A multi-scale gap-bridging CWE approach to windblown sand action on critical infrastructures: Modelling framework and case study on a high-speed railway line

Windblown sand action on critical infrastructures, such as high-speed railway lines, can completely inhibit their operation detrimentally affecting their safety and capacity. Several key components of the infrastructure are affected, among them the rolling stock material and infrastructure equipment. Computational Wind Engineering (CWE) is becoming more and more adopted during the different design stages to assess the impact of windblown sand. However, CWE-based analysis and design remain challenging because of the different scales involved in windblown sand transport starting from the full alignment scale (macro-scale), to the railway body (meso-scale), to the rolling stock (micro-scale). An innovative multi-scale modelling approach is proposed to bridge the gap between macro and micro scales involved in windblown sand processes, allowing to assess windblown sand action on key components. An exploratory case study addressing rolling stock operation in sandy environment along an high-speed railway line is analysed and discussed. This demonstrates the soundness of the approach in identifying most endangered railway segments, railway body sedimentation-prone areas and rolling stock components, and in quantifying windblown sand action at different scales. The proposed approach is well suited also to support the conceptual design of Sand Mitigation Measures.