METHOD OF ELIMINATING NEGATIVE FRICTION FORCE OF CAST-IN-PLACE PILE

摘要

PURPOSE:To eliminate a negative friction force, by a method wherein a reinfrocing cage, around which a cylindrical film material of a sheet material, having a friction force cutting material attached to its peripheral surface and a hollow ring part attached to its lowermost end part, is wound, is erected in a hole, and a ring part is expanded for concreting. CONSTITUTION:A reinforcing cage 21, around which a cylindrical film material 16 of a cut off sheet material, having a friction force cutting material 17, such as asphalt, attached to its outer peripheral surface, and a hollow ring part 18 located to its lowermost end part, is wound, is erected in an excavated hole 22. Water is poured through a water pouring pipe 19 in the ring part 18 for filling of the ring part with water to expand the ring part 18, resulting in firm adhesion of the ring part 18 to the wall surface of the excavated hole 22. When concrete is poured in a condition to holed the expansion of the ring part 18, the film material 16 is pressed against the wall surface of the excavated hole 22 by dint of the side pressure of the concrete.