Tool and method for forming piles

A method of forming an underground cast-in-situ pile having a shaft and an enlarged base, the method using a tool comprising:

• a first pile-forming member having a first base-forming member at a lower end thereof;
• a second pile-forming member having a second base-forming member at a lower end thereof, the first and second pile-forming members extending collinearly and being movable in a longitudinal direction relative to one another between:
• a digging state wherein the first and second base-forming members are proximate to one another so that the first and second pile-forming members can be driven underground to form an elongate hole having a first diameter;
• and
• a base-forming state wherein the first and second base-forming members are spaced apart from one another in the longitudinal direction so as to form an underground void between the first and second base-forming members at a depth of the elongate hole, the void having a second diameter that is greater than the first diameter and being fillable with a flowable fill to form the enlarged base of the underground cast-in-situ pile,
• the method comprising:
• (a) when the first and second pile-forming members are in the digging state, driving the first and second pile forming members underground to a predetermined depth to form the elongate hole;
• (b) moving the first and second pile-forming members towards the base-forming state to form the underground void at the depth of the elongate hole;
• (c) while moving the first and second pile-forming members towards the base-forming state, supplying the flowable fill to the void so as to form the enlarged base of the underground cast-in-situ pile;
• and
• (d) driving the first and second pile-forming members out of ground while supplying the flowable fill underground to form the shaft of the cast-in-situ pile.