SOILS AND FOUNDATIONSSOILS AND FOUNDATIONS

Testing

Experience

Theory

Lesson 03Lesson 03Chapter 3 Chapter 3 –– Subsurface ExplorationsSubsurface Explorations

Lesson PlanLesson Plan

ggTopic 1 (Section 3.0, 3.1, 3.2)Topic 1 (Section 3.0, 3.1, 3.2)-- Historical dataHistorical data-- Formation of soils and landformsFormation of soils and landforms-- Field reconnaissanceField reconnaissance

ggTopic 2 (Section 3.3, 3.4, 3.5, 3.6)Topic 2 (Section 3.3, 3.4, 3.5, 3.6)-- Sampling techniques and toolsSampling techniques and tools-- Boring methodsBoring methods-- Sampling methodsSampling methods

Lesson PlanLesson Plan

ggTopic 3 (Section 3.7, 3.8, 3.9, 3.10)Topic 3 (Section 3.7, 3.8, 3.9, 3.10)-- The Standard Penetration Test (SPT)The Standard Penetration Test (SPT)-- The Cone Penetration Test (CPT)The Cone Penetration Test (CPT)-- Log of boring information (Boring logs)Log of boring information (Boring logs)-- Groundwater measurementsGroundwater measurements

ggTopic 4 (Section 3.11, 3.12)Topic 4 (Section 3.11, 3.12)-- Guidelines for minimum subsurface explorationsGuidelines for minimum subsurface explorations-- Geophysical testsGeophysical tests

Subsurface ExplorationsSubsurface Explorations

Lesson 03 Lesson 03 -- Topic 1Topic 1Historical Data, Soils and Landforms, Field Historical Data, Soils and Landforms, Field

ReconnaissanceReconnaissance(Section 3.0, 3.1, 3.2)(Section 3.0, 3.1, 3.2)

Learning OutcomesLearning Outcomes

ggAt the end of this session, the participant will At the end of this session, the participant will be able to:be able to:-- Identify sources of subsurface informationIdentify sources of subsurface information-- Compare soil formations and landformsCompare soil formations and landforms-- Report relevant field reconnaissance informationReport relevant field reconnaissance information

Preparing for Subsurface ExplorationPreparing for Subsurface Exploration

“If you do not know what you should be “If you do not know what you should be looking for in a site investigation, you are not looking for in a site investigation, you are not likely to find much of value”likely to find much of value”

GlossopGlossop (1968)(1968)Eighth Eighth RankineRankine LectureLecture

Points to PonderPoints to Ponder

ggBy investing in a systematic approach to By investing in a systematic approach to developing subsurface information, overly developing subsurface information, overly conservative designs could be avoided and conservative designs could be avoided and costly construction claims can be minimizedcostly construction claims can be minimized

Developing a Developing a Subsurface ModelSubsurface Model

gg Figure 3Figure 3--11

gg Step 1:Step 1:-- Subsurface ExplorationSubsurface Exploration-- Field ExplorationField Exploration

gg Step 2:Step 2:-- Laboratory testingLaboratory testing-- Test interpretationTest interpretation

gg Step 3:Step 3:-- Subsurface Model for Subsurface Model for

Engineering DesignEngineering Design

Review available subsurface information and develop preliminary model of subsurface conditionsReview available subsurface information and develop preliminary model of subsurface conditions

Conduct laboratory testing

Site

Inve

stig

atio

n an

d Fi

eld

Tes

ting

Lab

orat

ory

Tes

ting

and

Tes

t Int

erpr

etat

ion

Eng

inee

ring

Des

ign

Identify material properties required for design and constructability and estimate scope of field program Identify material properties required for design and constructability and estimate scope of field program

Plan site exploration and field test programPlan site exploration and field test program

Conduct field investigations and field testingConduct field investigations and field testing

Perform sample descriptions and laboratory index testsPerform sample descriptions and laboratory index tests

Summarize basic soil/rock data and develop subsurface profileSummarize basic soil/rock data and develop subsurface profile

Are results consistent with

preliminary model?

