Multi-directional force–displacement response of underground pipe in sand

Abstract

Abstract:A methodology is presented to evaluate multi-directional force-displacement relationships for soil-pipeline interaction analysis and design. Large-scale tests of soil reaction to pipe lateral and uplift movement in dry and partially saturated sand are used to validate plane strain, finite element (FE) soil, and pipe continuum models. The FE models are then used to characterize force versus displacement performance for lateral, vertical upward, vertical downward, and oblique orientations of pipeline movement in soil. Using the force versus displacement relationships, the analytical results for pipeline response to strike-slip fault rupture are shown to compare favorably with the results of large-scale tests in which strike-slip fault movement was imposed on 250 and 400 mm diameter high-density polyethylene pipelines in partially saturated sand. Analytical results normalized with respect to maximum lateral force are provided on 360°plots to predict maximum pipe loads for any movement direction. The resulting methodology and dimensionless plots are applicable for underground pipelines and conduits at any depth, subjected to relative soil movement in any direction in dry or saturated and partially saturated medium to very dense sands.Key words: pipeline, Mohr-Coulomb, soil-pipe interaction, earthquake, liquefaction, ground failure.Résumé : Une méthodologie est présentée afin d'évaluer les relations force-déplacement multidirectionnel pour la conception et l'analyse des interactions sol-pipeline. Des essais à grande échelle de la réaction du sol aux mouvements latéraux ou au soulèvement de tuyau dans le sable sec et partiellement saturé servent à valider les modèles en déformation plane, les sols par élément fini (EF) et le continuum de tuyau. Les modèles EF sont ensuite utilisés pour caractériser les performances de force versus déplacement latéral, pour les orientations verticales, vers le haut, vertical vers le bas et obliques de mouvement du pipeline dans le sol. En utilisant les relations de force versus déplacement, les résultats des analyses pour une réponse à la rupture de faille par décrochement se comparent favorablement avec les résultats des essais à grande échelle, dont le mouvement de faille, par décrochement a été imposé à des pipelines en polyéthylène à haute densité de 250 et de 400 mm de diamètre dans du sable partiellement saturé. Les résultats analytiques normalisés en ce qui concerne la force latérale maximale sont fournis sur des parcelles de 360°pour n'importe quelle direction de mouvement. La méthodologie qui en résulte et les parcelles sans dimension sont applicables pour les pipelines souterrains et les conduits à n'importe quelle profondeur, sujettes à des mouvements de sol relatif dans tous les sens dans un milieu sec ou saturé et partiellement saturé aux sables très denses. [Traduit par la Rédaction] Mots-clés : pipeline, Mohr-Coulomb, interaction sol-tuyau, tremblement de terre, liquéfaction, échec de sol.

Development of a prototype for modelling soil–pipe interaction and its application for predicting uplift resistance to buried pipe movements in sand

“…Trautmann et al prepared sand beds at three different densities with ␥ = 14.8, 16.4, and 17.7 kN/m 3 , corresponding to loose (friction angle, = 31°), medium ( = 36°), and dense ( = 44°) CU sand, respectively, and tested pipes embedded at 1.5D, 4D, 8D, and 13D. For medium and dense CU sand, stress-dependent values of ps,p from Jung et al (2016) are used together with eq. (6) while for loose CU sand, a constant ps,p = 37.5°is considered.…”

Soil restraints on buried pipelines subjected to reverse-fault displacement

“…The design of pipelines to withstand the effects of large reverse fault displacements warrants inclusion of improved soil restraint boundary conditions that account for the reduction of vertical soil restraint as the pipe ploughs generally parallel to the fault dip plane (obliquely) through the backfill toward the ground surface. Except for a limited work addressing the problem of pipelines crossing faults (e.g., Hsu et al 2006;Hsu et al 2001;Jung et al 2016;Saiyar et al 2016;O'Rourke et al 2016), currently, there is a general absence of public literature relating to oblique soil restraint relationships, particularly relationships that have been validated by appropriate full-scale testing. To alleviate this gap in knowledge, a series of full-scale oblique-displacement pipe-soil interaction model tests have been undertaken at the University of British Columbia (UBC) Advanced Soil Pipe Interaction Research (ASPIRe TM ) laboratory.…”

“…Considering that the theory is based on soil block movements along an assumed failure surface, finite element or finite difference numerical analysis that has the ability to model the soil stiffness effects in a continuum basis should be considered for arriving at more robust assessments. The work undertaken by Jung et al (2016) is an example of the types of finite element analyses that can be employed. It is of relevance to note that the maximum horizontal (θ = 0°), inclined (θ = 45°), and vertical (θ = 90°) soil restraint values for sand generated from their work are also in good agreement with those presented herein.…”

Local Buckling Behavior and Plastic Deformation Capacity of High-Strength Pipe at Strike-Slip Fault Crossing

“…The soil-applied force on pipe or pile structures is commonly nonlinear, which can be described by the p-y curves derived by geotechnical researchers [12]. There is a lot of available literature on this topic, among which the design recommendations specified by the ASCE Guideline [46] and ASCE-ALA Guideline [39] is the most widely used one for design and assessment of buried pipelines.…”

“…Due to the restrictions of hydraulic loading facilities, experimental investigations were all focusing on low-to medium-strength steel pipes or high-density polyethylene (HDPE) pipes with similar nonlinear stress-strain response as steels. Ha et al [9,10] and O'Rourke et al [11,12] conducted centrifuge and full-scale tests of buried HDPE under compression strike-slip faults. Results show that these two methods derived similar pipe response with the similar parameters.…”