Establishment of analytical-numerical method to determine the water level in the railway ballast layer contaminated with sandy material

Abstract

Contamination of railway ballast can influence the permeability of ballast course and consequently the drainage potential of the track substructure. The present study elaborates the water level of the contaminated ballast with sandy material by establishment of laboratory test as well as analytical-numerical method. For this goal, the large-scale permeability tester is utilised to determine the hydraulic conductivity of ballast aggregate fouled with disparate ratios of sandy material. Then, the developed analytical-numerical procedure is applied to predict the elevation of water in the ballast course for considered conditions of boundary of ballast layer as well as specified values of rainfall rate. Based on the obtained results, the permeability of extremely contaminated ballast with sand is nevertheless appropriate. However, the estimated water level of the ballast course is drastically influenced by further contamination of railway ballast layer especially under higher rainfall rates. Meanwhile, the increment of water level on two sides of the ballast course eventuates in more uniform water table along the cross-section of the course which results in more saturation of track substructure.