Application of geocell reinforced coal mine overburden waste as subballast in railway tracks on weak subgrade

Abstract

An alarming volume of coal mining by-product in the form of waste rock, referred to as overburden (OB), is being dumped over vast areas of useful ground, leading to an ever-increasing demand for land space worldwide. Reusing this material in the form of industrial applications can provide an effective and environmentally sound solution for disposal of the unsightly and polluted stockpiles. The present study focuses on recycling the coal mine OB as an alternative to conventional subballast material in railways. A series of model tests have been conducted with the OB material as subballast layers of different thicknesses overlying a weak subgrade. Further, geocells of varying geometries have been used for additional performance improvement. The results portrayed that coal OB had the potential to be recycled as a subballast material in railways. Additionally, with geocell reinforced OB, the magnitude of vertical settlement and stresses in the track bed can be reduced significantly. Experimentally validated finite element models (FEM) were used to predict the lateral deformations and subgrade stresses in the track bed, which were also found to have exhibited substantial reductions with geocell reinforcement.