lesson 15 soil mechanical(土木工程专业英语).ppt

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1、Lesson 15Text:Soil Mechanics教学要求教学要求:1、掌握有关掌握有关Soil Mechanics的专业术语；的专业术语；2、熟悉一些常见的表达方式；熟悉一些常见的表达方式；3、延伸了解一些土力学历史和名人；延伸了解一些土力学历史和名人；4、能正确、流畅地翻译能正确、流畅地翻译 Soilmechanicsisconcernedwiththeuseofthelawsofmechanicsandhydraulicsinengineeringproblemsrelatedtosoil.Soilisanaturalaggregate ofmineralgrains,withor

2、withoutorganicconstituents,formedbythechemicalandmechanicalweatheringofrock.Itconsistsofthreephases:solidmineralmatter,water,andairorothergas.Soilsareextremelyvariablecomposition,anditwasthisheterogeneity thatlongdiscouragedscientificstudiesofthesedeposits.hydraulicshaidr:liks水力学水力学 aggregategrigeit

3、集合体集合体phasefeiz阶段阶段,相相heterogeneity.hetrudini:iti异质性异质性,多相性多相性 土力学研究的是在工程问题中与土相关的力学和水力学定土力学研究的是在工程问题中与土相关的力学和水力学定律的应用。土是矿物粒的天然集合物，这些矿物粒是岩石经过律的应用。土是矿物粒的天然集合物，这些矿物粒是岩石经过化学或物理风化而形成，含或者不含有机成分。土包含有三个化学或物理风化而形成，含或者不含有机成分。土包含有三个相：固态的矿物质，水，空气或其他气体。土的组成极其复杂，相：固态的矿物质，水，空气或其他气体。土的组成极其复杂，正是这种异质性，长期以来阻碍了对这个堆积物的研

4、究。正是这种异质性，长期以来阻碍了对这个堆积物的研究。(生物体,有机体)Gradually,theinvestigationoffailuresofretainingwalls,foundations,embankments,pavement,andotherstructuresresultedinabodyofknowledgeconcerningthenatureofsoilsandtheirbehaviorsufficienttogiverisetosoilmechanicsasbranchofengineeringscience.retainingwall:挡土墙挡土墙embankme

5、ntsimbkmnt堤防堤防,筑堤筑堤pavementpeivmnt路面路面 逐渐地，通过对那些失败的挡土墙、基础、堤坝、路面逐渐地，通过对那些失败的挡土墙、基础、堤坝、路面及其他结构的调查研究，人们积累了大量的有关土的类型及及其他结构的调查研究，人们积累了大量的有关土的类型及其性质的知识，从而形成了工程学科的分支其性质的知识，从而形成了工程学科的分支土力学。土力学。History.Littleprogresswasmadeindealingwithsoilproblemsonascientificbasisuntilthelatterhalfofthe18thcentury,whentheF

6、renchphysicistCharles-Augustin de Coulombpublishedhistheoryofpressure(1773).In1857theScottishengineerWilliam Rankinedevelopedtheoryofequilibriumofearthmassesandappliedittosomeelementaryproblemsoffoundationengineering.Thesetwoclassicaltheoriesstillformthebasisofcurrentmethodsofestimatingearthpressure

7、,eventhoughtheywerebasedonthemisconceptionthatallsoilslackcohesion,asdoesdrysand.Twentieth-centuryadvanceshavebeeninthedirectionoftakingcohesionintoaccount;understandingthebasicphysicalpropertiesofsoilsingeneralandofatheplasticityofclayinparticular;andsystematicallystudyingtheshearing characteristic

8、sofsoilthatis,theirp e rf o rma n c e u n d e r c o n d it io n s o f s lid in g.cohesionkuhi:n 内聚力内聚力,粘聚力粘聚力;plasticityplstisiti塑性塑性;历史。历史。18世纪后叶之前，人们在研究有关土的科学理论世纪后叶之前，人们在研究有关土的科学理论方面进展很小，直到法国物理学家查里方面进展很小，直到法国物理学家查里.奥古斯丁奥古斯丁.库仑（库仑（Charles-Augustindecoulomb）在）在1773年出版了他的土压力学说。年出版了他的土压力学说。1857年，苏格兰工程

