RAPID: Spectral Analysis of Sub-Track Accelerations Subjected to Long Term Heavy Axle Load Conditions

RAPID：长期重轴负载条件下子轨道加速度的谱分析

• 批准号: 0956960
• 负责人: Carlton Ho
• 金额: $ 11.92万
• 依托单位: University of Massachusetts Amherst
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-15 至 2011-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0956960&HistoricalAwards=false
• 关键词: RAPID; Spectral; Analysis; Sub; Track

This award is funded under the American Recovery and Reinvestment Act of 2009(Public Law 111-5).This RAPID award was made to take advantage of a unique opportunity to add a basic research component to an existing industry testing program that is about to begin. By taking advantage of a project being planned by the Transportation Technology Center, Inc. (TTCI) at their Facility for Accelerated Service Testing (FAST), this research can be accomplished for a small fraction of its costs as a stand-alone research project. The close collaboration with industry also enhances the opportunities for technology transfer. The research team will investigate the relationship between the dynamic response of sub-track geo-materials to dynamic excitation resulting from train traffic. In particular, the dynamic response will be monitored by six triaxial piezoelectric accelerometers placed in a test section, one in each subsection. The test bed consists of six sections with variations in percent fouling (passing 3/8" sieve) material in the track ballast and the type of tie used in the construction. The purpose of the installation and measurement is to record the acceleration time history when a heavy axle load (HAL) train passes over. Using the power spectral density (PSD), predominant frequencies can be identified. By recording the acceleration time histories over time, the PSD can be compared with the baseline PSD. Changes in the predominant frequencies will relate to the changes in the material behavior of the sub-track geo-materials. The fundamental theory is that as material stiffness changes, the frequency response will also subsequently change. Comparing the change to a baseline conditions would provide an indication of changes in material stiffness. A second part of the research project is to conduct plane strain box tests on the ballast and tie configuration. This is to be done with the same materials used to construct the test section. These tests will be used to evaluate stiffness and deformability of the test section.The primary objective of the research is to determine if the changes in natural frequency can be correlated to the need for maintenance of the sub-track material and provide a means to predict the need for maintenance prior to the physical manifestation of settlement and deflection that can be measured by conventional means. If successful, this research could lead to a fundamentally new method of evaluating ballast in an automated and continuous process, thereby reducing the number of accidents resulting from ballast degradation.

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。该RAPID奖项是利用一个独特的机会，为即将开始的现有行业测试计划增加一个基础研究部分。 通过利用交通技术中心公司正在规划的一个项目，（TTCI）在他们的加速服务测试设施（FAST），这项研究可以作为一个独立的研究项目完成其成本的一小部分。 与工业界的密切合作也增加了技术转让的机会。 研究小组将调查轨道下土工材料的动态响应与列车交通产生的动态激励之间的关系。 特别是，动态响应将由放置在试验段中的六个三轴压电加速度计监测，每个分段一个。 试验台由六个部分组成，轨道道碴中的污垢（通过3/8”筛）材料百分比和施工中使用的轨枕类型各不相同。 安装和测量的目的是记录重轴重（HAL）列车通过时的加速度时间历程。 使用功率谱密度（PSD），可以识别主导频率。 通过记录随时间的加速度时间历程，可以将PSD与基线PSD进行比较。 主导频率的变化将与子轨道土工材料的材料特性的变化有关。 基本理论是，随着材料刚度的变化，频率响应也随之变化。 将变化与基线条件进行比较将提供材料刚度变化的指示。 研究项目的第二部分是对道碴和轨枕结构进行平面应变箱试验。 这将使用与构建试验段相同的材料完成。 这些试验将用于评估试验段的刚度和变形能力。研究的主要目的是确定固有频率的变化是否与子轨道材料的维护需求相关，并提供一种方法，在沉降和挠度的物理表现之前预测维护需求，这些沉降和挠度可以通过传统方法测量。 如果成功，这项研究可能会导致一个全新的方法来评估镇流器在一个自动化和连续的过程，从而减少事故的数量造成的镇流器退化。