HELICAL PILE INSTALLATION
DESIGN & BUILD TURNKEY SOLUTION
The Helical (screw) pile is rotated into the ground by means of a bi-directional auger, hydraulically powered by an excavator or similar hydraulic powered equipment.
Throughout the installation process GTL monitors 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.
GRILLAGES & PILE CAPS
GTL design grillages to group piles together and to accommodate the structures specific performance requirements. All our grillage designs conform to International Standards.
The ICE Piling Specification stipulates certain maximum permitted deviation of the finished pile, these being:Vertical deviation at any level is 1 in 75. Any part of the finished pile from the specified rake is 1 in 25 for piles raking up to 1 in 6, and is 1 in 15 for piles raking more than 1 in 6. 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
TESTING - STANDARDS & REFERENCES
Pile testing is recommended to be performed on all sites but should only be carried out after taking into account the quality of site investigation information , the project programme and the number of piles.
GTL recommend that pile tests are performed on projects for which there are specific serviceability requirements or a requirement for proof of load carrying capacity.
Helical pile foundations are an environmentally conscientious and a sustainable construction practice. The construction of a helical pile foundation consumes less raw material and requires fewer deliveries compared to other types of deep and shallow foundations.
Substitution of helical piles for other foundations almost always reduces the carbon footprint.
Helical piles will reduce disturbance in sensitive natural areas.
The unique configuration of helical piles consisting of large bearing surfaces and slender shafts is an efficient use of raw materials. The construction of helical piles requires on the order of 65 % less raw materials by weight to construct compared to driven steel piles and 95% less raw material by weight compared to drilled shafts or auger cast piles.
Helical pile foundations require fewer deliveries to and from a construction site.
Installation of a helical foundation system requires the piles be shipped from the supplier to the site and mobilisation of the installation equipment. Construction of a drilled shaft foundation requires shipments of reinforcing steel and concrete as well as mobilisation of a drill rig and often a concrete pump truck.
The omission of concrete for the foundation piles also reduced pollution because the production of cement is one of the leading producers of carbon emissions. On many occasions, helical piles can be installed with smaller equipment with better fuel economy in a shorter time period than other foundations. Fuel savings and less air pollution during installation of helical piles reduce the carbon footprint still further.
Helical piles make excellent low-impact foundation for projects that are located in environmentally sensitive areas, such as wetlands, riverbeds, prairies, or historical sites.
Lightweight installation equipment minimises disturbance, making less impact on fragile ecosystems. Structures can be constructed over marshland by keeping the machine on the constructed sections and reaching out to install the helical piles.
Overall, helical piles may be one of the most environmentally friendly deep foundation systems.