The application of DAS for evaluating seasonal changes in seismic velocities of a railway embankment

Railway embankments, constructed in the 19th and early 20th centuries without modern engineering standards, are increasingly vulnerable to failure due to ageing, climate change, and rising transportation demands. Extreme weather events increasingly pose a risk to the resilience of these embankments, as prolonged wet and dry periods increase the risk of serviceability issues and progressive failure. Continuous monitoring and early intervention in earthworks are more cost-effective than addressing failures after they occur. This study explores the potential of Distributed Acoustic sensing (DAS) for long-term seismic monitoring of embankment slopes, capturing seasonal behaviour variations with high-resolution temporal and spatial data. Focused primarily on DAS, the study demonstrates its effectiveness in enabling frequent, distributed measurements along a 350m long fibre optic cable buried in the slope of a live railway embankment near London, UK. Four active seismic surveys were conducted along the fibre optic cable across different seasons. The findings highlight the sensitivity of DAS to changes in embankment condition throughout the monitoring period, emphasising its unique capability for continuous, detailed monitoring over time and space.