Evaluation of Geosynthetic-Reinforced Tracks on Clayey Subgrade

Abstract

In railroad track, geosynthetic is used for multiple functions, namely, reinforcement, separation, filtration, and drainage. In the present study, static and cyclic tests are performed on full-panel railway track models laid on compacted soil subgrades. Tests are performed on model tracks with two different thicknesses of subballast layer and laid on subgrade soil, namely, Dhanaury clay. Model tracks are reinforced with geogrid or geotextile or both at suitable interfaces. Track condition after a heavy rainfall was simulated. The models reinforced with geogrid at ballast–subballast interface were found to be more effective in reducing the tie displacements, ballast and subballast strains, and subgrade displacements as compared to the models reinforced with geotextile at subballast subgrade interface for tracks with Dhanaury clay as subgrade. The present study is also carried out by using a commercially available finite element software code, MIDAS/GTS (Midas manual 2013). Laboratory tests (triaxial tests and interface tests) are being conducted to calculate the constitutive parameters of the different track materials and interfaces which are used in the analyses. Model test results were extended to the field and subgrade modulus (Esg) and subballast thickness (dsb) as well as shear strength parameters (c’sg and ϕ’sg) of the subgrade soil, stiffness of geogrid, and coefficient of permeability of the subgrade soil were track parameters.