SCREW PILE APPLICATION SHEETS
Advantages of screw piles • Exceptionally fast installation rate – up to 2 . .. linear metres of pile installed per minute
• Minimal noise and vibration, with little ...disturbance of the soil
• Load bearing capacities of over 300kN SWL
• Environmentally friendly as no grouting …required and can be reused or recycled – …perfect for temporary structures
• Load bearing capacity is equal in tension . . …and compression – ideal for variable load ...situations • Requires only lightweight installation …equipment – can operate on soft terrain …without the need for piling mats • Ideal for restricted access sites and useable ...where headroom is limited and even from ...floating platforms • Installs to laser level accuracy, within +/...3mm tolerance necessary for modular ...construction
• No removal of spoil, and no casing or …dewatering required – well suited for …contaminated ground • Resistant to desiccation or heave • Sustains load immediately after installation – …enables rapid assembly of offsite construction • Thick walled tube and galvanizing provides a …truly permanent foundation
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OAK FRAMED STRUCTURES
Application
Specification
Benefits
• Housing • Garages • Barn conversions • Conservatories
• 88.9mm CHS screw piles • 5 ton excavator • At least 30 piles per day • Tension & compression connection
• Totally dry installation • Restricted access use • Positive connection • No curing time required
Method (Concrete pile cap free system) Screw piles are installed to the required depth based on load requirements and geological conditions, using a torque motor attached to a 5 ton excavator. Once each screw pile reaches the correct level, the torque motor is removed from the pile and a circular termination cap is fitted. A reciprocal circular termination cap is fitted into a pre-cut slot in the end of the oak post and is fixed by inserting 3no. dowels. The post then sits directly on top of the screw pile termination cap where it is attached using 4no. M20 bolts.
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TIMBER STRUCTURES
Application
Specification
Benefits
• Garden offices • Holiday cabins • Pavilions • School buildings • Visitor centres
• 88.9mm CHS screw pile • 5 ton excavator • Completion within 1 week • Loads up to 180kN SWL
• No piling mat required • Totally dry installation • Minimal noise/vibration • No muck-away required • Build off immediately
Method (Machine profiled log structure for a school) The topsoil is stripped back and a vegetation barrier installed, if needed. Using a 5 ton excavator, a grid of screw piles is installed to approximately 100mm above ground. Termination caps and self-levelling shoes are then fitted to the grid of piles. A timber ground beam is then assembled on top of the self-levelling shoes. Finally, the timber connection plates are bolted and screwed to both the perimeter termination caps and the timber ground beam to provide additional lateral restraint. A timber cassette floor or similar can then be mounted straight onto the timber joists.
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SCREW PILE FOUNDATIONS FOR CLOSED PANEL TIMBER FRAME BUILDINGS
Working in partnership with:
Application
Specification
Benefits
• Garden offices • Garages • Extensions • Self-build housing • Holiday accommodation
• 88.9mm CHS screw pile • Lower embodied energy • 5 ton excavator • Completion within 1 week • Loads up to 150kN SWL
• No piling mat required • Totally dry installation • Minimal noise/vibration • No muck-away required • Build off immediately
Method (Gluelam timber ground beam construction) The topsoil is stripped back and a vegetation barrier installed, if needed. Using a 5 ton excavator, a grid of screw piles is installed to approximately 100mm above ground. Termination caps are then fitted to the grid of piles. A timber ground beam is then assembled on top where timber connection plates are bolted and screwed to both the perimeter termination caps and the timber ground beam to provide additional lateral restraint. A timber cassette floor or similar can then be mounted straight onto the timber joists. Where isolated column loads exist (see above), piles have a cast in situ RC pile cap formed, ready to receive the column (timber, block-work or reinforced concrete).
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CONTAINERISED BUILDINGS
Application
Specification
Benefits
• Medical structures • Hotel accommodation • Temporary buildings • Construction site offices
• 88.9mm CHS screw pile • 5 ton excavator • Up to 30 piles per day • Up to 180kN SWL
• Speed of installation • Minimal noise/vibration • No ground beams required • Readily removable • Potentially reusable
Method Using a standard 5 ton excavator, screw piles are installed to precise levels at predetermined locations. Pre-cast or cast-in-situ pile caps are then constructed. Lateral restraint is not required as the structural design of the containers provides for this, saving the additional expense in the formation of ground beams. The buildings are then delivered to site and craned into position with the skids from the containers sitting directly on the pile caps (which can be formed partially above ground especially on sloping sites). The system is ideal for temporary structures as the piles can be unscrewed after use and are potentially reusable for the next project.
