Process for removing an earth core from a trenchless pipe and pig to carry out the process

摘要

In a process for removing the earth core (7) from a pipe (5) laid without excavation by ramming or pressing, both ends of which are free, a scraper (1) is inserted into one end of the pipe and moved longitudinally through the pipe (5) so that the earth core (7) is pushed out of the other end of the pipe by the scraper (1). The scraper (1) is advanced in stages by means of a variable-length thrusting device (10) supported on the inner wall (4) of the pipe (5). The thrusting device (10) is returned to its initial position after each thrusting stroke and its support in the drive device is adjusted by the length of the stroke made. The scraper (1) consists of a header plate (2), a variable-length thrusting device (10) and clamping devices (11, 22); the header plate (2) is secured to one end of the thrusting device (10) and a first clamping device (11) and the other end of the thrusting device (10) is secured to a second clamping device (22). The clamping devices (11, 22) can be moved alternately into a clamping position in which they can be pressed against the inner wall (4) of a pipe and into a released position in which they are released from the inner wall (4) of the pipe (5).