| 摘要 |
PROBLEM TO BE SOLVED: To improve safety by launching earth retaining face plates provided in the face plates of a shield machine, and removing obstacles while retaining earth for which ground improvement has been made in advance. SOLUTION: Earth retaining face plates 18 are arranged in recesses provided in the face plate of the front face of a shield machine 11 in a rotationally symmetrical state and are made withdrawable with an earth retaining face 21. At the time of excavation, the face plates 18 are withdrawn into the recesses and slits 16 are opened, the surfaces of the main body 12a of the face plate and the face plates 18 are positioned flush with each other, and the edges of bits 14 are projected forward from the face plate 12. When an obstacle such as an H-steel pile has appeared in the safe, excavations is suspended, the face ground is improved and the surfaces of the face plates 18 are pushed out as far as the heads of the bits 14, and earth is retained by pressing the face. And then the obstacle is cut and recovered with a water jet cutting and recovery unit 23, after the slits 16 are blocked by shutting opening/closing plates 15, mud water in a chamber is removed, and an iron plate 22 is removed. the face can be stabilized without applying compressed air, and accidental air blow can be prevented. |
