Field Testing and Centrifuge Modeling of Helical Piles in Sand

螺旋桩基础在加拿大各地的建筑业中得到了广泛的应用。与传统的直桩相比，螺旋桩具有容量大、可重复使用、安装速度快等优点，这些优点使螺旋桩特别适合加拿大的建筑业。近年来，加拿大的桩基制造商开发了创新的螺旋桩类型，以满足行业日益增长的需求。 RSP桩是一家总部位于艾伯塔省的公司，专门从事加拿大西部螺旋桩的制造、设计和安装。RSP为加拿大螺旋桩业的进一步发展确定了几个需要解决的技术问题。首先，还没有建立RSP桩的承载力-扭矩关联式。其次，螺旋板的最小厚度和焊接强度等力学设计很大程度上依赖于板上的土反力，尤其是砂土中的螺旋桩。一个逼真的土壤反力模型可以有效地改进螺旋板的机械设计，节约制造成本。第三，打桩公司通常需要对螺旋桩进行现场载荷测试，但现场测试成本高、耗时长；此外，由于载荷或桩型的复杂性，往往无法进行现场测试，例如安装在砂土中的一组承受弯矩和轴向载荷的螺旋桩。迫切需要一种更方便的螺旋桩检测方法，尤其是在砂土中。 艾伯塔大学(UAlberta)将通过与RSP合作，提供技术解决方案，以解决公司特有的问题。我们将对研究中的螺旋桩进行现场载荷试验，并对密实砂土中的小型螺旋桩进行离心机模型试验。通过这个为期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.