Review design objectives and initial resultsReview design objectives and initial results

Are there additional data needs

Select representative soil/rock samples and details of laboratory testing

Yes

No

Review quality of laboratory test data and summarize

Select material properties and finalize subsurface modelSelect material properties and finalize subsurface model

Are results consistent and valid

Is a Phase II Investigation

necessary?

Yes

No

Perform design and consider constructability issues

Phase II Investigation (if needed)

Yes

No

Yes

No

Historical DataHistorical Data

gg Table 3Table 3--11

gg Utility mapsUtility mapsgg Aerial photographsAerial photographsgg Topographic mapsTopographic mapsgg Existing subsurface exploration dataExisting subsurface exploration datagg Geological reports and mapsGeological reports and mapsggWater/brine well logsWater/brine well logsgg Flood insurance mapsFlood insurance mapsgg Soil surveySoil surveygg Sanborn fire insurance mapsSanborn fire insurance maps

Soil FormationSoil Formation

ggSoils are a result of weathering of rocksSoils are a result of weathering of rocks-- Rocks are igneous, sedimentary, metamorphicRocks are igneous, sedimentary, metamorphic

ggWeathering processesWeathering processes-- Mechanical (physical) processesMechanical (physical) processes

•• Expansion, abrasion, temperature changes, erosion by Expansion, abrasion, temperature changes, erosion by wind/rain, crystal growth, organic activitywind/rain, crystal growth, organic activity

-- Chemical processesChemical processes•• Hydration, hydrolysis, oxidation, solution, leachingHydration, hydrolysis, oxidation, solution, leaching•• Mainly occurs by fluids seeping in to the fractures Mainly occurs by fluids seeping in to the fractures

caused by mechanical processescaused by mechanical processes

Weathering of RocksWeathering of Rocks

Weathering of RocksWeathering of Rocks

Weathering of Weathering of RocksRocksggLook at range of Look at range of

particle sizesparticle sizes

Formation of LandformsFormation of Landforms

gg Once rock is broken into fragments, rate of Once rock is broken into fragments, rate of weathering depends on particle size and the weathering depends on particle size and the climateclimate

gg Smaller particles weather faster due to larger Smaller particles weather faster due to larger surface areasurface area

ggWeathering can break down particles to soil and Weathering can break down particles to soil and colloidal sizes (not visible to naked eye)colloidal sizes (not visible to naked eye)

gg Soils formed by a particular geologic process Soils formed by a particular geologic process assume characteristic topographic features called assume characteristic topographic features called LANDFORMSLANDFORMS

Types of LandformsTypes of Landforms

ggResidualResidualggTransportedTransported

Residual SoilsResidual SoilsggFigure 3Figure 3--22

Transported SoilsTransported Soils

ggWaterWatergg IceIceggWindWindggGravityGravity

Water Transported SoilsWater Transported Soils

ggTable 3Table 3--22

ggWaterWater-- Flood plainFlood plain-- Coastal plainCoastal plain-- TerracesTerraces-- Lakebed (Lakebed (lacustrinelacustrine, , varvesvarves))-- DeltaDelta-- Alluvial Fans (Filled valleys, basin deposits)Alluvial Fans (Filled valleys, basin deposits)

Ice and Ice and MeltwaterMeltwater Transported SoilsTransported Soils

ggTable 3Table 3--22

gg Ice (Glacier) and Ice (Glacier) and MeltwaterMeltwater-- Moraines (Terminal, lateral)Moraines (Terminal, lateral)-- Glacial till (ground moraine)Glacial till (ground moraine)-- OutwashOutwash-- EskersEskers-- DrumlinsDrumlins

Wind Transported SoilsWind Transported Soils

ggTable 3Table 3--22

ggWind (Aeolian)Wind (Aeolian)-- LoessLoess-- Sand DuneSand Dune

Gravity Transported SoilsGravity Transported Soils

ggTable 3Table 3--22

ggGravityGravity-- ColluviumColluvium-- Talus (Talus (ScreeScree))

Urban Fill SitesUrban Fill Sites

gg Insert slideInsert slide

What type of What type of geomaterialgeomaterial is this?is this?

