Verification of reinforcing effects of a tunnel face reinforcement method by centrifuge model tests and numerical analysis

摘要

In the past, the conventional method for excavating special ground having a low competence ratio and high expandability, was to make excavation areas small while stabilizing faces and crowns. However, that method was unable to prevent excessive displacement, and timbering frequently had to be replaced. In recent years, full-face excavation has been increasingly carried out on such unstable ground so as to restrain the final displacement by early closure. In full-face excavation, it is important to employ a forepoling method in combination with a face reinforcement method that utilizes long facebolts in order to stabilize the face.