A ballast box to study the effect of sand fouling on ballast, track stiffness, track deformation, and predicting maintenance time

Abstract

Railroad track crossings through sandy areas, like deserts, face the unique challenge of sand infiltrating into the ballast, leading to ballast fouling. Geographical conditions make these areas particularly prone to windblown sand infiltration, causing fine sand to gradually fill the ballast voids, ultimately resulting in fouling issues. Over time, fouled ballasts become a significant concern because of their negative impacts on track performance. ☐ This study explores the impact of ballast fouling primarily caused by sand infiltration on track deflection, stiffness (modulus), and overall track degradation. The main goal is to establish a clear relationship between these factors and fouling levels due to sand infiltration. ☐ The research was conducted at the University of Delaware's Civil Engineering laboratory, utilizing an 18-cubic-foot (0.67 cubic yards) ballast box. A rail/tie/fastener assembly was placed on the ballast and subjected to cyclic loading at a rate of 12 cycles per minute. The testing began with clean ballast, and dynamic load tests were carried out under simulated vehicle wheel loading conditions for up to five hours, with load-deflection behavior recorded during each cycle. Sand was introduced to the ballast in two series: Series 1, representing unconsolidated tests, and Series 2, simulating progressive fouling. These tests were repeated with varying levels of sand fouling, ranging from moderate to severe. Load deflection curves were analyzed using the Beam on Elastic Foundation (BOEF) theory to determine track modulus (stiffness) values and cumulative deformation, corresponding to cumulative plastic strain under repeated wheel loading. ☐ The study's results reveal a consistent pattern in load deflection curves, track modulus values, and cumulative plastic strain for different levels of sand fouling. It was observed that as sand fouling increased, both track stiffness (modulus) and track settlement also increased, aligning with field measurements conducted under similar conditions. ☐ As a result of these findings, a predictive application was developed to estimate maintenance time based on the degree of fouling. This application can offer valuable insights into maintenance planning and decision-making for tracks traversing sandy regions.