Where access is restricted, or heavy plant is prohibited, foundations may be constructed by the use of restricted access piling. Piles can be constructed in under 2.8m of headroom in a variety of sizes and within 550mm of existing walls by the use of specialist compliant rig guarding. Restricted access piles can be installed within and through, existing basements and foundations and are used for retro-fitting existing structures, accessing remote and/or logistically challenging locations such as active road & rail environments, base of shaft, upgrading power towers. They are also ideal for overcoming problem
Restricted access piles are the preferred solution in complex urban areas that comprise fill material of varying type or are adjacent to sensitive buildings with difficult access.
HOW IT WORKS
Bachy Soletanche offer a number of different solutions for restricted access piling and they are:
- Cased Auger: Temporary drill casings are drilled to the base of any unstable overburdened deposits in order to provide borehole stability. The bore is then extended beyond the casing to the full design depth using open-hole auger drilling techniques. Upon achieving the required depth, the augers are removed from the borehole and the pile shaft is filled with either concrete or grout. The reinforcement can either be installed pre or post the concreting phase and is dependent upon a number of considerations.
- Sectional Flight Auger: Piles are formed using sectional lengths of a hollow stemmed auger, bored until the required depth is reached. Concrete or grout is pumped through the stem of the auger string, as each section of auger is withdrawn from the bore. Once the augers are fully removed from the bore, the reinforcement is plunged to the required depth.
- Drilled: Similar to the cased auger technique, this method utilises an internal drill rod rather than an auger. The drill rod can be used in combination with a drill bit, a down the hole hammer utilising various flushing medium, including water, air, drill muds. Bachy Soletanche also offer a self-drilling restricted access piling system.
Capabilities: Depending on ground conditions and the nature of the restrictions, we can install piles from 100mm to 660mm diameter and to depths of up to 35m. The technique can also be used for creating contiguous or secant piled walls.
Advantages: Remote or logistically challenging sites can be accessed. Installation can occur without the need for the demolition of existing structures. Rigs are smaller and lighter, requiring less space to operate and require simpler temporary works to create the working platform.