Helical Pile Technology

We are leading international experts in Helical (screw) Pile technology.

The Helical (screw) Pile foundation is an innovative and sustainable foundation solution.

Innovation is always at the forefront of our minds, and in 2004 GTL identified the benefits of the helical pile as an innovative alternative to traditional foundations and piling.

From there we moved to develop a revolutionary method for constructing and installing foundations using Helical pile technology. Helical pile, also incorrectly referred to as a screw pile, consists of a central hollow shaft of various diameters and sectional thickness, with helical plates strategically welded at given spacing.

5 Facts

  1. Helical piles are not new
  2. Over 3 million HSP’s are installed per year in the UK, USA, China, Japan, Canada, New Zealand, Australia. This number is increasing every year.
  3. GTL were the first company to design and install in Iraq and Kazakhstan.
  4. In 1866 HSP’s were used to construct Brighton Pier and in 2013 GTL installed additional piles.
  5. Used for high profile projects.
  6. Endorsed by Major EPC Companies and Majors

Helical Pile Technology

Benefits

Helical piles make excellent low-impact foundation for projects that are located in environmentally sensitive areas, such as wetlands, riverbeds, prairies, or historical sites.

GTL’s foundation system is known for its ease and speed of installation. Some of the advantages are:

Speed of installation – typically, a standard 6m pile takes an average of ten minutes to install. This reduces contract time, on site preliminaries, speed to market and road/track closures amongst other factors.

No spoil – with the spiralling cost of muck away the solution proves to be financially and environmentally viable especially in contaminated ground.

No Concrete – no curing time so loads can be applied immediately.

Environmentally friendly – by reversing the installation process the helical pile can be decommissioned and re-used leaving a Greenfield site.

Reduced Environmental Impact – Installation procedure produces minimal vibration and noise, allowing installation close to noise sensitive areas and night time operations.

Restricted access – Segmented sections for reduced head heights – piles can be installed under pipe racks and in basements.

Helical Pile Technology

History

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The first recorded use of a helical pile was in 1836 by a blind Brick-maker and Civil Engineer named Alexander Mitchell. Mitchell was born in Ireland on April 13, 1780, and attended Belfast Academy. He lost his sight gradually from age 6 to age 21. Being blind limited Mitchell’s career options, so he took up brick making during the day and studied mechanics, mathematics, science, and building construction in his leisure time.

One of the problems that puzzled Mitchell was how to better found marine structures on weak soils, such as sand reefs, mudflats, and river estuary banks. At the age of 52 Mitchell devised a solution to this problem, the helical pile. In 1833, Mitchell patented his invention in London. Mitchell called the device a “screw pile” and its first uses were for ship moorings. The pile was turned into the ground by human and animal power using a large wood handle wheel called a capstan. Screw piles on the order of 6 m long with 127-mm diameter shafts required as many as 30 men to work the capstan. Horses and donkeys were sometimes employed as well as water jets.

In 1838, Mitchell used screw piles for the foundation of the Maplin Sands Lighthouse on a very unstable bank near the entrance of the river Thames in England. The foundation consisted of nine wrought-iron screw piles arranged in the form of an octagon with one screw pile in the centre. Nine piles were installed to a depth of 6.7 m by human power in nine consecutive days. In 1853, Eugenius Birch started using Mitchell’s screw pile technology to support seaside piers throughout England. The first of these was the Margate Pier. The piers themselves supported the weight of pedestrians, carts, buildings, and ancillary structures. The foundations had to support tidal forces, wind loads, and occasional ice flows. Screw piles also were used to support Blankenberg Pier in Belgium in 1895. During the expansion of the British Empire, screw piles were used to support new bridges in many countries on many continents. Technical ar ticles were published in ‘The Engineering and Building Record’ in 1890 and in ‘Engineering News’ in 1892 regarding bridges supported on screw piles. As a result of British expansion, screw piles were soon being applied around the World. From between 1900 – 1950 the use of helical piles declined.

During this time, there were major developments in mechanical pile-driving and drilling equipment. However, with the development of modern hydraulic torque motors, advances in manufacturing, and new galvanising techniques, the modern helical pile evolved primarily for anchor applications until around 1980 when engineer Stan Rupiper designed the first compression application in the U.S. using modern helical piles (Rupiper, 2000). The Helix (screw) pile design is just as effective in the 21st Century as it was back in the 19th Century. It continues to be installed throughout the World.

