《高等土力学》课程教学课件（讲稿）Soil Mechanics Review

05/05/2016武桥理工大学武汉理工大学Table of ContentsCourse IntroductionTypicalTrenchingandShoringProjectsApplled Soll Mechanics and Shoring DesignPart1:SoilMechanicsReviewPart2:TrenchingandShoringDesignDr.Jinyuan Liu,P.E.,P.EngAssociateProfessor,RyersonUniversityPart3:ExercisesandDiscussionsDirector,Jinyuan Liu&AssociatesInc实员理工大学实员理工大学CourseObjectlvesIntroductionofClassMembersDr.JinyuanLiu,P.E.,P.EngThepurposeofthecourseistoteachattendeeshowtodesign shoringEmail:Jinyuan.Liu@ryerson.caPhone:(416)979-5000x6469Thedesignexamplesshowthesafeandprovenhttp://www.nyerson.ca/j42liucalculation techniques for shoring design that can beResearch Interests: underground excavation and tunneling,soil.appliedtomostexcavation shoring situationsstructural interaction,urban geotechnology,physicalmodeling with transparent soil,and numerical simulationThecourseexplainswhypropertrenchingandshoringconstruction procedures are important for creatingasuccessfultrenching and shoring systemhttp://www.jinyuanliu.comConsultancy Areas: Design and training in geotechnical,Finally,theproper installationproceduresareexplained.undergroundexcavation,tunneling,and glassstructurefields武工大学武居理工大学ExpectedOutcomesTypical Trenching ProjectsAfterparticipatinginthecourse.youshouldbeabletoApply soll mechanics theory to actual and practical trenching andshoring designDerive the equations and loads for designing sheet piles andsoldier pilesDesign wale,strut,lagging.anchortiebacks,and soilnail wallsImplement requirements, procedures and techniques for safeeffective and efficient designPractice trenching and shoring safety precautions

05/05/2016 1 Applied Soil Mechanics and Shoring Design Dr. Jinyuan Liu, P.E., P.Eng. Associate Professor, Ryerson University Director, Jinyuan Liu & Associates Inc Table of Contents  Course Introduction  Typical Trenching and Shoring Projects  Part 1: Soil Mechanics Mechanics Review  Part 2: Trenching and Shoring Design  Part 3: Exercises and Discussions Introduction of Class Members Dr. Jinyuan Liu, P.E., P.Eng. Email: Jinyuan.Liu@ryerson.ca Phone: (416) 979‐5000x6469 http://www.ryerson.ca/~j42liu Resea cr h Inte ests terests: u de g ou d nderground e ca at o xcavation a dn tu e g, nn ling, soil‐ structural interaction, urban geotechnology, physical modeling with transparent soil, and numerical simulation http://www.jinyuanliu.com Consultancy Areas: Design and training in geotechnical, underground excavation, tunneling, and glass structure fields Course Objectives  The purpose of the course is to teach attendees how to design shoring  The design examples show the safe and proven calculation techniques for shoring design that can be applied to most excavation shoring situations applied to most excavation shoring situations  The course explains why proper trenching and shoring construction procedures are important for creating a successful trenching and shoring system  Finally, the proper installation procedures are explained. Expected Outcomes After participating in the course, you should be able to:  Apply soil mechanics theory to actual and practical trenching and shoring design  Derive the equations and loads for designing sheet piles and soldier piles  Design wale, strut, lagging, anchor tiebacks, and soil nail walls  Implement requirements, procedures and techniques for safe, effective and efficient design  Practice trenching and shoring safety precautions Typical Trenching Projects

05/05/2016武插理工大学武活理工大学Typlcal Shoring ProjectsShoringProjects InToronto实员理工大学实理工大学ShoringProjectsInBeljingShoring Projects InTorontonbinedwithtiebaackanchorforadeepsecantxcavationinBeijing武工大学武居理工大学ShoringProjects inNYCShorlng Projects InTorontoATimberLaggingandSoldierBeamWall inToronto,Canada

