TUNNEL SUPPORT BY ROCK QUALITY INDEX (Q) SYSTEM FOR ULTRABASIC ROCK: A CASE STUDY IN TELUPID, SABAH, MALAYSIA
Journal: Malaysian Journal of Geosciences (MJG)
Author: Ismail Abd Rahim, Mohamad Saiful Nizam Mohamad
This is an open access article distributed under the Creative Commons Attribution License CC BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited
The study area is underlain by the ultrabasic rock of partly Sabah Ophiolite Complex of Cretaceous ages. The objectives of this study are to determine the Q-value and to estimate the permanent support measures for 20m span, 10m high and eastern direction of the proposed tunnel in the study area. Engineering geological mapping (lithological and surface mapping and discontinuity survey), laboratory study (petrographical study) and testing (Uniaxial Compressive Strength testing) and data analysis (stereographic plots, Q system parameters evaluation and support estimation) was used in this study. The results show that the rock mass is classified as lherzolite, strong, excellent quality, more than four joint sets, slightly altered discontinuity wall, dry excavation and favourable stress condition. The equivalence dimension (De) are 15.4 for the permanent roof. The Q-value for permanent roof and wall of the proposed tunnel are 1.4 (Class D or poor and type 5) and 3.5 (Class D or poor and type 3), respectively. The permanent and temporary supports for the roof and wall are systematic bolting, 700J energy absorption of fiber reinforce sprayed concrete, 9-12 and 5- 6 cm thick fiber reinforce shotcrete, respectively.