还剩6页未读,继续阅读
文本内容:
附录英文论文Thecharacteristicsofearth-rockDAMSandtechnicalcontrol
1.selectionofembankmenttypeIngeneraltherearetwotypesofembankmentdams:earth(earthfilldam)androckfill(rockfilldam).Theselectionisdependentupontheusable__terialsfromtherequiredexcavationandavailableborrow.Itshouldbenotedthatrockfillscanshadeintosoilfillsdependinguponthephysicalcharacteroftherockandthatnohardandfastsystemofclassificationcanbe__de.Rockswhicharesoftandwilleasilybreakdownundertheactionofexcavationandpla__mentcanbeclassifiedwithearthfills.Rockswhicharehardandwillnotbreakdownsignificantlyaretreatedasrockfills.Theselectionandthedesignofanearthembankmentarebaseduponthejudgementandexperien__ofthedesignerandistoalargeextentofanempiricalnature.Thevariousmethodsofstabilityandseepage____ysisareused__inlytoconfirmtheengineer’sjudgement
2.freeboardAllearthdamsmusthavesufficientextraheightknownasfreeboardtopreventovertoppingbythepool.Thefreeboardmustbeofsuchheightthatwaveactionwindsetupandearthquakeeffectswillnotresultinovertoppingofthedam.Inadditiontofreeboardanallowan__mustbe__deforsettlementoftheembankmentandthefoundationwhichwilloccuruponcompletionoftheembankment.
3.topwidthThewidthoftheearthdamtopisgenerallycontrolledbytherequiredwidthoffillforeaseofconstructionusingconventionalequipment.Ingeneralthetopwidthshouldnotbelessthan30ft.ifadangerexistsofanovertoppingwavecausedeitherby__ssivelandslidesinthepoolorbysei__icblocktippingthenextratopwidthoferosionresistivefillwillberequired.
4.alig__entThealig__entofanearthfilldamshouldbesuchastominimizeconstructioncostsbutsuchalig__entshouldnotbesuchastoencourageslidingorcrackingoftheembankment.Nor__llytheshorteststraightlineacrossthevalleywillbesatisfactorybutlocaltopographicandfoundationconditions__ydictateotherwise.Damslocatedinnarrowvalleysoftenaregivenanalig__entwhichisarchedupstreamsothatdeflectionsoftheembankmentunderpoolloadwillputtheembankmentincompressionthusminimizingtransversecracking.
5.AbutmentsThreeproblemsaregenerallyassociatedwiththeabutmentsofearthdams:
①seepage
②instabilityand
③transversecrackingoftheembankment.Iftheabutmentconsistsofdepositsofpervioussoilsit__ybene__ssarytoconstructanupstreamimperviousblanketanddownstreamdrainagemeasurestominimizeandcontrolabutmentseepage.Wheresteepabutmentsexistespeciallywithsuddenchangesofslopesorwithsteepbluffthereexistsadangeroftransversecrackingoftheembankmentfills.Thiscanbetreatedbyexcavationoftheabutmenttoredu__theslopeespeciallyintheimperviousandtransitionzones.Thetransitionzonesespeciallytheupstreamshouldbeconstructedoffillswhichhavelittleornocohesionandawell-distributedgradationofsoilswhichwillpromoteself-healingshouldtransversecrackingoccur.
6.stageconstructionItisoftenpossibleandinsomecasesne__ssarytoconstructthedamembankmentinstages.Factorsdictatingsuchapro__dureare:
①awidevalleypermittingtheconstructionofthediversionoroutletworksandpartoftheembankmentatthesametime;
②aweakfoundationrequiringthattheembankmentnotbebuilttoorapidlytopreventoverstressingthefoundationsoils;
③awetborrowareawhichrequiresaslowconstructiontopermitanincreaseinshearstrengththroughconsolidationofthefill.Insomecasesit__ybene__ssarytoprovideadditionaldrainageofthefoundationorfillbymeansofsanddrainwellsorbymeansofhorizontalperviousdrainageblanket.
7.EmbankmentsoilsMostsoilsaresuitableforuseforembankmentconstructionhowevertherearephysicalandchemicallimitationssoilswhichcontainex__ssivesaltsorothersoluble__terialsshouldnotbeused.Substantialorganiccontentshouldnotexistinthesoils.Lignitesufficientlyscatteredthroughthefilltopreventthedangerofspontaneouscombustionisnotobjectionable.Fatclayswithhighliquidlimits__yprovedifficulttoworkandshouldbeavoided.
8.CompactionrequirementsThestrengthoftheimperviousandsemi-impervioussoilsdependsuponthecompacteddensities.Thesedependinturnuponthewatercontentandweightofthecompactingequipment.Thedesignoftheembankmentisthusinfluen__dbythewatercontentoftheborrowsoilsandbythepracticablealternationstothewatercontenteitherpriortopla__mentofthefillorafterpla__mentbutpriortorolling.Ifthenaturalwatercontentistoohighthenit__yberedu__dinborrowareabydrainageorbyharrowing.Ifthesoilistoodryitshouldbemoistenedintheborrowareaeitherbysprinklingorbypondingandthenpermittedtostabilizethemoisturecontentbeforeuse.Therangeofpla__mentwatercontentisgenerallybetween2per__ntdryto2or3per__ntwetofthestandardPorteroptimumwatercontent.Pervioussoilsshouldbecompactedtoatleast80per__ntofrelativedensity.Ifne__ssarytestfillsshouldbeconstructedwithvariationsinpla__mentwatercontentliftthicknessnumberofrollerpassesandtypeofrollers.Forcasesofsteepabutmentthefillmustbepla__dinthinliftsandcompactedbymechanicalhandtampers.Alloverhangsshouldeitherberemovedorfilledwithleanconcretepriortofillpla__ment.
