The performance prediction of impact hammers from Schmidt hammer rebound values in Istanbul metro tunnel drivages

Abstract

The construction of the first metro line in Istanbul was realized between Galata and Beyoglu by a French Engineer Henry Gavand in January 1875. Six different metro projects were submitted since then to the Turkish authorities. The construction of 7-km metro tunnels phase 1 started in 1992 and the metro line of the phase 1 is opened to the service in 2000. The tunnels of the phase 2 between Taksim and Yenikapi are under construction. This paper summarizes the construction methods of the Istanbul metro tunnels, the performance of the impact hammers, the factors effecting daily advance rates and the previous studies on Schmidt hammer test and performance prediction of impact hammers. At the end, a prediction model concerning instantaneous breaking rates of hydraulic impact hammers from Schmidt hammer rebound values is explained in detail.