Effects of pipe roof supports and the excavation method on the displacements above a tunnel face

Abstract Centrifugal model tests are conducted in order to clarify the effects of pipe roof supports and the excavation method on the displacements above a tunnel face. The excavation process must be taken into account when estimating the displacements. Therefore, an excavation robot is newly developed which is three-dimensionally controlled by computer programs and is able to excavate the tunnel face in arbitrary shapes. The robot can accurately simulate such excavation methods as the full-face excavation method and the ring-cut excavation method. The difference in displacements between the two excavation methods is discussed in terms of the existence or the nonexistence of pipe roof supports. The results of the model tests show the quantitative effects of the ring-cut excavation method and clarify that the method decreases the ground displacements remarkably. The model tests also indicate that the maximum settlement of a ground excavated by the full-face excavation method with pipe roof supports is one fourth of that without them.