Innovations in Screw Pile Foundations from Multi-scale Testing

Dr. Lijun Deng, Associate Professor (Geotechnical), presents his research on "Innovations in Screw Pile Foundations from Multi-scale Testing". Abstract: In recent decades, screw piles have become popular in applications where fast installation and cost effectiveness are required. Unlike conventional driven or cast-in-place piles, screw piles are installed by torque. Screw piles are designed with multiple helical plates, continuous threads, or other shaft modifications that are aimed to increasing the pile resistance or facilitating torsional installation. Because of this unique installation method and pile shape, the capacity, failure mechanism and soil response to pile installation are to be examined in order to understand the soil-pile interaction and guide the pile design. This presentation will introduce two example projects in the helical pile research at multiple scales, including full-scale field testing and geotechnical centrifuge modeling. The full-scale field research primarily determined the effects of pile spacing on the group capacity (i.e. group efficiency) in cohesive soils and delineated the pore pressure behaviour during pile installation and testing. For the second example, small-scale foot-long piles were installed by torque at a high centrifugal acceleration and loaded in axial directions. The centrifuge modeling tests were intended to investigate the helical pile failure mechanism and pore pressure response. The centrifuge tests confirmed that centrifuge modeling offers an economical and reliable alternative to the field research in soil-pile interaction. Speaker Bio: Dr. Lijun Deng is an Associate Professor of Geotechnical Engineering who joined the University of Alberta in 2013 after receiving his PhD from the University of California, Davis. His research interests include foundation engineering, earthquakes, geotechnical centrifuge modeling, cold regions engineering, and ground improvement. His research has been supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) and a number of industrial collaborators.