基于热量平衡和湍浮力流理论的积水对多年冻土和路基热稳定性影响研究

The thermal conditions of the permafrost and subgrade can be changed by the accumulation of accumulated water in the permafrost regions, which may aggravate disease of subgrade. Previous studies have focused on the thermal effects of thermal lakes on frozen soils and subgrades, and the main study methods are thermal the analysis of measured data and the calculation models whose thermal boundaries are based on the temperatures of lake bottom. However, the effects of heat balance on the surface of the water and internal heat transfer of the buoyancy flow are ignored. This project takes the water accumulation in permafrost regions as the research object, carries out field monitoring and indoor test, reveals the law of the variation of the accumulated water temperature with the atmospheric temperature and the influence of the accumulated water on the permafrost, revealing the surface heat balance and internal buoyancy respectively. According to the rules above, the rationality verification of the calculation model considering the surface heat balance and the internal buoyancy flow is carried out. From the frozen soil environment, the existence time, depth of the accumulated water and the distance between the subgrade, the thermal influence of the accumulated water on the permafrost and the subgrade is analyzed, and the critical depth, stable depth and thermal influence radius of the accumulated water are obtained. A prediction model for the long-term thermal stability of frozen soil subgrade under the warming climate is created. The research results provide a reference for the treatment and prevention of accumulated water in permafrost regions.

多年冻土区积水增多，改变了冻土和路基的热边界条件，加剧了路基冻融病害。以往研究主要关注热融湖对冻土及路基的热影响，手段主要为实测数据分析和湖底温度作为热边界模拟计算分析，但是均忽略了积水表面热量平衡和内部湍浮力流传热的影响。本项目以多年冻土区积水为研究对象，开展野外监测及室内试验，揭示积水温度随大气温度变化和积水对多年冻土热影响的规律，分别揭示了表面热量平衡和内部湍浮力流对积水传热的热影响机制；依据上述规律，对考虑了表面热量平衡和内部湍浮力流的积水与多年冻土及路基热交换的计算模型进行合理性验证；应用已构建的模型，从冻土环境、积水存在时间、深度及与路基间距等因素出发分析积水对多年冻土和路基的热影响，得到积水的临界深度、稳定深度和热影响半径的变化规律，并建立气候变暖情景下积水对冻土路基长期热稳定性的预测模型。研究成果为多年冻土区积水的处理与防治提供了参考依据。

多年冻土区积水增多，改变了冻土和路基的热边界条件，加剧了路基冻融病害。以往研究主要关注热融湖对冻土及路基的热影响，手段主要为实测数据和湖底温度作为热边界模拟计算分析，均忽略了积水表面热量平衡和内部湍浮力流传热的影响。本项目以多年冻土区积水为研究对象，开展野外监测及相关试验，揭示积水温度随大气温度变化和积水对多年冻土热影响的规律；依据上述规律，对考虑了表面热量平衡和内部湍浮力流的积水与多年冻土及路基热交换的计算模型进行合理性验证；应用已构建的模型，从冻土环境、积水存在时间、深度及与路基间距等因素出发分析积水对多年冻土和路基的热影响，得到积水的临界深度、稳定深度和热影响半径的变化规律，建立气候变暖情景下积水对冻土路基长期热稳定性的预测模型。研究成果为多年冻土区积水的处理与防治提供了参考依据。