简介：Athree-stepfiniteelementmethod(FEM)togetherwithLargeEddySimulation(LES)isap-pliedtoincompressibleturbulentflowaroundseabedpipelinesatrelativelyhighReynoldsnumbers.Bothtwo-dimensionalandthree-dimensionalnumericalsimulationiscarriedouttodeterminethethree-dimensionaleffect.Theresultsofnumericalsimulationagreequitewellwiththewaveforcesactingonpipelinemodelsmeasuredinphysicalmodeltest.

简介：BasedonBiot'sconsolidationtheory,atwo-dimensionalmodelforcomputationoftheseabedresponsetowavesispresentedwiththefiniteelementmethod.Numericalresultsfordifferentwaveconditionsareobtained,andtheeffectsofwavenon-linearityonthewave-inducedseabedresponseareexamined.Moreover,thewave-inducedmomentaryliquefactioninuniformandinhomogeneousseabedsisinvestigated.Itisshownthatthewavenon-linearityaffectsthedistributionofthewave-inducedporepressureandeffectivestresses,whiletheinfluenceofwavenon-linearityontheseabedliquefactionpotentialisnotsosignificant.

简介：Wave-inducedtransientresponseofdisplacements,effectivestressesandporepressureinsaturateseabedaresalvedbyaconsolidationfiniteelementmethod.Theinfluenceoftheresponsestothestabilityofseabedandcoastalstructuresisshownbyanimprovedslicemethodwithcirculararcslipsurface.Dynamicelasticconsolidationtheoryandlinearpermeabilitytheoryareemployedinthesolutionofseabedresponse.Theseabedcanbeconsistedoflayeredsoilwitharbitraryboundaries.Theactingwavecanberegularorirregular.Irregularwavepressureactingonthesurfaceofseabediscalculatedbylinearsuperpositionmethod.Wave-inducedexcessstressontheslipsurfaceisconsideredinthestabilityanalysis.Thespatialandtemporalvariationsofporepressureinsandyseabedcomparewellwithexperiment.Calculationsforaverticalbreakwatershowthatthesafetyfactorofseabedandstructurewilldecreaseifwave-inducedseabedresponseisconsidered.Thescopeofdecreaseismainlyre

简介：Inestuarineandcoastalareas,theseabedisinaconstantprocessofdynamicchangeundermarineconditions.Seabedsedimenterosionandresuspensionareimportantprocessesthatsafelycontrolthegeologicalenvironment.FieldtripodobservationsconductedintheJiaozhouBayinChinaarereported,toinvestigatetheeffectsofhydrodynamicconditionsontheerosionandresuspensionprocessesoftheseabed.Theobservationalresultsshowthatthemaximumshearstresscreatedbytidalcurrentscanreach0.35N/m~2,whichishigherthanthewave-inducedshearstressduringfairweatherconditions.Aseabederosionfrequentlyoccursduringthefloodtide,whereasaseabeddepositionoccursduringebbtide.WavescanproduceabottomshearstressapproximatelyequivalenttothatinducedbycurrentswhenthelocalwindreachesForce4withaspeedof5m/s.Whenthewindreaches7m/sandthesignificantwaveheightreaches26cm,wavesplayamoresignificantrolethancurrentsinthedynamicprocessesoftheseabedsedimentresuspensionandleadtoahighvalueofturbiditythatisapproximatelytwotoeighttimeshigherthanthatinfairweather.Theseanalysesclearlyillustratethatperiodiccurrent-inducedsedimenterosionandresuspensionaredominantinfairweather,whereasepisodichighwavesareresponsibleforsignificantsedimentresuspension.AdditionalworkisneededtoestablishamorethoroughunderstandingofthemechanismsofsedimentdynamicsintheJiaozhouBay.

简介：Anewseabedsedimentfidelitysamplerwasdevelopedanditsthermalinsulationperformancewasstudiedandanalyzed.Thetemperaturedistributionsimulationindicatedthatthesamplequalitycouldbeinsuredbyusingthisnewsampler.BasedonANSYS10,thetemperaturefiniteelementmodelofthesamplecylinderwasestablished.Accordingtothelawofconservationofenergy,theunsteadyheattransmitequationofthesamplerundersolid-liquidcouplingconditionwasderived,thenthemathematicalmodelcalculationwascarriedoutbyusingamixedfinite-elementfinite-differencemethod,andtwothermalinsulationmethodswereused.Thesimulationwascarriedoutbyusingthethicknessofthethermalinsulationlayerandheatconductivityasthevariableparametersandthetemperaturedistributionofthesamplerandrelatedinfluencingfactorswereobtained.Optimizationanalysiswasconductedusingthesimulationdataandrelatedparametersandthemagnituderangesoftheparameterswereobtainedthatcouldmeetthedesigntemperaturerequirements.Theexperimentaldataandsimulationresultsindicatedthattheresultswereingoodagreementwiththerealities,andthissamplermightbeofvalueforseabedsedimentsamplerdesignandmanufacture.

