| 摘要 |
Apparatus for forming a stone column in the ground is disclosed. The apparatus comprises a pair of concentric tubes (2,3) the inner one (2) of which is open at both ends, and at or near its lower end may be connected to the outer tube (3) by an outwardly extending wall portion (4). A driving plate (14) is attached at or close to the upper end of one of said inner and outer tubes, so as to extend around said one tube, so that the apparatus may be driven into or against the ground. In a preferred embodiment, the lower portion of the inner tube (2), the outwardly extending wall portion (4) and the lower portion of the outer tube (3) together define a cavity comprising an upper, relatively narrow portion (7) and a lower, relatively wide portion (9). A method of forming a stone column using the apparatus is also disclosed. After driving the apparatus into the ground, it is withdrawn in stages, after each of which a compacting force is applied in order to consolidate the stone column. By accentuating these compaction forces or their duration, it is possible to produce localized bulges along the stone column. In a modification, the method of the invention is used to form cast-in-place piles without the use of a pile shoe.
|
