عنوان مقاله [English]
Determination of bid prices for hard rock TBM drives needs to estimation of tunneling machine advance rate. On the other hand determination of machine advance rate requires to estimation of machine utilization. This paper propose an equation for estimation of open TBM utilization based on rock mass classification system (Q & RMR) and disc thrust of TBM machine. For this purpose Pearson test is used for evaluation of correlation between utilization, RMR, Q, Disc thrust, MQ (Modified Q), NRMR (None modified RMR). Whereas stability status of tunnel affect on the utilization factor, rock mass classification indexes have a significant relationship with the machine utilization. Statistical analyses show that there is significant relationship between MQ (Modified Q), NRMR (None modified RMR) and utilization factor. Ultimately the best equation is offered for estimation of utilization factor.