Field Testing and Centrifuge Modeling of Helical Piles in Sand

螺旋桩基础广泛应用于加拿大的建筑业。螺旋桩与传统的直桩相比，具有承载力大、可重复使用、安装快速等优点，这些优点使螺旋桩特别适合加拿大的建筑业。近年来，加拿大的桩制造商开发了创新的螺旋桩类型，以满足行业不断增长的需求。RSP Piling是一家位于艾伯塔省的公司，专门从事螺旋桩的制造，设计和安装。RSP已经确定了一些技术问题，以解决加拿大的螺旋桩行业的进一步发展。首先，RSP桩的承载力-扭矩相关性尚未建立。其次，螺旋板的最小厚度和焊接强度等力学设计主要取决于作用在板上的土反力，特别是对于砂土中的螺旋桩。真实的土反力模型可以有效地改进螺旋板的力学设计，节约制造成本。第三，打桩公司通常须就螺旋桩进行实地载荷测试，但实地测试费用昂贵及费时;此外，由于载荷或桩身结构复杂，例如一组螺旋桩安装在砂土中，承受弯矩及轴向荷载，往往无法进行实地测试。因此，迫切需要一种更为简便的螺旋桩试验方法。阿尔伯塔大学（U阿尔伯塔）与RSP合作，将提供技术解决方案，以解决公司特有的问题。我们会就研究用螺旋桩进行实地载荷测试，并在极密砂层中进行小型螺旋桩的离心模型测试。通过3年的项目，UAlberta和RSP将培训一名博士生和一名研究助理，他们最终将熟悉螺旋桩的行为。

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.