Towards the Innovation of Screw Piles: Lab Pile Testing and Rotary Penetrometer Development

螺旋桩在加拿大是一种创新的深基础形式。加拿大的螺旋桩业代表着一个10亿美元规模的潜在市场。加拿大的螺旋桩业支持加拿大的基础设施建设、矿业、铁路和北极开发。加拿大的地基手册和技术导则均采用螺纹桩。尽管螺旋桩得到了广泛的应用，但仍然可以发现一些不足之处。对于工程师或研究人员来说，导致螺旋桩失败的因素尚不清楚。目前螺纹桩的设计方法尚需改进。该方案将解决与土-螺杆桩相互作用相关的基本问题。该计划由三个主要项目组成。在第一个项目中，将在实验室内进行不同土型中安装的螺旋桩的土体反力和孔隙水响应；将测量不同尺寸的螺旋桩的轴向和横向阻力；将使用粒子图像测速技术来量化轴向荷载下螺旋桩周围的土体变形规律。第一个项目的目的是解决详细的土-螺旋桩相互作用，以进一步了解螺旋桩的破坏模式，并辅助螺旋桩的设计。在第二个项目中，将开发旋转贯入仪(RPT)并在实验室进行测试。本项目的目的是支持螺旋桩的直接设计方法，为岩土场地勘察提供一种新的工具。RPT可以被认为是一个由轴和螺旋组成的微型螺旋桩。在RPT贯入过程中收集的安装扭矩剖面和孔压可以支持对土壤性质和行为类型的解释。与其他将竖井向下推进的勘察技术不同，RPT将竖井螺丝插入地面进行现场勘察。该计划的第三个项目将在艾伯塔大学农场的田野上验证RPT的表现。根据RPT得出的土性和桩阻力将与先前确定的实际值进行比较。RPT将比传统的调查方法有几个优势，并可以在螺杆桩行业找到一个独特的利基市场。该项目将培养两名博士生、一名硕士研究生和几名本科生。该方案的成果将改进现有的螺旋桩设计方法，并开发出一种创新的岩土场地勘察技术。该研究计划将使加拿大在螺杆桩行业和现场勘察方面保持世界领先地位。

Screw piles are an innovative type of deep foundations in Canada. The screw pile industry of Canada represents a potential market at the scale of $1B. The screw pile industry of Canada supports the infrastructure construction, mining sector, railway, and Arctic development in Canada. Screw piles have been adopted to foundation manual and technical guides of Canada. Despite wide use of screw piles, several deficiencies can still be identified. The factors that governs the failure of screw piles are not clear to engineers or researchers. The current design methods for screw piles may need to be improved. The proposed program will address the fundamental questions related the soil-screw pile interaction. The program consists of three major projects. In the first project, the soil reaction and pore water response to screw piles installed into various soil types will be conducted in the laboratory; the axial and lateral resistance of screw piles of varying dimensions will be measured; the soil deformation pattern around screw piles subjected to axial loading will be quantified using the Particle Image Velocimetry technique. The objective of the first project is to address the detailed soil-screw pile interaction that can further be used to understand failure modes of screw piles and assist in the screw pile design. In the second project, a rotary penetrometer (RPT) will be developed and tested in the laboratory. The objectives of this project are to support the direct design method of screw piles and offer a new tool for geotechnical site investigation. RPT may be considered as a miniature screw pile consisting of a shaft and helix. The installation torque profiles and pore pressure collected during RPT penetration can support the interpretation of soil properties and behaviour types. Unlike other investigation techniques that drive a shaft downwards, RPT screws a shaft into ground for the site investigation purpose. The third project of this program will validate the performance of RPT in the field located on the farm at the University of Alberta. Soil properties and pile resistance, derived from RPT, will be compared with actual values that had been previously determined. RPT will have several advantages over conventional investigation methods and can find a unique niche in the screw pile industry. The program will train two PhD students, one MSc student, and several undergraduate students. The outcomes of proposed program will improve the current design approaches for screw piles and develop an innovative technique for geotechnical site investigation. The research program will make Canada maintain a world leader in the screw pile industry and site investigation.