CONSTRUCTION METHOD FOR REINFORCEMENT OF PILE FOUNDATION GROUND BY USING TIP-DIAMETER-EXPANDING PILE, DIAMETER-EXPANDING APPARATUS FOR TIP-DIAMETER-EXPANDING PILE, AND DIAMETER-EXPANDING-APPARATUS ROTATING-AND-PRESSURISING DEVICE

摘要

The present invention concerns: a construction method for the reinforcement of pile foundation ground by using a tip-diameter-expanding pile, whereby it is possible to reinforce the foundation ground of the pile by rotating and cutting and at the same time expanding an expanding element at the bottom of the main pile body, such that the diameter-expanding apparatus seals off the space between the diametrically outer pile part and the ground inner wall so as to prevent the rising of underlying slime and also ensure support against the unworked ground on the outside of the borehole such that the density of the surrounding ground is substantially increased; and a diameter-expanding apparatus for the tip-diameter-expanding pile. The construction method for the reinforcement of pile foundation ground by using a tip-diameter-expanding pile of the present invention involves the use of a tip-diameter-expanding pile incorporating a main pile body of which the inside is shaped as an empty tube and incorporating a diameter-expanding apparatus of which the diameter expands and which couples to the bottom part of the main pile body, and the construction method of the present invention comprises: (a) a step in which the tip-diameter-expanding pile is driven into the ground; and (b) a step of sealing off all or part of the space between the ground inner wall and the diametrically outer pile part by means of expansion of the expanding element by pressurising the rear end of a pressurised part of the expanding element by inserting a pressurising element, which has a conical rear end, through an upper through-hole of the diameter-expanding apparatus and into a linking member while at the same time rotating the expanding element of the diameter-expanding apparatus, centred on the central axis of the pile.