05/05/2016 2 Typical Shoring Projects Shoring Projects in Toronto Shoring Projects in Toronto Shoring Projects in Beijing A secant pile wall combined with tieback anchor for a deep excavation in Beijing Shoring Projects in Toronto A Timber Lagging and Soldier Beam Wall in Toronto, Canada Shoring Projects in NYC 5/5/2016 12

05/05/2016卖活理工大学武活理工大学Market Needs in GTAShorlngProjectsInNYC实员理工大学实员理工大学ARlskyJob:CollapseInSlngaporeARlskyJob:CollapseInChinaCut-&-CoverSMRTStationCollapseDestroysNicollHighway-Singapore2004武工大学武居理工大学ARiskyJob:CollapseInShanghalARiskyJob:SNWFallureinIranShanehaiSubwavLineNo,4Colapse,Shanghai,China2003SNWFailureinlranonOctober3,20133

05/05/2016 3 Shoring Projects in NYC 5/5/2016 13 Market Needs in GTA A Risky Job: Collapse in Singapore Cut-&-Cover SMRT Station Collapse Destroys Nicoll Highway-Singapore 2004 A Risky Job: Collapse in China Hangzhou Subway Collapse, Hangzhou, China 2008 16 Very careful near water!!! A Risky Job: Collapse in Shanghai Shanghai Subway Line No. 4 Collapse, Shanghai, China 2003 5/5/2016 17 A Risky Job: SNW Failure in Iran 5/5/2016 SNW 18 Failure in Iran on October 3, 2013 Pay Attention to Nail Details!

05/05/2016卖居珠工大学武居理工大学Part1:SollMechanlcsRevlewReviewwillfocusonlyonmostrelatedpropertiesThreePhaseDiagramSoilClassificationsPermeabilityShearingStrengthLateralEarthPressureBorehole LogguDmxtigstrcuresduringuelecationurbaLeaneCoeTunnel, Sydney, Right: Heathrow Express, London),.19实员理工大学实员理工大学Soil Mechanics Revlew:Three Phase DlagramSoll Mechanlcs Review:Three Phase DiagramWeinAirSolidParticlesWaterVoids (water)Solid Voids (air) Idealization:Mineral SkeletonThree Phase Diagram武居理工大学武武居理工大学Soll MechanicsRevlew:Typlcal Values(Cont'd)Soil MechanlcsRevlew:TvplcalValuesTABLE 4-2 Typical IndexProperties forGranular SoiAPenwkSueand GradanoDmiyM/ayPoromly ()Areroa RangtVoidRatioApprot.SucApgeexDryDesialy.WetDesity.Subaerged Desaity.Range(mm)MiaMAM.一dnfFndurdOeasauo3.130.911.1228.1.84885E2141.402.3032.2() Cem.t1231.951.2419tipbyby62.41obisn/n

05/05/2016 4 5/5/2016 19 Part 1: Soil Mechanics Review Review will focus only on most related properties  Three Phase Diagram  Soil Classifications  Permeability  Shearing Strength  Lateral Earth Pressure  Borehole Log Soil Mechanics Review: Three Phase Diagram Air Water Solid Particles Solid Mineral Skeleton Idealization: Three Phase Diagram Voids (water) Voids (air) Soil Mechanics Review : Three Phase Diagram e, w Soil Mechanics Review: Typical Values Soil Mechanics Review: Typical Values (Cont’d)

