Performance Evaluation of Micropiles as a Ground Improvement Technique for Existing Railway Tracks: Finite-Element and Genetic Programming Approach

Abstract

There are various methods for reinforcing a railway track subgrade, but the greater challenge lies in improving an existing railway track in the least possible time with minimum disruption to rail traffic. Micropiles can provide an alternative solution for the improvement of existing railway tracks. The application of micropiles does not require blocking of rail traffic or dismantling of existing tracks. This study aims to evaluate the effectiveness of micropiles as a ground improvement technique for existing railway tracks. Micropiles were tested on two types of soil–clay and silt. A complete parametric study varying the geometrical configurations of micropiles was conducted using the FEM. Variation of micropile geometry in terms of, for example, diameter, length, spacing, and angle of inclination was also discussed. The results of FEM analysis were further utilized to train a genetic programming (GP) model. Empirical equations for the prediction of track displacement were drawn up using GP analysis; the behavior of tracks for different reinforcement conditions was also discussed. The resultant equations can also be effectively used for predicting track performance under given conditions.