Studying the Effect of Tunnel Depth Variation on the Specific Energy of TBM, Case Study: Karaj–Tehran (Iran) Water Conveyance Tunnel

The tunnel-boring machine ( TBM) is a common piece of equipment used in tunneling projects. For planning a mechanical excavation project, prediction of TBM performance and the specification of design elements such as required forces are critical. The specific energy of excavation (SE), i.e. drilling energy consumption per unit volume of rock mass, is a crucial parameter for performance prediction of a TBM. In this study, the effect of variation of tunnel depth on SE by considering the post-failure behavior of rock mass was investigated. Several new relations between SE and tunnel depth are proposed according to the statistical analysis obtained from Karaj–Tehran Water Conveyance Tunnel real data. The results showed that there is a direct relation between both parameters and .A polynomial equations are proposed as the best expression of the correlation between these parameters.