This download is an excerpt from the Piling & Deep Foundations Australasia Conference, presented on Tuesday the 18th of October 2016.
This describes the techniques used to design the deep pile foundation for the oxidation furnace building as part of the Nyrstar Port Pirie lead smelter redevelopment. Due to the soft soil parameters, the design required more than 100 closely spaced piles, each reaching a depth of 26m below ground. On top of the pile group is a 1.6m deep pile cap, with a total volume of 1300m3; as well as a large pile ‘plinth’ supporting the 150 tonne lead smelting furnace.
The design consisted of deep piles using a continuous flight auger (CFA) piling rig and reinforced concrete pile cap design. When there are a large number of closely spaced piles under a highly loaded structure, load can distribute from one pile to the other through the surrounding soil. Various innovative techniques were used in the design to allow for the soil interaction, as well as to overcome any uncertainty in soil conditions. Additionally, a non-linear analysis was used to prove additional overload capacity from the piled raft.
For the pile cap, large prefabricated reinforcing cages were designed with openings for pile starter bars so they could be simply dropped into place; cutting cost of labour and providing an efficient construction process.