| 摘要 |
The invention relates to a process of extracting a hollow unit laid in the ground, such as a lead pipe (2) which is accessible at both its open ends. For this purpose a flexible tube (14) which may be pressurized is introduced, in its unpressurized state, into a lead pipe (2), then the flexible tube (14) is pressurized to press against the inner wall of the pipe (2), then, while maintaining the internal pressure in the flexible tube, the lead pipe (2) is pulled along its longitudinal axis by means of the flexible tube (14), without any axial movement therebetween. The lead pipe rupture during the extraction is thus avoided. A new pipe to be laid in the ground as the old one is being removed, may be connected to the flexible tube (14) or to the lead pipe (2) behind the rear end of the lead pipe (2 in the pulling direction. An additional traction element (12) may be introduced into the pipe together with the flexible tube (14) both being forced against the inner wall of the pipe (2) by the inner pressure of the pressurized flexible tube (14).
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