Experimental Investigation of Open-Ended Pipe Piles Subjected to Axial and Lateral Loads

开口管桩(OEPP)通常用于支撑一系列陆上和海上民用基础设施系统，如对美国经济至关重要的建筑物和其他结构。然而，对土方工程安装和运营过程中的土-桩相互作用的基本了解仍然有限。这种有限的认识在某些情况下导致了灾难性的后果，如地基和结构故障以及非常重大的经济损失。在这项研究中，将对安装过程中和复杂加载条件下的OEPP的响应进行实验表征和研究。将利用国际合作，在普渡大学和格勒诺布尔阿尔卑斯大学进行一系列安装和加载测试。该项目的广泛影响是多种多样的，包括为本科生和研究生教学开发解决与基础工程有关的数学问题的教育工具，为可供业界使用的OEPP开发可靠的设计方法，增加学术界和工业界之间建立伙伴关系的机会，以及为强有力和持久的国际合作铺平道路。研究的目的是：(1)对OEPP安装过程中的桩堵塞过程有一个基本的了解；(2)开发有效的方法来预测安装过程中的桩堵塞；以及(3)开发方法来解释OEPP的荷载响应中的土壤堵塞历史。这些目标将通过全面的模型桩测试计划实现，使用独特的仪器方案和先进的图像分析方法：数字图像相关(DIC)和X射线计算机层析(CT)。试验方案包括一系列试验，涉及不同的安装过程(顶进和打入)和加载过程(轴向和横向、单调和循环加载)的顺序和组合。试验方案中考虑的参数有管桩直径、桩身表面粗糙度、砂型、砂土相对密度和土层厚度。从项目研究中获得的基本知识将作为开发可靠的方法来预测堵塞形成和桩安装阻力的基础，以及考虑桩堵塞效应的OEPPS阻力计算的设计方法。这项工作预计将显著提高基于OEP的陆上和海上结构的安全性和性能。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Open-ended pipe piles (OEPPs) are often used to support a range of onshore and offshore civil infrastructure systems such as buildings and other structures that are vital to the economy of the United States. However, fundamental understanding of soil-pile interactions during the installation and operation of OEPPs remains limited. This limited understanding has led, in some cases, to disastrous consequences, such as foundation and structural failures and very significant economic losses. In this research, the response of OEPPs will be experimentally characterized and investigated during installation and under complex loading conditions. A series of installation and loading tests will be performed at Purdue University as well as at Université Grenoble Alpes by leveraging international collaborations. The broader impacts of this project are diverse and include developing educational tools on the solution of mathematical problems related to foundation engineering for undergraduate and graduate teaching, developing reliable design methods for OEPPs that can be used by the industry, increasing opportunities for partnerships between academia and industry, and paving the way for a strong and enduring international collaboration. The objectives of the research are: (1) to develop a fundamental understanding of pile plugging processes during installation of OEPPs; (2) to develop effective methods to predict pile plugging during installation; and (3) to develop methods to account for the soil plugging history on the load response of OEPPs. These goals will be achieved through a comprehensive model pile testing program, using unique instrumentation schemes and advanced image analysis methods: Digital Image Correlation (DIC) and X-Ray Computed Tomography (CT). The experimental program consists of a series of tests involving varying sequences and combinations of installation processes (jacking and driving) and loading processes (axial and lateral, monotonic and cyclic loading) on model pipe piles. The parameters considered in the test plan are the pipe pile diameter, pile surface roughness, sand type, sand relative density and soil layering. The fundamental knowledge that will result from the project research will serve as the basis for the development of reliable methods to predict plug formation and pile installation resistance, as well as design methods for calculation of the resistances of OEPPs accounting for the pile plugging effect. The work is expected to significantly improve the safety and performance of onshore and offshore structures founded on OEPPs.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.