A method for injecting back-filling material into a space between the outside of double-wall pipes and the ground in the pipe-jacking method

摘要

A conduit comprised of double-wall pipes A is laid in the ground by the pipe-jacking method. Each double-wall pipe A comprises inner pipe 1 and outer pipe 2 and is provided with sheath pipe 3 between inner pipe 1 and outer pipe 2 and with check valve 4. Back-filling material supply pipe 11 is moved in sheath pipes 3 from a first vertical shaft. When injecting member F is opposed to check valve 4, at the centre of the conduit, packing means 16, 17 are inflated to be brought into contact with the inside of sheath pipe 3 by which injecting member F is fixed to sheath pipe 3. Back-filling material is driven to a space between packing means in sheath pipe 3, and injected through check valve 4 into space 5 between the outside of outer pipe 2 and the ground. The injecting member is then moved to the next check valve nearest the start vertical shaft and the process is repeated until a first half of the conduit is backfilled. Subsequently the supply pipe is driven along the sheath pipes 3 from the second vertical shaft, and the second half of the conduit is backfilled in the same way.