PhD Geophysical Subsurface Railway Embankment and Soil Monitoring

Embankment stability is crucial for safe railway operation. Geophysical methods can be used to detect and characterize subsurface structures and materials and monitor changes over time. A ground-penetrating radar system mounted under a train can be used to delineate soil layering and moisture content in 3D. A buried fibre-optic cable can be connected to an interrogator and used as a distributed acoustic sensing (DAS) instrument to measure surface wave vibrations. Surface Wave Tomography (SWT) can be applied to the data to deliver soil strength parameters. Both methods allow for a continuous and frequent visualization of track embankment profiles without disrupting regular railway operation. Joint seismic-GPR analysis and interpretation has the potential to aid in embankment stability assessment. This is the state of the art, and the project is open for new and emerging technologies to be included. Your research will be conducted on the reference project site(s) and V-track, after which it will be calibrated/validated on CTO.

This project aims at developing an effective monitoring approach, quantifying and visualizing geophysical soil properties, mapping geophysical soil properties to geotechnical parameters, and identifying problematic places along railway tracks. This involves 3D modelling of seismic surface waves and GPR data, developing seismic-interferometry processing to obtain dispersion curves for SWT, joint GPR-SWT inversion to estimate subsurface parameters, and collaboration with other PhD projects to develop a geophysical-to-geotechnical parameter conversion model.

For this aim, the project will build upon and develop new GPR and DAS monitoring techniques, methods to estimate layer thickness, P-wave and S-wave velocities, water content, and possibly density, from the collected data. To compute geotechnical parameters from the geophysical parameters, the project will develop an operational method calibrated by CPT-data. The newly developed advanced processing methods should enable identifying problematic places. A field trial or demonstration of the geophysical monitoring technique forms an important part of the project. The project will be conducted in close collaboration with almost all other PhD projects and with all partners in RESET.