Effect of pile shape on effectiveness of ground improvement by compaction piling

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Ground improvement by compaction pilling is widely used to increase the resistance of loose sands toliquefaction. Better understanding of seismic risk and the increasingly severe design criteria in modern designcodes have led to a need for technically and cost efficient approaches to remediation of existing infrastructure.Experience during remediation of the Mission Bridge in Abbotsford, B.C., using driven piles, indicated that theshape of piles used for densification had a marked effect on the degree of improvement achieved. Field testresults showed that cylindrical concrete piles were much less effective than tapered timber piles fordensification. This has shown a gap in our understanding of soil improvement by compaction piling. As such,there is a strong need to undertake further research to advance knowledge on this front. Working with anindustry collaborator, a comprehensive research program on this subject is proposed. The projected researchproject will investigate the reasons for the apparent greater effectiveness of tapered piles compared tocylindrical piles for the compaction of sands. It will build on work carried out elsewhere to study thesoil-structure interaction mechanism governing the behaviour of tapered piles and pile groups under axialloading. It will focus on the different soil deformation mechanisms created by cylindrical and tapered pilesduring pile installation. Highly qualified personnel will be trained during this work, thus adding to expertise onground improvement by compaction piling in Canada. The research outcomes will be of direct high-valueapplicability to the Company and will improve understanding of ground treatment techniques for improving theground supporting new and existing infrastructure. It will also improve the cost-effectiveness of treatment. Theproject will also build a strong new working relationship with the applicant and an industry collaborator. Thisinvestigation will lead to journal publications and will contribute to the ground improvement industry.