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Studying the effect of some parameters on the stability of shallow tunnels

Research Authors
Wael R. Abdellah, Mahrous A. Ali, Hyung-Sik Yang
Research Member
Research Year
2018
Research Journal
Journal of Sustainable Mining
Research Publisher
ScienceDirect
Research Vol
17 (2018)
Research Rank
1
Research_Pages
20-33
Research Website
http://www.elsevier.com/locate/jsm
Research Abstract

Several factors have crucial impact on the serviceability of underground openings including: the quality of rock mass; the presence of rock joints and their geometrical properties; the state of in-situ stress ratio; the depth below surface and opening geometry. This paper only investigates the effect of two parameters on the stability of underground shallow tunnels, namely: the presence of rock joints in the rock mass matrix and the shape of the excavation. A series of two-dimensional elasto-plastic finite-element models has been constructed using rock-soil, RS2D, software. Consequently, parametric stability analysis has been conducted for three different tunnel shapes (e.g. circular, square and horseshoe) with/without joint inclusion. Four reference points have been assigned in the tunnel perimeter (e.g. back, sidewalls and floor) to monitor the state of stress-displacement in the rock mass around them. The results indicate that the weak performance of a tunnel opening occurs with a square-shaped opening and when joints exist in the rock mass. In addition, the normal stress along joints sharply drops in the vicinity of a tunnel opening. Moreover, the direction of shear stress is reversed. Thus, it causes inward shear displacement.