Holdfast Training Services Trial Blog

This blog is a response to Auggy’s post below (Screw It!) as I can’t add images to the comment (apparently there is a plug-in, but I don’t have it).

Auggy, having spoken offline about never seeing these used before, I am now seeing screw piles everywhere!

I am currently working in the design office for a level crossing removal project (Level Crossing Removal Project) which is grade separating the road and rail network at 75 locations across Melbourne. We are just about to start the developed design on two level crossings at Mentone and Cheltenham. In these areas the grade separation is achieved by lowering the rail line into a trench (approx. 9m below current ground level) and then bridging the road crossings. The works package includes retaining structures, multiple bridges, two new stations, three high-rise over rail developments and an urban regeneration project; so lots of scope to get involved in a number of disciplines.

Anyway, screw piles. At certain chainages, the trenching of the rail line will be below the ground water table and therefore a tanking slab is required. From looking at the design drawings (below) it appears that screw piles are being used as tension piles to assist the tanking slab in resisting the uplift forces. As you’ll see from the drawings the tanking slab is only 400mm thick which, without looking at the calculations, seem thin to me. This construction is undertaken close to the beach and the ground in this region is a local formation of sand and clay, so there likely considerations for heave with the design of the tanking slabs, however, I have not yet been able to uncover the geotechnical report to confirm.

In summary, it seems that the application of screw piles is more widely used than I first thought and would interesting to see if these are being used more widely in the UK?