The problem of large deformations is very pronounced when excavating longer tunnels in poorer rock mass, which can result in serious potential hazards to safety, costs and time of tunnel construction. Taking the Golubinja tunnel, located on the route of corridor Vc, as an engineering background, displacement monitorings were carried out on a certain section of the right tunnel tube with a length of approximately 230 m’. Displacement monitorings were carried out in relation to different distances during the excavation of the top heading-bench and the bench-primary invert in a poorer rock mass with a defined RMR of 17 to 26 points. The designed tunnelling method is based on the principles of the New Austrian Tunneling Method „NATM“. The results show that in complex geological conditions, displacements can be effectively controlled by defining the optimal distance between the excavation phases of the top heading-bench and the bench-primary invert. Through a detailed analysis of the collected data, the mathematical functions of the dependence of the displacement in relation to the distances between the excavation phases of the top heading-bench and the bench-primary invert were obtained. The functions can be used as a tool for a quick and simple analysis of displacements depending on the distance between the excavation phases of the top heading-bench, and the bench-primary invert in a poor rock environment.

tunnel, excavation, displacements, rock mass, bench, top heading, invert