NUMERICAL INVESTIGATION INTO EFFECTS OF LONG FACEBOLTING ON THE PREVENTION OF GROUND SURFACE SETTLEMENT

Abstract

Long facebolting, as an auxiliary method in mountain tunneling, is used not only for the measure of face stabilization but also for the measure of preventing surface settlement. In this paper, the mechanism of preventing the surface settlement by means of long facebolting is investigated for shallow tunnels using three-dimensional numerical analysis. It is found that the facebolting words effectively in sandy ground resulting from the confining stresses in the ground ahead of face reinforced with the long facebolts.