Field Field ReconnaissanceReconnaissanceggFigure 3Figure 3--33

ggRecommended for Recommended for all projectsall projects

Learning OutcomesLearning Outcomes

ggAt the end of this session, the participant will At the end of this session, the participant will be able to:be able to:-- Identify sources of subsurface informationIdentify sources of subsurface information-- Compare soil formations and landformsCompare soil formations and landforms-- Report relevant field reconnaissance informationReport relevant field reconnaissance information

Any Questions?Any Questions?

THE ROAD TOUNDERSTANDING

SOILSAND

FOUNDATIONS

Subsurface ExplorationsSubsurface Explorations

Lesson 03 Lesson 03 -- Topic 2Topic 2Sampling techniques and tools, Boring Sampling techniques and tools, Boring

methods, Sampling methodsmethods, Sampling methods(Section 3.3, 3.4, 3.5, 3.6)(Section 3.3, 3.4, 3.5, 3.6)

Learning OutcomesLearning Outcomes

ggAt the end of this session, the participant will At the end of this session, the participant will be able to:be able to:-- Contrast field testing and field samplingContrast field testing and field sampling-- Compare field boring methods for soil and rockCompare field boring methods for soil and rock-- Select appropriate field sampling and handling Select appropriate field sampling and handling

techniques in soil and rocktechniques in soil and rock-- Calculate rock quality designation (RQD)Calculate rock quality designation (RQD)

Soil Exploration for Soil Exploration for GeostratificationGeostratification

ggNumber of layersNumber of layersggThickness and depth of layersThickness and depth of layersggTypes of Types of geomaterialsgeomaterials and propertiesand propertiesggGroundwater Groundwater table(stable(s))

Invasive Exploration TechniquesInvasive Exploration Techniques

SPT CPT DMT PMT VST

TruckTruck--Mounted Drill RigsMounted Drill Rigs

Layne Drilling

AllAll--Terrain Drill RigsTerrain Drill Rigs

McLean, VA GT Campus, Atlanta, GA

TrackTrack--Mounted Drill RigsMounted Drill Rigs

Tucson, Arizona

Specialty Rigs (“Specialty Rigs (“WinkyWinky”)”)Tucson, Arizona

Specialty Rigs for Difficult AccessSpecialty Rigs for Difficult AccessUS 60 Pinto Valley, Arizona

Helicopter Helicopter Transported RigsTransported RigsggSedona, ArizonaSedona, Arizona

For Extra Credit, Can you Spot the For Extra Credit, Can you Spot the Inspector?Inspector?

Auger BoringsAuger Borings

Solid Stem Auger DrillingSolid Stem Auger Drilling

HollowHollow--StemStemAuger BoringAuger Boring

Hollow Stem Auger (HSA) DrillingHollow Stem Auger (HSA) Drilling

Rotary Wash BoringsRotary Wash Borings

gg In rotary wash method, In rotary wash method, borehole is stabilized borehole is stabilized either by temporary steel either by temporary steel casing or drilling fluid.casing or drilling fluid.

ggFluids include water, Fluids include water, bentonitebentonite or polymer or polymer slurry, or foam that are slurry, or foam that are recirculatedrecirculated in tub or in tub or reservoir at surface.reservoir at surface.

Rig conducting rotary wash boring

Rotary Wash BoringsRotary Wash BoringsggRotary wash techniques Rotary wash techniques

are are areare best for borings best for borings extending below extending below groundwater tablegroundwater table

ggRotary wash can achieve Rotary wash can achieve great depths > 300 ft great depths > 300 ft (>100 m) (>100 m)

ggDrilling bits:Drilling bits:-- Drag bits for claysDrag bits for clays-- Roller bits for sandsRoller bits for sands

Drag, Roller, andDiamond Bit Types

Rotary Wash Boring MethodRotary Wash Boring Method

Wash BoringWash Boring

Soil Sampling MethodsSoil Sampling MethodsggDisturbed Sampling Disturbed Sampling