9、师朗肯（年，苏格兰工程师朗肯（WilliamRankine）发展了土的）发展了土的平衡理论，并将其用于基础工程的基本问题中。尽管这两个平衡理论，并将其用于基础工程的基本问题中。尽管这两个经典理论是建立错误的假设上，即认为土和干燥的沙子一经典理论是建立错误的假设上，即认为土和干燥的沙子一样是缺乏粘聚力的，但仍然形成了当前估算土压力方法的理样是缺乏粘聚力的，但仍然形成了当前估算土压力方法的理论基础。这方面的研究，在论基础。这方面的研究，在21世纪有了突破，粘聚力计入计世纪有了突破，粘聚力计入计算，了解了一般情况土的物理性质和特殊情况下土的塑性，算，了解了一般情况土的物理性质和特殊情况下土的塑性，还

10、系统地研究了土的剪切性质还系统地研究了土的剪切性质也就是土滑动时的性能。也就是土滑动时的性能。CharlesAugustindeCoulomb (17361806)was a French physicist.He is best known as the discoverer of Coulombslaw,which defines the force of electrostatic attraction and repulsion.The SI unit of charge,the coulomb,was so named in his honour.WilliamJohnMacquor

11、nRankine(1820-1872)was a Scottish engineer and physicist.Rankine 被后人誉为那个时代的天才，他在热力学、流体力学及土力学等领域均有杰出的贡献。BothCoulombsandRankinestheoriesassumedthatthesurfaceofrupture ofsoilsubjectedtoashearingforceisaplane.Whilethisisareasonableapproximation forsand,cohesivesoilstendtoslipalongacurvedsurface.Intheear

12、ly20thcentury,Swedishengineersproposedacirculararcasthesurfaceofslip.Duringthelasthalfcenturyconsiderableprogresshasbeenmadeinthescientificstudyofsoilandintheapplicationoftheoryandexperimentaldatatoengineeringdesign.rupture rpt(r)rpt(r)断裂断裂approximation 接近、近似值接近、近似值cohesive kuhi:siv kuhi:siv 粘性的粘性的(

13、有结合性的有结合性的,有粘聚性的有粘聚性的)AsignificantadvancewasmadebytheGermanengineerKarl Terzaghi,whoin1925publishedamathematicalinvestigationoftherateofconsolidationofclaysunderappliedpressure.Hisanalysis,whichwasconfirmedexperimentally,explainedthetimelagofsettlementsonfullywaterloggedclaydeposits.Terzaghicoinedth

14、etermsoilmechanicsin1925whenhepublishedthebookErdbaumenchanik(“Earth-.BuildingKarlTerzaghi （1883 1883 1963 1963）卡尔）卡尔特扎吉特扎吉consolidation kn.slidein kn.slidein 固结固结waterlogged w:tlgd w:tlgd 浸满水的浸满水的mechanics”)Karl TerzaghiTheFatherofSoilMechanics.Born:October2,1883inPragueDied:October25,1963inWinches

15、ter,MassachusettsHewasmarriedtoRuthD.Terzaghi,ageologist.HewontheNormanMedalofASCEfourtimes(1930,1943,1946,and1955).Hewasgivenninehonorarydoctoratedegreesfromuniversitiesineightdifferentcountries.Hestartedmodernsoilmechanicswithhistheoriesofconsolidation,lateral earth pressures,bearing capacity,ands

16、tability.nutshell:Researchingonsubgradematerials,thenaturalfoundationunderpavements,wasbegunabout1920bytheU.S.Bureau of Public Roads.Severalsimpletestswerecorrelatedwiththepropertiesofnaturalsoilsinrelationtopavementdesign.InEngland,theRoad Research Boardwassetupin1993.In1936thefirstinternationalcon

17、ferenceonsoilswasheldatsubgrade 路基路基U.S.BureauofPublicRoads美国公路局美国公路局 RoadResearchBoard 公路研究部公路研究部HarvardUniversity.Today,thecivilengineerreliesheavilyonthenumericalresultsofteststoreinforceexperienceandcorrelatenewproblemswithestablishedsolutions.Obtaining truly representative samples of soils for

18、such tests,however,is extremely difficult;hence there is a trend toward testing on the site instead of in the laboratory,and many important properties are now evaluated in this way.今天，土木工程师都会借重于试验的数据来加强经今天，土木工程师都会借重于试验的数据来加强经验，把新问题和已确定的解决方法联系起来。但是，要验，把新问题和已确定的解决方法联系起来。但是，要获得具有代表性的土样做测试，是非常困难的，因此，获得具

19、有代表性的土样做测试，是非常困难的，因此，现在倾向于用在现场做测试来取代实验室的试验。现在，现在倾向于用在现场做测试来取代实验室的试验。现在，大多数重要的土特性采用这种方法来评定。大多数重要的土特性采用这种方法来评定。Engineering properties of soils.Thepropertiesofsoilthatdeterminetheirsuitabilityforengineeringuseincludeinternal friction,cohesion,compressibility,elasticity,permeability,andinternalfriction

