Research on risk assessment and control of water level rising during operation of Jinan Metro based on similar physical model experiments

Introduction Underground metro structures can obstruct groundwater flow, causing upstream water-level rise and pore-pressure redistribution. This study investigates the groundwater-blocking effect associated with Jinan Metro and evaluates measures for reducing the resulting engineering risk. Methods A physical model system was developed to reproduce groundwater seepage during metro station construction and operation under different hydraulic gradients and diversion conditions. Pore-water pressure responses were monitored, and repeated tests were conducted to assess measurement repeatability. Six indicators were selected for risk assessment, with subjective and objective weights determined using the analytic hierarchy process and principal component analysis, respectively. TOPSIS and a normal cloud model were applied to 12 validation cases. Results Without diversion, the maximum upstream water-level rise reached 2.10 m at a hydraulic gradient of 0.07. Diversion reduced water-level backwater by 74.07%–98.09% across the tested conditions. The 3,000 mm 2 gravel channel provided the greatest reduction, while the 700 mm 2 gravel channel and the seven connecting pipes of 5 mm diameter also performed effectively. The normal cloud model agreed with the reference results in 75.00% of cases, compared with 58.33% for TOPSIS. Discussion The experiments clarify the mechanisms of local groundwater blocking and support the selection of diversion measures and risk-based engineering controls. The normal cloud model showed better agreement within the tested cases; however, the limited validation sample and simplified aquifer representation require further verification using site-specific monitoring and hydrogeological data.