Impact of Ballast Fouling on Rail Tracks

Abstract

Ballast fouling is understood as major cause of track deterioration in many countries over the world. It decreases the drainage and load bearing capacity of the ballast layer. A series of large scale hydraulic conductivity tests were conducted with different proportions of fouling to access the drainage capacity of the track. A numerical analysis was conducted using SEEP/W to quantify the drainage capacity of ballast under different degrees of fouling. Subsequently, track drainage classification in relation to the degree of fouling, which is a very useful tool for practical engineers, is presented in this paper. The analysis showed that both the location and extent of fouling played an important role when assessing the overall drainage capacity of track. In order to establish the relationship between the extent of fouling and the associated strength-deformation properties, a series of large scale monotonic triaxial tests were carried out for different levels of fouling for three different confining pressures. Based on the laboratory findings, a novel empirical relationship between the peak deviator stress and VCI has been proposed to assist the practitioner in their preliminary track condition assessment. By considering drainage and strength aspects, a critical level of fouling to assist in track maintenance planning has been considered. AbstractBallast fouling is understood as major cause of track deterioration in many countries over the world. It decreases the drainage and load bearing capacity of the ballast layer. A series of large scale hydraulic conductivity tests were conducted with different proportions of fouling to access the drainage capacity of the track. A numerical analysis was conducted using SEEP/W to quantify the drainage capacity of ballast under different degrees of fouling. Subsequently, track drainage classification in relation to the degree of fouling, which is very useful tool for practical engineers, is presented in this paper. The analysis showed that both the location and extent of fouling played an important role when assessing the overall drainage capacity of track. In order to establish the relationship between the extent of fouling and the associated strength-deformation properties, a series of large scale monotonic triaxial tests were carried out for different levels of fouling for three different confining pressures. Based on the laboratory findings, a novel empirical relationship between the peak deviator stress and VCI has been proposed to assist the practitioner in their preliminary track condition assessment. By considering drainage and strength aspects, a critical level of fouling to assist in track maintenance planning has been considered.

Evaluation of lateral stability of railway tracks due to ballast degradation

“…They are followed by subgrade intrusion (3%) and sleeper wear (1%) [42]. Ballast fouling has been emphasized to greatly undermine the stability and strength of railway track by many researchers [36,43]. Further, ballast fouling may cause drainage issues in ballasted track since the voids are filled up and water is blocked, leading to higher levels of moisture accumulating in the track substructure [44].…”

Railway ballast fouling, inspection, and solutions - A review

“…[43][44][45] In addition, it has been demonstrated that different fouling materials have different effects on hydraulic conductivity; for example, a small increase in VCI of the clay fouled ballast significantly decreased the hydraulic conductivity. 46 Another study indicated that the hydraulic conductivity of fouled ballast converged to that of fouling materials with high VCI (VCI>90% and VCI>50% for clay and coal, respectively). 47 Another study showed that clay contamination reduced the hydraulic conductivity more than coal contamination when the VCI exceeded 50%; however, they acted in the opposite direction at VCI<50%.…”

Influences of ballast degradation on railway track buckling

“…They are followed by subgrade intrusion (3%) and sleeper wear (1%) [27]. It should be noted that ballast fouling greatly undermines the stability and strength of the railway track as mentioned by many researchers [28,29]. Further, ballast fouling may cause drainage issues in ballasted track since the voids are filled up and water is blocked, leading to higher levels of moisture accumulating in the track substructure [30].…”