20、内摩擦力内摩擦力cohesion kuhi:n kuhi:n 粘聚力粘聚力compressibility km.presibiliti km.presibiliti 压缩性压缩性permeability.p:mibiliti .p:mibiliti 渗透性渗透性capillarity kpilriti kpilriti 毛毛细性性Capillarity.Internalfrictionistheresistancetoslidingofferedbythesoilmass.Sandandgravelhavehigherinternalfrictionthanclays;inthelattera

21、nincreaseinmoisturelowerstheinternfriction.Thetendencyofasoiltoslideundertheweightofastructuremaybetranslatedintoshear;thatis,amovementofamassofsoilinplans,eitherhorizontal,vertical,orother.Suchashearingmovementinvolvesadangerof 内摩擦力土体是抵抗滑动的力。沙子和沙砾比粘土的内内摩擦力土体是抵抗滑动的力。沙子和沙砾比粘土的内摩擦力大，后者的内摩擦力随着湿气的增加而降低。

22、土在结摩擦力大，后者的内摩擦力随着湿气的增加而降低。土在结构的重力下，其滑动的趋势可能会转换成剪切，也就是土的构的重力下，其滑动的趋势可能会转换成剪切，也就是土的平面的，水平的、竖向的或者其他方向的运动。这种剪切运平面的，水平的、竖向的或者其他方向的运动。这种剪切运动会造成危险的建筑事故。动会造成危险的建筑事故。buildingfailure.Alsoresistingthedangerofshearisthepropertyofcohesion,whichisthemutualattractionofsoilparticles duetomolecularforcesandtheexiste

23、nceofmoisturebetweenthem.Cohesionisgenerallyveryhighinclaysbutalmostnonexistentinsandsor silts.Cohesionvaluesrangefromzerofordrysandto2,000poundspersquarefootforverystiffclay.mutual mju:tjul mju:tjul共同的共同的,相互的相互的 particle p:tikl p:tikl 粒子粒子,点点,极小量极小量molecular mulekjul mulekjul 分子的分子的silt silt silt 淤

24、泥淤泥 Compressibilityisanimportantsoilcharacteristicbecauseofthepossibilityofcompactingthesoilbyrolling,tamping,vibration,orothermeans,thusincreasingitsdensityandload-bearingstrength.An elastic soil tends to resume its originalcondition aftercompaction.Elastic(expansible)soilareunsuitableassubgradesfo

25、rflexible pavementssincetheycompactandexpandasavehiclepassesoverthem,causingfailureofthepavement.rolling r:uli r:uli碾压碾压 tampingtmpi tmpi 夯实夯实vibration vaibrein vaibrein 振动振动flexible pavements柔性路面柔性路面Crosssectionsofmodernpavement Permeabilityisthepropertyofasoilthatpermitstheflowofthewaterthroughit.

26、Freezing-thawingcyclesinwinterandwetting-dryingcyclesinsummeralterthepacking densityofsoilgrains.Permeability Capillaritycauseswatertorisethroughthesoilabovethenormalhorizontalplaneoffreewater.Inmostsoilnumerous channelsforcapillaryactionexist;inclays,moisturemayberaisedasmuchasthawing:i :i 融化融化 pac

27、kingdensity 堆积密度堆积密度numerous nju:mrs nju:mrs 许多许多canbereducedbycompaction.30feetbycapillarity.Densitycanbedeterminedbyweightandvolumemeasurementsorbyspecialmeasuringdevices.Stability ofsoilsismeasuredbyaninstrumentcalledastabilometer,whichspecificallymeasuresthehorizontalpressuretransmittedbyavertic

28、alload.Consolidationisthecompactionorpressingtogetherofsoilthatoccursunderaspecificloadcondition;thatstability stbiliti stbiliti 稳定性稳定性 stabilometer.steibilmit .steibilmit 稳定仪稳定仪,稳定性量测仪稳定性量测仪 密度可以通过测定重量和体积得到，或者用特殊的测量密度可以通过测定重量和体积得到，或者用特殊的测量仪器测得。土的稳定性可用一种稳定仪测得，稳定仪可明确仪器测得。土的稳定性可用一种稳定仪测得，稳定仪可明确测出竖向荷载带来

29、的水平压力。固结是土在一种特殊荷载下测出竖向荷载带来的水平压力。固结是土在一种特殊荷载下的发生的压实或者挤压，同样也可以测试出来。的发生的压实或者挤压，同样也可以测试出来。propertyisalsotested.Site Investigation.Soilsurveysareconductedtogatherdataonthenature and extentofthesoilexpectedtobeencounteredonaproject.Theamountofeffortspentonsiteinvestigationdependsonthesizeandimportanceofth

