ABSTRACT
Kerman water conveyance tunnel (KrWCT) is located in central Iran. The tunnel is under construction both from northern and southern portals using two refurbished TBMs. In order to excavate northern section, a double-shield machine was employed, which was used in Alborz Mountains in northern Iran. Geological conditions of KrWCT is quite different from previous tunnel, and a long section of tunnel will pass through massive, very strong and abrasive rocks. Preliminary investigations revealed the necessity of improving the old machine particularly its cutterhead design and disc cutter arrangement on the head. In this paper, using empirical performance prediction models, the effect of cutterhead design and various operational parameters on penetration and advance rates of the machine is evaluated; Furthermore, optimum cutterhead design parameters are suggested to cope with KrWCT tunnel geological setting. Eventually, the effect of modifications on boring operation is discussed by comparing performance of new cutterhead and the original head in two short sections.