-- Bulk samples (from auger cuttings or test pit excavations)Bulk samples (from auger cuttings or test pit excavations)-- Drive samples (Drive samples (e.ge.g, split, split--barrel)barrel)-- Table 3Table 3--5(a), 35(a), 3--5(b)5(b)

ggUndisturbed SamplingUndisturbed Sampling-- Push Tubes (Shelby, Piston)Push Tubes (Shelby, Piston)-- Rotary & Push (Denison, Pitcher)Rotary & Push (Denison, Pitcher)-- Table 3Table 3--66

ggBulk SamplingBulk Sampling-- Used for testing of borrow materials for controlled Used for testing of borrow materials for controlled

fill (compacted samples)fill (compacted samples)-- Testing includes index, classification, moistureTesting includes index, classification, moisture--

density, and higherdensity, and higher--order tests on compacted order tests on compacted specimens.specimens.

Disturbed Soil Sampling MethodsDisturbed Soil Sampling Methods

gg SplitSplit--Barrel (“SplitBarrel (“Split--Spoon”) SamplingSpoon”) Sampling-- Drive a splitDrive a split--barrel into the soil and collect samplebarrel into the soil and collect sample-- Samples used for index, classification and moistureSamples used for index, classification and moisture--

content testscontent testsgg Discussed more with SPTDiscussed more with SPT

Disturbed Soil Sampling MethodsDisturbed Soil Sampling Methods

SplitSplit--Barrel (SplitBarrel (Split--Spoon) SamplerSpoon) Sampler

Undisturbed Soil Sampling Methods Undisturbed Soil Sampling Methods

ggThinThin--Walled Shelby TubeWalled Shelby TubeggPiston Push SamplersPiston Push SamplersggPitcher (Rotary & Push)Pitcher (Rotary & Push)ggDenison (Rotary & Push)Denison (Rotary & Push)

ThinThin--walled “Shelby” Tube walled “Shelby” Tube Sampling Sampling ggASTM D 1587 standardASTM D 1587 standardgg3.03.0--inch O.D. with 2.8inch O.D. with 2.8--inch I.D. tubeinch I.D. tubeggUsed in soft to firm silts and clays to clayey Used in soft to firm silts and clays to clayey

and and siltysilty sandssandsggLengths of about 30 inchesLengths of about 30 inchesggMade of carbon steel, brass, stainless, or Made of carbon steel, brass, stainless, or

galvanized steelgalvanized steel

Shelby Tube SamplingShelby Tube Sampling

ThinThin--Walled Tube SamplersWalled Tube Samplers

Preparing the Shelby TubePreparing the Shelby Tube

Sampling DisturbanceSampling Disturbance

PhotoelasticityStudies

Sampling DisturbanceSampling Disturbance

Radiography (X-rays) of Tubes

Protection of SamplesProtection of SamplesggProvide care in Provide care in

transporttransportggMinimize Minimize

VibrationsVibrationsggDo not expose to Do not expose to

heat, sun, heat, sun, drying, freezingdrying, freezing

ggNot extrude in Not extrude in fieldfield

Field-Extruded Tube Samples

Special SamplersSpecial SamplersggPiston, Piston, SherbrookeSherbrooke, ,

Laval, NGI, and Laval, NGI, and Japanese SamplersJapanese Samplers

ggLarge diameters tube Large diameters tube samplers for soft and samplers for soft and sensitive clays & sensitive clays & silts.silts.

ggLess disturbance for Less disturbance for quality lab testingquality lab testing Sealing & Waxing Tubes

Stationary Piston SamplerStationary Piston Sampler(also Osterberg Sampler, Hvorslev Sampler)

g Thin walled tube with piston, rod, and modified sampler head

g Piston head fixed and vacuum applied to increase & maintain sample recovery

gUseful in very soft soils

Pitcher and Denison SamplersgPitcher is tube sampler with outer rotating

core barrelgUsed in stiff to hard clays and soft rocksg Inner thin walled tube is spring-loaded and

remains stationary while outer barrel cuts through material.