30、eproject;itmayrange fromvisualinspectionto elaborate subsurfaceexplorationbyboringandlaboratorytesting.Collectionofrepresentativesampleisessentialforproperidentificationandclassificationofsoils.survey s:vei s:vei 测量测量 elaborate ilbrt ilbrt 精细的精细的,详尽的详尽的 boring b:ri b:ri 钻孔钻孔identification ai.dentifi

31、kein ai.dentifikein 鉴定鉴定,确认确认Thenumberofsamplestakendependsonpreviouslyavailabledata,variationinsoiltypes,andthesizeoftheproject.Generally,inthenaturalprofileatalocation,thereismorevariationinsoilcharacteristicswithdepththanhorizontaldistance.Itisnotgoodpracticetocollectcompositesamplesforanygivenho

32、rizon(layer),sincethisdoesnottrulyrepresentanyonelocationandcouldprovemisleading.Evenslightvariationinsoilcharacteristicsinahorizonshouldbedulynoted.Classificationofthesoilintermsofgrainsizeandtheliquidandplastic limitsareparticularlyprofile prufail prufail 剖面，侧面剖面，侧面plasticlimit限限importantsteps.An

33、understanding of the eventual use of the data obtained during site investigation is important.Advanceinformationonthesiteconditionsishelpfulinplanninganysurveyprogram.Informationontopography,geologicalfeatures(outcrops,roadandstreamcuts,lakebeds,weatheredremnants,etc.),paleontological maps,aerialpho

34、tographs,welllogs,andexcavationscanproveinvaluable.Geophysicalexplorationmethodsyieldusefulcorroboratorydata.Measurementoftheelectricalresistivity ofsoilsprovidesaninsightintoseveralsoiltopography tpgrfi tpgrfi 地形学地形学,地势地势geological dildikl dildikl 地质学的，地质的地质学的，地质的outcrops autkrp autkrp 露头露头paleonto

35、logical古生物学的；古生物学的；geophysical地球物理学的；地球物理学的；electricalresistivity：电阻：电阻 characteristics.Seismic techniques often are used to determine the characteristics of various subsurface strata by measuring the velocity of propagation of explosively generated shock waves through the strata.Thepropagationveloc

36、ityvarieswidelyfordifferenttypesofsoils.ShockwavesalsoareutilizedtodeterminethedepthofbedrockbymeasuringthetimerequiredfortheshockwavetotraveltohebedrockandreturnSeismic saizmik saizmik 地震的地震的 strata streit pl streit pl层层(地层地层,阶层阶层,薄片薄片)stratum:streitm streitm velocity vilsiti vilsiti 速度速度propagatio

37、n.prpgein .prpgein 传播传播 地震学技术通过测定激震波穿过地层的传播速度来确定不地震学技术通过测定激震波穿过地层的传播速度来确定不同地层的性质。不同类型的传播速度差距是非常大的。通过测同地层的性质。不同类型的传播速度差距是非常大的。通过测定震动波传到基岩和作为反射波回到地面所需的时间，可确定定震动波传到基岩和作为反射波回到地面所需的时间，可确定基岩的深度。基岩的深度。tothesurfaceasareflectedwave.Dependablesubsurfaceinformationcanonlybeobtainedbyexcavation.Aprobe rodpushed

38、intothegroundindicatesthepenetrationresistance.Waterjetsoraugersareusedtobringsubsurfacematerialstothesurfaceforexamination.Colorchangeisoneofthesignificantelementssuchanexaminationcanproberod探测棒探测棒penetration penitrein penitrein 贯入贯入,侵透侵透,auger:g :g 麻花钻麻花钻,钻孔机钻孔机reveal.Variousdrilling methodsareemp

39、loyedtoobtainchipsfromdepths.Trenchesorpitsprovidemorecompleteinformationforshallowdepths.Pneumaticordiamonddrillingmayberequiredifhardrockisencountered.Atleastafewoftheboreholesshouldexceedthedepthofsignificantstressthatisdrilling drili drili 钻孔钻孔trench trent trent 沟沟pneumatic nju(:)mtik nju(:)mtik

40、 气气动的的 establishedforthestructure.Avoidanceofstructuraldisturbanceofthesamplesisnotcriticalforsometestsbutisveryimportantforin-placedensityorshearing strengthmeasurement.Completeandaccuraterecords,suchasborehole logs,mustbepreparedandmaintained,andthesamplesthemselvesmustberetainedforfutureinspection.in-place 原状，原位原状，原位boreholelog测井曲井曲线