Calculation model of heaving amount on embankments using multi-factor coupling of low swell potential mudstone as foundation for high-speed railways

Abstract

With the swelling behaviour of red-bed low swell potential mudstone in the foundation of railway tracks, ballastless tracks for Lanzhou-Xinjiang high-speed railway (LXRH) may encounter transfinite heaving deformation on embankments. These are difficult to repair, can easily relapse and may persist for long periods of time. In this study, a theoretical calculation model for estimating the heaving amount on ballastless track embankments, caused by the low swell potential mudstone foundations, was established using the principle of viscoelasticity, Mindlin's elastic solution and the superposition method. The model comprehensively considered the expansibility, water content, thickness, density and overlying load of mudstone, and was built by quantifying the free and constrained heaving amounts. Two in-situ expansive rock foundation tests and a large-scale model test were conducted to validate the proposed theoretical model. The results of Case 2 indicated that 89.3% of the samples exhibited a relative error less than 20%; Cases 1 and 3 exhibited relative errors of less than 20% between the theoretical and experimental values. The theoretical calculation model can compensate for the deficiencies of existing theoretical analysis and estimate the heaving amount on embankments. It can also be used as a reference for the design and construction of ballastless track subgrades in low swell potential mudstone areas.