Hydraulic Response to Geometry: Finite Element Modeling of Underground Spaces in Saturated Environments

Abstract

Tunneling operations face a significant challenge in managing water inflow into excavated underground spaces, primarily initial or excavating caused discontinuities in tunnel walls. The water flow rate is intricately linked to the geometric shape of the tunnel, making it a crucial consideration during infrastructure design and construction to mitigate the risks associated with water infiltration. This study employs the finite element numerical method to explore how different geometric shapes (circular, D-shaped, rectangular, and irregular hexagon tunnels), along with parameters like excavated space area, excavated space perimeter, water head, and permeability coefficient anisotropy, influence steady-state water inflow into tunnel as saturated environments. Results demonstrate that the geometric shape of underground spaces has a substantial impact on water ingress, with circular tunnels exhibiting notably lower inflow rates compared to other shapes under similar conditions. However, the overall dimensions of the simulation model may also influence the observed impact. The research underscores the necessity of considering both geometric shape and overall dimensions for effective drainage in tunnel design. While circular tunnels generally prove to be a safe choice, further project-specific analysis may be warranted. It is crucial to acknowledge that accurately predicting the influence radius requires intricate numerical modeling or physical experiments accounting for all relevant factors, as the impact of shape is just one facet, with other design and geological factors playing equally crucial roles.