| 摘要 |
PROBLEM TO BE SOLVED: To provide an execution method of a bored pile capable of preventing an uneven step between general section of bottom-reamed steel pipe pile and diameter widening section from adhering an inappropriate material linked with the lowering of front end bearing force to the inside of a corner section thereof in the bottom-reamed steel pipe pile and construction of the under-reamed steel pipe pile. SOLUTION: The excavation of ground and settlement of a bottom-reamed steel pipe pile 1 are carried out by means of a pile installation by inner excavation, and when a diameter widening section 1b is fixed to a foot protection section A, a bond prevention wing 4 capable of widening the diameter approximately equivalent to the inside diameter of the diameter widening section 1b is provided to the upper part of an excavation head 3. When the bottom-reamed steel pipe pile 1 is settled, an inappropriate material such as viscous soil or slimy earth and sand, etc., going to adhere to the inside of a corner section of the diameter widening section 1b is forcedly removed by the bond prevention wing 4, and a bored pile using the bottom-reamed steel pipe pile 1 can ensure high front end bearing force.
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