gDenison sampler similar but tube projection is manually- adjusted

Pitcher SamplerPitcher Sampler

Pitcher Pitcher SamplerSampler

Denison SamplerDenison Sampler

Exploration of RockExploration of Rock

gg Investigative methods:Investigative methods:-- Geophysical methods (section 3.12)Geophysical methods (section 3.12)-- Geologic mapping (need qualified geologists)Geologic mapping (need qualified geologists)-- Drilling and coring (this section)Drilling and coring (this section)-- Exploration test pitsExploration test pits

Exploration of RockExploration of Rockgg RefusalRefusal

-- Auger refusalAuger refusal-- SPT refusal (> 50 blows per 1 inch penetration)SPT refusal (> 50 blows per 1 inch penetration)

gg Rock Coring (ASTM D 2113)Rock Coring (ASTM D 2113)

gg NoncoreNoncore drillingdrilling

gg Percussive methodsPercussive methods

Percussive DrillingPercussive Drilling

Air-Tracks Drilling for Placement of Dynamiteto Remove Rock, Penobscot, Maine

Rock Coring MethodsRock Coring Methods

gg Standard rotary equipment or Standard rotary equipment or wirelinewirelinegg Drill bits for cutting rockDrill bits for cutting rockgg Different core barrels for sampling rockDifferent core barrels for sampling rockgg Drilling fluids and casings.Drilling fluids and casings.gg Observations noted during drilling.Observations noted during drilling.gg Logging of recovery and rock qualityLogging of recovery and rock quality

Rock Coring MethodsRock Coring Methods

Layne Rock DrillingLayne Rock Drilling

Types of Rotary Wash BitsTypes of Rotary Wash Bits

Tricone, Roller, Plug Bit Roller Bits

Drilling and Coring BitsDrilling and Coring Bits

ggDiamond bits are the best and hardest, Diamond bits are the best and hardest, producing high quality core. Fastest producing high quality core. Fastest cutting rates. Expensivecutting rates. Expensive

ggSynthetic bits. Less expensive. Generally Synthetic bits. Less expensive. Generally good quality cores.good quality cores.

ggTungsten carbide. Least expensive. Tungsten carbide. Least expensive. Slower coring rates. Slower coring rates.

Types of Coring BitsTypes of Coring Bits

Diamond, Carbide Tungsten, Sawtooth

Carbide Type Bits

Diamond Core BitsDiamond Core Bitsgg Core Size: Larger better but more $Core Size: Larger better but more $gg Diamond setting: hardest vector set against the Diamond setting: hardest vector set against the

workworkgg Bit Profiles: FullBit Profiles: Full--round, semiround, semi--round, flat crown, round, flat crown,

semisemi--flatflatgg Diamond size: relates to hardness and fineness of Diamond size: relates to hardness and fineness of

rock mineralsrock mineralsggWaterways: flushing cuttings & rock flour; Number Waterways: flushing cuttings & rock flour; Number

of ports, slots, discharge direction.of ports, slots, discharge direction.gg Matrix: secure diamonds & dissipate heatMatrix: secure diamonds & dissipate heat

www.ackerdrill.com

Diamond Coring BitsDiamond Coring Bits

www.ackerdrill.com

Core BarrelsCore Barrels

ggCore barrel retains rock core samples from Core barrel retains rock core samples from drilling operations.drilling operations.

ggSingle tube core barrel: most rugged, Single tube core barrel: most rugged, least expensiveleast expensive

ggConsists of head section, core recovery Consists of head section, core recovery tube, reamer shell, & cutting bittube, reamer shell, & cutting bit

ggOften used as starter when beginning core Often used as starter when beginning core operationsoperations

Core BarrelsCore Barrels

Core BarrelsCore BarrelsggDouble tube core barrel is the standard. Double tube core barrel is the standard. ggOuter barrel rotates with cutting bitOuter barrel rotates with cutting bitgg Inner barrel is either fixed or swivel type Inner barrel is either fixed or swivel type

