Introduction of geomorphological rock mass strength classification as a criterion for estimating the groundwater inflow into tunnels

Prediction of groundwater inflow into tunnels during excavation is one of the most important problems of tunneling projects. There are many analytical and empirical methods to predict the amount of groundwater entering the tunnels, which are generally not highly accurate. Permeability and water head are the main affecting parameters in estimation of groundwater inflow in current prediction methods. Due to the complexity of the geological and hydrogeological conditions of hard rock formations, it is necessary to enter other geological factors to estimate groundwater inflow into the tunnel. In this paper, for the first time, Geomorphological Rock Mass Strength (GRMS) classification is used as a criterion for estimating the groundwater entering the tunnel. The obtained data from two tunnels in different geological setting were used to study the effect of rock mass classification parameter on estimation of groundwater entering the tunnel. The results show that for both tunnels, GRMS have a significant correlation with the amounts of groundwater inflow into the tunnels.