DOUBLE WALL PIPE FOR PROPULSION TECHNIQUE AND CONSTRUCTION OF PIPE END OF LEADING PIPE

摘要

According to the present invention, a double wall pipe for propulsion, which is constructed such that an inner pipe and an outer pipe are relatively movable with each other in the longitudinal direction, is provided and a propulsive force is acted only on the outer pipe. With this arrangement, this double wall pipe for propulsion can be laid under the ground without damaging the rear end surface of the inner pipe and without generating an internal stress in the inner pipe, thereby achieving the laying being high in the reliability, in which pinholes, cracks and the like can be prevented from occurring in the inner pipe during the use.