Assessment of the Bearing Capacity of a Subballast Layer Using a Numerical Model in a Railway Context
Résumé
Trackbed mechanical quality, and more precisely bearing capacity, is one of the key parameters to plan renewal projects. It depends on the subballast's properties (aggregate's physical and mechanical properties, layer thickness, and compaction) and on the types of materials below the subballast (capping layer and subgrade). The interaction between all these geotechnical parameters governs the overall load-bearing behaviour of the railway trackbed. Predicting the real-world results of various combinations of the aforementioned parameters is often difficult. The main objective of this study is to assess the load-bearing capacity of a railway trackbed (top of the subballast layer) by performing a cyclic plate loading test (NF P 94-117-1). A methodology implementing a numerical modelling approach is proposed. The continuum-based numerical model is 2D-axisymmetric, using the commercial software FLAC2D. A numerical procedure simulating the 2-stage plate loading test is developed. A wide range of trackbed layer configurations are simulated, leading to a numerical estimation of its bearing capacity.
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