Nevertheless there are occasions when this equipment can be invaluable and a useful weapon in the armory of pile construction

CASE STUDY

Oil exploration is still taking place in some areas of the UK and to facilitate one particular exploratory hole in North Yorkshire they required a lined pilot hole down to at least 20m at 500 mm diameter. The rock roller equipment used in the industry to drill oil wells is obviously good at penetrating rock of varying strength but is not so good in the softer overburden soils. Tripod equipment in this instance offered an economical method of penetrating this overburden and adding casing as required to provide an open hole down to the rockhead. Although it was necessary to telescope the permanent 500 mm casing through 600mm to achieve the depth required (22m) with a stable dry lined bore.