PURPOSE: To prevent the generation of cracks in sheathing concrete due to the deformation of a tube body by interposing a cushioning material between the tube body in a propulsive tube and sheathing con crete.
CONSTITUTION: The outer circumference of the drum section of a cast iron tube 12, on an inner circumference of which polyethylene lining 15 is executed, is covered with a cushioning material 13 composed of an expanded polyethylene sheet, and the outer circumference of the material 13 is covered with sheathing concrete 14 into which vinylon fibers 23 are mixed, thus constituting a propulsive tube 11(21). A rubber ring 18 is arranged into a groove 17 formed into the cast iron tube 12. When driving force is applied so that the end face of an inserting port 22 is pushed by the inward end face of a faucet 16 in the propulsive tubes 11, 21, bulges in the tubular radial directions of the propulsive tubes 11, 21 are absorbed by the cushioning material 15, and energizing force in the tubular radial direction of sheathing concrete 14 is inhibited and the generation of cracks in sheathing concrete 14 is prevented.
SAKURAI YOSHIKI
NAGAI AKIRA
OHAMA HIROYASU
Next Patent: PREVENTIVE STRUCTURE OF SLIPPING-OFF OF SHEATHING OF PROPULSIVE TUBE