9.typesofinstrumentsThetypeofinstrumentationdependsuponthesizeandcomplexityoftheproject.Thedevi__sincommonuseare:
①piezometers;
②su_____movementmonuments;
③settlementgadges;
④inclinometers;
⑤internalmovementandstrainindicators;
⑥pressure__lls;
⑦sei__icac__lerationmeter;
⑧movementindicatorsatconduitjointsandotherconcretestructures中文译文土石坝的特征及筑坝技术控制
1、土石坝坝型的选择一般来说,土石坝有两种类型土坝和堆石坝坝型的选择取决于能从需要开挖的地点和可用的料场处取得合用材料的情况应当指出的是,根据岩石的物理特性,堆石可以逐渐变化为填土,因而不能对土石料作出严格而固定的分类那些软弱的和在开挖填筑时容易破碎的岩石可被归入填土类而坚硬和不会大量破碎的的岩石,则列为堆石类一座土坝的选定和设计都有赖于设计人员的判断和经验,而且在很大程度上是属于经验性的各种稳定和渗透分析方法,主要是作为证实工程师的判断而使用的
2、超高所有的土坝都必须有一个足够的额外高度,称为超高,以防止水库漫顶超高的高度必须足以在波浪作用、风浪壅高和地震影响下,不会导致坝的漫顶除了超高外,对于坝建成时发生的坝体和地基沉陷,还必须在高度上留有余地坝顶宽度土坝的坝顶宽度一般用常规设备便于施工的填筑宽度来控制通常,坝顶宽度应不小于30英尺如果存在着大规模塌方进入水库,或者有因地震使岩块倒落而引起波浪漫顶的危险,则需要采用抗冲刷的材料填筑更宽的坝顶高度定线土坝的坝轴线选定应尽量使建设费用降到最少,但是也不能因此引起坝体发生滑动或开裂一般来说,一条横跨河谷的最短的直线,可能满足要求但是,当地的地形和地基条件可能要求采用另外的方案对于峡谷的坝,常采用向上游拱出的坝轴线,以便在坝体受库水压力作用而发生变形时,能使坝体压紧,从而尽量减少其横向开裂
5、两岸坝座一般有三个问题与土坝坝座有关
①渗透;
②不稳定;
③坝体的横向开裂如果坝座是由透水的沉积土构成,就可能需要建造一道上游不透水的铺盖和下游排水设施,可尽量减少和控制坝座内的渗透在坝座岸坡很陡的地方,特别在边坡突变或有陡壁处,那里的坝体填土会产生横向裂缝的危险这个问题可以用开挖坝座放缓边坡来处理,这样的处理在不透水区和过渡区特别需要过渡区,尤其是在上游侧的过渡区,必须用粘着力很小或无粘着力且颗粒级配良好的土料来填筑,这种土料如发生横向裂缝时能自行愈合
6、分期施工土坝的分期施工往往是可能的,而且在一些情况下是必须的要求这样施工程序的因素是
①河谷宽阔,可以允许导流或泄水工程与一部分坝体同时施工;
②地基软弱,要求坝体不要过快填筑,以防止地基中产生过大的应力;
③料场潮湿,要求放慢施工,以使土料能通过固结作用来增加抗剪强度在某些情况下,可以需要增设基础排水设施或填筑排水沙井,或采用水平透水的排水铺盖
7、坝体的土料大多数土料适合于坝体填筑,然而,在物理和化学性质上也有一定的局限,含有过多盐和可溶性物质的土料,不可以使用在土壤里不应存在大量的有机质成分褐煤若能通过填筑而充分分散,无自然之虞,就不妨碍使用而具有高度流限的肥粘土,多半难以施工,必须避免使用
8、压实的要求不透水和半透水的土料的强度取决于压实的密度压实密度又取决于土料的含水量和压实设备的重量因此,料场土料的含水量和在填筑前或堆筑后而未碾压前的填土实际含水量的变化,都会影响坝体的填筑如果天然含水量太高,可以在料场用排水或将土料耙松的办法来减低如果土料太干燥,则需在料场用洒水和泡水的办法把土料润湿,然后再让土料在使用以前保持稳定的含水量填筑时的含水量范围一般介于比标准普氏最优含水量低2%到高2%~3%之间透水性土料至少压实到相对密度的80%如果需要,应该变换填筑层的含水量、铺层厚度、碾压遍数和碾压机的型式等,进行填筑试验对于坡度很陡的坝座部位,必须用薄层填筑,并用手扶打夯机夯实所有外悬突出部位,均应在填土堆筑以前挖除或用贫混凝土填平
9、观测仪器的类型观测仪器的类型取决于工程的规模和复杂性通用的装置是
①测压计;
②表面位移标志;
③沉陷量测仪(计);
④测斜仪;
⑤内部位移和应变指示仪;
⑥压力盒(压力传感器或压应力计);
⑦地震加速度仪;
⑧在管道接头和其他混凝土结构上的位移标志。