05/05/2016卖活共工大学西武隆理工大学Soil Mechanics Revlew:Typlcal Values (Cont'd)Soll MechanlcsRevlew:GralnSlze AnalvslsTABLE2-1 SomeTypical ValuesforDifferentDensities of SomeU.S.StandardSieve-No.200Common Soil Materials#0.0029inches0.074mmDensity (Mg/m)Soil Type"No.200"meansPuAatSands and gravels1.9~2.41.52.31.01.3Silts and clays1.42.10.61.80.4-1.1Glacial tills2.12.41.7-2.31.1-1.4Crushed rock1.92.21.52.00.9-1.2Peats1.01.10.10.30.00.1Organic silts and clays1.31.80.51.50.30.8*Modified after Hansbo (1975)实员理工大学实理工大学Soil MechanicsRevlew:ConslstencyofSollsSoll Mechanics Review: Atterberg LlmitsConsistencyoffine-grained soil varies in proportiontothewatercontentStrainliquid(peasoup)Liquid limitShrinkagelimitSLPlasticlimit,PLLiquid limit,LLPlasticityplasticIndex(pea nut butter)LiquidSolSemisolidPlasticPlastic limitMoisture contentPlastic index, PI0E1(cheese)Shrinkage limitStrength and modulus decreasesolid(hardcandy)Compressibility increases武工大学武居理工大学Soil Mechanics Revlew:Atterberg LilSoll MechanicsRevlew:GralnSizeDistrlbutionNLL-Themoisture content atwhicha2.mm-widegroove ina soll patwillcloseforadistanceof0.5inwhendropped25times in a standard brass cup falling 1Cm each time at a rateof 2drops/sec inastandard liquidlimitdevicePLThemoisturecontentatwhichathreadof soil justbeginstocrack and crumblewhenrolledtoadiameterof1/8inchesPI=LL-PLorI,=W,-WpNote:These are watercontents,but thepercentage sign is not typically shown.Which soil is good for trenching and shoring work?5

05/05/2016 5 Soil Mechanics Review: Typical Values (Cont’d) How about void ratio? Which matters most in granular and clay? Soil Mechanics Review: Grain Size Analysis  U.S. Standard Sieve - No. 200  0.0029 inches  0.074 mm  “No. 200” means. Soil Mechanics Review: Consistency of Soils Strain Stress Moisture content Solid Semisolid Plastic Liquid Shrinkage limit, SL Plastic limit, PL Liquid limit, LL Plastic index, PI Strength and modulus decrease Compressibility increases Soil Mechanics Review: Atterberg Limits  Consistency of fine-grained soil varies in proportion to the water content Liquid limit liquid (pea soup) Shrinkage limit Plastic limit Liquid limit solid semi-solid plastic Plasticity Index (cheese) (pea nut butter) (hard candy) Soil Mechanics Review: Atterberg Limits LL: The moisture content at which a 2 mm￾wide groove in a soil pat will close for a distance of 0.5 in when dropped 25 times in a standard brass cup falling 1 cm each time at a rate of 2 drops/sec in a standard liquid limit device PL: The moisture content at which a thread of soil just begins to crack and crumble when rolled to a diameter of 1/8 inches PI = LL – PL or IP=wL-wP Note: These are water contents, but the percentage sign is not typically shown. Soil Mechanics Review: Grain Size Distribution Which soil is good for trenching and shoring work?

05/05/2016卖居理工大学SollMechanlcsReylew:Uscs-PlasticltyChartCreeptestsarrequired for anchorsan实员理工大学实员理工大学Soil Mechanics Revlew:PermeablltySoll Mechanics Revlew:FlowNetKHNLXLXM0:N.FSpg=i,/i-[(Gs-1)e+1)/mWhatisthematterCH method is usedwithwaterfor permeable soils0(k>10-*cm/s), and FHtrenchingtest is mainly used forandless permeable soilsshoring?(k<10cm/s)FIG Permeability, drainage, soil type, and methods to determine thecoefficient of permeability (after AL Casagrande, 1938)武居理工大学武汉理工大学Soll MechanicsRevlew:EffectiveStressTheorySollMechanlcsReylew:ShearStrengthG=Hy.+(H,-H)yG=[P,+P,++P.JAG=α+uA-a,)]/A=0+Total stress can be divided into two parts:-A portion carried by water in the void -u-The contact between particles, cG-EYH,-YH.Hi = layer thicknessmoisture (above WT) or saturated unitweightHw=ThedepthofthepointtoGWT6

