Foundations
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When building on many sites with poor ground conditions the most economical approach to the foundations is to improve the bearing pressure rather than attempt to by pass the weaker soils with piled foundations.
Ground Improvement systems can typically be 50% of the cost of a piling scheme but, more importantly, further cost benefits are provided by adopting simpler sub structures and in most cases the lack of spoil generation.
Keller Ground Engineering offer a range of ground improvement systems that include Vibro Stone Columns; Vibro Compaction; Dynamic Compaction and Compaction Grouting.
The choice of system is determined by the particular ground conditions, design loads, the size of treatment area and site location.
Vibro Stone Columns [VSC].
Also known as Vibro Replacement the system uses stone columns to improve a wide range of soil conditions, including made ground comprising clays, ash, clinker, brick and concrete rubble etc, along with weak natural alluvial soils comprising sands, silts and or soft clay.
The VSC system is generally unsuited for the treatment of very soft organic or degradable soils.
Vibro Compaction[VC]
The original Vibro process first developed by Keller in the 1930's is used for the direct compaction of wholly granular material [ie with less than 20% silt and clay]. VC is particularly effective for the densification of loose granular soils to control liquefaction in seismic areas.
Dynamic Compaction.
[DC]A highly economical compaction system generally only suited to large open sites with development areas in excess of 5000m2. Dynamic Compaction involves the controlled dropping of large weights from set heights to compact relatively deep layers of soil.
Suitable soils include made ground comprising rubble, boulders, ash clinker and clay fills etc. The DC system is also frequently used to reduce site levels and accelerate the long term settlement of old landfills comprising degradable material.
Driven Cast in Situ Piling
Highly efficient, the Keller Driven Cast in Situ Pile is designed to make maximum use of the available skin friction and end bearing potential of the surrounding soil. It is capable of achieving high working loads in a variety of weak subsoil conditions, regardless of water table.
Robust, the construction method used is ideally suited to piling 'brownfield sites' where obstructions can frequently create programme and cost control problems. The Keller Driven Pile system can frequently drive through obstructions that would create problems for other piling techniques.
Environmentally Friendly, apart from the key benefit of not producing spoil, the construction method produces a pile that is tightly interlocked with the surrounding ground giving a reduced risk of vertical migration of contamination.
Keller's Augercast Continuous Flight Auger (CFA) piling system provides a quiet low vibration form of piling that is ideal for providing foundation support in built-up or environmentally sensitive areas.
Keller's CFA rigs can construct piles in most soils including sands, gravels, silts, clays, chalk and weak bedrock, in high water tables without the need for temporary support systems.
Where headroom is limited or the site is confined structures of all types can be founded on Minipiles and our range of rigs for difficult access sites is unrivalled.Similarly our obstruction drilling expetrise,such as through quay walls or old foundations leads the industry.
At the other end of the scale... where large diameter piles are constructed in granular soils grouting tubes can be attached to the reinforcement cages enabling base grouting to enhance pile capacity. Some of the country's tallest structures are founded on piles Base Grouted by Keller.