(with bearings) that retains core sample.(with bearings) that retains core sample.ggCore diameters generally range from 0.85 to Core diameters generally range from 0.85 to

3.35 inch) 3.35 inch) -- See Table 3See Table 3--77

gg NX core: standard diameterNX core: standard diameter-- 2.15 inches (54 mm)2.15 inches (54 mm)

Core BarrelsCore Barrels

Outer Barrel Assembly Inner Barrel Assembly

Double Tube Core Barrel (Swivel Type)

Triple Core BarrelTriple Core BarrelggGood for obtaining core samples in Good for obtaining core samples in

fractured rock and highly weathered rocksfractured rock and highly weathered rocksggOuter core barrel for initial cut and second Outer core barrel for initial cut and second

barrel to cut finer size. Third barrel to retain barrel to cut finer size. Third barrel to retain cored samplescored samples

ggReduces frictional heat and vibration that Reduces frictional heat and vibration that may damage samplesmay damage samples

Rock CoringRock Coring

Drilling FluidsDrilling FluidsggRotary wash with water, foam, or drilling Rotary wash with water, foam, or drilling

mud (mud (bentoniticbentonitic or polymeric slurries), or or polymeric slurries), or “Revert”“Revert”

ggFluids reduce wear on drilling and coring Fluids reduce wear on drilling and coring bits by coolingbits by cooling

ggFluids remove cuttings & rock flour.Fluids remove cuttings & rock flour.ggRecirculateRecirculate to filter fluids and to minimize to filter fluids and to minimize

impact on environmentimpact on environment

Core RecoveryCore RecoveryggCore Runs taken in either 5Core Runs taken in either 5-- or 10or 10--foot foot

sections (1.5sections (1.5-- or 3or 3--m sections).m sections).ggLog the amount of material recovered.Log the amount of material recovered.ggCore RecoveryCore Recovery is percentage retained.is percentage retained.

Core RecoveryCore Recovery

Core RecoveryCore RecoveryggCores should be stored in either wooden Cores should be stored in either wooden

boxes or corrugated cardboard box.boxes or corrugated cardboard box.

ggBox marked with boring number, depth of Box marked with boring number, depth of core run, type core, bit type, core recovery core run, type core, bit type, core recovery (CR), rock type, RQD, and other notes.(CR), rock type, RQD, and other notes.

ggCore operations should be documented:Core operations should be documented:-- Loss of fluid, rates, sudden drop in rods, Loss of fluid, rates, sudden drop in rods,

poor recovery, loss of core poor recovery, loss of core

Rock Quality Designation (RQD)Rock Quality Designation (RQD)

ggThe RQD is a modified core recoveryThe RQD is a modified core recoveryggMeasure of the degree of fractures, joints, Measure of the degree of fractures, joints,

and discontinuities of rock massand discontinuities of rock massgg RQD = sum of pieces > 4 inches (100 mm) RQD = sum of pieces > 4 inches (100 mm)

divided by total core rundivided by total core runggGenerally performed on NXGenerally performed on NX--size coresize core

Rock Quality DesignationRock Quality Designation

QualityQuality RQDRQDVery PoorVery Poor 0 to 25%0 to 25%PoorPoor 25 25 -- 50%50%FairFair 50 50 -- 75%75%GoodGood 75 75 -- 90%90%ExcellentExcellent 90 90 -- 100%100%

)runtotal(TX)inches4ix(RQD >Σ

=

5-foot core run = 60 inches

16" 10" 6" 11"6" 8" 3"

RQD = 43"/60" = 72%

Care & Preservation of Rock CoresCare & Preservation of Rock Cores

ggRoutine: Rock samples in core boxesRoutine: Rock samples in core boxesggGeneral: Avoid shock and vibration General: Avoid shock and vibration

during handling and transport. during handling and transport. ggManMan--made fractures may result from made fractures may result from

excessive movements, temperatures, excessive movements, temperatures, and exposure to air.and exposure to air.

