Abstract
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.
Highlights
The Q-system was developed at NGI between 1971 and 1974 [1]
Since the introduction of the Q-system in 1974 there has been a considerable development within support philosophy and technology in underground excavations
Analytical research updating with respect to the thickness, spacing and reinforcement of reinforce ribs of sprayed concrete (RRS) as a function of the load and rock mass quality have been done by [2]
Summary
Since the introduction of the Q-system in 1974 there has been a considerable development within support philosophy and technology in underground excavations. The types of rock bolts and fiber reinforced technology had been introduced and continuously develops as support procedure. Two revisions of the support chart have been carried out and published in conference proceedings. An extensive updating in 1993 was based on 1050 examples mainly from Norwegian underground excavation. Analytical research updating with respect to the thickness, spacing and reinforcement of reinforce ribs of sprayed concrete (RRS) as a function of the load and rock mass quality have been done by [2]. The most updated guideline for RRS in the support chart based on case histories in Norway can be found in a study [3]
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