简介:Thestabilityofasubmarinepipelineontheseabedconcernstheflow-pipe-soilcoupling,withinfluentialfactorsrelatedtotheoceanwavesand/orcurrents,thepipelineandthesurroundingsoils.Aflow-pipe-soilcouplingsystemgenerallyhasvariousinstabilitymodes,includingtheverticalandlateralon-bottominstabilities,thetunnel-erosionoftheunderlyingsoilandthesubsequentvortex-inducedvibrations(VIVs)offree-spanningpipelines.Thispaperreviewstherecentadvancesoftheslip-linefieldsolutionstothebearingcapacity,theflow-pipe-soilcouplingmechanismandthepredictionforthelateralinstability,themulti-physicalcouplinganalysisofthetunnel-erosion,andthecouplingmechanicsbetweentheVIVsandthelocalscour.Itisrevealedthatthemechanismcompetitionalwaysexistsamongvariousinstabilitymodes,e.g.,thecompetitionbetweenthelateral-instabilityandthetunnel-erosion.Finally,theprospectsandscientificchallengesforpredictingtheinstabilityofalong-distancesubmarinepipelinearediscussedinthecontextofthedeep-wateroilandgasexploitations.
简介:Theinitiationofpipelinespanninginvolvesthecouplingbetweentheflowoverthepipelineandtheseepage-flowinthesoilunderneaththepipeline.Thepipelinespanninginitiationisexperimentallyobservedanddiscussedinthisarticle.Itisqualitativelyindicatedthatthepressure-dropinducedsoilseepagefailureisthepredominantcauseforpipelinespanninginitiation.Aflow-pipe-seepagesequentialcouplingFiniteElementMethod(FEM)modelisproposedtosimulatethecouplingbetweenthewaterflow-fieldandthesoilseepage-field.Acriticalhydraulicgradientisobtainedforobliqueseepagefailureofthesandinthedirectiontangenttothepipe.Parametricstudyisperformedtoinvestigatetheeffectsofinflowvelocity,pipeembedmentonthepressure-drop,andtheeffectsofsoilinternalfrictionangleandpipeembedment-to-diameterratioonthecriticalflowvelocityforpipelinespanninginitiation.Itisindicatedthatthedimensionlesscriticalflowvelocitychangesapproximatelylinearlywiththesoilinternalfrictionangleforthesubmarinepipelinepartially-embeddedinasandyseabed.