Laboratory and numerical investigation of tunnel reinforced with face bolts

During the excavation of tunnel, to prevent the collapse of tunnel face and settlement of ground the face bolts have been being frequently used in the soft ground. In this study, the face bolts were installed near to excavation line upwardly and radially on purpose and their supporting effects according to the installation angles were examined. Based upon the results of the laboratory and numerical investigation, the following conclusions were obtained. The axial displacement of the tunnel face depends on the installation angel under the same construction condition. The upward installation of the face bolts is fairly effective on controlling the vertical settlement. Inclined installation of face bolts depending on the purpose of support may be required for effective control of axial displacement of the face and/or the vertical settlement of surface.