ch1 physical properties and classification 1（2014)

1 Ch 1physicalpropertiesandclassificationofsoil Content 1 1Soilformation1 2Phasecompositionofsoil1 3Physicalstatesofsoil1 4Soilstructure1 5Soilclassification1 6Soilcompaction 1Soilformation Compositionoftheearth Innercore outercore earthmantle Rock soil Compositionoftheearth Compositionoftheearth crosssection ParentRock formedbyoneofthesethreedifferentprocesses Igneous 火成 Sedimentary 沉积 Metamorphic 变质 formedbycoolingofmoltenmagma 岩浆 formedbygradualdeposition andinlayers formedbyalterationofigneous sedimentaryrocksbypressure temperature e g limestone shale e g marble e g granite SoilFormation Physicalweathering rockbrokenandsmashedbydrastictemperaturealteration Frostaction Windandwateraction Scouredbyriverwave rock sand Scouredbywindandrain Rock岩石 block块石 boulder漂石 gravel砾石 pebble卵石 coarsesand粗砂 finesand细砂 siltysand粉砂 Physical mechanical weatheringmakesrocksdecomposedbutwithnomineralcompositionalternation 物理 机械 风化使得岩石解体破碎 但是不带来矿物成分的变化 Keypoint decomposition SoilFormation insituweathering Transportation Residualsoil Transportedsoil 残积土 运积土 ParentRock Residualsoil Transportedsoil insituweathering byphysical chemicalagents ofparentrock weatheredandtransportedfaraway bywind waterandice SoilFormation TransportedSoils Transportedby Specialname wind Aeoliansoil 风积土 sea saltwater Marinesoil 海积土 lake freshwater Lacustrinesoil 湖积土 river Alluvialsoil 冲积土 ice Glacialsoil 冰积土 Slopewash slopedebris 坡积土 Mountainflood diluvialsoil 洪积土 15 Ch 1physicalpropertiesandclassificationofsoil Lesson2 Content 1 1Soilformation1 2Phasecompositionofsoil1 3Physicalstatesofsoil1 4Soilstructure1 5Soilclassification1 6Soilcompaction 1 2Phasecompositionofsoil 1 2 1Threephasesofsoil1 2 2Physicalindex1 2 3Grainsizedistribution1 2 4Mineralcomposition1 2 5Waterinsoil clay Soilelement gravel SurfaceofMars 火星表面 sand 1 2 1Threephasesofsoil土的三相 5 1Threephasesdiagram三相图 MineralSkeleton Unsaturatedsoil saturatedsoil drysoil Idealization SoilPhases ThreePhaseDiagram PartlySaturatedSoils Vs 1 Vv e V 1 e volume Idealization概化 Threebasicindex土粒的比重 土的含水率 土的重度 1 2 2physicalindex物理性指标 Othercommonlyusedindex V 1 e 比体积 孔隙率 Vs 1 Vv e Thespecificgravityofsoilsrangesfromapproximately2 6to2 8 Formostproblems Gscanbeassumed withlittleerror tobeequalto2 65forsandysoils and2 70forclaysoils Gs Example1 VolumetricRatios Determinevoidratio porosityanddegreeofsaturationofasoilcoresample I e Determine e n Sr Or 1 2 3Grainsizedistribution颗分曲线 P finer Size mm Accumulatedgradation 1 2 3Grainsizedistribution颗分曲线 固体颗粒 粒径级配 筛分法适合于粗粒径 d 0 075mm 密度计法适合于细粒径 d 0 075mm 1 2 3Grainsizedistribution颗分曲线 MethodsofGSDanalysis Sieving forgrain 0 1mmhydrometermeasuring forgrain 0 1mm 105 02 01 00 50 250 1 200g 10161824223872 P finer Size mm P 958778665536 Accumulatedgradation Sievingandhydrometermeasuring Question ForsamplesA BandC howtoevaluatetheirGSDs HowdoweknowtheGSDSaregoodornot 小于某粒径之土质量百分数 