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Center for Accelerating InnovationAdvanced Geotechnical Methods for Exploration:The A-GaMEBring It!Benjamin S. Rivers, P.E.FHWA- Resource CenterTh64 Alabama Transportation ConferenceFebruary 10th, 20211
Center for Accelerating InnovationWhat are the Advanced GeotechnicalMethods in Exploration?The A-GaME is a toolbox of underutilizedsubsurface exploration tools that will assistwith: Assessing risk and variability in sitecharacterization Optimizing subsurface exploration programs Maximizing return on investment in projectdelivery2
Center for Accelerating InnovationThe A-GaME’s MissionMitigate risks to project schedule and budget, andimprove reliability by optimizing geotechnical sitecharacterization using proven, effective explorationmethods and practices.3
Center for Accelerating InnovationRiskSource: OhioFHWADOTSource: ALDOT4
Center for Accelerating InnovationRiskSource: Florida DOTSource: Kentucky Transportation Cabinet5
Center for Accelerating InnovationBenefit of Upfront Site Investigation InvestmentSource: NCHRP Synthesis 484 - Influence of GeotechnicalInvestigation and Subsurface Conditions on Claims, ChangeOrders, and Overruns (After Figure 1)6
Center for Accelerating InnovationMODOT Approach for Relating Design Reliability toVariability. 1.0Example Shown: Tip resistance – shafts in clayBridges on Minor RoadsBridges on Major RoadsMajor Bridges ( 100 million)Major Bridges ( 100 million)Resistance Factor for End Bearing, ϕ 400.500.600.700.80COV of Mean Undrained Shear Strength, COVsu0.90Source: Missouri DOT1.007
Center for Accelerating InnovationMainstream Effective Underutilized MethodsCPT - Cone Penetration TestTDEM - Time-Domain ElectromagneticSCPT - Seismic Cone Penetration TestFDEM - Frequency-Domain ElectromagneticER - Electrical ResistivityVLFEM - Very Low Frequency ElectromagneticIP - Induced PolarizationOTV - Optical TeleviewersSP - Self PotentialACT - Acoustic TeleviewersMWD - Measurement While DrillingGPR - Ground Penetrating RadarSeismic: RefractionMicroGravitySeismic: ReflectionPMT - Pressuremeter TestSeismic: FWI - Full Waveform InversionDMT - Flat Plate Dilatometer TestSeismic: SASW - Spectral Analysis of SurfaceRock Discontinuities from PhotogrammetryWavesPore-water pressure from Field PiezometersSeismic: TomographySuspension LoggingSeismic: DownholeSeismic: Crosshole8
Center for Accelerating InnovationSite Characterization – Current PracticeBoring/CPT LocationsBorings: Typ. SPT every 5 feet;18 inch of SamplingTo ScaleTotal Volume Tested or Sampled 0.01% (typically)9
Center for Accelerating InnovationSite Characterization – Bringing your A-GaME 6-MileSection 1-day FieldTesting ½-dayProcessingConfirmconditionsSoft SoilsLikelyConcentrateadditionalinvestigationwhere mostvaluableSource: Florida DOT10
Center for Accelerating InnovationGeophysics for final designApplying geophysics to pile design/layoutSheet Pile EndSheet Pile StartDRIVEN PILEDRILLED PILESSHEET PILE EXTENT769770771772773Depth and location of sheeting & king pilesSource: MNDOT
Center for Accelerating InnovationSeismic Refraction – Top of BedrockSource: Jeff Reid, HagerRichter12
Center for Accelerating InnovationMainstream Effective Underutilized MethodsCone Penetration Testing(CPTu/SCPTu) More reliableparameters than fromconventional SPT Small strata changeseasily discernable Pore-water pressuremeasurements Shear-wavemeasurements withSCPTu 3-10 times faster thanconventional drillingSource: FHWA13
Center for Accelerating InnovationMainstream Effective Underutilized MethodsTeleviewers – Optical andAcoustic (OTV/ATV) High-resolution, 360o, GIS,spatially oriented rockdrillhole images Continuous In-place rock structure andcondition Eliminates difficult orientedcoring Independent of core qualityCourtesy of Jeff Reid,Hager-Richter Assoc.14
Center for Accelerating InnovationMainstream Effective Underutilized MethodsMeasurement WhileDrilling (MWD) Continuousprofile Discernablestratigraphic andmaterial changes Rock or Soil Standardized inEurope ISO 224761515Source: FHWA
MWD Equipment Requirements Drilling equipment requirementsMeasuring system requirements(modified after Jean Lutz S.A., 2020)Slide Courtesy of Anahita Modiriasari, 2020
Center for Accelerating InnovationMost Basically, MWD provides Continuous quantitativedrilling recordMeans to assess sitevariabilityQC/QA valueSource: Harry Moore(Retired TN DOT)Courtesy of Liz Smith, Terracon
Center for Accelerating InnovationImmediate Applications Karst FeaturesDetecting Boulders, Lenses, BedrockInterfacesCharacterization of PiedmontResiduum and PWRStratification and materialidentification (contrasting)Source: FHWA(Gui et al., 2002)
Center for Accelerating InnovationContinuing Work Needed to Understandinterdependencies whilemaintaining production: Between drillingparameters Bit types and size Drilling methods –Including HSACorrelate to engineeringindex parameters(Reiffsteck et al., 2018)
Examples of MWD Investigations in Geotechnical EngineeringQuantitative analysisMeasuring rock strength while drilling shafts socketed into Florida limestone(Rodgers et al., 2018)Slide Courtesy of Anahita Modiriasari, 2020
Center for Accelerating InnovationA-GaME: What’s Next?In-The-Works User Groups Virtual Demos/Workshops/Deep-Dive Webinars (in partnershipwith A-GaMEr DOTs, DFI, Industry) A-GaME Web Platform (in partnership with DFI) Archived “A-GaME Winter Webinar Series” RecordedWebinars MWD Implementation Document Geophysics Webtool Case-Histories/References/Resources User-Group Links DIGGS Implementation (in partnership with GI) Look Up AASHTO PP 102 AASHTO Manual on Subsurface Investigation (AASHTO COMPTS1b) Influence of COV in LRFD (AASHTO COBS T-15) Stop-Gap Standards of Practice (collaboration with DFI, GI,EEGS)A-GaME e-News New!Kaye Chancellor Davis,Thank You for YourLeadership!Browser Search:“fhwa agame”Sign-Up!21
Center for Accelerating InnovationQuestionsBenjamin S. Rivers, FHWAResource Centerbenjamin.rivers@dot.gov404-562-3926
Advanced Geotechnical Methods for Exploration: The A-GaME Bring It! Benjamin S. Rivers, P.E. . CPT -Cone Penetration Test. SCPT - Seismic Cone Penetration Test. ER -Electrical Resistivity. IP - Induced Polarization . Cone Penetration Testing (CPTu/SCPTu) More reliable parameters than from conventional SPT
