Resonance behaviour of railway embankments on soft subsoil
Sulongge Gong (TU Delft - Civil Engineering & Geosciences)
Li Wang (TU Delft - Civil Engineering & Geosciences)
Chen Shen (TU Delft - Civil Engineering & Geosciences)
Cristina Jommi (Politecnico di Milano, TU Delft - Civil Engineering & Geosciences)
Zili Li (TU Delft - Civil Engineering & Geosciences)
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Abstract
Railway track on a layered substructure, such as an embankment-subsoil system, may exhibit subgrade resonance, and the influence of soft subsoil on the resonance is not yet fully understood. The present study investigates the subgrade resonance behaviour using falling weight tests at two sites in the Netherlands, supported by three-dimensional finite element modelling. The two sites have similar geometrical and material properties of track and embankment, but different subsoil conditions: sand at one site and peat at the other. The field measurements show clear amplification at about 25 Hz at the sandy site, whereas no distinct peak is observed at the peaty site. The measured resonance frequency at the sandy site can be reproduced with reasonable accuracy by a finite element model calibrated on field and literature data. The model is further used in a parametric study, which confirms that decreasing subsoil stiffness reduces the peak of the subgrade resonance. Experimental and numerical results demonstrate the effects of the embankment-subsoil impedance contrast on the dynamic behaviour of railway embankments: a soft-on-stiff configuration may lead to resonance, whereas a stiff-on-soft configuration results in a less pronounced resonant response.
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