Abstract
In this paper, we used two empirical rock classification systems of rock mass rating (RMR) and rock quality tunnelling index (Q-system) for the support design of a tunnel in District Battagram, Khyber Pakhtunkhwa, Pakistan. Along the tunnel route, the rocks of Precambrian namely Gandaf Formation, Karora Formation and Besham Complex were exposed. During the field investigations, two shear zones were marked in the schist of Karora Formation. The discontinuities parameters collected during the field investigations, results of laboratory testing and material constants determined from RocData version 5.0 software were used during the empirical classification and numerical modelling. The support was designed for the rock mass units from RMR and Q. The quantification of the thickness of plastic zone and total displacement around the tunnel were achieved by the numerical modelling of RS2 9.0 software in both unsupported and supported conditions. The empirically designed support was installed in the model prepared in the RS2 software. According to the results, the empirically designed support when installed in models prepared in RS2 significantly reduced the plastic zone around the tunnel. The reduction in the plastic zone and displacement around the tunnel verified the support design by empirical methods. The present research concludes that empirical designed support can be used for the complex geology of Pakistan.
Highlights
Empirical methods are designed for the determination of qualities of the rock mass and support design for underground excavations
The present study focuses on the verification of proposed support system by empirical methods (RMR and Q) using numerical modeling by Finite Element Method (FEM Codes) RS2 – commonly known as Phase2
The shear zones marked in the schist makes these units the most critical among others and the poor rock quality were determined from rock mass rating (RMR) while poor to very poor were determined from Q-system
Summary
Empirical methods are designed for the determination of qualities of the rock mass and support design for underground excavations. These classification systems are based on a number of case histories and are being used at various stages of the construction of the project for decades. The verification of empirically design support system through numerical modeling requires the detail information about the geology and geotechnical parameters of rock masses. The details of these parameters are given in the section 3.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
