Ground treatment

Apparatus for forming a stone column in the ground, which comprises a pair of concentric tubes the inner one of which is open at both ends, and at or near its lower end is integrally connected to the outer tube by an imperforate outwardly extending wall portion;

• a driving plate attached at or close to the upper end of one of said inner and outer tubes, so as to end around said one tube;
• and driving means for applying a downwardly acting driving force against said driving plate whereby the apparatus may be driven into or against the ground;
• wherein the lower portion of said inner tube, said outwardly extending wall portion and the lower portion of said outer tube together define a cavity comprising an upper, relatively narrow portion and a lower, relatively wide portion.

A method of forming a stone column, which comprises positioning an apparatus as defined hereinabove at a location where a stone column is to be formed;

• pre-positioning stone at said location before positioning the apparatus, or adding stone to the interior cavity of the apparatus after it has been positioned at said location;
• driving the apparatus downwardly to a depth equivalent to the desired depth for the stone column which is to be formed;
• and thereafter extracting the apparatus in a plurality of stages while delivering stone through the inner tube of the apparatus, and applying to the apparatus between each of the removal stages during extraction a downward force in order to compact stone expelled from the lower end of the apparatus.

A method of forming a cast-in-place pile without the use of a pileshoe, which comprises positioning an apparatus as defined hereinabove at a location where a pile is to be formed;

• pre-positioning dry or nearly dry concrete at said location before positioning the apparatus, or adding dry or nearly dry concrete to the interior cavity of the apparatus after it has been positioned at said location;
• driving the apparatus downwardly to a depth equivalent to the desired depth for the pile which is to be formed;
• and thereafter extracting the apparatus in a plurality of stages while delivering dry or nearly dry concrete through the inner tube of the apparatus, and applying to the apparatus between each of the removal stages during extraction a downward force in order to compact the concrete expelled from the lower end of the apparatus.