Diameter mm SampleA SampleB P finer SampleC UniformitycoefficientCurvaturecoefficient UniformitycontentUniformityCoefficient Cu d60 d10 EvaluationofGradation P finer d30 UniformitycontentUniformityCoefficient Cu d60 d10 EvaluationofGradation BismoreuniformthanA P finer Forwell gradedsoils Cu 5i e Cu 5areconsideredtobe poorlygraded TheminimumvalueofCuis TheminimumvalueofCuisoneandcorrespondstoanassemblageofparticlesofthesamesize Thegradationcurveforauniformsoilisalmostvertical 级配不均匀 gradationcontinuity连续性coefficientofcurvature Cc d302 d60 d10 曲率系数 EvaluationofGradation Flatstep 平台 WiththesamevalueofCu whichoneisgradedbetter Accumulatedgradation Flatstep平台 lackofmiddlesizes中间粒组缺乏 Cc 1 3 goodcontinuity级配连续性好 平台 A B C coefficientofcurvature Cc d302 d60 d10 曲率系数 Forwell gradedsoils Cc 1 3 gradedcontinuously 级配连续性好 AsCc 10rCc 3时 gradedwithdiscontinuity级配曲线不连续 如果粒径级配累积曲线斜率不连续 在该曲线上的某一位置出现水平段 Forwell gradedsoils 1 Cu 5 2 Cc 1 3 1 2Phasecompositionofsoil 1 2 1Threephasesofsoil1 2 2Physicalindex1 2 3Grainsizedistribution1 2 4Mineralcomposition1 2 5Waterinsoil 1 2 4Mineralcomposition Allrocksandsoilsarecomposedofminerals Soils Coarsegrainedsoils Finedgrainedsoils Originalminerals secondminerals Physicalweathering Reductioninsizewithoutchangeincompositionfromparentrock Reductioninsizeandchangeincompositionfromparentrock weatheringofrock chemicalweathering Coarsegrainedsoils graval sand finedgrainedsoils claysoils Originalminerals secondminerals Originalminerals原生矿物 石英 金刚石 黄铁矿 橄榄石 方铅石 正长石 赤铁矿 Originalminerals原生矿物 在岩石或矿石形成之后 其中的矿物遭受化学变化而改造成的新生矿物 其化学组成和构造都经过改变而不同于原生矿物 如橄榄石经热液蚀变而形成的蛇纹石 正长石经风化分解而形成的高岭石 方铅矿经氧化而形成的铅矾 铅矾进一步与含碳酸的水溶液反应而形成的白铅矿等 均是次生矿物 次生矿物中最主要的是粘土矿物 其他是可溶盐和氧化物胶体 Claymineral BasicStructuralUnits Claymineralsaremadeoftwodistinct 截然不同的 structuralunits Silicontetrahedron硅四面体 AluminiumOctahedron铝八面体 secondminerals次生矿物 Tetrahedral OctahedralSheets Forsimplicity let srepresentsilicatetrahedralsheetby Si Trapezium Tetrahedral OctahedralSheets andaluminaoctahedralsheetby Al rectangle DifferentClayMinerals Differentcombinationsoftetrahedralandoctahedralsheetsformdifferentclayminerals 1 1ClayMineral e g kaolinite高岭土 halloysite埃洛石 Kaolinite Typically70 100layers H bond 一纳米 nanomete 等于十亿分之一米 DifferentClayMinerals Differentcombinationsoftetrahedralandoctahedralsheetsformdifferentclayminerals 2 1ClayMineral e g montmorillonite蒙脱石 illite伊利石 Montmorillonite easilyseparatedbywater expandsoncontactwithwater vanderWaal sbond hydrophilic Illite fitintothehexagonalholesinSi sheet Others A2 1 1mineral montmorillonitefamily 2interlayersofwater chainstructure nosheets needle likeappearance Chlorite绿泥石 Vermiculite蛭石 Attapulgite绿坡缕石 AClayParticle ClayFabric Flocculated絮凝结构 Dispersed分散结构 edge to facecontact face to facecontact 1 2Phasecompositionofsoil 1 2 1Threephasesofsoil1 2 2Physicalindex1 2 3Grainsizedistribution1 2 4Mineralcomposition1 2 5Waterinsoil土中水 毛细水 由于土体孔隙的毛细作用升至自由水面以上的水 毛细水承受表面张力和重力的作用重力水 