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Analysis and design of geotechnical structures

Geotechnical characterization: In situ testing IntroductionGeotechnical investigationPreliminary surface surveyGeophysical investigationIntroductionElectrical resistivity methodSeismic refraction methodSpectral-analysis-of-surface-waves (SASW) methodGeomechanical investigationIntroductionTrial pits and shaftsBorehole drillingRotary coringNote on undisturbed soil samplingIntroductionDirect samplingIndirect samplingSampling of sandsIn situ testingIntroductionStandard penetration test (SPT)Essential aspects of the equipment and test procedureSPT correctionsEquipment calibrationCorrelations of (N1)60 with soil properties and parametersCone penetrometer test (CPT/CPTu)Essential aspects of the equipment and test procedure: measured parametersInterpretation of results: soil classification chartsCorrelations with soil characteristics and parametersDynamic probing test (DP)Essential aspects of the equipment and test procedureComment regarding the use of dynamic probing tests: interpretation of resultsVane shear test (VST)Essential aspects of the equipment and test procedureInterpretation of test results for deriving cuPlate load test (PLT)Essential aspects of the equipment and test procedureInterpretation of resultsFinal remarkCross-hole seismic test (CHT)Essential aspects of the equipment and test procedureInterpretation of resultsFinal remarkDown-hole seismic testsSelf-boring pressuremeter test (SBPT)Essential aspects of the equipment and test procedureInterpretation of resultsMénard pressuremeter test (PMT)Essential aspects of the equipment and test procedureInterpretation of resultsFlat dilatometer test (DMT)Essential aspects of the equipment and test procedureInterpretation of resultsTests for permeability characterizationPumping testsBorehole or Lefranc testsGlobal overview on site characterizationSummary of in situ testsIn situ versus laboratory testsIntroductionAdvantages and limitations of laboratory testsAdvantages and limitations of in situ testsStiffness characterization by means of in situ and laboratory testsGeneral overview: definitionsSmall is beautifulRelation of the tests to the strain level in the soilMethodology for characterization of soil stiffness for all strain levelsOverall stability of soil massesIntroductionIntroduction to limit analysis theoryFormulation: upper and lower bound theoremsExample of application – excavation with vertical face under undrained conditionsLimit equilibrium methodsIntroductionMethod of slices: general formulationFellenius methodSimplified Bishop methodSpencer methodCommentStability of embankments on soft clayey soilIntroductionApplication of the method of slices in total stress analysesMethods to improve stability conditionsLateral stabilizing bermsStaged constructionFoundation soil reinforcement with stone columnsReinforcement of the base of the embankment with geosyntheticsUse of lightweight aggregates as fill materialCommentUnsupported cuts in clayey soilIntroduction: basic featuresThe question of safety and its evolution with timeNote about the maximum depth of tension cracks on the ground surfaceCuts under undrained conditionsVertical cutsInclined face excavationsExcavations in drained conditions: effective stress analyses: Hoek and Bray chartsAnnex A2.1 Stability analysis of embankments during staged constructionAnnex A2.2 Stone column reinforcement oF the foundation of embankments on soft soilAnnex A2.3 Method of Leroueil and Rowe (2001) for the stability analysis of embankments oN soft soil with base reinforcement with geosyntheticAnnex E2 Exercises (resolutions are included in the Final Annex)Basis of geotechnical designGlobal safety factor methodDefinition of global safety factor: typical valuesLimitations of the global safety factor methodLimit state method and partial safety factorsGeneral considerationsDistinct forms of application of the limit state methodProbabilistic methodsSafety margin, reliability index, and probability of failureApplication of probabilistic methods in geotechnical designIntroduction to Eurocode 7 – geotechnical designThe Structural Eurocodes: generalitiesDesign values of the actions, material properties, and geometric dataThe question of the characteristic value of a geotechnical parameterThe concept of characteristic values of a structural and a geotechnical material parameter: Eurocode 0 versus Eurocode 7The dependence on the structure and on the limit state under considerationThe dependence on the size of the ground region that