Abstract Underground structures and infrastructures within urban areas cause disturbance to the groundwater flow. Groundwater abstraction in Milan decreased of more than 30% since the 1970s generating a groundwater rebound which caused submergence and flooding of multiple underground structures and infrastructures. In order to evaluate the impact of underground structures on the groundwater flow in the Milan city area, a detailed analysis based on a groundwater flow model was carried out. The 3D FEM groundwater flow model was calibrated against high resolution monitoring data and used to evaluate both the disturbance induced by underground structures and their sequence of construction, and to verify the performance of mitigation strategies. Major modifications of groundwater head distribution are observed when structures transversally cut the groundwater flow, resulting in the fragmentation of the groundwater flow pathways and leading to changes in groundwater head from about ±0.05 m, at a regional scale, to about ±0.45 in relative proximity (few hundred metres) of underground structures. The effectiveness of a traditional-grey (i.e. a drainage tunnel) and a blue-green infrastructure (i.e. water extraction wells combined with heat pump systems) mitigation scenarios is discussed. Blue-green infrastructures result the most effective and efficient mitigation solutions with direct impact on sustainability and environmental conditions.

中文翻译：

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模拟米兰地下结构对地下水流的干扰和补救措施

摘要 城市地区的地下结构和基础设施对地下水流造成干扰。自 1970 年代以来，米兰的地下水抽取量减少了 30% 以上，导致地下水反弹，导致多个地下结构和基础设施被淹没和洪水淹没。为了评估地下结构对米兰市区地下水流的影响，基于地下水流模型进行了详细分析。3D FEM 地下水流模型根据高分辨率监测数据进行校准，用于评估地下结构及其施工顺序引起的扰动，并验证缓解策略的性能。当结构横向切断地下水流时，观察到地下水水头分布的重大变化，导致地下水流路径破碎，并导致地下水水头从区域范围内的±0.05 m左右变化到相对接近的±0.45左右（几百米）地下结构。讨论了传统灰色（即排水隧道）和蓝绿色基础设施（即与热泵系统相结合的抽水井）缓解方案的有效性。蓝绿色基础设施产生最有效和最高效的缓解解决方案，直接影响可持续性和环境条件。在区域范围内，地下结构的相对接近度（几百米）约为 ±0.45。讨论了传统灰色（即排水隧道）和蓝绿色基础设施（即与热泵系统相结合的抽水井）缓解方案的有效性。蓝绿色基础设施产生最有效和最高效的缓解解决方案，直接影响可持续性和环境条件。在区域范围内，地下结构的相对接近度（几百米）约为 ±0.45。讨论了传统灰色（即排水隧道）和蓝绿色基础设施（即与热泵系统相结合的抽水井）缓解方案的有效性。蓝绿色基础设施产生最有效和最高效的缓解解决方案，直接影响可持续性和环境条件。