垃圾渗滤液侵入黄土的冻结温度演变特征试验研究

Experimental study on freezing temperature evolution characteristics ofloess contaminated by landfill leachate

土体的冻结温度是土壤冻结过程和结果分析中的关键物理指标之一,对冻结缘的形成和冻结深度的判定影响意义重大.通过室内试验研究了不同含水率、垃圾渗滤液浓度、冻融循环次数下的黄土试样冻结温度的变化特征,探讨了垃圾渗滤液污染黄土在不同条件下冻结温度的演变机制.试验结果表明:垃圾渗滤液污染黄土冻结温度低于0℃,冻结温度随含水率的增加而升高并逐渐趋近于0℃,降温平台持续时长随含水率的增加而增加.随着垃圾渗滤液浓度的增大,土体冻结温度与降温平台持续时长呈现出下降趋势.随着冻融循环次数的增加,土体冻结温度与降温平台持续时长出现下降并在循环次数为10次时基本达到稳定状态.基于上述试验结果,拟合了考虑含水率、垃圾渗滤液浓度、冻融循环次数的土体冻结温度变化经验公式;进一步通过数值模拟方法讨论了冻深的变化规律.

Soil freezing temperature is one of the key physical indexes in the analysis of soil freezing process and results,which has great influence on the formation of freezing edge and the determination of freezing depth.In this paper,the variation characteristics of freezing temperature of loess samples with different moisture content,landfill leachate concentration and freeze-thaw cycles are studied by laboratory tests,and the evolution mechanism of freezing temperature of loess contaminated by landfill leachate under different conditions is discussed.The experimental results show that the freezing temperature of the landfill leachate contaminated loess is lower than 0℃,the freezing temperature increases with the increase of water content and gradually approaches 0°C,and the duration of the cooling platform increases with the increase of water content.With the increase of landfill leachate concentration,the freezing temperature of soil and the duration of cooling platform show a downward trend.With the increase of the number of freeze-thaw cycles,the freezing temperature of the soil and the duration of the cooling platform decrease and basically reaches a stable state when the number of cycles is 10.Based on the above test results,the empirical formula of soil freezing temperature change considering water content,landfill leachate concentration and freeze-thaw cycles is fitted,and the variation law of freezing depth is further discussed by numerical simulation method.