简介：Monolithicstoppersplayaveryimportantroleincontinuouscasting(shortforCC).Sometimes,thestopperslaglineisseriouslyerodedandbroken,CChastopause.Theresearchshowsthattherearethreemainreasonswhichbringsevereerosionofmonolithicstopperslagline.Firstly,muchFe_2O_3andMnOinslagreactwithcarbon(C)inthestopper,Cisgraduallyerodedanderosionresistanceofthestoppergreatlyweakens.Secondly,Fincreaseintundishcoveringfluxwillquickenerosionofthestopperslagline.Thirdly,HighLOIoftundishcoveringfluxalsomakeserosionofthestopperslaglinespeedup.Ononehand,CaCO_3intundishcoveringfluxdecomposesandbringsCO_2;ontheotherhand,mineralswithwaterintundishcoveringfluxdecomposeathightemperaturesandbringwatervapor.ThenCO_2andwatervaporreactwithCinthestopper,Cisgraduallyeroded,aggravatingtheerosion.

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：Retrogressiveerosion,awidespreadphenomenonofsedimenttransportinreservoirs,oftenimpactsonboththereservoircapacityandthesedimentationinthedownstreamriverchannel.BasedonfielddatafromtheSanmenxiaReservoirandtheLowerYellowRiveroverthepastdecades,threecoursesofretrogressiveerosionwithdistinctivefeatureswereanalyzed.Theresultsindicatethatretrogressiveerosion,especiallycausedbyrapidreductioninthewaterleveltillthereservoirisempty,oftenresultsintheserioussiltationofthelowerYellowRiverandthreatensthesafetyofthefloodcontrolintheLowerYellowRiver.Unreasonableoperationofthereservoirandincominghyperconcentratedfloodsaccompaniedbyretrogressiveerosionalsoaggravatethesiltationofthemainchanneloftheriver.However,areasonableoperationmodeofthereservoirsonamed”storingtheclear(lowsedimentconcentration)waterinthenon-floodseason,andsluicingthemuddy(highsedimentconcentration)waterinthefloodseason”wasfound,whichmightmitigatethedepositioninboththereservoirandtheLowerYellowRiver.Thisoperationmodeprovidesimportantexperienceforthedesignandoperationoflargereservoirsinotherlargeriverscarryinghugeamountsofsediment.