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FOUNDATION REINFORCEMENT
Application
Specification
Benefits
• Subsidence • Foundation repair • Storey extensions • Loft extensions
• 88.9mm CHS screw pile • 5 ton excavator • Up to 20 piles per day • Cantilevered needles • Up to 180kN SWL
• No internal works • Minimal noise/vibration • Laser level accuracy • Restricted access use • Works can be carried out . with occupancy
Method 1.75m trenches are dug at 2m intervals, including localised excavation of the existing footing in preparation for the needle formation. Two screw piles are installed in each trench, offset by 500mm and 1500mm from the centre line of the wall being supported. A termination cap is then bolted to each pile ready for the formation of a reinforced concrete needle in the trench. The piles take compressive and tensile loads so that all works can be carried out externally, allowing continued occupancy of the building. Once the needles have cured, the brickwork immediately above is removed between each needle to allow installation of a pre-cast lintel or steel beam to span the loads. Alternatively, a masonry beam can be formed within two beds of chopped out mortar, 4 to 6 courses of brickwork apart, using grouted-in helical steel reinforcing rods.
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MARINE CONSTRUCTION
Application
Specification
Benefits
• Jetties • Boardwalks • Pontoon Guides • Moorings
• 88.9mm CHS screw pile • Up to 3m spacing • 3 to 5 ton excavator • Square termination cap • Timber or GRP frame
• Minimal access required • No floating working ...platforms required • Laser level accuracy • No muck-away required • Build off immediately
Method (Jetties) Using a standard 3 to 5 ton excavator, the first four screw piles are installed from the side of the marina until the appropriate torque and level is reached, after which a frame is constructed over the top from the edge of the marina. The excavator then moves out onto the newly-created frame and installs the next set of piles, whereupon another frame is added and the process repeated until the full length of the jetty is created. The machine is then removed and the final surface of the jetty is installed (normally a GRP-wood composite offering increased longevity).
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SCREW ANCHORING
Application
Specification
Benefits
• Lateral loads on foundations • Excavated wall tie-backs • Soil nailing • Embankment stabilization • Retaining walls
• 38.1mm SSS screw pile • 5 to 7 ton tracked rig • Up to 30 anchors per day • Dry installation • Up to 165kN SWL
•No grouting required •Minimal noise/vibration •High load capability •No reliance on skin friction •Restrains immediately
Method (Tie-backs) Initial excavation of the ground takes place reducing the level by up to 1.5m. At regular intervals, tension piles are installed at an inclination into the side of the newly-formed bank, using a standard tracked rig with a torque motor attached to a rotating mast. Universal steel columns are then installed vertically at each anchor location, with slots to receive the end of the tension pile, and pattress plates are then fitted to provide the tensional restraint of the column. Finally, sleepers are installed into the columns to complete the lateral restraint of the excavated earth wall. The process is repeated for each further reduction in level. Each time sleepers will be inserted into the columns from the top, pushing the existing ones into the latest set of columns at the base of the wall.
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MAST CONSTRUCTION
Application
Specification
Benefits
• Telecommunications • Wind turbines • Rail infrastructure • Signal posts • Matrix columns
• 88.9mm CHS screw pile • 5 ton excavator • Installed in one day • Up to 180kN SWL
• Restrains variable loads • Minimal noise/vibration • Laser level accuracy • Restricted access use • Totally dry installation • No curing time required
Method (Telecommunication) Using a standard 5 ton excavator, screw piles are installed to precise levels at predetermined locations. A steel grillage is then attached using bolting arrangements which enable it to withstand the variable compressive and tensile loads and the overturning moments associated with mast construction. In the example shown above, piles are installed at a raked angle to increase performance. The mast can be lifted into position immediately after the grillage has been attached, allowing a very swift installation, without the need for curing time and a further visit to site.
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MEZZANINE FLOOR CONSTRUCTION
Application
Specification
Benefits
• Retail stores • Car decks • Office extensions • Commercial buildings
• 88.9mm CHS screw pile • 3 ton excavator • Live working environment • Inside existing buildings • Up to 150kN SWL
• No spoil created • Minimal noise/vibration • Laser level accuracy • Restricted access use • Totally dry installation
Method (Retail store) Using a standard 3 ton excavator working in a live store at night, screw piles are installed into a pre-excavated holes through the existing floor without creating any spoil, vibration or requiring the use of grout. Reinforced concrete pile caps are then formed and a temporary steel plate is placed on top to protect the plate whist the pile cap cures. The steel frame can then be erected after 7 days curing. Screw piles are best suited to mezzanine floor construction as CFA creates spoil which has to be removed from within an existing store and steel cased driven through vibration may cause damage to existing foundation and the building itself, both piling systems also require grouting adding further cost to the remediation of the site once piling has taken place.
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