Novel Spatial Soil Arching Effect on a Steep-Slope High Embankment in a Double-V Narrowing Gully

Abstract

A novel spatial soil arching (SSA) effect and the arching mechanisms and characteristics of a steep-slope high embankment in a double-V narrowing gully (DVNG) were investigated. First, the consistency between the results obtained via a lab-scale experiment and the three-dimensional finite-element model (FEM3D) confirmed the existence of SSA in the DVNG (DVNG-SSA) and validated the numerical model feasibility. The enlarged FEM3D revealed that the DVNG-SSA was generated by stress redistribution caused by uneven soil displacement. Moreover, the DVNG-SSA could generally be divided into horizontal (H-) and vertical (V-) DVNG-SSAs, which could interact with each other to form large-scale spatial soil arches at the front and bottom of the embankment. Parameter sensitivity analysis revealed that increasing the Poisson’s ratio of the soil negatively affected both arches. The H-DVNG-SSA only had side banks acting as arch feet, while the V-DVNG-SSA had an additional ditch bottom. Compared with H-DVNG-SSA, V-DVNG-SSA had a broader range, flatter shape, longer length, deeper thickness, lower height, and smaller maximum rise–span ratio. Finally, the strength of the DVNG-SSA was lower than that of the conventional pile–soil SSA despite its extensive coverage, which could considerably impact the overall embankment stability.