Abstract
Rock bolts have become a common measure for providing ground support. However, the effect of rock bolts in sandy ground is not verified theoretically and it is presumed that rock bolts in sandy ground exert the ability on the ground stability if its length and arrangements are designed appropriately and rock bolts are installed at the proper timing. In this paper, to clarify the mechanism of rock bolts effect in sandy ground, trapdoor model tests with various bolt length, inclination of rock bolts and time for installing rock bolts were carried out. It was found that in deep tunnel the longer bolts than loosened zone have the effect of integrating ground around a tunnel and rock bolts installed after the occurrence of loosened zone have the similar effect as the rock bolts installed before the occurrence of loosened zone.
