PROBLEM TO BE SOLVED: To suppress influence on already built building by measuring vibration energy during sand pile reclamation and regulating the eccentric moment of a vibro-hammer so that the vibration level for the building is within an allowable value at the time of hollow pipe penetration. ;SOLUTION: Same vibration energy of a vibro-hammer 2 is not needed after penetration down to a design depth in a process for driving a hollow pipe 1 into soft ground and penetrating it. At the time, discharge of sand from the hollow pipe 1 and vibration energy needing compaction are small, and it is possible to easily perform drawing-out of the hollow pipe 1. For instance, quick driving and penetration are performed by executing the vibration level in the full allowable value, and at the time of drawing-out the vibration level is remarkably lowered to draw out it. When the hollow pipe 1 is drawn out, the vibration energy is smaller than that at the time of driving and penetration. The eccentric moment of the vibro-hammer 2 can be lowered at the same degree as the vibration level at the time of drawing-out.;COPYRIGHT: (C)1998,JPO
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