Simulation of the Mechanical Response Characteristics of Buried Pipelines in Mountain Landslide Areas and Optimisation of Anti-landslide Piles

As energy pipeline networks expand into increasingly complex geological regions, mountain landslides present a significant threat to the safety of buried pipelines. This study develops a nonlinear finite element model of landslides, soil, and circular piles using ANSYS software, grounded in a case study of a buried pipeline project in a landslide-prone area in Southwest China, characterised by an arc-shaped landslide surface. By employing the nonlinear contact finite element method and integrating the coupled mechanics of the pipe-soil-pile system, this research investigates in depth how landslide displacement and anti-landslide pile parameters (spacing and outer diameter) influence the mechanical response of the pipeline. The findings reveal that as landslide displacement increases from 1.0 to 1.8 m, the pipeline’s maximum axial tensile stress rises from 467 to 613 MPa, while compressive stress increases from −298 to −575 MPa. The resulting strain notably exceeds the allowable threshold specified in industry codes, thereby escalating the risk of pipeline failure. For the optimisation of anti-landslide pile parameters, reducing the pile spacing from 6 to 4 m decreases tensile stress on the pipeline’s landslide-facing side, while increasing the pile diameter from 1.2 m to 1.5 m lowers the pipeline’s maximum equivalent stress. Based on these results, an optimal design scheme of anti-landslide piles based on key parameters of pipelines affected by landslides: in high-risk areas, a local densification scheme with 4 m pile spacing and 1.5 m pile diameter is adopted; in low-risk areas, a configuration of 6 m spacing and 1.2 m diameter is used to balance safety and economy. This study validates the applicability of the strain design criterion in anti-landslide pile optimisation. The model and optimisation strategy outlined herein provide theoretical support and practical guidance for the safety design of pipelines in landslide-prone regions and related disaster prevention and control efforts.