05/05/2016 6 Soil Mechanics Review: USCS-Plasticity Chart Creep tests are required for anchors in soils with PI larger than 20 Soil Mechanics Review: Permeability FIG Permeability, drainage, soil type, and methods to determine the coefficient of permeability (after A. Casagrande, 1938). CH method is used for permeable soils (k>10-4 cm/s), and FH test is mainly used for less permeable soils (k<10-4 cm/s). Soil Mechanics Review: Flow Net FS i / i [(Gs 1)/(e 1)]/ i L t N kHN Q d f        max max FS i / i [(Gs 1)/(e 1)]/ i piping  cr    What is the matter with water in trenching and shoring? Soil Mechanics Review: Effective Stress Theory u A a A u P P P A H H H s v v nv w A sat             ' [ ( )]/ ' ' [ . ]/ ( ) 1 2        Total stress can be divided into two parts: A portion carried by water in the void A portion carried by water in the void –u The contact between particles, ’ Hi = layer thickness i = moisture (above WT) or saturated unit weight Hw = The depth of the point to GWT iHi wHw '   Soil Mechanics Review: Shear Strength

05/05/2016心卖居理工大学卖居理工大学Soll MechanlcsRevlew:ShearStrengthSollMechanlcsRevlew:ShearStrengthSoilderives its shearstrengthfromtwosources:Laboratory:Cohesion between particles (stress independent)Direct sheartestCementation between sand grainsUnconfined compression testElectrostatic atractionbetween clayparticlesTriaxial compressiontest Frictional resistance between particles (stress dependent)Field.Vane sheartestShear.SPTStrengths=c'+o'tang"CPTetcc'= cohesion= angle of intemal frictionlormalStress.c武员理工大学实员理工大学Soil Mechanics Revlew:Peak Vs ResidueSoll MechanicsReview:Dralned vs UndrainedWhichstrength楼Hdo youdesignfor?Before loadingAfterloadingInclaysdrainagedoesnotoccurquickly:thereforeexcessporewaterpressure does not dissipate quickly.Therefore,in clays the short-termshear strength may correspond to undrained conditions.Even in clays.long-termshearstrengthisestimatedassumingdrainedconditionsInsands.normallyitisdrainedcondition武隆政工大学武活理工大学Soll Mechanics Revlew:Trlaxlal TestSoll MechanicsRevlew:UnconflnedCompresslonForcohesive soils under saturated conditionsUnconfinedcompressiontestisused0=0,S=Cwhen = 0 assumption is validThough withCylindrical TestspecimenNoonfningstress(emanyawh.maybetheTriaxialcompressionis amoreAxialstress=01mostpopularingeneralized versionourdesignoSampleis firstcompressedisotropically..and then sheared by axial loadingTypeoftriaxial compressiontestsUnconsolidated Undrained (UU)L6-5Consolidated Drained (CD)6Consolidated Undrained (CU)q,=Unconfined Conmpression StrengtS, = Undrained Shear Strngth =g_ /2a

05/05/2016 7 Soil Mechanics Review: Shear Strength Soil derives its shear strength from two sources:  Cohesion between particles (stress independent)  Cementation between sand grains  Electrostatic attraction between clay particles  Frictional resistance between particles (stress dependent) s  c  tan angle of internal friction c cohesion      Soil Mechanics Review: Shear Strength Laboratory  Direct shear test  Unconfined compression test  Triaxial compression test Field  Vane shear test  SPT  CPT  etc Soil Mechanics Review: Peak Vs Residue Which strength do you design for? Soil Mechanics Review: Drained vs Undrained  In clays, drainage does not occur quickly; therefore excess pore water pressure does not dissipate quickly. Therefore, in clays the short-term shear strength may correspond to undrained conditions. Even in clays, long-term shear strength is estimated assuming drained conditions  In sands, normally it is drained condition Soil Mechanics Review: Unconfined Compression  For cohesive soils under saturated conditions,  = 0, Su=c.  Cylindrical Test specimen  No confining stress (i.e. 3 = 0)  Axial stress = 1 Though with many flaws, this may be the most popular in our design 3 = 0 1 / 2 u u u S Undrained Shear Strngth q q Unconfined Compression Strength    Symbols qu vs su/cu Soil Mechanics Review: Triaxial Test  Unconfined compression test is used when  = 0 assumption is valid  Triaxial compression is a more generalized version  Sample is first compressed isotropically and then sheared by axial loading  Type of triaxial compression tests  Unconsolidated Undrained (UU)  Consolidated Drained (CD)  Consolidated Undrained (CU) 1 3

