The Wodonga Rail Bypass Project is a five kilometre dual track rail bypass, which incorporates 12 bridges situated in the Murray River floodplain, crossing local rivers and creeks. Vibropile commissioned with the construction of the bridges, specialise in Continuous Flight Auger (CFA) piling. This technique involves injecting concrete under pressure as the auger is being extracted to form the concrete column, and then the reinforcing cage is lowered into position. The Wodonga Rail Bypass was the first infrastructure project in Victoria to utilise the CFA construction technique for the piled foundations of permanent structures. Compared to the conforming scheme and traditional piling techniques, CFA piling is more efficient and enabled Vibropile to complete up to six piles per day. Given the location and soil condition, this technique alleviated a number of construction issues and offered environmental benefits
InfraBuild Construction Solutions prefabricated 320 pile cages totaling 850 tonnes, with the heaviest cage weighing 4.8 tonnes. The piles ranged from 900 - 1200 CFA with typical pile depths of 12 - 15 metres, with the deepest pile being 23 metres.
Unique to this project was the use of N40 500PLUS® REBAR, each prefabricated pile cage comprises of 24 x N40 15 metre longitudinal reinforcement with an N16 spiral at varying pitch down the cage. The N40 REBAR also had to be threaded at the top so they could couple into the crosshead. The cages had very tight tolerances, given the pile constraints it was a very demanding project. The cage diameter must be exact, so quality control of the prefabrication in the factory was critical. In a piling project, where the bars for the column that are placed on top are able to be spliced, some adjustments can be made. Australian standards state you cannot splice N40 REBAR so all the couplers to connect the pile reinforcement and the columns had to be in a precise location.
The cage diameter must be exact, so quality control of the prefabrication in the factory was critical. [InfraBuild Construction Solutions] accomplished this excellently”
Sean Holt, Senior Project Engineer, Vibropile Southern- Ben Symons, BLL Construction Manager
The final construction technique evolved where Vibropile could offer prefabricated column reinforcement as part of the pile reinforcement. We installed those into the piles, setting to the column tolerances. This demanded a better performance than the Australian Standard and what you would come to expect on most piling projects. This rapidly sped up the works and offered substantial time and cost savings and eliminated the need for some follow-on trades
To ensure a constant supply chain, InfraBuild Construction Solutions ran 24 hour shifts that aided in Vibropile staying ahead of construction schedules. InfraBuild Construction Solutions quality checked the pile cages and columns for compliance prior to leaving the fabrication factory and being delivered to site by semi-trailer.
InfraBuild Construction Solutions increased the construction speed and cost-effectiveness as well as simplified administration and site management through the inclusion of prefabricated steel piling cages and columns.
Article published on Thursday, 01 January 2015