Helical Pile Technology

Installation

The Helical (screw) pile is rotated into the ground by means of an auger, hydraulically powered by an excavator. The pile depth is achieved by mechanically connecting additional shaft sections prior to installation. The diameter of the helical plates is governed by the pre-determined loading and soil conditions.

The technology of the GTL helical pile foundation is not so much in the manufacturing of the product but rather in the specific engineering design, with the foundation being designed as a solution to a particular requirement or condition.

Throughout the installation process GTL monitor the installation torque and pile alignment. Installation can be undertaken anywhere that you can accommodate an excavator or hydraulic equipment i.e. crane, forklift etc Installation over water can be performed from a barge, floating pontoon and an engineered platform, as designed for Brighton Pier.

GTL monitor the installation torque for the following reasons:

✦ To provide a qualitative assessment of the soils being penetrated at various depths. The recorded installation torque and depth will be interpreted against the existing soil data, by way of a graph. By interpreting the soil data against the installation torque, a correlation can be obtained that enables a simple verification strategy to be determined.

✦ To maintain the integrity of the Helical (screw) pile during installation and to mitigate damage through exceeding torsional strength to any of the pile’s components.

Each Helical (screw) pile has a maximum stress level and this must not be exceeded. Tolerances The ICE Piling Specification stipulates certain maximum permitted deviation for a finished pile, these being:Vertical deviation at any level is 1 in 75.

The maximum deviation of the pile centre from the centre point shown in the setting out drawings is 75mm in any direction at commencing surface level. The top elevation should be within 25mm of the design vertical elevation. In the vast majority of situations GTL are able to better these tolerances, however, we design our pile cap frame/grillages to accommodate these tolerances.

Old Technology Re-engineered

The first recorded use of a helical pile was in 1836 by a blind Brick-maker and Civil Engineer named Alexander Mitchell. Mitchell was born in Ireland on April 13, 1780, and attended Belfast Academy. He lost his sight gradually from age 6 to age 21. Being blind limited Mitchell’s career options, so he took up brick making during the day and studied mechanics, mathematics, science, and building construction in his leisure time.

One of the problems that puzzled Mitchell was how to better found marine structures on weak soils, such as sand reefs, mudflats, and river estuary banks. At the age of 52 Mitchell devised a solution to this problem, the helical pile.

In 1833, Mitchell patented his invention in London. Mitchell called the device a “screw pile” and its first uses were for ship moorings. The pile was turned into the ground by human and animal power using a large wood handle wheel called a capstan. Screw piles on the order of 6

m long with 127-mm diameter shafts required as many as 30 men to work the capstan. Horses and donkeys were sometimes employed as well as water jets.

In 1838, Mitchell used screw piles for the foundation of the Maplin Sands Lighthouse on a

very unstable bank near the entrance of the river Thames in England. The foundation consisted of nine wrought-iron screw piles arranged in the form of an octagon with one screw pile in the centre. Nine piles were installed to a depth of 6.7 m by human power in nine consecutive days.

In 1853, Eugenius Birch started using Mitchell’s screw pile technology to support seaside piers throughout England. The first of these was the Margate Pier. The piers themselves supported the

weight of pedestrians, carts, buildings, and ancillary structures. The foundations had to support tidal forces, wind loads, and occasional ice flows. Screw piles also were used to support Blankenberg Pier in Belgium in 1895.

During the expansion of the British Empire, screw piles were used to support new bridges in many countries on many continents.

Technical articles were published in ‘The Engineering and Building Record’ in 1890 and in ‘Engineering News’ in 1892 regarding bridges supported on screw piles. As a result of British expansion, screw piles were soon being applied around the World.

From about 1900 to 1950, the use of helical piles declined. During this time, there were major developments in mechanical pile-driving and drilling equipment. However, with the development of modern hydraulic torque motors, advances in manufacturing, and new galvanising techniques, the modern helical pile evolved primarily for anchor applications until around 1980 when engineer Stan Rupiper designed the first compression application in the U.S. using modern helical piles (Rupiper, 2000).