青藏高原风积沙堆积对多年冻土水热过程的影响机理研究

The extensive aeolian sand accumulation was formed on the permafrost due to the wind-sand activity in some areas of the Tibetan Plateau. The upper sand accumulation has a serious influence on the hydro-thermal dynamics and evolution of underlie permafrost. In this research project, laboratory and field experiments, and numerical modeling method will be used to investigate the mechanism of hydro-thermal dynamics in the permafrost influenced by the upper sand layer. The basic hydro-thermal parameters of aeolian sand will be tested in the laboratory. Bowen ratio method and eddy-correlation technique will be employed to obtain the energy and moisture exchange characteristics near the sand surface based on the monitored field data. The hydro-thermal dynamics in the sand-permafrost system will be also monitored in the field experiments. Then, a series of laboratory model experiments will be carried out in different sand layer thicknesses and rainwater infiltration to investigate the hydro-thermal mechanism. Also, the mathematical model can be carried out based on the above study, and it can be validated and improved according to the results of experiments and numerical modeling analysis. The research findings are expected to have practical significance on the sand hazard controlling, permafrost protection, and roadway construction in the Tibetan Plateau.

青藏高原风沙活动形成了多年冻土上部的大规模风积沙堆积现象。这些上伏沙层会对多年冻土的水热过程和演化规律形成很大影响。本项目拟通过室内外试验和数值模拟相结合的方法来揭示风积沙堆积对多年冻土水热过程的影响机理。用室内试验来测定风积沙的基本水热过程参数。在野外监测数据的基础上，用能量平衡法和涡动相关法来获得沙层表面和大气之间的水热交换特征和参数。通过野外试验和室内试验相结合的方法研究不同沙层厚度以及降水入渗条件下多年冻土的水热过程变化特征和规律。在试验研究的基础上，结合数值模拟方法，对建立的沙层-多年冻土系统的水热过程数学模型进行验证和改进。最后综合分析得到风积沙堆积对多年冻土水热过程及其本身演化规律的影响机理。研究成果对于高原沙害防治、多年冻土保护和道路工程建设具有重要的理论及现实意义。

青藏高原风沙活动在多年冻土上部形成了大规模的风积沙堆积现象。这些上伏沙层会对多年冻土的水热过程和演化规律造成很大影响。本项目通过室内外试验揭示了风积沙堆积对多年冻土水热过程的影响机理。用室内试验测定了风积沙的基本粒度特征和水热过程参数，并提出了一种新的风积沙导热系数计算的模型。在青藏高原红梁河地区建立了野外观测场地，对风积沙堆积条件下多年冻土的水热过程进行了观测分析。通过野外试验和室内试验相结合的方法研究了沙层堆积对多年冻土的水热过程变化的影响特征和规律。研究成果对于青藏高原沙害防治、多年冻土保护和道路工程建设具有重要的理论及现实意义。