水盐传感器；f.位移计；g.温度传感器；h.马氏瓶无压补给系统；i.盐渍土.
Figure 1.Equipment installation
图 3盐渍土柱不同位置温度时程曲线
Figure 3.Temperature-time history curves of saline soil samples at different locations
图 4不同时刻盐渍土柱等温线分布
Figure 4.Isotherm distribution of saline soil columns at different moments
图 10不同时刻样品模型中温度分布云图
Figure 10.Nephogram of temperature distribution in samples at different times
图 11土柱液态水含量模拟结果与实测值对比
Figure 11.Comparison of simulation and measured liquid water contents in soil columns
图 12不同时刻样品中结晶冰含量分布特征
Figure 12.Distribution characteristics of crystalline ice content in samples at different moments
图 13盐渍土柱不同高度位置浓度时程曲线
Figure 13.Time history curves of concentration at different heights of saline soil column
图 14不同时刻样品含盐量分布云图
Figure 14.Nephogram of salt content distribution of samples at different moments
表 1脱盐后土壤物理力学指标
Table 1.Physical and mechanical indexes of soil samples after desalination
参数 Gs ρmax/（g·cm−3） ωopt/% wL/% wP/% Cu Cc 取值 2.70 1.78 13.7 25.35 12.62 5.29 0.59 
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表 2模型参数
Table 2.Model parameters
参数 数值 参数 数值 a0 2 Li/（kJ·kg−1） 334.6 m 0.15 Lc/（kJ·kg−1） 210 l 0.5 Cw/（J·（kg·℃）−1） 4180 ɵr 0.002 Ci/（J·（kg·℃）−1） 2090 ɵs 0.397 Cc/（J·（kg·℃）−1） 1090 ks/（m·s−1） 10−6 Cs/（J·（kg·℃）−1） 850 B 0.61 λw/（W·（m·K）−1） 0.58 ρw/（kg·m−3） 1000 λi/（W·（m·K）−1） 2.22 ρi/（kg·m−3） 918 λc/（W·（m·K）−1） 0.14 ρc/（kg·m−3） 1460 λs/（W·（m·K）−1） 1.50 ρs/（kg·m−3） 2700 D0/（m2·h−1） 1.098 × 10−5 ρd/（kg·m−3） 1600 a 0.00261 Mw/（g·mol−1） 180 b 10 Mc/（g·mol−1） 322 α/mm 7.021 下载:
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