自由水面以下的孔隙自由水 在重力作用下可在土中自由流动 自由水 不受颗粒电场引力作用的孔隙水 Waterincoarsegrainedsoils Waterincoarsegrainedsoils Gravitywater Capillarywater Waterstate Saturatedsand gravel PartiallySaturated Selflearning calculationofcapillaryheight Waterinfinegrainedsoils Gravitywater Strongbondedwater Waterstate Thestateofwaterinaclaysoilismorecomplexthaninasandysoil Weakbondedwater Capillarywater Clayparticleformelectricfieldinwater Negativeanion 负离子 spreadatthesurfaceofclayparticle theanionsabsorbthecationsofwatermolecules CationConcentrationinWater cation 阳离子 concentrationdropswithdistancefromclayparticle freewater AdsorbedWater Athinlayerofwatertightlyheldtoparticle likeaskin 1 4moleculesofwater 1nm thick moreviscousthanfreewater ClayParticleinWater freewater Weakbondedwater 结合水 排列致密 定向性强密度 1g cm3冰点处于零下几十度具有固体的的特性温度高于100 C时可蒸发 强结合水 位于强结合水之外 电场引力作用范围之内外力作用下可以移动不因重力而移动 有粘滞性 弱结合水 strongbondedwaterbehavelikesolid Content 1 1Soilformation1 2Phasecompositionofsoil1 3Physicalstatesofsoil1 4Soilstructure1 5Soilclassification1 6Soilcompaction 1 3Physicalstatesofsoil 1 3 1conceptofdensedegree 密实度 1 3 2Relativedensityofcohesionlesssoil1 3 3thecompactionofclaysoils1 3 4consistencystatesofclaysoils 1 3 1conceptofdensedegree 密实度 26 6cm Problem settlementoutofnormaluse 1 3 2Relativedensityofcohesionlesssoil Questions 1 Ifwejustknowthedensityorvoidratioofagivensoil canweassessitsstate Isitdenseorloose whichsoilisdenser Ifwejustknowthedensity wecan tanswerthesetwoquestions Soil2 G 2 65e 0 743 Soil1andsoil2maybeatthesamedensestate Soil1 G 2 68e 0 811 Soil2 G 2 68e 0 811 Soil1andsoil2maybeatdifferentdensestate emaxandemin determinedbytests advantege simpleandeasytouse disadvantage unabletoreflecttheinfluenceofgraingradation Measure relativedensity eorn or loose dense emax Sandinahopper emin measuringcylinder emax 最大孔隙比 将松散的风干土样通过长颈漏斗轻轻地倒入容器 避免重力冲击 求得土的最小干密度再经换算得到最大孔隙比 漏斗量桶法 min emin 最小孔隙比 将松散的风干土样装入金属容器内 按规定方法振动和锤击 直至密度不再提高 求得土的最大干密度再经换算得到最小孔隙比 振动锤击法 max 最大干密度 在一定的击实功能下所能达到的最紧密状态时的干密度 击实试验 max 粗粒土的密实状态指标 Densestandard Dr 1 densestDr 0 loosestDr 1 3 loose1 32 3 dense GrainsizedistributionisaimportantfactorInfluencingthecompactioneffectofsandysoils 1 3 3thecompactionofclaysoils 1 3 3compaction Lookat 1 3Physicalstatesofsoil 1 3 1conceptofdensedegree 密实度 1 3 2Relativedensityofcohesionlesssoil1 3 3thecompactionofclaysoil1 3 4consistencystatesofclaysoil 粘土的稠度状态 1 3 4consistencystatesofclaysoils Crackedsoilbyshrinkage Sludge Losewater soilsmightshrinkorexpandexcessivelyinanuncontrolledmannerafterthey vebeenplacedingeotechnicalstructures roadwaysubgrades dams levees foundationmaterials etc soilsmightlosetheirshearstrength andabilitytocarryloadssafelywhenwatercontentincreaseremarkably Watercontentisamajorfactorinfluencingsoil sbehavior Housecrackingasagreatquantityofwaterentertheexpansivesoilground So itisnecessarytoverifyhowthewatercontentinfluenceitspotentialbehavior 1 AtterbergLimits 1 3 4consistencystatesofclaysoils