affects a given limit stateTypes of limit statesVerification of safety for STR and GEO limit statesThe three design approachesComment about the justification for adopting a unit safety factor for the permanent actionsFinal comment and perspectivesApplication of LRFD: AASHTO Code (2012)Note about Eurocode 8: definition of seismic actionAnnex A3.1 Summary of some probabilistic conceptsAnnex A3.2 Partial safety factors for the EQU, UPL AND HYD limit states, according to Eurocode 7Annex A3.3 Design Approaches 1, 2 and 3 of Eurocode 7 for limit state types STR and GEOA3.3.1 Partial safety factors on actions and the effect of actionsA3.3.2 Partial safety factors on material strengths and resistancesAnnex A3.4 Resistance factors from LRFD bridge design specifications (AASHTO, 2012)Consolidation theories and delayed settlements in clayIntroductionStress–strain relations in soils loaded under constrained conditionsConstrained loading: oedometer testsTime effect: hydromechanical analogyLoad diagrams obtained in the oedometer testTreatment of the compressibility curveParameters for the definition of the stress–strain relationshipsExpressions for calculation of the consolidation settlementSome practical issuesThe Terzaghi consolidation theoryBase hypotheses: consolidation equationLayer with only one draining boundaryConsolidation settlement change over timeEstimation of cv from oedometer testsSettlement change taking into account construction timeLoading in general (non-constrained) conditionsIntroduction: generalization of the hydromechanical analogyConsolidation settlement calculation: classical method of Skempton and BjerrumTwo- and three-dimensional consolidationBiot theory resultsSolutions of Terzaghi’s theory for any distributions of the initial excess pore pressureSecondary consolidationIntroductionOverconsolidation by secondary consolidationSecondary consolidation settlement: conventional and Brazilian approachesAcceleration of consolidationIntroductionPreloadingBase schemeCalculation of the temporary surchargeComment: control of secondary consolidation settlementsVertical drainsGeneral scheme: types of drains – installationRadial consolidationSmear effectCalculation of the vertical drain networkVacuum preloadingNote on the use of stone columnsObservation of embankments on soft soilInstallation points, equipment, and parameters to monitorThe Asaoka methodAnnex A4.1 Deduction of EquationsA4.1.1 Equation 4.1Annex A4.2 Evaluation of by the Casagrande constructionAnnex A4.3 Treatment of log –e curves by the Schmertmann constructionAnnex A4.4 Evaluation of the vertical consolidation coefficient, cvA4.4.1 The Taylor methodA4.4.2 The Casagrande methodAnnex E4 Exercises (resolutions are included in the Final Annex)Earth pressure theoriesIntroductionRankine’s active and passive limit equilibrium statesIntroduction of the conceptEarth pressure coefficients: coefficients of active and passive earth pressure, according to RankineActive and passive thrusts according to RankineDisplacements associated with active and passive statesTerzaghi experimentsStress paths: typical results of triaxial testsConsequences for the design of civil engineering structuresGeneralization of Rankine’s methodIntroductionVertical, uniformly distributed surcharges applied to the ground surfaceStratified groundGround with water tableExtension of Rankine’s theory to soils with cohesionExtension of Rankine’s theory to soil masses with inclined surface interacting with vertical wallExtension of Rankine’s theory to soil masses with inclined surface interacting with non-vertical wallBoussinesq, Résal, and Caquot theories for the consideration of soil wall frictionIntroductionThe Boussinesq theory: the Caquot-Kérisel tablesCohesive soil masses: theorem of corresponding statesCoulomb’s theoryGeneral presentation and hypothesesCulmann constructionDetermination of the thrust application pointAnalytical solutionThrust calculation due to uniform surcharge at the surface to be used in Coulomb’s methodComparison of the Rankine, Caquot-Kérisel, and Coulomb methodsActive and passive thrusts under seismic conditions: Mononobe-Okabe theoryIntroductionExpression deductionCritical horizontal accelerationInclination of the surfaces that limit the thrust wedgesGraphical solution of the problemThrust application pointGeneralization to submerged soil massesIntroductionSeismic thrust of a free water mass on a vertical wallThrust of a very permeable submerged soil massNote about the seismic thrusts on walls with null displacementsAnnex A5.1 - Caquot–Kérisel tables (extract)Annex