Rotary boring device for concentric enlargement of boreholes - used for bored piles, in loose or cohesive soils

摘要

This is a rotary boring arrangement for enlarging vertical boreholes, in particular for producing bored piles for building construction. The device is driven through a rotary head and a kelly, and has rotating cutting tools. Two alternative versions of the arrangement, one for making a greater enlargement than the other, are claimed, and a number of variants are claimed for both versions. USE/ADVANTAGE - The device enables, in loose, cohesive or varying soils, a previously-drilled lined or unlined borehole to be enlarged concentrically without the use of a protective or guide lining. Lined holes can be enlarged in the unlined part.