Evaluating effects of geological conceptualization on simulated pore pressure reduction from groundwater leakage to excavation

Paper in proceeding, 2025

Underground construction such as tunneling or deep excavations in saturated soil or rock can lead to groundwater leakage, resulting in lowered groundwater pressure and subsequent time-dependent consolidation in subsidence-sensitive soils. In Sweden, permeable sand layers within clay deposits, formed during fluctuating sea levels during sedimentation, can significantly affect the hydraulic conductivity of these sequences but are often neglected in site characterization for groundwater modeling. This study aims to assess the impact of geological uncertainty on pore pressure reduction due to groundwater leakage. Numerical groundwater models simulated pore pressure changes for two geological scenarios: homogeneous clay and clay with interbedded sand. Sand distribution was modeled using Multiple Point Statistics (MPS), and groundwater flow models were developed in MODFLOW-NWT. The results showed substantial differences in pore pressure behavior between the two scenarios, highlighting the critical role of sand layers in influencing pore pressure dynamics and subsidence risks.