Propulsion process of buried pipe

A propulsion process of burying a pipe in a burying hole while forming the burying hole by propelling a leader in the ground, comprising the steps of:

• joining at least one propulsion support having pipe supporting means on an external surface thereof to said leader;
• extending said propulsion support by joining at least one additional propulsion support to said propulsion support;
• providing an endless pipe concentric with an external surface of said propulsion support;
• feeding a pressure medium to an inflation mechanism of said pipe supporting means;
• expanding said inflation mechanism of said pipe supporting means outward from said propulsion support by said pressure medium;
• pressing an outer surface of the inflation mechanism against an internal surface of said endless pipe;
• firmly supporting said internal surface of said endless pipe with said pipe supporting means so as to rigidly fix said pipe to said propulsion support;
• axially moving said propulsion support by propulsion power to form a burying hole;
• successively inserting and propelling said endless pipe into said burying hole;
• and
• forming said endless pipe by sequentially curving a pipe material of long hoop shape made of a plastic material.