Presenting Equations for estimating utilization coefficient of tunnel boring machine (case study: Zagross1 tunnel)

Tunnel Boring Machines (TBMs) are considered as the major boring machines in tunnels and underground spaces. Regarding the high cost of TBMs, performance assessment in a boring method using these machines is of paramount importance. Penetration rate and utilization coefficient are the major performance assessment indices of a TBM. There are various methods and equations for predicting the utilization coefficient, each having specific features and developed based on parameters of rock masses and machine specifications. Employing multivariate linear regression method and taking the key parameters of rock masses and TBM into consideration, this study proposed some relations for utilization factor in Zagros 1 tunnel (located near Hirvi village on the route Paveh- Nowsud, about 10 km to Nowsud, near Paveh city in Kermanshah Province, and about 120 km northwest of Kermanshah Province). To validate the developed equations, utilization factor was calculated in some sections of Ghomroud tunnel as well. Errors of the obtained results from regression method are lower than the ones obtained from NTH and CSM methods. In some cases, they exceed the ones obtained from NTH method and become lower than CSM method. In fact, regression method is ranked between the two methods. The results indicate that the equation proposed in this project predict utilization coefficient with an appropriate approximation as compared with the real condition.