Rainfall Scouring Mechanism of the High-Speed Railway Subgrade Slope with Coarse-Grained Soil

The hydraulic erosion of the subgrade slope can lead to serious loss of filling materials and landslides, affecting stability. In particular, there is no quantitative consideration of the scouring calculation method for the design codes of High-Speed Railway Subgrade Slope (HRSS). This paper mainly focuses on the anti-erosion stability of HRSS with coarse-grained soil and analyzes the current research shortcomings. The scouring on the subgrade slope was analyzed by establishing an incipient flow velocity formula that optimized the derivation process and parameters. Compared with the two types of cases, the exactitude of the formula derivation is verified. Finally, combined with orthogonal grouping, a single-factor analysis was conducted on the slope gradient and soil shear strength. With the same particle size, the incipient flow velocity decreases with the increase of the slope gradient (29.7° – 45°). When the particle size is upwards of 0.1 mm, the slope gradient has a great impact on the incipient flow velocity. And as the slope gradient decreases, the acceleration of incipient flow velocity with the same particle size increases. The incipient flow velocity increases with the increase of C (Cohesion) or φ (internal friction angle). The value of φ influences more deeply in the particle size range of 0.1 – 20 mm, that is, to advance the resisting erosion capacity, the shear strength of the slope soil is encouraged to improve when designing slope protection measures.