PURPOSE: To improve workability by mechanically excavating the ground by an excavation means at a first caisson-body front end section having the excavation means and removing a truck together with the excavation means from the upper section of a rail when the excavation means reaches a reaching hole. ;CONSTITUTION: A rail 9 is laid in the front-end opening section of a first caisson body I1 in the width direction, and a bearing strut 13, an upper end of which can be abutted against the ceiling section of the caisson body I1, is disposed upright onto the rail 9. A truck 10, in which a bent or expansion arm 19 with a derrick bucket 15 is installed at a front end, is arranged. Outriggers 11 are expanded and contracted at specified positions and the truck 10 is grounded, the upper end of the bearing strut 13 is abutted against the ceiling section of the caisson body I1 and truck 10 itself is fixed, and required excavation is conducted. Reaction at the time of excavation receives the bearing strut 13 operated in this manner. The truck 10 is removed from the upper section of the rail 9 when an excavation means reaches a reaching hole, thus simply detaching the excavation means.;COPYRIGHT: (C)1994,JPO&Japio
展开▼
