Assesment of Factors Affecting Groundwater Ingress into Tunnel Cebrat using Numerical Modelling

Abstract

The thesis deals with the assessment of water ingress mechanisms in the tunnel Čebrať, located in the Ružomberok district, Slovakia. To estimate the water inflow in tunnels, fully 3D geo-hydromechanical numerical modeling has been performed. This project can be divided in two stages of modeling; the first is a geomechanical simulation by considering CWFS, HoekBrown and Ubiquitous-joint models. Once the strain and deformation changes around tunnels were quantified, boundaries given by EDZs, were obtained to be imported into FEFLOW as supermeshes, to perform the second stage of modeling, where main hydrogeological features of studied area and impact of tunnel construction were considered under a steady-state water flow regime. Several cases of analysis were then studied in order to quantify the impacts of tunneling and fractures on the water budget in surface creeks, as well as on the tunnel itself. The groundwater recharge was assessed by interpolating linearly with elevation, precipitation data from years 2001 to 2016. Although results seem to be sound with observed data, parameter calibration is still a required task for future analysis.