Estimation of the Performance of the Tunnel Boring Machine (TBM) Using Uniaxial Compressive Strength and Rock Mass Rating Classification (RMR) – A Case Study from the Deccan Traps, India

Abstract

The competency of any TBM in any geological condition is determined by a rock or rock mass breakage process. A 12.24 km long tunnel between Maroshi and Ruparel College was excavated by Brihanmumbai municipal corporation (BMC) to improve water supply system of greater Mumbai, India, using open-type hard rock tunnel boring machines (TBMs). In this paper an attempt has been made to establish the relationship between rock mass characteristics i.e. RMR and UCS of the Deccan trap rocks and TBMs performance characteristics for 5.83 km long Maroshi–Vakola tunnel section of the Maroshi–Ruparel college tunnel project. To analyze the effect of variable rock mass conditions on the TBM performance, the operating parameters i.e. thrust force, torque and RPM of the machine, were recorded and intact rock strength was determined. The effect of rock mass properties on machine penetration rate (PR) and the relation with other operational parameters were analyzed. The rock strength affects the rock behaviour under compression. When the rolling cutters indent the rock, the stress exerted must be higher than the rock strength i.e.; the rock strength is directly relevant to the performance of TBM. Studies show that the penetration rate decreases with increase in uniaxial compressive strength (UCS). The comparison of measured penetration rate with empirical model developed by Graham, in which, the penetration rate is computed using UCS and average thrust per cutter, showed good agreement with coefficient of determination (R2), i.e. 0.97. The study shows that the TBM performance was maximum in rock mass rating (RMR) range from 40 to 75, while slower penetration was recorded both in very poor and very good rock masses.

BP Network for Predicting the TBM utilization

“…In the region where RMR is about 60, the downtime is the shortest. P. JAIN [2] established the relationship between rock RMR, uniaxial compressive strength (UCS) and TBM performance characteristics. The results show that the utilization rate of TBM is linearly related to the uniaxial compressive strength of rock, and the utilization rate of TBM reaches the maximum in the range of RMR between 40 and 75.…”

Archives of Mining Sciences

“…Owing to the easy execution, less input and compr ehensive consideration, the RMR system is widely used to evaluate the geomechanical features and stability of engineering rock mass and to determine the tunnel support type worldwide (Aksoy, 2008;Lowson & Bieniawski, 2013). Meanwhile, a number of further studies on the RMR system have been conducted, including improvements of the RMR model (Sen, 2003;Sereshki et al, 2010;Jalalifar et al, 2011Jalalifar et al, , 2014Nikafshan et al, 2015;Mutlu, 2017), the estimations of rock mass properties based on the RMR system (Liu et al, 1999;González et al, 2006;Palmstrom, 2009;Khademi et al, 2010;Justo et al, 2010;Paul et al, 2012;Jain et al, 2016;Chen et al, 2017), the characterizations of RMR spatial heterogeneity (Ferrari et al, 2014; and several specialized rock mass classifications relating to the RMR system (Romana, 1993;Atr, 2001;Liu et al, 2014;Warren et al, 2016).…”