A refined analytical model for landslide or debris flow impact on pipelines – Part II: Embedded pipelines

In deepwater, the pipeline is directly laid on the seabed without any protection, but the heavy pipelines will embed into the seabed during installation. The behavior of heavy pipeline under the impact of landslide is different from that of light pipeline because the heavy pipeline will move downwards when moving laterally under the impact of landslide. This work divides the pipeline into four segments: the first segment in the landslide zone, which is exposed to landslide drag force and nonlinear lateral soil resistance; the second one adjacent to the landslide zone, which is only externally loaded by lateral soil resistance; the third one is further away from the landslide, which is loaded by linearly increasing lateral soil resistance; the last segment is uniquely loaded by axial resistance. The governing equations of the four segments are expressed according to their different loading conditions, and an equation system is established on the basis of boundary conditions and continuity conditions. The final solution is obtained through a numerical method. The model proves to be simple and reliable. The parametric study reveals that the behaviors of heavy pipelines are different from those of the surface light ones.

► In this study we investigate the pipeline behavior in submarine landslides.
► The study is based on a refined analytical model.
► We find that the heavy pipeline has better stability and safety than the light pipeline in landslide.
► Larger landslide width does not mean a greater risk to pipeline safety for heavy pipelines.
► The increases in axial soil resistance induces larger peak pipeline strain.
► The bending strain is an important component of the combined strain.