Modelling of Groundwater Flow in the Vicinity of Tunnel Structures

The paper deals with determination of the effect of newly built driven road tunnels within the capital city of Prague on the groundwater flow pattern and groundwater table position. In order to assess the changes in groundwater flow in the vicinity of these underground structures, a numerical model was used. Despite the three-dimensional nature of groundwater flow in the vicinity of tunnel structures, under certain conditions the flow may be simulated as two-dimensional flow in a vertical plane. This plane’s direction corresponds to the prevailing direction of groundwater flow, and runs perpendicular to the tunnel tubes’ axis. The used numerical model is based on the equation of two-dimensional steady groundwater flow with free surface in a non-homogeneous anisotropic porous domain. The effect of tunnels on groundwater flow was subject of research in several versions considering different conditions before, during and after the construction of the tunnel structures. The results of numerical modelling have been assessed by means of piezometric head isolines, trajectories, hydraulic head values and seepage values.