Steel Cased Bottom Driven Piles are constructed using a displacement piling method, comprising an internally acting drop hammer driving a thin wall casing to a pre-determined design depth or driving resistance.
The internal drop hammer impacts the pile at toe level, resulting in low levels of vibration at ground level.
Thin wall casings for driven piles are typically supplied in sectional lengths of up to 3.0m and are successively welded as the pile is driven to depth. This casing acts as a void former to enable the placement of a structural concrete core and reinforcement.
Once at design depth, the pile is concreted to ground surface level, and a reinforcement cage plunged into the fresh concrete to provide fixity between the pile head and foundations.
The Steel Cased Bottom Driven Piling Process
From start to finish, what is the process of constructing steel cased bottom driven piles?
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 – A crimped starter casing will be positioned over the first point, and the drop weight lowered into it. Verticality of the casing will be checked before the drop hammer is lifted and begins progressing the pile below ground level.
Step 4 – The first casing is left 0.5m above ground level, allowing the next section of casing to be added, and fully welded at the pre swaged collar. This process is repeated until all casings are driven to the pre-determined design depth or driving resistance.
Step 5 – Ready mix concrete is placed in the open casing, and a reinforcement cage plunged into the fresh concrete. This will provide fixity between the piles and reinforced concrete foundations.
Advantages of Steel Cased Bottom Driven Piles
Some of the key advantages of Steel Cased Bottom Driven Piles include:
- Zero spoil generated during the piling process.
- Low noise and vibration compared to alternative driven approaches.
- All piles can be cast in a single operation, avoiding the need for daily concrete deliveries into site.
- Small rigs – our 9.0t drop hammer rigs can be delivered into restricted access sites using flatbed lorries. This requires a reduced working platform thickness compared to alternative driven piling approaches.
- Using steel casings as a void former to enable casting the internal structural concrete core offers the ability to leave pile concrete either above, or below working platform level. This minimises the amount of pile cropping work required.
When are Steel Cased Bottom Driven Piles used?
Fully welded casing joints permit piles to be driven on sites with a shallow water table, without risk of water ingress affecting the integrity of the structural concrete core.
A further benefit of the external casing is the ability it offers to leave piles projecting above piling mat level, providing an opportunity to form raised foundations in floor risk areas.
We have successfully used Steel Cased Bottom Driven piles on projects ranging from residential housing, commercial development & refurbishment, to civil engineering projects.
Our Steel Cased Bottom Driven Piling Service
Steel cased bottom driven piles, installed using our 9.0t operating weight drop hammer rigs, are well suited to Soft Soil conditions. They are particularly efficient on sites where access is restricted, or where headroom restrictions exist.
Our invoice covers the total length of pile driven below piling mat level (or agreed termination height if piles are left projecting above working platform), meaning that you will only pay for the length of pile you need.
Our rigs can be configured in variable mast heights, allowing them to be used on sites where working headroom is as little as 3.5m, and, through the addition of an exhaust extraction filter, our rigs can be safely used inside existing buildings.
Contact us to find out more about our Steel Cased Bottom Driven Piling service.
Contact our expert Piling team / engineers for advice on your project and get a no obligation quote
What We Offer
- Free site visits
- Free no obligation quotes
- 12 Year warranty of all work
- Estimates based on detailed tender stage designs
FAQs
Q – Are driven piles the same as continuous flight auger?
A – driven piles use displacement methods, whereas continuous flight auger (CFA) piles, are formed using replacement methods.
Steel cased bottom driven piles are formed using hollow steel casings driven through soft/loose soils into deeper competent material. Once driven to a suitable depth, the hollow casings are filled with ready mixed concrete, and a reinforcement cage placed in the top of the pile to provide a connection with the foundation.
Pre-cast driven piles are formed using concrete sections driven through soft/loose soils into deeper competent material. The precast sections used are formed with either a reinforcement cage, or central reinforcement bar cast in, to provide a connection with the foundation once cropped to level.
Q – When not to use driven piles
A – Driven displacement piling methods lead to increased levels of ground borne vibration when compared to dynamic replacement methods and may not be suitable for use in close proximity to sensitive structures or services. Owing to the driving method, steel cased bottom driven piles result in lower levels of ground borne vibration than associated with pre-cast concrete driven piles.
Both steel cased and pre-cast concrete driven piles can be susceptible to damage during driving through obstruction laden fill materials, or on sites with shallow or steeply sloping bedrock, and alternative driven pile types, or even percussively drilled ODEX piles might be more suitable in these conditions.
Q – What is the maximum diameter of driven piles?
A – Steel cased bottom driven piles typically range from 100mm to 327mm diameter, whereas pre-cast concrete driven piles typically range from 200mm, up to 400mm square.
Capabilities
- Pile diameter 100mm – 273mm
- Working loads up to 450kN
