Stability assessment of Seyrantepe caves in Gaziantep

The collapse of caves due to excessive spans or insufficient rock cover is a major geotechnical hazard in rock masses that are prone to the stability problems. Analytical solutions for the stability of near surface caves in rock masses are rarely used because of the inherently discountinuous nature of the problem; instead, numerical approaches such as the finite element, discrete element, or hybrid methods of analysis are typically employed. In this thesis integrated experimental, analytical and numerical analyses were undertaken to assess the stability condition of Seyrantepe caves which were excavated into limestone. The sizes of the caves were measured in the field. Rock mass characterization was performed. The RMR, GSI and Q indexes were utilized for rock mass classification. A back analysis was performed on the recently collapsed section of the caves. The RocLab software based on Hoek-Brown failure criteria, and Mohr-Coulomb failure criteria were also used to determine the geotechnical parameters of the rock mass. The effects of the adjacent spans of the caves on the stability and failure zone were investigated. Back anaysis results gave the lower strenght parameters compared with Mohr Coulomb. RocLab results became on the safe side for this massive rock mass. The results showed that limit roof span was between 12 and 15 m for the roof thickness of 9 m and some countermeasures against instability were necessary.