Method for producing in-situ concreted piles with enlarged bases

A method for producing a concrete pile with an enlarged base, comprising the steps of:

• providing a tube carrying at its lower end a shoe having a larger diameter than the tube for forming a gap between the tube and the ground, and an outer casing of a diameter substantially equal to the diameter of the shoe so that a space is left between the tube and the outer casing, said outer casing being slidably attached to the tube by a sliding joint that allows a predetermined length of relative sliding between the tube and the outer casing, said outer casing having a lower end attached to the shoe and an upper end open to permit free flow of concrete within said space,
• driving the tube, with outer casing attached, into the ground to a depth greater than the length of the outer casing, thereby forming an opening in the ground and defining the gap between the tube and the ground,
• filling the gap and the space with concrete as the tube with attached outer casing is driven into the ground,
• when the shoe has reached a desired depth, expelling the shoe and from the lower end of the tube and the outer casing, along with some of the concrete, so as to form an enlarged base,
• after said enlarged base is formed, raising the tube away from the shoe, thereby causing at first a sliding of said tube with respect to said outer casing which allows concrete from said space to enter the volume of space previously occupied by the lower end to the tube, and
• thereafter removing both the tube and the outer casing from the ground and allowing concrete from the gap and space to fill the opening to form the pile.