E5 – Exercises (resolutions are included in the Final Annex)The leaning bell-tower of PisaThe towerThe groundThe tiltThe stabilization worksShallow foundationsIntroductionBearing capacity under vertical loadingIntroductionGeneral expression of the load-bearing capacity under vertical loadingConditions of application of the bearing capacity equation: total and effective stress analysesInfluence of the parameters integrating the bearing capacity expressionExtension of the bearing capacity expression to cases of practical interestIntroductionEccentric loadsShallow foundations on stratified groundBearing capacity for vertical loading under seismic conditionsSafety against foundation soil failure due to insufficient bearing capacity for vertical loadingGlobal safety factorPartial safety factors: structural Eurocodes and LRFD codesEstimation of foundation settlementIntroductionImmediate settlement: elastic solutionsGeneral expressionHomogeneous semi-indefinite soil formationHomogeneous layer with rigid lower boundaryFoundation rotation associated with moment actionShortcomings of the elastic solutionsImmediate settlement in sandSchmertmann’s methodElastic theoretical method versus Schmertmann’s methodDeformation modulus of sandy soilsImmediate settlement in claySettlement expressionDeformation modulus of clayey soilsNote about settlement by secondary consolidation or by creepVerification of structural serviceability limit states due to foundation movement: actions to considerDesign of the foundations of a structureMovement of the foundation of a structure: definitions and limitsSizing based on allowable stress or allowable pressureDesign based on identical foundation settlementAllowable design settlement for structural foundationsDesign sequence for shallow building foundationsEvaluation of site seismic behavior: liquefaction susceptibility of sandy soilsIntroductionThe cyclic stress procedure: general formulationRepresentation of seismic loadingCharacterization of liquefaction potentialEvaluation of safety against liquefactionThe cyclic stress approach: more recent application proposalsResults from the NCEER Workshops, USA (1996, 1998)New developments from Idriss and BoulangerSettlement evaluation in sand formations above the water tableGround improvement for liquefaction mitigationMost common densification methods for sand strataDegree of improvement to be achieved and area to be treatedAnnex A6.1 Evaluation of the bearing capacity for vertical loading by direct application of PMT results (Melt, 1993)Annex A6.2 INCREMENTAL Stress in an elastic, homogeneous half-space loaded at the surfaceA6.2.1 Solutions of Boussinesq and Flamant and “stress bulbs”A6.2.2 Uniform pressure on infinite stripA6.2.3 Triangular pressure on infinite stripA6.2.4 Uniform pressure on circular areaA6.2.5 Uniform pressure on rectangular areaAnnex A6.3 Settlement evaluation by direct application of PMT results (Melt, 1993)Annex E6 exercises (resolutions are included in the Final Annex)Pile foundationsIntroductionTypes of pile foundations and construction methodsSingle axially loaded pileShaft and base resistance mobilizationInfluence of the construction process on pile axial resistanceUltimate resistance of a single axially loaded pileBearing capacityAssessment from analytical methodsShaft resistanceAssessment from semi-empirical methods based on field testsGeneral aspectsMethod based on CPT and PMT results (French or LCPC method)Methods based on SPT resultsAssessment from axial load testsGeneralConventional static load test (compression)Bi-directional (Osterberg) load testAssessment from high-strain dynamic load testsA note on negative skin frictionSingle laterally loaded pileBasic phenomenology of the soil–pile interaction for rigid and slender pilesStructural analysis of slender pilesWinkler theory: analytical solutionsPile groupsGeneral aspectsGroup effect in axially loaded pilesGroup effect in laterally loaded pilesIntegrity pile testingGeneralSonic-echo testCross-hole testIntroduction of safetyGeneralGlobal safety factorsPartial safety factors (Eurocode 7)Ultimate compressive resistance from static load testsUltimate compressive resistance from ground test resultsUltimate compressive resistance from dynamic impact testsLoad and Resistance-Factored Design (LRFD)Annex A7.1 Evaluation of the pile axial capacity by direct application of PMT or CPT resultsAnnex E7 ExercisesE7.2E7.3E7.4E7.5E7.6Earth-retaining structuresIntroductionGravity wallsWall types: conceptionUltimate limit states of gravity walls by external failureSoil thrust to