地铁沿线地下水壅高规律及其对极端降雨事件的响应

Pattern of Groundwater Rising along Metro and Its Response to Extreme Rainfall Event

地下水保护是济南市地铁规划建设的关键环节之一,由于地铁工程构筑物对地下水渗流的阻挡作用可能引发地下水壅高,因此亟需定性、定量地探究地铁工程建设目标区域的地下水壅高风险,并针对愈加频发的极端降雨事件,关注其对壅水现象的影响。对此,主要针对济南地铁4号线典型区段所处研究区,基于传统网格剖分方法优化建模流程,构建包含地铁工程构筑物的三维地质体结构,以建立地下水非稳定流数值模型,分析地铁沿线地下水壅高规律及成因,并设计极端降雨事件以模拟地下水壅高的响应。结果表明:济南西部平原区地铁工程引发的地下水壅高现象具有空间分布规律,其规律性主要受控于地铁走向-地下水流向夹角、含水层厚度,地铁-地下水流向夹角为关键主控因素;极端降雨情景下地铁沿线各区域间的壅高幅度差异有所增大,而壅高现象的空间规律与正常降雨情况下保持一致。越接近研究南侧山区地下水补给带,极端降雨事件影响越大,整体上短期极端降雨事件对地下水壅高并无较大影响。研究成果可为济南市地下水保护提供切实可靠资料,也将为地下工程扰动地下水流场这一过程对极端降雨事件的响应形成突破性认识。

Groundwater protection is one of the key aspects in the planning and construction of Jinan metro system.Due to the potential risk of groundwater level rising caused by the blocking effect of metro engineering structures on groundwater flow,it is necessary to qualitatively and quantitatively investigate the groundwater level rising risk in the target area of metro engineering construction,and focus on the impact of increasingly frequent extreme rainfall events on the groundwater rising phenomenon.It is mainly focused on the study area of the typical section in Jinan Metro Line 4,the modeling process was optimized based on traditional mesh generation method,and the three-dimensional geological structure containing the metro engineering structure was constructed to establish a numerical model of groundwater unsteady flow,thus to analyze the law and causes of groundwater rising along the metro line.A extreme rainfall event was further designed to simulate the response of groundwater rising.The results show that groundwater rising caused by metro engineering in west plain area of Ji nan exhibits a spatial distribution pattern,which is mainly controlled by the angle between metro and groundwater flow direction,as well as the thickness of the aquifer.The angle between metro and groundwater flow direction is the dominant factor.Under extreme rainfall scenario,the difference in the magnitude of groundwater rising between different areas along the metro line has increased,while the spatial regularity of groundwater rising remains consistent with normal rainfall scenario.The closer to the groundwater recharge zone in the southern mountainous area,the greater the impact of extreme rainfall events.Generally speaking,short-term extreme rainfall events have minor impact on groundwater rising.The research results can provide reliable data for the groundwater protection in Jinan,and will break new ground in understanding the response of the groundwater flow field to extreme rainfall events during the process of underground engineering.