Due to the geomorphology and route scheme, the construction of Yinchuan⁃Xi’ an High⁃speed Railway would unavoidably traverse loess aquifer in Dongzhiyuan. Taking the Shangge tunnel as an example, this paper first analyzed the distribution characteristics of loess aquifer in Dongzhiyuan, then evaluated the physical and mechanical properties, permea⁃bility as well as the water⁃content characteristics of the middle pleistocene aquifer loess. By establishing a two⁃dimensional seepage model, this paper simulated the seepage characteristics of tunnel excavation, and studied the influence of groundw⁃ater seepage in tunnel engineering. The research indicated that the buried depth of Dongzhiyuan groundwater was about 50~70 m, the thickness of aquifer was about 30~50 m, natural moisture content of the loess was up to 24. 9%, the permea⁃bility coefficient was 0. 15 m/d, characterized by soft⁃plastic state. The results of seepage simulation indicated that the in⁃fluence of the groundwater seepage was at the beginning of the excavation, thus the choice of the most effective supporting measures was of vital importance, meanwhile, the waterproof and drainage measures should be strengthened to reduce the harm of groundwater towards the loess tunnels.%受黄土地形地貌及线路方案控制，银西高铁以隧道工程通过董志塬地区时，不可避免地穿越黄土含水层。以上阁隧道为例，首先分析了董志塬地区黄土含水层的分布特征，评价了中更新统含水层黄土的物理力学性质、渗透性及含水特征，其次通过建立二维渗流模型，模拟了隧道开挖后渗流特征，同时研究了地下水渗流对隧道工程的影响。结果表明，董志塬地下水水位埋深约50～70 m，含水层厚约30～50 m，含水层黄土天然含水率达到了24�9％，渗透系数为0．15 m／d，以软塑为主。渗流模拟结果表明，地下水渗流的影响往往是在开挖初期，选择合理支护时间及支护措施尤为关键，并应加强防排水措施，以降低地下水对黄土隧道的危害。
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