| 摘要 |
PURPOSE:To reduce the construction cost of a pile by increasing the bearing force of the pile by a method in which a pit is excavated and a drill bit is pushed out toward the right angled direction to the axis of the excavated pit in a given position to form a pit having large diameter. CONSTITUTION:Under the condition that the hole expanding cases 17 of a head 10 remain unchanged on the original positions, drill bits 18 are rotated to excavate the columnar portion A1 of a pit A. The hole expanding cases 17 of the head 10 are turned and the drill bits are pushed out toward the right angled direction to the pit axis and rotated to excavate a bell-shaped expanded bottom portion A2. Slime is treated, concrete is placed, and on-site pile having an expanded diameter portion is formed. The bearing force of the pile can thus be greatly increased, construction cost can be also greatly reduced, and excavation can be made with exact shape and dimension in a given position. |
