Abstract
In order to quantitatively evaluate the support effect of rock bolts in tunnel practice, first physical model tests were carried out to reveal a functioning mechanism of rock bolts reinforcing the discontinuities of rock joints. Secondly, field measurement results were collected from published data of tunnel projects. They were then analyzed taking into consideration the mechanism of functioning of rock bolts revealed by the physical model test. As a result, it became clear that serious deformation problems such as failure of shotcrete, breakage of rock bolts, buckling of steel ribs, etc., occurring during the excavation of tunnels were closely related to the softening behaviour of rock masses.
