To increase the execution precision by providing a fluid ejection nozzle for excavating the ground inside a cylindrical body at a cutter brade equipped at the lower end peripheral edge of the cylindrical body composed of steel divided rings.
Divided rings 23 on which a skin plate 31 is spread are connected to a frame body composed of a main girder 25, a joint plates 27, and vertical ribs 29 to form a cylindrical body. A plurality of nozzles 47 facing the inside of the cylindrical body are provided at the periphery through nozzle pipes 45 in the cutter blade 37 equipped at the rind of the lowermost part of the cylindrical body. Concrete is charged in the cutter blade 37 to increase the rigidity. A pipe 51 sending a fluid to nozzle pipes 45 is arranged at the rear side of the ribs 29, between the skin plate 31 and a backing plate 33 to protect it from contact with a hammer crab backet or the like and further, the pipe 51 is protected by the ribs 29 at the divided rings within 2-4 m above the cutter blade. A coupler 53 connecting the upper and lower pipes 51 is provided in respective rings 23. In this way, ground can be excavated to form a corrugated form in the circumferential direction. And as the cylindrical body is supported by the ground, the body is not tilted on pressin it in the ground and hence the vertical precision thereof can be kept.
HAMADA YOSHIYUKI
ITO ATSUSHI
KATO KENSETSU KK
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