Mechanical Response and Soil Arching Mechanism of Buried Pipelines in Landslide Zones

Mechanics of Buried Pipelines Loading under Localized Subsidence: A Three-Dimensional Soil-Arching Approach

The combined effects of localized subsidence-induced size effects and pipe–soil interaction render conventional load calculation theories inadequate for accurately evaluating pipeline loads after foundation subsidence. To overcome this limitation, the 3D transfer characteristics of vertical loads acting on buried pipelines under localized subsidence are investigated from the perspective of the spatial deflection of 3D principal stresses and the evolution of stress trajectories. On this basis, a 3D soil arching model is established by incorporating the combined contributions of overburden self-weight, lateral passive earth pressure, and boundary friction. Further, a 3D pipe–soil load-transfer framework consisting of the top zone, the up zone, and the gap zone is constructed, through which a unified analytical expression for the vertical load at the pipe crown under localized subsidence is derived. The analytical predictions are validated against data from two laboratory trapdoor tests, which reveal considerable differences in pipeline crown loads between tests and pronounced variations in vertical earth pressure within the same test as trapdoor displacement increases. The results demonstrate that the proposed model provides a more comprehensive representation of stress redistribution in deformation zones induced by pipe–soil interaction under localized subsidence. By explicitly incorporating the geometric configuration and mechanical characteristics of the soil segments within the collapse area, the model offers enhanced explanatory power and predictive accuracy compared with traditional approaches.

Numerical Investigation of the Formation Mechanism and Mitigation of a Clayey Landslide Under Excavation–Rainfall Coupling

An excavation-induced clayey landslide in Jianshui County, Yunnan Province, China, threatens a national refined oil pipeline near the rear slope. Field investigation, borehole logging, laboratory testing, and three-dimensional finite-element analyses were integrated to investigate the excavation–rainstorm instability mechanism and evaluate circular anti-slide piles with toe backfilling. Under natural excavation, the reported factor of safety was 1.39, and the maximum displacement was 2.35 mm. Under a 60 mm/day rainstorm, increased pore-water pressure and saturation in the shallow sliding mass and strongly weathered claystone, together with saturated-state strength parameters, reduced the shear-strength reserve. The deformation and stability analyses yielded a maximum computed displacement of 1.36 m and a factor of safety of 0.95, respectively, indicating pronounced pre-failure deformation and loss of stability. After mitigation, the factor of safety increased to 1.41, while the maximum slope and pile-head displacements were both approximately 6.90 mm. The pile row redistributed nonuniform landslide thrust and reduced deformation transfer toward the pipeline. The results are site-specific engineering estimates for the investigated rainfall and parameter conditions.

Mitigation of Dynamic Load-Induced Pipeline Displacements Using EPS Geofoam

Seismic Response and Failure Mechanisms of Tunnels Constructed Using the Pipe Roof Preconstruction Method

Iterative Approach for Analyzing Jointed Pipeline Response Considering Pipeline‐Soil Gap Induced by Down‐Crossing Tunnel

In underground space engineering, the down‐crossing of a tunnel beneath an existing pipeline often leads to soil settlement beneath the pipeline, creating a gap between the pipeline and the soil. This can result in the loss of local support under the pipeline, significantly decreasing its safety and reliability. To analyze the effects of such gaps on pipelines, this study proposes a matrix transfer and iteration approach based on a discontinuous Timoshenko beam theory, aiming to evaluate the mechanical response of pipelines due to pipeline‐soil gap. Through the comparisons with centrifuge model tests, the accuracy and correctness of this approach are validated. Finally, a parameter analysis is conducted to exhibit the influence of ground loss volume, the trough width parameter, eccentricity, shear layer thickness, pipeline‐tunnel clearance ratio, and relative stiffness between the pipeline and soil on the pipeline responses. Based on the analysis results, some recommendations for practical engineering are provided.

Soil–Structure Interaction and Arching Effect for Buried Flexible Pipelines in an Induced Trench: Experimental and Numerical Investigation

Flexible culverts have been widely used in underground engineering, but the deformation control of buried flexible pipelines during trench backfilling remains challenging. In this study, foamed concrete was introduced as a lightweight backfill material below the pipe springline, with a maximum relative height of 0.5 D , and its influence on pipe–soil interaction and soil arching behavior was investigated through 1 g physical model tests and numerical simulations. The soil arching effect was evaluated using the relative deformation of the pipe and the normalized vertical stress ratio λ = σ v / σ i within a 1 D range of crown, where λ min and λ max were used to characterize load reduction and stress concentration, respectively. Based on these indices, the influence of foamed concrete height, pipeline number, and pipe diameter ratio on earth pressure distribution and structural deformation were analyzed. The experimental data showed reasonable agreement with the numerical results in terms of the overall deformation pattern, internal force distribution, and stress redistribution characteristics, indicating that soil arching played a major role in governing the mechanical response of the pipe–soil system. The results show that foamed concrete placed below the pipe springline effectively reduced pipe deformation by improving support stiffness around the pipe invert and lower pipe region, but it also restrained the differential soil deformation required for the development of positive soil arching above the crown. Compared with the single-pipe configuration, the double-pipe configuration produced an overlapping arching effect between adjacent pipes and formed a double-arched stress redistribution pattern in the surrounding soil. Parametric analyses further indicated that the modulus and height of foamed concrete, pipe diameter, burial depth, trench base width, and pipe clearance significantly affected λ min , λ max , and the development of soil arching.