05/05/2016武理工大学西武隆理工大学Soll MechanlcsRevlew:U-UTestSoll Mechanlcs Revlew:C-U TestProcedures:Procedures:1.Sample is put into the1.Sample is put into theCylindercyinder2.Apply confining pressure wfo2Apply confiningconsolidation (valve closed)pressurewconsolidation(valve opened,take time)3Applydeviate stressto3.Applydeviate stress tofail the sample (valve closed)fail the sample (valve clostake time)武理工大学实员理工大学Soll Mechanics Revlew:C-D TestSoll MechanicsReview:ShearStrengthProcedures:=c+otand1.SampleisputintothecylinderCDTests2.Apply confining pressurewconsolidation(valveopened, take time)Applydeviate stressto fail the sample (valvefc+oacUTestsopened,taketime)Te武居理工大学武居理工大学Soll MechanicsRevlew:ShearStrengthSoll MechanlcsReylew:Typlcal StrengthYatuesCequalsto zerofor NC clay andsandFor saturated clay.Cuis the mostpopularly usedparameterwith=0 (conservative)8

05/05/2016 8 Soil Mechanics Review: U-U Test Procedures: 1.Sample is put into the cylinder 2.Apply confining pressure w/o consolidation (valve closed (valve closed) 3. Apply deviate stress to fail the sample (valve closed). Soil Mechanics Review: C-U Test Procedures: 1.Sample is put into the cylinder 2. Apply confining pressure w consolidation pressure w consolidation (valve opened, take time) 3. Apply deviate stress to fail the sample (valve closed, take time) . Soil Mechanics Review: C-D Test Procedures: 1.Sample is put into the cylinder 2.Apply confining pressure w consolidation w consolidation (valve opened, take time) 3. Apply deviate stress to fail the sample (valve opened, take time) . Soil Mechanics Review: Shear Strength s  c  tan CD Tests CU Tests Soil Mechanics Review: Shear Strength  C equals to zero for NC clay and sand  Fo satu ated c ay, r saturated clay, Cu is the most popularly used parameter with =0 (conservative) Cu and =0 Soil Mechanics Review: Typical Strength Values

05/05/2016卖活共工大学武居理工大学Soll MechanlcsRevlew:StrengthParametersSollMechanlcsRevlew:StrengthParameterstNo工字装三Tbk122Rle,arsHardViny SehMndurVery SuifrSeh823-300-10010-1025-100ETale 1.8 ReationshnTand Ancle of Erction of Cohesioniess SolltaieofpackingAngle of tiction, (deg)Very losse20?Loose40:6036:40Rede武服北工大学实理工大学Soil Mechanics Revlew: ConsolldatlonSoll Mechanics Revlew: Lateral Earth PressureInahomogenaturalsoildeposit-GLXThe raftio on/o,'is a constant known as coefficient of earth pressure at rest (K0)Importantly, at Ko state, there are no lateral strainsCFor NC clays and granular soils, K=1 sin EffectivestressonlForOC clays,Ka.ocKo,uc OCRWhy?Frmlasticanalys,K0Palacio de las Bellas Artes, Mexico CityPoisson'sraticBuilt1932-1934Total settiement=9ft武工大学武居理工大学Soll Mechanlcs Revlew:Actlve EarthPressureSoll Mechanlcs Revlew:Active EarthPressure-in granular soilsInitially, there is no lateral movement.Failureplane is atActive state45+@/2tohorizontalay=yZO=Ko,=KoYzAsthewallmoyewayfrom thesoil.,a,remains the same; and on'decreases tillfailuret,occurs.WJMR(1820-1872)active earthInitially (K,state)pressureFrictionless WallFaiure state[o,'lacme=KgRankine's coefficient ofactive earth pressure-sinetan*(45-/2)I+sinedecreasing 9

