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.
Research Member
Research Department
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