| 摘要 |
Apparatus for use in the laying and/or replacement of pipes underground comprises a sleeve having a front end and a rear end, a percussive drive means in the form of a pneumatically-operated impact mole mounted in the sleeve and arranged to drive the front end of said sleeve through the ground, means for securing the leading end of a pipe to the rear end of the sleeve and means for pushing the pipe through a bore formed in the ground as the sleeve is advanced through the ground by the mole. The means for securing the end of the pipe to the sleeve includes an annular spigot which allows relative axial movement to take place between the pipe and the sleeve in order to prevent impact stresses on the sleeve from the mole from being transmitted to the pipe. The pipe pushing means desirably comprise hydraulic rams arranged to bear on a plate located at the rear end of the pipe.
|
