Hafeezur Rehman - Department of Mining Engineering, Balochistan University of Information Technology Engineering and Management Sciences, Quetta, Pakistan
Wahid Ali - Department of Mining Engineering, Balochistan University of Information Technology Engineering and Management Sciences, Quetta, Pakistan
Kausar sultan Shah - Department of Mining Engineering, Karakoram International University, Gilgit, Pakistan
Mohd Hazizan Mohd Hashim - School of Materials and Mineral Resources Engineering, University Sains Malaysia, Engineering Campus, Nibong Tebal, Penang, Malaysia
Naseer Khan - Department of Sustainable Advanced Geomechanical Engineering, Military College of Engineering, National University of Sciences and Technology, Risalpur, Pakistan
Muhammad Ali - Department of Mining Engineering, Balochistan University of Information Technology Engineering and Management Sciences, Quetta, Pakistan
Muhammad Kamran - Department of Mining Engineering, Institute of Technology Bandung, Indonesia
Muhammad Junaid - Department of Mining Engineering, Karakoram International University, Gilgit, PakistanUniversiti Technologi Malaysia

Support design is the main goal of the Q and rock mass rating (RMR) systems. An assessment of the Q and RMR system application in tunnelling involving high-stress ground conditions shows that the first system is more appropriate due to the stress reduction factor. Recently, these two systems have been empirically modified for designing the excavation support pattern in jointed and highly stressed rock-mass conditions. This research work aims to highlight the significance of the numerical modelling, and numerically evaluate the empirically suggested support design for tunnelling in such an environment. A typical horse-shoe-shaped headrace tunnel at the Bunji hydropower project site is selected for this work. The borehole coring data reveal that amphibolite and Iskere Gneiss are the main rock mass units along the tunnel route. An evaluation of the proposed support based on the modified empirical systems indicate that the modified systems suggest heavy support compared to the original empirical systems. The intact and mass rock properties of the rock units are used as the input for numerical modelling. From numerical modelling, the axial stresses on rock bolts, thrust bending moment of shotcrete, and rock load from modified RMR and Q-systems are compared with the previous studies. The results obtained indicate that the support system designed based on modified version of the empirical systems produce better results in terms of tunnel stability in high-stress fractured rock mass conditions.

High in-situ stresses, tunnel support, Jointed rock mass, Numerical Modelling, Empirical Methods