Soil arching is one of the most important mechanisms in piled embankments. To investigate the development of soil arching in piled embankments, 14 unreinforced and 8 geosynthetic-reinforced model tests were carried out using a two-dimensional (2D) multitrapdoor test setup with analogical soil. This study revealed that basal geosynthetic reinforcement changed the three deformation patterns into two development patterns with concentric elliptical arches under the same conditions. The stress reduction ratios (defined as the ratio of the average pressure on the trapdoor at a certain settlement to the initial pressure on the trapdoor at zero settlement) corresponding to the three deformation patterns in the unreinforced tests were distinctively different. The change of the stress reduction ratio during the settlement of the subsoil also showed how basal reinforcement affected soil arching in piled embankments. The geosynthetic with lower tensile stiffness resulted in more soil arching than that with higher tensile stiffness.

Three soil-arching evolution patterns in unreinforced piled embankments were observed in a series of two-dimensional (2D) model tests using a multitrapdoor test setup. These include the triangular expanding pattern, the tower-shaped evolution pattern, and the equal settlement pattern. The inclination of the slip surfaces and the height of the vertical slip surfaces that enclose the tower-shaped arches were found to be the critical parameters describing the arching evolution. Three analytical models were proposed to describe the evolution processes of the three arching-evolution patterns and to find the stress distributions of the corresponding processes. Load distribution equations were also derived from these models. Using the empirical relationships between the inclination of the slip surfaces and the tower height and settlement, the stress distribution ratio during the entire evolution process was calculated. The models matched the model tests well.