Behaviour of tapered screw pile foundations in unfrozen soils

加拿大多年冻土区基础设施的传统基础是直轴桩，研究人员和实践表明，这不是一种优化设计。加拿大北部经济的快速增长增加了对新建和维护基础设施系统的需求，这需要更安全而经济的基础。该研究提出了一种创新的基础类型，锥形螺旋桩（也称为地螺钉），作为传统桩基础的替代方案。由于特殊设计的轴，地螺钉表现出优异的性能，如大轴向容量，易于安装和可重复使用。然而，多年冻土区和非冻土区地脚螺栓的性能研究尚不完善，也没有针对多年冻土区地脚螺栓的设计指南。拟议的研究将弥补这一研究差距。通过与Thugga有限公司合作，研究团队将系统地研究埋在冻土和冻土中的地螺钉的轴向和横向行为；确定荷载传递和破坏机制；研究永久冻土层中地脚螺钉的短期和长期性能；优化安装工艺。为了实现这些目标，该小组将对安装在加拿大西部典型冻土和加拿大北部典型冻土上的地面螺钉进行现场试验。该团队将对受轴向载荷影响的螺杆段进行实验室测试，开发模拟土-螺杆相互作用的数值模型，并提出设计指南。拟议研究的结果将有助于工业合作伙伴扩大地螺钉在加拿大现有和新兴工业中的应用。该研究将促进我们对非冻结和冻结环境下地螺杆和土螺杆相互作用性能的理解。这项研究将为加拿大的基础设施系统提供一个有能力和经济的基础类型

Conventional foundations for infrastructure in Canada's permafrost regions are straight-shaft piles, which are not an optimized design as shown by researchers and practitioners. Quick economic growth in Northern Canada has increased the need for new construction and maintenance of infrastructure systems, which require more safe yet economic foundations. The proposed research introduces an innovative foundation type, tapered screw piles (also known as ground screws), as an alternative to the conventional pile foundation. As a result of the specially designed shaft, ground screws have **shown superior behaviour such as large axial capacities, ease of installation, and reusability. However, the performance of ground screws in permafrost or unfrozen soils are still not well engineered and design guidelines for ground screws in permafrost are nonexistent. The proposed research will bridge this research gap. By partnering with Thugga Ltd., the research team will systematically investigate the axial and lateral behaviour of ground screws embedded in unfrozen and frozen soils; identify the load-transfer and failure mechanisms; investigate the short-term and long-term performance of the **ground screws in permafrost; and optimize the installation technique. To fulfill the objectives, the team will conduct in-situ tests of ground screws installed in typical unfrozen soils in Western Canada and typical frozen soils in Northern Canada. The team will conduct laboratory testing of screw segments subject to axial loading, develop numerical models for simulating soil-screw interactions, and propose a design guideline. The outcome of the proposed research will help industrial partner expand the applications of ground screws in existing and emerging industries across Canada. The research will advance our understanding of the performance of the ground screws and soil-screw interactions in unfrozen and frozen environments. The research will benefit Canada's infrastructure systems by providing a capable and economic foundation type.**