Hydrology
Masoud Morsali
Abstract
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 ...
Read More
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.
M. Morsali; M. Nakhaie; M. Rezaie; H. R. Naseri; J. Hassanpour
Abstract
Tehran- Karaj water conveyance tunnel (part 1), 16 kilometers in length, in the Karaj formation was excavated in order to convey the water from the Amir-Kabir dam to the Tehran refinery plant. The hydrogeology studies of the Karaj tunnel were done to discover the affecting parameters on the groundwater ...
Read More
Tehran- Karaj water conveyance tunnel (part 1), 16 kilometers in length, in the Karaj formation was excavated in order to convey the water from the Amir-Kabir dam to the Tehran refinery plant. The hydrogeology studies of the Karaj tunnel were done to discover the affecting parameters on the groundwater inflow into the tunnel. Groundwater inflow was estimated by means of empirical and analytical methods. Daily measurements of inflow rate show that there are some differences between the calculated and the observed inflow value. In this research, based on the comparison between the observed and calculated groundwater inflow, some relations have been derived for similar hydrogeological conditions. In many hydrogeological conditions, the analytical equations are supervised on empirical formula. According to this research, addition to permeability and water head; geological structure, Precipitation and bedding dip have a significant effect in water inflow into tunnels. Also, most of groundwater inflow along the Karaj tunnel is largely related to the main geological features, such as folds, faults, dykes and open fractures and inflow is correlated with precipitation.
M. Heydari; Sharafi M.
Abstract
The use of remote sensing combined with field surveys can be used as an economic approach to detect the areas that are susceptible to the influx of water into tunnels. This study aims at investigating potential zones of groundwater influx in part 1-A of the Nosoud water-transport tunnel located in the ...
Read More
The use of remote sensing combined with field surveys can be used as an economic approach to detect the areas that are susceptible to the influx of water into tunnels. This study aims at investigating potential zones of groundwater influx in part 1-A of the Nosoud water-transport tunnel located in the NW of Kermanshah province. Stratigraphic units of the area are composed of limestone and shale layers, which have formed alternating hard and soft sequences at the tunnel site. Fractured brittle limestone layers alternating with impermeable shale layers are the most important factor controlling the influx of water into the Nosoud tunnel. The danger of possible mine explosions prevented us from a survey along the whole length of the tunnel. Hence we classified these lithologies into two types labeled as Li and Sh which representing limestone and shale respectively. In order to explore layers that could potentially lead to water influx, we used ASTER satellite images to analyze the geohydrologic evidences across the area. Results suggest that the tunnel has a high risk of groundwater influx in places where the Li3 and Li-Sh3 units are encountered. Moreover, observations during tunnel excavation show that the major cause of water influx into the tunnel are preferentially concentrated in zones where hard layers with open fractures are crossed. This is considerably compatible with the results of satellite image processing model.
