冻融循环条件下细粒硫酸盐渍土盐冻胀机理研究

Study on the Mechanism of Salt Frost Heaving in Fine Grained Sulfuric Acid Saline Soil under Freeze-Thaw Cycles

摘要: 针对不同含盐量细粒硫酸盐渍土，采用自制试验箱进行冻融循环试验，测定土样不同高度处温湿度及含盐量，分析冻融循环条件下水盐分布与迁移规律，结合微观结构特征，开展细粒硫酸盐渍土盐冻胀机理研究。试验结果表明：冻融循环过程中，从土样底部到顶部，土体降温速率和温度变化区间均有所增大；含盐量不同，土样不同高度处的温度变化也有所不同，但其变化趋势相似，含盐量越大的盐渍土水分向冷端迁移越大，底部与顶部的含水率差越大，热量损失逐渐减小。冻融循环结束后，不同含盐量盐渍土盐分向冷端迁移，含盐量越大盐分迁移量越大，顶部与底部的含盐量差越大。土样自土层底部到顶部的土颗粒中大孔隙数量增加且分布不均匀，土体顶部产生明显膨胀变形，说明冻融循环条件下，盐渍土中水盐均向冷端迁移，冷端产生较多冰结晶与盐结晶，使得土体产生了盐冻胀变形。

Abstract: For fine-grained sulfuric acid saline soil with different salt contents, a self-made test chamber was used to conduct freeze-thaw cycle tests. The temperature, humidity, and salt content of the soil samples at different heights were measured, and the distribution and migration of water and salt under freeze-thaw cycle conditions were analyzed. Based on the microstructure characteristics, the mechanism of salt frost heave in fine-grained sulfuric acid saline soil was studied. The experimental results show that during the freeze-thaw cycle, the cooling rate and temperature variation range of the soil sample increase from the bottom to the top; the temperature changes at different heights of soil samples vary with different salt contents, but their trends are similar. The higher the salt content, the greater the water migration of saline soil towards the cold end, the greater the difference in water content between the bottom and top, and the gradual reduction of heat loss. After the freeze-thaw cycle, the salt content of saline soil with different salt contents migrates towards the cold end. The higher the salt content, the greater the salt migration, and the greater the difference in salt content between the top and bottom. The number of large pores in the soil particles from the bottom of the soil layer to the top of the soil sample increases and their distribution is uneven, resulting in significant expansion deformation at the top of the soil. This indicates that under freeze-thaw cycling conditions, water and salt in saline soil migrate towards the cold end, resulting in more ice crystals and salt crystals at the cold end, resulting in salt frost heave deformation of the soil.