RECOVERY METHOD OF GUIDING PIPE IN SMALL DIAMETER JACKING MACHINE

PROBLEM TO BE SOLVED: To provide a recovery method of a guiding pipe in a small diameter jacking machine capable of advancing boring again by inputting the guiding pipe recovered in a buried pipe laid in advance or a new guiding pipe, by easily recovering its guiding pipe to the starting shaft side via the inside of the laid buried pipe, by accurately jacking the guiding pipe, by reducing jacking resistance to soil of a wide range such as a base rock layer from a gravel layer. SOLUTION: A cutter head 6 is diametrally contracted, and after releasing the connection between the guiding pipe C and an outer cylinder A put in a connecting state when laying the buried pipe 2, a protective wall is made by retreating by a predetermined quantity by applying pulling-back force to the guiding pipe C, while injecting chemicals into the front of the guiding pipe C, by using a screw conveyor for discharging sediment, and afterwards, the guiding pipe C is recovered via the inside of the outer cylinder A and the inside of the buried pipe 2. COPYRIGHT: (C)2006,JPO&NCIPI