Comparison of Equivalent Continuum and Discontinuum Methods in Stability Analysis of a Natural Underground Karst

Geotechnical Geology

دوره 14، شماره 1، شهریور 2018، صفحه 158-166   

نوع مقاله: Original Research

نویسندگان

Mahnaz Laghaei^{* 1}؛ Alireza Baghbanan¹؛ Masoud Torkan¹؛ Siavash Norouzi²؛ Meysam Lak³

¹Department of Mining Engineering, Isfahan University of Technology, Isfahan, Iran

²Department of Mineral Engineering, New Mexico Tech, Socorro, NM 87801, USA

³Department of Mining and Metallurgy, Yazd University, Yazd, Iran

چکیده

Stability analysis of the underground karsts around excavated and supported tunnels is one of the most important tasks in terms of safety evaluation of tunnels and underground excavations. In this paper, the stability and the stabilization method of a natural hole which existed before excavation above a transportation tunnel were investigated. The hole was modeled in form of continuous and discontinuous media. Several realizations with different crack patterns were generated in order to eliminate random effect. The stability was analyzed numerically. The results show that the equivalent continuum method induces overestimation upon strength parameters and consequently results in higher uncertainty compared to the discontinuum method which is a better representation of the problem. The generated models in discontinuous medium were highly unstable and showed prominent signs of collapse. As per the agreement between the discontinuous models with the real problem’s conditions, this instability and collapse of rock blocks may disturb the tunnel lining and yield to catastrophes. The results of using concrete foam as the filling and the whole support confirm the proper applicability of this approach alongside its practicability under the conditions specific to this project.

کلیدواژه‌ها

Equivalent continuum method؛ Discontinuum method, Karst؛ Discrete Fracture Network؛ Numerical modeling