Investigating the possibility of occurrence of geological hazards in the existing formations at the Hamrov tunnel

Knowledge of geological hazards plays an important role in the selection and installation of timely support system for underground structures. The Hamrov tunnel with an approximate length of 1294 meters in the main way of Sanandaj- Marivan is under construction. Based on the geo-mechanical conditions of rock masses in the tunnel, it is necessary to investigate the possible geological hazards such as squeezing. In this study, using geological surveys and drilling of boreholes, the way of the tunnel been divided into different units and then the severity of squeezing in each section have been investigated. By comparing the different methods of squeezing evaluation, it was found that the empirical Hoek-Marinos method evaluate the minimum of squeezing and the Jethwa method evaluate the maximum of squeezing for the rock masses of the tunnel. The utmost squeezing potential is related to section of the tunnel where there is the alternation of sandy shale and limestone with shale. According to the survey, the Hamrov tunnel is divided into three sections: A (km 5293 to 5543) with squeezing extreme serious to serious, B (km 5543 to 5973) with squeezing severe to very low, and C (5973 to 6133 km) almost without risk of squeezing.