黄土重大工程的水文循环响应与孕灾效应研究

黄土重大工程完全改变了工程区的原始地形地貌，再造了一个新的含水层系统，重塑了水文循环过程。在剧烈变化的水环境条件下，该类工程的地质灾害孕育机制尚不清楚，防控思路尚不明晰。本项目结合延安“削山造城”等实际工程，采用小尺度原位试验、数值模拟、原型观测等手段，开展黄土重大工程的水文循环响应、地质灾害孕育机制、地下水优化调控研究。以期阐明填埋黄土体的渗透特征及其尺度效应，探究重塑黄土与原状黄土渗透特性的异同及其对地下水循环的影响机制，解析黄土重大工程引发的地下水补径排条件变化及动态演化过程，揭示水环境变化条件下黄土重大工程人工边坡失稳、工后沉降及渗透破坏的发育、发展规律，探索黄土重大工程的地下水优化调控模式与措施。在此基础上，对原型工程的地质灾害发育规律进行模拟预测，提出基于地下水优化调控的工程灾害防控对策。研究成果可对新建黄土重大工程的建设提供理论指导，并对已建黄土重大工程的管理提供科学依据。

The mega projects in the loess area completely changed the original topography and landform. Under these conditions, the aquifer system has been reconstructed and the hydrologic cycle process has been recreated. However, given the dramatic changes of water environment, the disaster-pregnant mechanism of these mega projects is still unclear, and how to prevent geological disasters is still unknown. Combined with the land-creation project in Yan’an, this project focused on the response of hydrologic cycle, the disaster-pregnant mechanism and the optimal regulation of groundwater of mega loess project by using small-scale in-situ tests, numerical simulation and prototype observation. Through this research, the characteristics and scale effects of permeability in the mega loess project will be clarified. Meanwhile, the differences of seepage properties between the remolded loess and undisturbed loess will be investigated, and the mechanism of their influences on groundwater cycle will be identified. The changes in the recharge-runoff-discharge conditions and the dynamic evolution process of groundwater caused by mega projects will be elucidated. Finally, the laws of artificial slope instability of mega loess projects, post-construction settlements and seepage failure of landfill soil will be revealed, and the optimized measures of controlling groundwater in the mega projects will be put forward. Based on these, the law of geological disasters development in the land-creation project will be simulated and predicted, and the countermeasures for preventing and controlling engineering disaster will be proposed. This research can provide theoretical guidance for the construction of new loess projects, and afford scientific basis for the management of the established loess projects.