Narrowing longitudinally coupled prefabricated slab track maintenance duration with field data analysis of slab deformation under high temperature

Abstract

The deformation of longitudinally coupled prefabricated slab track (LCPST) due to high temperature may lead to a reduction in ride comfort and safety in high-speed rail (HSR) operation. It is thus critical to understand and track the development of such defects. This study develops an online monitoring system to analyze LCPST deformation at different slab depths under various temperatures. The trackside system, powered by solar energy with STM8L core that is ultra-low in energy consumption, is used to collect data of LCPST deformation and temperature level uninterruptedly. With canonical correlation analysis, it is found that LCPST deformation presents similar periodic variation to yearly temperature fluctuation and large longitudinal force may be generated as heat accumulates in summer, thereby causing track defects. Then the distribution of temperature and deformation data is categorized based on fuzzy c-means clustering. Through the distribution analysis, it is suggested that slab inspection can be shortened to 6 hours, i.e. from 10:00 am to 4:00 pm, reducing 14.3% track inspection workload from the current practice. The price of workload reduction is only a 2% chance of missed detection of slab deformation. The finding of this research can be used to enhance LCPST monitoring efficiency and reduce interruption to HSR operation, which is an essential step in promoting reliable and cost-effective track service.

A Feasibility Analysis of the Infrared Thermography Technique in Surface Crack Detection for High-Speed Rail Slab Track

“…Consequently, the infrared radiation from the slab surface can be read by an infrared thermometer which converts the infrared radiation into temperature so that the temperature diference at the slab surface can be obtained and the surface crack can be detected. Te relationship between the temperature at the slab surface and the radiation emitted from the slab surface can be determined by the Stefan Boltzmann law, as expressed by [27] W � εσT 4 object ,…”

“…Another important step is to determine the initial temperature feld of the slab track. It is also based on feld measurement, and the temperature distribution of track slab is obtained by installing resistance temperature sensors at diferent depths inside the slab (the distance between each temperature sensor and the upper surface of the track slab is 0 mm, 50 mm, 100 mm, 150 mm, 200 mm, and 230 mm [4]). Subsequently, the measurement data can be used to ft a temperature distribution curve which will then be input into the FE model.…”

“…Ten, the temperature at diferent depths inside the slab is calculated. Te simulation results can be compared with the monitoring data of temperature, which are measured by an online temperature monitoring system [4] (see Figure 6). Te measure points are located at the distances of 50, 100, 150, and 200 mm from the slab surface.…”

“…Among the defects, the surface crack is a critical one which can cause structural deterioration and reduce the service safety of the track system [3]. To solve the problem, the maintenance-of-way department has formulated a crack management code by defning the width and length threshold of the surface crack and carrying out the manual inspection during the window time for track maintenance [4]. However, the manual inspection for track defects is a time-consuming and labor-intensive task, which is not suitable to be adopted on the busy HSR lines.…”