SMALL BORE SHIELD METHOD WITH TRISECTION SEGMENT AND SHIELD EXCAVATOR USED SUCH METHOD

摘要

PURPOSE:To form a high strength of back-fill material layer in a soft ground by filling the back-fill material in the ring-form clearance between a tail skin plate and a segment ring, and after that, sliding a seal device which has provided the clearance to press the back-fill material closely. CONSTITUTION:In a tail skin plate 22, an inner tube 47 which can slide freely in the direction of the axial line by an actuator 24 is provided. Then, a seal device 23 between the plate 22 and a segment ring 20 is provided at the end of the inner tube 27. Then, while an excavation is carried out in a unit stroke by operating a shield jack 19, the seal 23 is displaced to the rear side to push out a back-fill material already filled, to prevent a collapse. By displacing the seal 23 to the front side, a new back-fill material is filled to the clearance. Furthermore, the seal 23 is pushed out to the rear side to press the back-fill material closely. As a result, a precise back-fill material layer can be formed by using a mud pressure process concurrently.