What is an Uncased Drilled Shaft?
Drilled Shafts (also known as bored piles or caissons) have been used as deep foundations load bearing elements for over 100 years. They have been developed for the transfer of high loads and as a vibration less alternative to driven piles, which require large pile cap foundations and have certain installation limitations in difficult ground conditions.
Uncased drilled shafts are one option when the soil is stable enough to support itself or caving of the borehole can be prevented with the use of a water head or drilling slurry (Bentonite or Polymer). Shaft diameters typically range from 24 inches to 96 inches with extreme sizes of 144 inches or more which are only possible in very stable ground conditions.
Standard shaft lengths vary from 20 feet if bearing layers are relatively shallow to common depth of 60-80 feet. Extreme depths of more than 250 feet are only possible with specialized drilling equipment.
Malcolm’s extensive equipment fleet includes a multitude of restricted access rigs, for difficult site access, as well as with long and/or high reach capabilities and importantly for very deep and very hard drilling conditions. Our modern equipment fleet ranges from specialized low headroom drill rigs as well as very adaptable LoDrill machines to the most powerful European hydraulic drilling rigs. Malcolm Drilling will continue to maintain its tooling and equipment in order to facilitate capital investment back into the company in the form of state of practice equipment, tooling and other cutting edge technologies.