Abstract: Embankments constructed in V-shaped gullies(EVG)are commonly encountered in mountainous regions of China, yet the soil arching mechanism under such topographical conditions remains insufficiently studied. To address this, scaled model tests and numerical simulations were conducted based on similarity ratios determined for the filling materials, aiming to investigate the arching mechanism, analyze the influence of topographic factors and material properties, and elucidate the characteristics of soil arching in EVG. The results indicate that the spatial V-shape induces relative displacement between the embankment and the side banks, leading to the formation of a spatial stress arch with the side banks or gully bottom serving as the arch foot. The strength of the soil arch increases gradually from the slope toe toward the interior of the embankment, with the most pronounced effects observed at the starting cross-section of the embankment's rear edge and at 0.23 times the embankment height from the base. Increasing embankment height enhances the arching effect, expanding the arching area toward the rear, shifting the arch foot from the bottom to the side banks, and increasing both arch length and thickness. The most significant arching effects occur under the following conditions: bottom ditch width within 15 m, side bank angle between 50°~70°, internal friction angle of filling material less than 30°, and a higher ratio of elastic modulus of the valley foundation to that of the filler. The friction coefficient and elastic modulus of the contact surface have relatively minor influence on spatial arching, while the effects of slope rate and embankment cohesion are negligible. Compared to traditional soil arching, the EVG arch exhibits a broader arch foot range, an arch shape that transitions gradually from saddle-like to circular with height, and enhanced arch length and thickness from bottom to top. These findings provide a valuable reference for the design and stability analysis of EVG slopes.