be considered for the evaluation of external safetyPractical questions about design and constructionParameters of the soil and interfacesBackfill drainageEvaluation of the soil thrust in some practical casesConsideration of seepage forcesRetaining walls with a non-rectilinear back faceReinforced concrete cantilever wallsPressure induced by point loads or uniform surcharges applied on a limited surface areaEvaluation of the external safety of gravity retaining wallsGlobal safety factorsGravity retaining walls under seismic action: selection of kh and kvInternal designGeneral considerationsReinforced concrete retaining wallsStone masonry, gabion, and cyclopean concrete retaining wallsEmbedded flexible wallsIntroductionCantilever embedded wallsAnalysis methods: safety factorsBrief parametric studyVertical equilibrium of cantilever embedded wallsSingle-propped embedded wallsAnalysis method: safety factorsBrief parametric studyVertical equilibrium of single-propped and single-anchored wallsNote on water-related pressureConstruction sequence combining cantilever and single-propped walls in distinct stagesAnchorsIntroduction: terminology and executionMechanical behavior of anchorsLimit states: force-displacement graphMobilization of the grout bulb–ground interface resistanceAnchor designLimit State DesignEstimation of anchor resistance: anchor load tests and the role of comparable experienceEstimation of anchor resistance from testsConfirmation of the anchorage resistance from the results of the acceptance testsVerification of global stabilityAnnex A8.1 Seismic coefficients for design of retaining walls, according to Eurocode 8Annex E8 Exercises (resolutions are included in the Final Annex)The Vajont catastropheStability and stabilization of natural slopesIntroductionInfinite slopesIntroduction: geological-geotechnical scenariosInfinite slope in granular material, above the ground water levelInfinite slope in a material with cohesion and angle of shearing resistance, above the ground water levelInfinite slope with seepage parallel to the ground surfaceIntroductionInfinite slope under seismic actionGeneral method for slope stability analysis: the Morgenstern and Price methodIntroductionHypothesesEquilibrium equations for a slice of infinitesimal widthSolution of the system of equationsMethod of sliding wedgesContext of slope stability studiesIntroductionActive zone, passive zone, and neutral line in a natural slopeCircumstances and symptoms of slope instabilityInterpretation of the potential failure mechanismStages of slope movements: reactivation of landslidesNote on factor of safetyStabilization measuresIntroductionAlteration of the slope geometrySuperficial and deep drainageStructural solutionsGround anchors connected to reinforced concrete wallsGround reinforcement with inclusions that intersect the failure surfaceMethods of analysis of the stabilization solutionsObservation of natural slopesGeneral remarksObservation planAnnex A9.1 Seismic coefficients to be used in slope stability analyses, according to Eurocode 8Annex A9.2 Inclinometer measurementsA9.3 In situ measurement of pore water pressureAnnex E9 exercises (resolutions are included in the Final Annex)IntroductionCompactionCompaction curvesThe w−γd relationship in soils with a significant fraction of finesEffect of the compaction effortThe w − γd relationship in clean granular soilsLaboratory compaction testsProctor testsVibration compaction testsCompaction parameters of soils with coarse gravel (material retained in the 19-mm sieve)Field compaction equipmentMechanical behavior of compacted soilsIntroduction: soils with significant fines content and the effect of soil suctionDam failures during construction and the practice of compacting on the dry side of the optimumVolume change in a soil saturated by inundation. The phenomenon of soil collapseCompaction chartsIntroduction to earthworksThe peculiar context of earthwork design and constructionSelection of materialsAssessment of the compaction characteristics: mechanical and hydraulic characterizationPhase of conception and designSpecifications for field compactionField compactionControl of compaction through physical characteristicsControl by Hilf’s Rapid MethodFrequency of the compaction control operations and statistical analysis of resultsControl of the compaction through mechanical characteristicsControl by means of soil testingControl using a compaction plant: intelligent compactionFinal remarksFinal annex: Resolution of the exercisesSymbolsIndex

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