| 摘要 |
PURPOSE:To promote the penetration of a hollow pipe into the ground by a method in which the injection of a fluid from jet nozzles and the vertical movement of a penetration promoter are combinationally and automatically controlled according to the variations in the penetrating rate of a hollow pipe. CONSTITUTION:A proper number of fluid jet nozzles 4 and a penetration promoter 7 are provided at proper places of the lower part of a hollow pipe 1, and a penetration rate detector 14 is also provided. When a penetrator 3 is actuated and the hollow pipe 1 is penetrated into the ground, a moving part 13 moves in the direction of arrow to turn the rotators 11 and 12 of a leader 5, but when the penetrating rate is lowered on the way, output voltage from a D-A converter 15 becomes smaller than that of a setter 17, and thereby output signal is generated from a comparator 16. Then, water is injected from the nozzles 4, and when the penetrating rate does not exceed a set rate even after the elapse of a certain period of time after the beginning of injection, the signal is sent from a controller 18' to a fluid unit 22 and a high-speed switch valve 23, and the penetration promoter 7 is actuated. |
