Field Testing and Centrifuge Modeling of Helical Piles in Sand

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Helical pile foundations are widely used in the construction industry across Canada. Helical piles have many advantages such as large capacities, reusability, and rapid installation, compared to conventional straight-shaft piles; these advantages make helical piles especially suitable for the construction industry of Canada. In recent years, innovative helical pile types have been developed by pile manufacturers of Canada to meet the increasing demand of the industry. RSP Piling is an Alberta-based company specializing in the manufacturing, design, and installation of helical piles across Western Canada. RSP has identified a few technical problems to be solved for the further growth of Canada's helical pile industry. Firstly, the capacity-torque correlations of RSP's piles have not been established. Secondly, the mechanical design of helical plate such as minimum thickness and the welding strength is significantly dependent on the soil reaction pressure on the plate, particularly for helical piles in sand. A realistic model of soil reaction pressure can effectively improve the mechanical design of the helical plates and saves the cost of manufacture. Third, piling companies are usually required to conduct field loading tests of helical piles, but the field tests are costly and time-consuming; in addition, it is often impossible to conduct a field test due to the complexity of loading or pile configuration, such as a group of helical piles installed in sand subjected to moment and axial loads. A more convenient test method of helical piles particularly in sand is strongly needed. The University of Alberta (UAlberta), by partnering with RSP, will provide the technical solutions to address the company-specific questions. We will conduct field loading tests of research helical piles and carry out centrifuge model tests of small-scale helical piles in very dense sand. Through the 3-year project, the UAlberta and RSP will train one PhD student and one research assistant who will eventually be familiar with the behaviour of helical piles.