A contiguous piled wall is an embedded pile earth retaining system, that consists of a series of vertical piles designed to resist earth pressures and applied loads. A Contiguous piled wall consists of a row of concrete piles with small gaps between the individual piles – typically in the order of 150mm – with pile size and reinforcement content designed relative to the height of soil to be retained and forces to be resisted.
Contiguous piled walls are best suited to sites with low ground water levels, or where water ingress can be safely controlled by pumping. Where water is present, or where ground conditions and proximity to neighbouring structures preclude the use of contiguous methods, GeMech can offer a secant piled alternative.
Contiguous piles can be designed as embedded cantilevers, or as propped cantilevers with single or multiple layers of props or anchors.
GeMech have experience of designing and installing contiguous piled walls for deep basement construction, highway support, and in slope stability applications.
A number of our rigs are capable of installing piles within 0.5m of neighbouring buildings, maximising internal space in congested urban sites.
In addition to lateral earth support, contiguous piled walls can be designed to carry vertical loads from the structure, giving them a dual purpose, with loads applied to the contiguous piled wall reducing the number of piles required to support the primary structure.
The Contiguous Piled Wall Process
GeMech typically use continuous flight augered (CFA) methods to form contiguous piled walls, although on occasion we may revert to rotary bored piling, or percussive drilling.
The process of forming a CFA pile is completed in one continuous operation, using instrumented piling rigs to monitor the pile construction process in real time as the auger is progressed to depth, and whilst concrete is being placed.
The CFA piling method is fast and efficient, generating low levels of noise, and is virtually vibration free.
From start to finish, what is the process of CFA piling?
Step 1 – Prior to the rig arriving to site the client surveys the area for services, prepares a suitable working platform at top of foundation level, and drives a numbered pin into the working platform at each pile position.
Step 2 – A health and safety briefing will take place, the rig will be prepared to work, and moved to the first pile position.
Step 3 – The auger is positioned over the setting out point and zeroed at working platform level. The auger is then progressed to a predetermined designed depth, pausing occasionally to bring spoil to the surface.
Step 4 – Readymix concrete will be delivered to site and pumped to the rig using a system of hoses connected to the top of the auger. The rig operator begins extracting the auger string, ensuring a constant head of concrete is maintained within the auger to avoid the risk of borehole collapse during construction. This process is fully computerised in CFA rigs, providing the rig operator a continuous profile of pile diameter during auger extraction.
Step 5 – The attendant excavator clears spoil from piling mat level, exposing the fresh concrete at the head of the pile.
Step 6 – A reinforcement cage, meeting the design requirements, is plunged into the fresh concrete, to provide structural capacity and fixity between the piles and reinforced concrete capping beam.
Construction Note – When forming a contiguous piled wall we will operate on a ‘hit one, miss three’ sequence, ensuring a minimum of 48 hours between installing neighbouring piles.
After completion of the pile installation work, the piles will be cropped by the groundwork contractor, and a reinforced concrete capping beam formed at the head of the piled wall to ensure piles act uniformly.
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Our Testimonials:
We have always found GeMech to be professional, straight talking and a pleasure to work with.
Simon Blackledge, Commercial Director, Gr8Space Group
GeMech handle all aspects of our ground improvement projects together with transparency and professionalism.
Darren Faircloth, Faircloth Construction Ltd
GeMech have always been courteous, knowledgeable and honest throughout our dealings with them.
Charlie Barker, Deep Living London Ltd
I have always found all members of the GeMech team to be extremely customer focused, technically proficient and totally driven to provide the best possible service and quality on site.
James Sinclair, Blue Dot Construction
In a competitive market GeMech has always stood above the competition as an exceptional ground improvement solution provider.
Daniel Calnan, Kent Structures
We have worked with GeMech on a number of projects, both complex with restricted access and large housing schemes. They have always been pro active providing solutions and costings. They have delivered all of our schemes to programme.
John Reed, Capstan
Clear, professional & practical communication during the pre-construction phase allowed for a smooth operation on site. Correct methods of piling for the presenting ground conditions were discussed and employed, resulting on hitting programme targets aswell as budget constraints.
James Scott, Willmott Dixon
Talus Solutions Ltd enjoys a harmonious relationship with the team at Ge-Mech Ltd, working together on various industrial, commercial and private sector housing projects. We have found Ge-Mech to be dependable and competitively priced in what they do and always ready to assist.
Philip Halford, Talus Solutions Ltd
Having worked with Gemech for over 20 years, they have always provided a first class engineered solution for our schemes.
Julian Mitchell, Mitchell Design & Construction
From start to finish the GeMech team take care of everything from the initial design to bringing each project to a successful conclusion on site.
Mark Blackhurst, Barnack Estates UK Ltd
Capabilities:
- Pile diameter 350mm – 900mm
- Maximum depth of 25.0m.
