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

螺旋桩是加拿大一种新型的深地基。加拿大螺旋桩行业具有10亿美元规模的潜在市场。加拿大螺旋桩产业支撑着加拿大的基础设施建设、矿业、铁路和北极开发。螺旋桩已被采用在加拿大的基础手册和技术指南中。尽管螺旋桩得到了广泛的应用，但仍存在一些不足。控制螺旋桩破坏的因素对工程师和研究人员来说并不清楚。现有的螺旋桩设计方法有待改进。提出的方案将解决有关土-螺杆桩相互作用的基本问题。该计划包括三个主要项目。在第一个项目中，将在实验室进行安装在各种土型中的螺旋桩的土反力和孔隙水响应；测量不同尺寸的螺旋桩的轴向和侧向阻力；采用质点图像测速技术对螺旋桩在轴向荷载作用下的土体变形模式进行定量分析。第一个项目的目标是解决详细的土-螺杆桩相互作用，可以进一步用于了解螺杆桩的破坏模式，并协助螺杆桩的设计。在第二个项目中，将研制一种旋转穿透仪，并在实验室进行测试。本项目旨在为螺旋桩的直接设计方法提供支持，并为岩土工程现场勘察提供新的工具。RPT可以看作是一个由轴和螺旋组成的微型螺旋桩。在RPT穿透过程中收集的安装扭矩曲线和孔隙压力可以支持对土壤性质和行为类型的解释。与其他向下驱动竖井的调查技术不同，RPT将竖井钉入地面以进行现场调查。该计划的第三个项目将验证RPT在阿尔伯塔大学农场现场的性能。由RPT得出的土壤性质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，可以在螺旋桩行业找到一个独特的利基。该项目将培养两名博士研究生、一名硕士研究生和几名本科生。该计划的成果将改进目前螺旋桩的设计方法，并开发一种创新的岩土工程现场调查技术。该研究计划将使加拿大在螺旋桩工业和现场调查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.