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

螺旋桩是加拿大一种创新的深基础。加拿大的螺旋桩行业代表了一个10亿美元规模的潜在市场。加拿大的螺旋桩产业支持了加拿大的基础设施建设、采矿业、铁路和北极开发。螺旋桩已被加拿大基础手册和技术指南所采用。尽管螺旋桩被广泛使用，但仍存在一些缺陷。工程师和研究人员还不清楚决定螺旋桩失效的因素。目前螺旋桩的设计方法可能需要改进。 建议的程序将解决有关的基础问题的土-螺旋桩相互作用。该计划包括三个主要项目。在第一个项目中，将在实验室中进行安装到不同土壤类型中的螺旋桩的土壤反应和孔隙水反应;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量化受到轴向载荷的螺旋桩周围的土壤变形模式。第一个项目的目标是解决详细的土壤螺旋桩的相互作用，可以进一步用于了解螺旋桩的破坏模式，并协助螺旋桩设计。在第二个项目中，将在实验室中开发和测试一种旋转磁电阻计（RPT）。本课题的研究目的是支持螺旋桩的直接设计方法，并为岩土工程现场勘察提供一种新的工具。RPT可以被认为是一个微型螺旋桩组成的轴和螺旋。在RPT贯入过程中收集的安装扭矩剖面和孔隙压力可以支持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将竖井拧入地面进行现场调查。 该计划的第三个项目将验证RPT在位于阿尔伯塔大学农场的田间的性能。将根据RPT得出的土壤特性和桩阻力与先前确定的实际值进行比较。与传统的调查方法相比，RPT有几个优点，可以在螺旋桩行业找到一个独特的利基市场。 该计划将培养两名博士生，一名硕士生和几名本科生。建议的程序的结果将改善目前的螺旋桩的设计方法，并开发一个创新的技术，岩土工程现场勘察。该研究计划将使加拿大在螺旋桩行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.