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Business profile


Time-saving foundations S


ScrewFast Foundations has been designing foundations solutions since 2000 and pioneered the re-introduction of helical piles into many sectors around the world


crewFast has installed more than 100,000 metres of helical pile, and carried out more than 200 pile tests without a single failure in service it says.


The company was contracted by Balfour Beatty Rail Ireland to install 14 overhead line equipment (OHLE) foundations and four anchors in the new station at Clongriffen just outside Dublin.


Minimising inconvenience


All foundations had to be completed in a single weekend possession because the structures had to be erected the following week. This also minimised the number of possessions and inconvenience to the public of closed train lines. Overhead lines needed to be reduced in height within the station and this had to be done to a very tight schedule as the possession to complete the work was during three nights over one weekend period. The ScrewFast design team created 12 No 4 helical pile solutions and two No 6 helical pile solutions, each with a grillage. To give extra lateral stability, anchor foundations with a single raked helical pile were added to three structures. As some of the foundations had to be sited close to the track and services, offset grillages were used to accommodate the situation. The helical pile solutions were individually designed based on the soil type to support the following typical loads: Vertical = 20kNm Horizontal = 13kNm


Overturning Moment = 176kNm. Foundation lifespan


Each foundation has a guaranteed lifespan of 60 years; which if required could be increased further by increasing pile wall thickness and/or adding sacrificial anodes to the top of the pile. The foundations were installed in three night shifts (Friday- Sunday). Weeks were saved from the project programme by reducing the number and duration of track possessions thereby reducing the overall project costs.


The simplicity of the installation process, compared to concrete, ensured that the risk of the project being held up was minimised. Three teams of three installers and an RRV per team were utilised to complete the works, with each location taking approximately four hours to complete.


John Keaveney, managing director, Balfour Beatty said: ‘From Balfour Beatty’s side I have to commend the guys on a very professional job. The whole Screwfast system is very impressive.’ ScrewFast Foundations was approached by Amey Colas and asked to provide a foundation solution to support two Twin Track Cantilever (TTC) Overhead Line Electrification (OLE) structures and two anchor masts each with a tieback anchor. The solution had to be competitively priced and installed in as few possessions as possible. ScrewFast selected Network Rail approved UK1 series 610 pile foundations, which the company says could be installed more quickly and easily than concrete foundations, and was the most economical solution. Installation of all the foundations took place over one Sunday shift.


The ground contained poor quality embankment fill: 11 metres of pile length was required and installed in three bolted


modular spliced sections for the TTC foundations. Form B design was completed in-house and lateral bending moment analysis was undertaken using OASYS ALP software. The driven piles were installed by ScrewFast subcontractor, Terrawise Construction using a vibro-hammer, followed by a percussion hammer attached to a road rail vehicle.


ScrewFast also offers the following solutions and services:


• Helical piles • GRIP piles • Single driven pile up to 605diameter • Angel piles • Concrete bored piles • Slope stability analysis • Desktop studies • Geotechnical design services • Geotechnical reporting • Structural analysis • Production of formal approval documentation.


For further information, contact Dan Dye, managing director, ScrewFast Foundations. Tel: 01727 821 282, www.screwfast.com


April 2013 Page 177


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