Permanent earthquake‐induced actions in buried pipelines: Numerical modeling and experimental verification

Abstract

Summary Buried pipelines are often constructed in seismic and other geohazard areas, where severe ground deformations may induce severe strains in the pipeline. Calculation of those strains is essential for assessing pipeline integrity, and therefore, the development of efficient models accounting for soil‐pipe interaction is required. The present paper is aiming at developing efficient tools for calculating ground‐induced deformation on buried pipelines, often triggered by earthquake action, in the form of fault rupture, liquefaction‐induced lateral spreading, soil subsidence, or landslide. Soil‐pipe interaction is investigated by using advanced numerical tools, which employ solid elements for the soil, shell elements for the pipe, and account for soil‐pipe interaction, supported by large‐scale experiments. Soil‐pipe interaction in axial and transverse directions is evaluated first, using results from special‐purpose experiments and finite element simulations. The comparison between experimental and numerical results offers valuable information on key material parameters, necessary for accurate simulation of soil‐pipe interaction. Furthermore, reference is made to relevant provisions of design recommendations. Using the finite element models, calibrated from these experiments, pipeline performance at seismic‐fault crossings is analyzed, emphasizing on soil‐pipe interaction effects in the axial direction. The second part refers to full‐scale experiments, performed on a unique testing device. These experiments are modeled with the finite element tools to verify their efficiency in simulating soil‐pipe response under landslide or strike‐slip fault movement. The large‐scale experimental results compare very well with the numerical predictions, verifying the capability of the finite element models for accurate prediction of pipeline response under permanent earthquake‐induced ground deformations.

Pipeline Performances under Earthquake-Induced Soil Liquefaction: State of the Art on Real Observations, Model Tests, and Numerical Simulations

“…Sarvanis et al [39] evaluated the soil-pipe interaction in axial and transverse directions. In the first case, the principle is that the soil resistance develops due to the friction at the soil-pipe interface.…”

“…e following options were addressed: (i) beam on elastic springs; (ii) shell model for large diameter buried pipelines; (iii) plane-strain model of the structure; and (iv) hybrid model. Sarvanis et al [39] identified two different approaches to the problem of buried pipelines subjected to PGD: the less-refined method of modelling the pipe as a beam element while nonlinear springs are deployed to describe the soil behaviour and a more advanced method that defines the pipe with shell elements and the soil with solid elements. In addition, Karamitros et al [44] proposed an approach that weaves the main features of both methodologies, by considering shell elements to define the pipe behaviour and nonlinear spring elements to describe the soil constitutive behaviour.…”

“…A strong effort to simulate the pipeline response under seismic loads, with a specific focus on the crossing of active faults, was taken within the GIPIPE research project [53]. In this framework, Sarvanis et al [39] performed a wide experimental program of numerical analyses with a view to evaluate the parameters to be defined for a proper prediction of the soil-structure interaction when a pipeline is subjected to deformations generated by an earthquake. In the finite element context, 4-node reduced-integration shell elements were adopted to define the cylindrical pipeline, while 8-node reduced-integration brick elements were selected for the soil.…”

Can a buried gas pipeline experience local buckling during earthquake ground shaking?

“…Standard Coulomb friction is chosen to describe the relative tangential motions which can be arbitrarily large, while loss of contact in the normal direction (detachment) is allowed at the same time. More realistic empirical models for axial SPI have been recently reported in the literature [58] that account for soil dilatancy effects and post-peak soil resistance decay, but are not adopted herein. The surface-to-surface contact discretization option is used in the Abaqus environment, which in this case ensures coupling between the tangential and normal components of relative motion.…”

A critical review on the vulnerability assessment of natural gas pipelines subjected to seismic wave propagation. Part 1: Fragility relations and implemented seismic intensity measures

“…An increasing seismic vulnerability of NG pipelines was actually reported on steel pipelines that were previously weakened by corrosion or poor quality welds (EERI, 1986;Gehl et al, 2014). Permanent ground deformations commonly induce a higher straining on the steel pipelines, compared to transient ground deformations; therefore, most research efforts have been mainly focused on this seismic hazard (Karamitros et al, 2007;Vazouras et al, 2010;Vazouras et al, 2012;Kouretzis et al, 2014;Vazouras et al, 2015;Vazouras et al, 2016;Karamitros et al, 2016;Melissianos et al, 2017aMelissianos et al, , 2017bMelissianos et al, , 2017cDemirci et al, 2018;Sarvanis et al, 2018,;Tsatsis et al 2018, among many others). However, statistically it is more likely for a pipeline to be subjected to transient ground deformations rather than seismically induced permanent ground deformations.…”