Tunnel excavation by blasting inevitably results in the rock mass damage around the excavation profile. The rock mass damage immediately next to the tunnel profile emerges as the expanding of the existing cracks and the appearance of new cracks, i.e. as the change of the physical and mechanical properties of the rock mass. Measurements were obtained from the surface and from the tunnel opening by using geophysical and visual methods.

blast induced damaged zone, underground excavation, in situ investigations, rock mass physical and mechanical properties