简介：Anumericalmodel,EvolutionEquationofMild-SlopeEquation(EEMSE)developedbyHsuetal.(2003),wasappliedtostudytheBraggreflectionofwaterwavesoveraseriesofrectangularseabed.ThreekeyparametersoftheBraggreflectionincludingthepeakcoefficientofprimaryBraggreflection,itscorrespondingrelativewavelength,andthebandwidth,haveshowntobeeffectiveindescribingthecharacteristicsoftheprimaryBraggreflection.ThecharacteristicsoftheBraggreflectionwereinvestigatedunderthevariousconditionscomprisingnumber,height,andspacingintervalofaseriesofrectangularseabed.TheresultsrevealthatthepeakofBraggreflectionincreaseswiththeincreaseofrectangularseabedheightandnumber,thebandwidthandtheshiftvalueoftheBraggreflectiondependontheincreaseoftherectangularseabedheightaswellasthedecreaseofrectangularseabednumber,andtherelativerectangularseabedspacingintherangof3and4couldproducehigherBraggreflection.Finally,acorrelativeandregressiveanalysisisperformedbyuseofthecalculateddata.Basedontheresultsoftheanalysis,empiricalequationswereestablished.Ourstudyresultscanprovideanappropriatechoiceofaseriesofrectangularseabedfieldforapracticaldesign.

简介：-Thecyclicrotationofprincipalstressdirectionwithaconstantamplitudeisthecharacteristicsofcyclicstressinseabeddepositinducedbytravellingwaves.Presentedinthepaperaretheresultsobtainedfromtestssimulatingthecyclicstresscharacteristics,withemphasislaidonthebuildupofporewaterpressureinsoilsamples.Regressionanalysisoftestdatashowsthattheporewaterpressurecanbeexpressedasthefunctionofthenumberofcyclesofcyclicloading,orasthefunctionofgeneralizedshearstrain.Usingtheresultsthusobtained,thepossibilityoffailureofseabeddepositundercyclicloadinginducedbytravellingwavescanbeevaluated.Thecomparisonwiththeresultsofconventionalcyclictorsionalsheartestsshowsthatneglectoftheeffectofthecyclicrotationoftheprincipalstressdirectionwillresultinconsiderableover-estimationofthestabilityofseabeddeposit.

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简介：在经历8天的联合潮汐的电流，循环和波浪行动以后，搜索包围自由地在1月在华东海(ECS)在沙的海床上休息的柱体目标的深度数字地用设计为的DRAMBUIE模型被预言广泛地搜索埋葬，它是使用并且验证由在原处实验。在数字集成的时期期间，timet的值通常是可变的在每次，经由特殊走时间的途径的步由这份报纸发展了消除时间错误。潮汐的当前的速度，波浪在ECS的轨道的速度和平均深度的发行量被数字模拟与沿海的河口和海洋模型(ECOM)获得了，模仿的波浪Nearshore(天鹅)模型和地区性的海洋建模系统(ROMS)分别地当模特儿。有影响的因素在的控制实验和几个理想化的测试用例搜索深度表明主导的水动力学因素是在在正常天气条件下面的ECS的潮汐的电流，并且本地人上的循环和波浪运动搜索的架的影响能几乎与自台湾东面的菲律宾海流向日本的暖流的高速度的主流流动的自台湾东面的菲律宾海流向日本的暖流区域的一个例外被忽略。这也被显示在沙的沉积，分发将近搜索深度跟随潮汐的水流的模式，当时第二等的影响因素在上搜索深度看起来是在ECS的沙的沉积的谷物尺寸。沉积谷物尺寸上的数字测试进一步证明那么更好的沙容易搜索的更多，和一个增加的趋势为与谷物尺寸的减小搜索深度由于更大的大小的粒子的强加的电阻被显示。三个方面由这篇论文探索了，包括在防卫研究机构矿埋葬环境(DRAMBUIE)模型，的实验方程输入和填入过程的精确性能严重地影响预言搜索包围自由地在ECS在沙的海床上休息的柱体目标的深度。

简介：Ascientifichypothesisisproposedandpreliminarilyverifiedinthispaper:underthedrivingofseepageflows,theremightbeaverticalmigrationoffine-grainedsoilparticlesfrominteriortosurfaceofseabed,whichisdefinedas‘sub-bottomsedimentpumpaction’inthispaper.FieldexperimentswereperformedtwiceontheintertidalflatoftheYellowRiverdeltatostudythisprocessviabothtrappingthepumpedmaterialsandrecordingtheporepressuresinthesubstrate.Experimentalresultsarequiteinterestingaswedidobserveyellowslurrywhichismainlycomposedoffine-grainedsoilparticlesappearingontheseabedsurface;seepagegradientswerealsodetectedintheintertidalflat,undertheactionoftidesandsmallwindwaves.Preliminaryconclusionsarethat‘sedimentpump’occurswhenseepageforceexceedsacertainthreshold:firstly,itisbigenoughtodisconnectthesoilparticlesfromthesoilskeleton;secondly,thedegreeofseabedfluidizationorbioturbationisbigenoughtoprovidepreferredpathsforthedetachedmaterialstomigrateupwards.Thentheywouldbefirstlypumpedfrominteriortothesurfaceofseabedandtheneasilyre-suspendedintooverlyingwatercolumn.Influentialfactorsof‘sedimentpump’aredeterminedashydrodynamics(waveenergy),degreeofconsolidation,indexofbioturbation(permeability)andcontentoffine-grainedmaterials(sedimentaryage).Thisnewperspectiveof‘sedimentpump’mayprovidesomeimplicationsforthemechanisminterpretationofseveraluncleargeologicalphenomenaintheYellowRiverdeltaarea.