CPD Accredited Training

We are delighted to announce that ABC Anchors is now an approved Continuing Professional Development (CPD) training provider.

Being CPD accredited ensures that the training offered by ABC Anchors meets strict standards and quality benchmarks, whilst also demonstrating our continued commitment to education within the construction industry. Attending any of our training courses counts towards achieving your annual professional CPD quota as a Fellow, Associate, Chartered, Incorporated, Graduate or Technician member with all of the relevant professional institutions.

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RD Residential – Garden Studio

This project involved the construction of a timber-built garden studio in West London.

Screw piles were a preferred choice for the foundations, as the proposed location for the structure was at the base of a mature tree and in a tree root protection area.

The access to the site was also restricted allowing only hand held equipment to be used.

Both the customer and contractor for the build were new to screw piles and had been referred to us by their structural engineer, all the information was provided to each party and the system and method was approved.

The 60R product range was chosen due to the loading and the structure, and the unique 400H Hand Held anchor driver was chosen for the installation. The ground conditions varied across the site so additional extensions were used to achieve the required torque for the design load.

The foundations for the garden studio were successfully completed and the contractor was very happy with the service received:

“From start to completion ABC Anchors were a pleasure to deal with, very supportive, and easy to talk to when queries arose.  We would highly recommend both their products and service and will definitely be using them again for any piling needs we have.”

Ed O'Donnell, RD Residential

Julia’s House Children’s Hospice

This project involved installing 6 quantity 60RL* screw piles to support a small wooden Cabin.

Screw piles were the preferred choice of foundation for two reasons, firstly as there were tree roots and secondly, the ground dropped away by up to 1meter in some pile positions.

Using our 400H hand held torque head 2 rows of 3 piles were installed with the front 3 piles being installed to ground level and the back 3 protruding above ground level by approximately 1m.

As a precaution a cross brace of the 3 rear piles was designed to be used to ensure lateral stability.

The piles were terminated with a flat 200mm x 300mm plate which allowed easy connection of the steel ring beam for the cabin to sit on.

Once installation was complete it was found that the stability of the piles was adequate and cross bracing was not required on this occasion.

 

Customer’s feedback-

 A brilliant system which I wouldn’t hesitate to use in the future

Maurice Fishlock

 

*the 60RL is a light duty of the 60R, a cheaper option for low loadings, the difference between the 60R and 60RL is the tube thickness.

Tree Roots

Foundations near Tree Roots

"Having specified and witnessed the installation of screw piles I consider they must be one of the most tree friendly foundation systems around. Easy to install from low ground pressure machines working on ground protection they can be installed without material impact to roots."

Jago Keen, Keen Consultants

Disadvantages of conventional Concrete Footings around Tree roots

There are many reasons for not using conventional concrete footings near trees:

Trees will cause desiccation of soils in dry weather and subsequent expansion in wet, resulting in soil movement.

Excavating a trench may well cut through critical roots.

The concrete may have a detrimental effect on the tree, and will certainly reduce the flow of oxygen and nutrients to the tree.

Kew Gardens have shown that the top metre of soil is critical to the health of the tree.

Trees inevitably get bigger so foundation design needs to allow for this.

How do Screw Piles get over these issues?

We arrange for the highest Helix to be at least 2.5m below ground where there is no soil movement, and other Helices will be deeper.

The comparatively slender pile shaft may damage a very small portion of the roots, but the Aeration to the soil round the roots may well actually improve tree viability.

An average pile will be around 4m minimum length, so if we assume that the top 1.5 m of shaft is in soil which moves (up or down) the skin friction will be cancelled by that acting on the lower 2.5m, so resulting in no net movement. Pile capacity does not depend on the skin friction on the pile shaft, it rests entirely on the helices.

Generally structures will be designed to be above the ground, so movement of the soil does not affect the building itself.

Screw piles have both Tension and Compression capacities (about 20-25% more in compression) so can resist any uplift.

Each pile is driven to a specified Torque, and hence known capacity, unlike all other foundations which can only be tested after installation.

Scaffolding – Dyrham Park Roof Repair

When the 150 year old leaking roof of the 17th century Dyrham Park House needed to be repaired, the first step was to cover the whole house in a temporary scaffolding cover to keep the elements at bay.

Investigation showed that the ground around the house could not support the load imposed by the scaffolding.

ABC Anchors were asked by the main contractor Ken Biggs Construction to install over 100 screw piles to absorb the tensile and compressive forces from the complex structure, which weighs well over 200 tonnes.

With a 3 tonne mini digger, installation proceeded quickly, despite the need to work around the delicate building and paved garden structures. Some areas were inaccessible using the 3t digger. It was therefore only possible to install the piles using the ABC 400H hand held torque head.

The screw pile solution was proposed by Integral Engineering Design who worked with the National Trust to bring the project to fruition.

One feature that is quite unusual on this structure is the public access viewing platform, from May 2015 they will have a fully accessible scaffolding tower and lift, with a walkway where you can see the conservation in action and enjoy the views over the gardens.

