Numerical Analysis of Imperceptible Mechanical Behavior in Soil Arch Evolution

The trapdoor test has been widely used to study engineering scenarios where pressure calculation methods need to be re-evaluated due to relative soil displacements. To propose a more reasonable calculation theory, over the past few decades, researchers have primarily focused on understanding soil deformation mechanisms and stress evolution on the surface of the trapdoor. However, the limited availability of experimental data has hindered the development of a universally accepted theory. In contrast, FEMs offer a powerful tool for capturing more comprehensive and precise stress–strain information. In this study, various active trapdoor models were established, each with a width of 2 m and differing burial depths, using the FEM. By integrating the ground reaction curve, the normalized stress distribution on the trapdoor was analyzed to reveal significant stages in soil stress evolution. Additionally, the Mohr–Coulomb failure criterion was applied to differentiate between sliding and failure surfaces, shedding light on the evolution trend of the failure surface. Moreover, three lines and four points were selected to monitor the evolution of principal stresses in the soil. Drawing on principles of plane strain mechanics, the distributions and evolutions of the three principal stresses were presented in the xy-plane using vector graphics. Notably, this study highlights the crucial role of the intermediate principal stress in soil arch calculation theory.