ggStorage for future referenceStorage for future reference

Storage of Rock Core BoxesStorage of Rock Core Boxes

Geologic MappingGeologic MappingggNeed experienced Engineering GeologistsNeed experienced Engineering GeologistsggFHWA Manual on Rock Slopes (1989)FHWA Manual on Rock Slopes (1989)ggField mapping of exposed rock outcropsField mapping of exposed rock outcrops

-- Discontinuities, types, orientation, infilling, Discontinuities, types, orientation, infilling, surface aspects, spacingsurface aspects, spacing

-- Directions of faults, shear zones, evidence of Directions of faults, shear zones, evidence of tectonic activitiestectonic activities

ggSpecial drilling to orient fracture directionsSpecial drilling to orient fracture directions

Learning OutcomesLearning Outcomes

ggAt the end of this session, the participant will At the end of this session, the participant will be able to:be able to:-- Contrast field testing and field samplingContrast field testing and field sampling-- Compare field boring methods for soil and rockCompare field boring methods for soil and rock-- Select appropriate field sampling and handling Select appropriate field sampling and handling

techniques in soil and rocktechniques in soil and rock-- Calculate rock quality designation (RQD)Calculate rock quality designation (RQD)

Any Questions?Any Questions?

THE ROAD TOUNDERSTANDING

SOILSAND

FOUNDATIONS

Subsurface ExplorationsSubsurface Explorations

Lesson 03 Lesson 03 -- Topic 3Topic 3SPT, CPT, Boring Logs, GroundwaterSPT, CPT, Boring Logs, Groundwater

(Section 3.7, 3.8, 3.9, 3.10)(Section 3.7, 3.8, 3.9, 3.10)

Learning OutcomesLearning Outcomes

ggAt the end of this session, the participant will At the end of this session, the participant will be able to:be able to:-- Describe the Standard Penetration Test (SPT)Describe the Standard Penetration Test (SPT)-- Explain energy and overburden correctionsExplain energy and overburden corrections-- Recall components of a boring logRecall components of a boring log-- Discuss the Cone Penetration Test (CPT)Discuss the Cone Penetration Test (CPT)-- Identify the differences between SPT and CPTIdentify the differences between SPT and CPT-- Identify groundwater measurement techniquesIdentify groundwater measurement techniques

Sequence of SPT (ASTM D 1586)Sequence of SPT (ASTM D 1586)140 lb (63.5-kg)Hammer dropping30” (0.76 m)Anvil

Split-SpoonDrive sampler2” OD1-3/8” ID30” LongNo Liner

Drill Rod

Seating Spoon 6” (150 mm)

Second Increment 6” (150 mm)

SPT Resistance(N-value) is total number of blows to drive sampler the 2nd

and 3rd 6” (150 mm) increments Third Increment 6” (150 mm)

Drill Rod SizesSymbol OD, in

A 1-5/8N 2-3/8

SplitSplit--Spoon SamplingSpoon Sampling

AdvantagesAdvantages

ggObtain a sample and NObtain a sample and N--valuevalueggSimple and ruggedSimple and ruggedggSuitable in many soil typesSuitable in many soil typesggCan be performed in weak rocksCan be performed in weak rocksggReadily available throughout the U.S.Readily available throughout the U.S.

DisadvantagesDisadvantages

ggDisturbed samples (index tests only)Disturbed samples (index tests only)ggNN--value is a crude number for analysisvalue is a crude number for analysisggNot applicable in soft clays and siltsNot applicable in soft clays and siltsggHigh variability and uncertaintyHigh variability and uncertaintyggUnreliable in gravelly soilsUnreliable in gravelly soils

SPT Hammer TypesSPT Hammer TypesDonutDonut SafetySafety AutomaticAutomatic

Hammer Lifting MechanismsHammer Lifting MechanismsRope and CatheadRope and Cathead SafetySafety AutomaticAutomatic