Eachsoiltypewillgenerallyhavedifferentwatercontentsatwhichitbehaveslikeasolid semi solid plastic andliquid Watercontent respecitively watercontent volume solid Semi solid plastic liquid lowerstrength Visiblecrackappear Deformwithoutvisiblecrack Flowslikeaviscousliquid WSL WPL WLL Changesinsoilstatesasafunctionofsoilvolumeandwatercontent DrySoil Fluidsoil watermixture Increasingwatercontent AtterbergLimits TestsofmeasuringtheAtterberglimits LiquidLimitPlasticlimitShrinkaglimit TestofmeasuringtheAtterberglimits LiquidLimit ConePenetrometerMethod 圆锥法 presentmethod ThismethodisdevelopedbytheTransportandRoadResearchLaboratory UK CasagrandecupMethod 碟式仪法 oldmethod ProfessorCasagrandestandardizedthetestanddevelopedtheliquidlimitdevice 运输与道路研究试验所 N 25blowsClosingdistance 12 7mm 0 5in HoltzandKovacs 1981 CasagrandecupMethod 碟式仪法 handshank 手柄 1将制各好的试样充分调拌均匀 铺于铜碟前半部 用调土刀将铜碟前沿试样刮成水平 使试样中心厚度为l0mm 用开槽器经蜗形轮的中心沿铜碟直径将试样划开 形成v形槽 2 以每秒两转的速度转动摇柄 使铜碟反复起落 坠击于底座上 数记击数 直至槽底两边试样的合拢长度为13mm时 记录击数 并在槽的两边取试样不应少于10g 放人称量盒内 测定含水率 3将加不同水量的试样 重复本条1 2款的步骤测定槽底两边试样合拢长度为12 7mm所需要的击数及相应的含水率 试样宜为4 5个 碟式仪液限试验是将土碟中的土膏用划刀分成两半 以每秒2次的速率将土碟由高度下落 当击落25次时两半土膏在碟底的合拢长度刚好达到12 7mm 此时的含水率为液限 Thewatercontent inpercentage requiredtocloseadistanceof0 5in 12 7mm alongthebottomofthegrooveafter25blowsisdefinedastheliquidlimit CasagrandecupMethod 碟式仪法 Handrubbingmethod 手工搓条法 PlasticLimit WPL TheplasticlimitPLisdefinedasthewatercontentatwhichasoilthreadwith3 2mmdiameterjustcrumbles HoltzandKovacs 1981 ConePenetrometerMethod 圆锥法 液塑限联合测定 光电式液 塑限仪 photoelectricliquid plasticcombinetester 在双对数坐标纸上绘出圆锥下沉深度和含水量的关系直线 圆锥下沉深度为10mm所对应的含水量为该试样的10mm液限 建筑地基基础设计规范 下沉深度为17mm所对应的含水量为试样的液限 水工试验标准 下沉深度为2mm所对应的含水量为塑限 液限和塑限联合测定 Doublelogarithmiccurve plasticindex塑性指数 theabilityofabsorbingbondedwater extentofcohesion contentofclayparticle aneffectiveindexusedforsoilclassificationoffinegrainedsoils 2 Consistencyindex 稠度指标 1 4 4consistencystatesofclaysoils Liquidityindex液性指数 反映粘土稠度状态 wp w wl IL1 HardstatePlasticstateFluidstate 0 00 0 250 25 0 750 75 1 00 硬塑hardplastic可塑plastic软塑softplastic Example Wll 45 WPl 31 IP Ifw 40 Whatconsistencystateisthesoillocatedat IP 45 31 14 Plasticstate 1 4SoilStructure 1 4 1whatissoilstructure 1 4 2structureofcohesionless coarse grainedsoils1 4 3structureofcohesive fine grainedsoils 1 4 1whatissoilstructure Soilisan aggregate ofparticleswith different sizes Question aggregate different Howtheparticlesareconnectedtogetherinasoil whatissoilstructure Thisisa important problem 1 4 1whatissoilstructure Soilstructuredescribesthearrangementofthesolidpartsofthesoilandoftheporespacelocatedbetweenthem Marshall Holmes 1979 1 4 2StructureofCohesionless Coarse GrainedSoils singlegrain 单粒结构 Singlegrainstructure eachparticlebeingdirectcontactwithadjoiningparticleswithoutanybondbetweenthem particlesbeingdirectcontact singlegrain 单粒结构 1 4 2StructureofCoarse GrainedSoils Coarseparticleshapes angular 有陵角的 round 圆的 Thestateofthep