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

为了提高松散砂土的抗液化能力，挤密桩加固地基被广泛采用。对地震风险的更好理解和现代设计规范中日益严格的设计标准导致需要技术上和成本效益高的方法来修复现有基础设施。在修复不列颠哥伦比亚省阿布斯福德的使命桥期间的经验，使用打入桩，表明用于密实的桩的形状对所实现的改善程度有显著影响。现场试验结果表明，圆柱形混凝土桩的密实效果远不如锥形木桩。这显示我们对以挤密桩改善土壤的理解有差距。因此，迫切需要开展进一步的研究，以增进这方面的知识。与行业合作者合作，提出了一个关于这个问题的综合研究计划。预计的研究项目将调查锥形桩比圆柱桩在压实砂方面明显更有效的原因。它将建立在其他地方进行的工作，研究土-结构相互作用机制，控制锥形桩和群桩在轴向荷载下的行为。它将集中在不同的土壤变形机制所产生的圆柱形和锥形桩在桩安装。高素质的人员将在这项工作中进行培训，从而增加了加拿大的压实桩地面改善的专业知识。研究成果将对公司具有直接的高价值适用性，并将提高对地基处理技术的理解，以改善支持新的和现有基础设施的地基。它还将提高治疗的成本效益。该项目还将与申请人和行业合作者建立强有力的新的工作关系。这项调查将导致期刊出版，并将有助于地面改善行业。

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.