An integrated study on stability assessment of the Seyrantepe underground openings (Gaziantep, Turkey)

Abstract

In view of the geotechnical engineering and engineering geology, the Seyrantepe underground openings have important characteristics. Although these underground openings have thin roof thickness, large parallel span, thin pillars and low rock mass strength, they are standing up for years. Due to the rock masses being complicated and inhomogeneous material and containing discontinuities, it is commonly difficult to obtain the required mechanical parameters for the analyses. In this paper, a combined analysis, including failure-based back analysis, Hoek–Brown and Mohr–Coulomb failure criteria, was executed to determine the cohesion, frictional angle and tensile strength of the rock mass. Integrated numerical, analytical and empirical analyses were performed to assess the stability of the underground openings, which were excavated from limestone. The effects of the adjacent openings on the stability and failure zones were also investigated. The analysis shows that considerably important parameter for the roof stability is the tensile strength of the rock mass. While the lowest tensile strength is obtained from Hoek–Brown criterion, Mohr–Coulomb criterion gives the highest tensile strength. Numerical analysis shows that adjacent openings affect the stability and failure process. According to the bending theory, the limit of the roof span ranges between 11 and 22.5 m depending on roof thicknesses of 9 and 25 m, respectively. Although these underground openings are standing for a long time, results of the analyses show that some protective measures against instability are necessary. © 2021, Saudi Society for Geosciences.