Drills for piles and soil stabilization, and drilling method

A drill for piles including:

• a central stem;
• a drilling point or tool at the lower end of the stem;
• a helical flyte around the stem;
• and
• a belling tool interposed between the drilling point or tool and the lower end of the helical flyte, and comprising a housing, substantially circular in plan view, a central bore through the housing to receive the stem of a drill in rotational driving engagement, at least one cavity in the periphery of the housing, and at least two cutting tools hingedly mounted on the belling tool in the at least one cavity, said cutting tools being vertically offset and diametrically opposed, the cutting tools each normally occupying a retracted non-drilling position with its cavity when the drill is rotated in its drilling direction but being movable to an extended position to cut a respective substantially annular chamber around the hole formed by the drill when the drill is rotated in the opposite direction;
• and
• each cutting tool being curved in plan view and having a pair of hardened-faced teeth provided about their outer periphery, each cutting tool having a back tooth which cuts a greater diameter than the drilling point or tool.

A drill for drilling holes for in-situ cast piles including:

• a stem connectable at one end to a drilling machine and having a drilling point at the other end,
• a helical drilling flyte or spiral around the stem;
• and
• a plurality of cutting tool provided at spaced intervals along the stem to enable a plurality of chambers or "bells" to be formed about the hole, said cutting tools being hingedly mounted on the stem, each cutting tool normally occupying a retracted non-drilling position adjacent the stem when the step is rotated in the drilling direction of the helical flyte or spiral but being movable to an extended position to cut a respective chamber or "bell" around the hole when the stem is rotated in the reverse direction.