| 摘要 |
PURPOSE:To improve the ground having differently dispersed strengths to an evenly improved ground by setting up the pushing force of a sand-discharging and compacting part as a control target for the formation work of sand piles. CONSTITUTION:Either one or both of the diameter and strength of formed sand pile are varied in such a way that the pushing force of a sand-discharging and compacting member 4 provided at the lower end of a hollow pipe 1 for forming sand pile is kept at a set value in the course of forming sand piles while moving the member 4 by a forced vertical moving mechanism 5. Also, the pushing force of the member 4 is set as a control target for the formation work of sand piles. The pushing force value detected of the member 4 is compared with a set pushing force value, and when they are out of accord, a signal is sent to a controller 22 and by control signal from the controller 22, a factor related to the diameter of sand pile formed, e.g., winding speed of a winding winch 10, is controlled. In this way, since the diameter of sand pile is varied with changes in the strength of the ground, uniformly improved ground can be obtained by controlling the diameter of sand pile in such a way as to keep the pushing force of the member 4 at a set value. |