05/05/2016 9 Soil Mechanics Review: Strength Parameters Very dense > 80 > 45 Compact 40 - 60 35 - 40 Dense 60 - 80 40 - 45 Very losse < 20 < 30 Loose 20 - 40 30 - 35 Table 1.8 Relationship between relative Density and Angle of Friction of Cohesionless Soils State of packing Relative density (%) Angle of friction, '(deg) Soil Mechanics Review: Strength Parameters Soil Mechanics Review: Consolidation Palacio de las Bellas Artes, Mexico City Built 1932-1934 Total settlement = 9ft Soil Mechanics Review: Lateral Earth Pressure GL In a homogeneous natural soil deposit, X h’ v’ The ratio h’/v’ is a constant known as coefficient of earth pressure at rest (K0). Importantly, at K0 state, there are no lateral strains. For NC clays and granular soils, K0 = 1 – sin ’ For OC clays, K0,OC= K0,NC OCRsin’ From elastic analyses,     1 Ko Poisson’s ratio Effective stress only Why? Soil Mechanics Review: Active Earth Pressure A v’ h’ z As the wall moves away from the soil, Initially, there is no lateral movement. v’ = z, h’ = K0 v’ = K0 z v’ remains the same; and h’ decreases till failure occurs. Active state Frictionless Wall  v’  decreasing h’ Initially (K0 state) Failure state active earth pressure Soil Mechanics Review: Active Earth Pressure - in granular soils  A v’ h’ 45 + /2 Failure plane is at 45 + /2 to horizontal v [ ’ h’]active   90+ [ '] '  h active  KA v tan (45 / 2) 1 sin 1 sin 2        KA  Rankine’s coefficient of active earth pressure WJM Rankine (1820-1872)

05/05/2016心卖理工大学卖居理工大学Soll Mechanlcs Revlew:Actlve EarthPressureSoll MechanlcsRevlew:Passlve EarthPressure-in granular soilsincohesivesoilsAsthewall movestowardsthesoil,[o,',=K,o,-2cKFailure plane is atInitially (Ko state)45-/2tohorizontalFailure (Passive stateVK45-0/2passiveearthpressureRankine's coefficientofpassiveearthpressureicreasingo,I+sing=tan (45+/2)[oN Jrasshe = Kpo,'KI-sing实理工大学实员理工大学Soil Mechanics Revlew: Lateral Earth PressureSoll Mechanics Revlew:Lateral Earth Pressure-in.cosivesoils- in granular soilsHowtoitinshorine[onTachse=Ko+2cK[a]attention toSthePaand P,are theresultant active andagnitudepassive thrusts on the wallClo,1OP-Q5K.YHWhere to start()amtaw-inrealdesign?frshdyB-=0.5Ka(w)ttentionto++ M150KorhCrHine武居理工大学武武居理工大学Soil Mechanics Revlew: Lateral Earth PressureSoll MechanlcsRevlew:Coulomb'sTheoryErictionalWa(1976)to10

05/05/2016 10 Soil Mechanics Review: Active Earth Pressure - in cohesive soils h active A v KA [ ']  K  '2c Soil Mechanics Review: Passive Earth Pressure - in granular soils  Initially (K0 state) Failure (Passive state) As the wall moves towards the soil, Failure plane is at 45 - /2 to horizontal 45 - /2 v’  increasing h’ passive earth pressure tan (45 / 2) 1 sin 1 sin [ '] ' 2          h passive  KP v KP  Rankine’s coefficient of passive earth pressure Soil Mechanics Review: Lateral Earth Pressure - in cohesive soils h passive P v KP [ ']  K  '2c Pay attention to the magnitudes How to use it in shoring design Soil Mechanics Review: Lateral Earth Pressure - in granular soils [h’]active PA and PP are the resultant active and passive thrusts on the wall [h’]passive H h KA KPh H PA=0.5 KAH2 PP=0.5 KPh2 Where to start in real design? Pay attention to this part Soil Mechanics Review: Lateral Earth Pressure From  Goldberg et al. (1976) to consider the disturbance and overxcavation during construction. S td uggested for your d i es gn Soil Mechanics Review: Coulomb’s Theory Difference btwn Rankine’s theory and Coulomb’s theory: Frictional Wall