Analysis of Geocell-Based Track Design for the Reduction of Stresses in the Track Substructure

Abstract

This paper presents an analysis of a new railroad track design based on substructure containing a double layer of geocells plus an additional geogrid layer for application on a new rail line being constructed. This new line is designed to accommodate both passenger and freight operations. The analysis looked at the applicability of the proposed design to the track substructure conditions on this new line with a primary emphasis on the bearing strength of poor subgrade locations on the new line. The analysis approach used Beam on Elastic Foundation theory to generate stresses on the top of the ballast layer and top of sleeper and then follow-up analysis to include use of test results to analyze the distribution of these stresses through the substructure and the determination of the subgrade bearing stresses. These bearing stresses were then compared with the strength of soils representative of those found on the proposed line segment. Based on the results of the analyses, the proposed substructure design (with 2 geocell layers and one geogrid layer) was found to significantly reduce stresses on the subgrade so that the proposed track was appropriate for use on even the poorest soil types identified on this line segment. This is because of the improved strength and stiffness characteristics of the geocell reinforced ballast layer.