Rock reinforcement design for unstable tunnels originally excavated in very poor rock mass

摘要

Number 7 Malatya railroad tunnel was excavated through the toe of a paleo-landslide material in 1930. Ever since that date, this horseshoe shape tunnel, having width and height of 5 m and 6 m, respectively, struggled with stability problems. A large amount of deformation (170 cm) developing through the years and leading to miss alignment of the tunnel was observed. In this paper, firstly a new approach developed for classifying very poor quality rock mass was presented. Secondly, evaluations were made on the stability of the tunnel. Thirdly, information is provided on rock reinforcement design. Finally, the results of finite element analysis (FEA) conducted for evaluating the stability of unreinforced tunnel and the tunnel reinforced by self drilling anchors (MAI-bolt) designed based on empirical method were given.