This system is commonly used for heavily loaded structures where the soil profile is saturated over all or part of the profile resulting in unstable side-wall conditions for conventional auger piles. The term ‘underslurry’ indicates that the pile is excavated under a head of bentonite slurry, which prevents collapse of the pile excavation. Both auger and grab excavation methods can be used, resulting in circular and rectangular cross-sections. These two methods are referred to as Auger Underslurry and Barettes, respectively.
- Economical pile solution for heavy structures on saturated soil profiles
- Noise levels are low and limited to engine noise from the equipment
- There is no vibration associated with underslurry piles
- A good range of pile sizes from 600mm to 1500mm diameter
- Underslurry piles can be installed to depths in excess of 50 metres
- Barette type piles can be shaped
- High establishment costs
- Large site area required
- Suited to heavily loaded structures only
- Only vertical piles can be constructed
- The slurry-contaminated spoil must be disposed of at an approved waste site
The maximum depth to which Barettes can be installed is really unlimited, but a practical limit of 60 metres is suggested. Barettes cannot be installed on a rake.