Temporary Structures

Temporary Structures

Screw piles make excellent temporary foundations, quick and easily to install and just as easy to remove. Being able to offer instant tensions they are perfect for use as temporary staging, bridges, secure site storage, toilet blocks etc. The removal of the screw piles causes very minimal ground disturbance and piles can often be used again.

We have also used screw piles to support high loads from tower cranes, strand jacks and other vehicles requiring temporary proven solid foundations.

These often have cyclic or reversing loadings. The ability of screw piles to resist both tension and compression plus the low impact of installation and removal is usually key to a successful job.

Transport costs are reduced – 1 tonne of screw piles and extensions can provide 80 tonnes (200 tonnes ultimate) holding power.

Examples

Tents up to 600m2 (65000ft2) are quickly and safely erected using screw anchors, developed specially by ABC Anchors. Tension loads up to 200kN (20 tonnes) are easily accommodated, yet the anchors are quickly removed and reused time and again.

The scaffolding for the temporary roof over the house at Dyrham Park required over 100 screw piles resisting both compressive and tension forces. These piles can be removed and reused once the roof has been repaired.

Concert stages, previously secured using concrete, can now be restrained with hand installed lightweight screw piles.

Wind turbines suit screw piles really well as they can be quickly erected and repositioned if required with very little effort.

 

Blue forest – Belton House Adventure Playground Bridge and Walkway.

This project involved installing foundations for a wooden footbridge and wooden walkway in an area that was very difficult to access with plant machinery and was protected because of listed ruins in the area. The area was also extremely boggy and could only be accessed for a short period between the wet seasons.

All these restrictions meant that the majority of the foundations would have to be installed by hand and all the equipment would have to be brought to site manually.

It was decided that this project could be undertaken using our 60R piles and installing them with the 400H hand held torque head.

For the bridge abutments we installed 6 screw piles at either end onto which a reinforced concrete slab was poured. The screw piles had to be installed to 5m deep to ensure they were in good quality stable ground. Great care had to be taken not to damage any tree roots in the top 1-2m of soil.

The boardwalk piles proved to be even more of a challenge due to the pile positions being in a partially flooded area of natural bog. The only access was via a temporary wooden sleeper bridge which was only floating on the saturated land.

One row of piles was 4m to the side of the access bridge which made it impossible to reach using the 400H hand held unit as before.

It was decided to use a 3t mini digger to install these 12 piles but it was touch and go whether or not the temporary bridge would take the weight of the 3t machine. Careful manoeuvring and a skilled driver proved that it would be possible to install the piles in this way.

Additional sleepers had to be placed into the bog to allow the digger to reach out the 4m to the pile position and once the pile tip was installed into good ground the excavator could then use the pile for support.

The 12 piles were all installed to 6m deep before adequate torque was reached.

This challenging installation proved a great success as the 12 piles now form the base of a spectacular wooden walkway over an area of natural marshland.

 

Bridge Foundations

Bridge foundations

Installing bridge foundations is inherently an interesting challenge but convenient because loads will be known. River and watercourse banks are usually soft although there may be hard gravels or boulders a few meters below water level. Temporary bridges also benefit from screw piles as they can be easily removed and reused.

Piles can be protected against corrosion using a variety of tested solutions and may have relatively large diameter final extensions to give sufficient lateral and vertical resistance. We produce piles with working loads up to 250kN on a regular basis with much larger capacity available if required.

The additional benefit of using raked screwpiles is that increased support is provided for river banks. They are also particularly useful where the avoidance of cement is an environmental benefit.

Example

An early project was to create foundations for a footbridge in an area renowned for winter floods which had washed earlier bridges out to sea. The soil included small boulders up to 300mm diameter down to 3m deep. Thereafter the soil was very soft until a depth of 12m when strength improved significantly. 89mm piles were driven to maximum torque at depths of 14-15m and despite the bridge being  occasionally submerged 3m deep the foundations and bridge remain intact.

New Build – 89R Screw Piles Henley on Thames

89R piles were installed for foundations on this site in Henley on Thames. The site was particularly sensitive as it contained roman artefacts which if exposed would have halted the build. The installation of the piles also included a load test on a single pile which is sometimes asked for by the structural engineer to verify installation torque against pile capacity.

Underpinning – Conservatory

A conservatory which had been unsuccessfully underpinned using concrete, has now been restored to its original level using 60R helical screw piles.

Initial soil tests indicated that competent ground would be located at approx. 2m depth. However, inspection of the failed foundation and the local presence of trees shed some doubt on this information.

Pile installation was very quick with all equipment hand portable on site.

On this site conventional foundations looked OK but were in fact terminated just above a layer of poor ground.

A two man crew took 1½ days to complete the operation.

Piles were positioned to avoid a number of underground services/utilities.

 

Using the ABC 400H hand held driver, which has a continuous torque read out, our operators discovered that the competent ground overlay a 2m thick band of soft material. The piles shown were driven to depths of 5-6m before achieving satisfactory installation torques and standard underpinning brackets were then installed and carefully jacked using our 40KN/pile system.

The photos show the ground beam has now lifted from the conventional concrete underpinning and is restored to its original level.