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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. [ABSTRACT FROM AUTHOR]

The failure mode of the soil behind the rigid support structure of excavations parallel to tunneling was simulated using the adaptive finite-element limit analysis method. This study showed the effects of tunnel diameter, tunnel construction clear spacing, excavation insertion ratio, and soil strength on the failure mode of the soil. Based on the simulated results obtained from finite-element software, a stress field was constructed for the portion above the horizontal plane at the bottom of the excavation support structure. Three types of boundary value problems were solved based on different regional divisions. Eventually, the stress state at any point within the plastic zone was calculated, providing the active earth pressure on the support structure adjacent to the tunnel during its construction. A comparison between the stress characteristic method calculation results and the finite-element simulation results showed consistency, confirming the efficiency and accuracy of the stress characteristic method in calculating the earth pressure on the support structure of excavations parallel to tunneling. [ABSTRACT FROM AUTHOR]

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Copyright of Rare Metals is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)