PURPOSE:To facilitate a work, by a method wherein a running span frame is disposed on rails on a banking, a moving platform is placed on the span frame, and a tower body having a excavating device is mounted on the platform. CONSTITUTION:A running span frame 3 is disposed on guide rails installed on a banking 16 of a river 28 so that it is movable longitudinally along the guide rails 5. A moving platform 2, mounted on the span frame 3 is laterally moved toward a ground bed to be improved to set a given place. After a rotary rod 8, positioned in parallel to a tower body 1 erected on the moving platform 2, is penetrated into a river 28 through the working of a driving device 7, a hardener is poured through an injection hole 18 as the rod 8 is lifted up, and the hardener is mixed with earth by an agitating vane 10 to build an improved ground column 6. Further, a work is effected as the span frame 3 is moved longitudinally along the rails 5 and the moving platform 2 is moved laterally along the span frame 3, and the improved ground columns 6 are built throughout a whole river bed.
展开▼
