Uniform support from the surrounding soil is important for maintaining the stable operation of buried pipelines. For segmented prestressed concrete cylinder pipe (PCCP), localized soil voids around the joint due to leakage or engineering activities make the pipe unsupported partially and threaten its integrity and strength. In this paper, the impact of a localized soil void on a pipe joint is qualitatively assessed using a beam-on-elastic-spring approximation model. It further provides quantitative analysis through a nonlinear finite element (FE) model of PCCPs and the surrounding soil. The derived algebraic solutions indicate that a unilateral local void induces shear force and rotation at the joint, whereas shear force becomes negligible when the void spans the joint, leading to increased rotation. Moreover, the rotation angle shows a positive correlation with soil load and a negative correlation with pipe diameter. Numerical analysis reveals that void elongation along the pipe length has a more pronounced effect on structural response than void depth and angle. When the void length reaches 2.5 m, the maximum principal stress on the mortar layer of the PCCP increases approximately eight-fold compared to the scenario without voids. Due to the rigidity and safety factor of the PCCP, small voids in the bedding typically do not cause immediate pipe damage or joint leakage; however, they can significantly alter the stress distribution within both the pipe and surrounding soil. As the void develops, the soil may collapse and compromise support, leading to additional secondary disaster risks and potential threats to pipeline safety. This research emphasizes the importance of effective pipe-soil interactions and provides theoretical insights for developing repair strategies for PCCP.

This study conducted five centrifuge model tests to investigate the deformation characteristics of the Geosynthetics Reinforced Soil (GRS) abutments under vertical loads, considering the setback distance ab and beam seat width B as two major influencing factors. Test results show that a linear correlation existed between the maximum lateral facing displacements DL and the maximum settlements at the top of the GRS abutments Dv. The ab and the B had different effects on the deformation characteristics of the GRS abutments as well as the relationship between the DL and the Dv. The total volumetric strains of the GRS abutments were smaller than 0.3% for all the cases investigated in this study, indicating that it was reasonable to use the assumption of zero-volume change for the deformation calculation of the GRS abutments. This study proposed an improved semiempirical method to describe the relationship between the DL and the Dv. Centrifuge test results and data collected from the literature were used to validate the improved method. It was concluded that the improved method had the advantage of considering the effects of the ab and the B separately and therefore significantly improved the prediction accuracy of the deformations of the GRS abutments.

With the rapid development of urban rail transit systems, the shield tunneling technology has become indispensable for urban tunnel construction. However, the theoretical study of the shield tunneling process is not mature enough in view of the complex mechanical properties of the shield machine and the surrounding soil. In this paper, the attitudinal change behavior of earth pressure balanced shield machines (EPB) during the tunneling process is investigated, and comprehensive theoretical expressions for the normal and frictional forces acting on the shield periphery and cutter face are derived. The discretization equations for the normal forces acting on the shield periphery are given based on the meshing and interpolation method. Based on the above studies, the mechanical equilibrium equations of the shield are established to accurately solve for the shield forces and shield attitude characteristics, as well as to verify the computational accuracy of the theoretical solution. Through the analysis of a practical project involving longitudinal tunneling, it is confirmed that the theoretical calculation model can better reflect the mechanical behavior of the earth pressure balanced shield.