Energy Considerations in Energy Considerations in SPTsSPTs

Comparison of SPT NComparison of SPT N--valuesvalues

Company #2Automatic Hammer

Company # 2Manual Hammer

Company #1Manual Hammer

0 10 20 30 400

10

20

30

40

50

60

70

Dep

th in

Fee

t

N-values

Energy Efficiency of HammersEnergy Efficiency of Hammers

N60 = (Ef/60) NmeasEf = 60 for Rope & Cathead Ef = 80 for Automatic system

4

6

8

10

12

14

16

0 10 20 30 40 50

Measured N-valuesD

epth

(met

ers)

Donut

Safety

Sequence

4

6

8

10

12

14

16

0 10 20 30 40 50

Corrected N60

Dep

th (m

eter

s)

Donut

Safety

Trend

ER = 34 (energy ratio)

45

40

41

41

39

47

56

5560

5663

63

63

64

69

Correlations Based on NCorrelations Based on N--valuesvaluesSands (Reliable) Silts and Clays (Unreliable)

N60 Relative Density N60 Consistency0-4 Very loose 0-2 Very soft

5-10 Loose 2-4 Soft11-30 Medium Dense 5-8 Medium31-50 Dense 9-15 Stiff> 50 Very dense 16-30 Very stiff

Over 30 Hard

If your agency uses an automatic hammer, make sure that you correct the measured N-value accordingly to N60-value

Effect of Overburden on NEffect of Overburden on N--valuesvalues

ggNN--values of similar materials increase with values of similar materials increase with increasing effective overburden stressincreasing effective overburden stress

ggTo ensure comparison on a consistent basis, To ensure comparison on a consistent basis, normalize the Nnormalize the N--values to a certain pressurevalues to a certain pressure

N160=CN N60

Effect of Overburden on NEffect of Overburden on N--valuesvalues

gg1 1 tsftsf (= 1 (= 1 atmatm) is the normalization pressure) is the normalization pressure

N160=CN N60

CN = [0.77 log10 (20/po)] CN < 2.0 ; po is in tsf

Graph of CGraph of CNN

ggDo no apply Do no apply CCNN in in induratedindurated and and cemented cemented soilssoils

0

1

2

3

4

5

6

7

8

9

10

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Overburden Correction Factor, CN

Vert

ical

Eff

ectiv

e Pr

essu

re, t

sf

SPT Test ErrorsSPT Test Errors

ggSection 3.7.4, Table 3Section 3.7.4, Table 3--1010

Boring LogsBoring Logs

ggRecord maximum Record maximum information information accuratelyaccurately

ggField Field vsvs Final logFinal logggMany log formatsMany log formatsggEvery log must Every log must

have certain have certain minimum minimum informationinformation

Boring Log (Upper half)Boring Log (Upper half)

Boring Log (Lower half)Boring Log (Lower half)

Cone Penetration Testing Cone Penetration Testing (ASTM D 5778)(ASTM D 5778)

AdvantagesAdvantagesgg Fast and continuous Fast and continuous

profiling of strataprofiling of stratagg Economical and Economical and

productiveproductivegg Results not operatorResults not operator--

dependentdependentgg Strong theoretical basis Strong theoretical basis

for interpretationfor interpretationgg Particularly suited to Particularly suited to

soft soilssoft soils

DisadvantagesDisadvantagesgg High capital investmentHigh capital investmentgg Requires skilled Requires skilled

operator for field useoperator for field usegg Electronics must be Electronics must be

calibrated & protectedcalibrated & protectedgg No soil samplesNo soil samplesgg Unsuited to gravelly Unsuited to gravelly

soils and cobbles.soils and cobbles.

Advantages / DisadvantagesAdvantages / Disadvantages

Cone Cone PenetrometersPenetrometers

Cone Penetration Vehicles Cone Penetration Vehicles

Mobile 25-tonne rigs with hydraulic pushing systems. Enclosed cabins to allow testing for all weather conditions

Cone Penetration VehiclesCone Penetration Vehicles

Electronic Friction Cone Electronic Friction Cone PenetrometerPenetrometer

0

2

4

6

8

10

12

14

16

18

20

0 2 4 6 8

qT (MPa)

Dep

th (m

)

0

2

4

6

8

10

12

14

16

18

20

0 100 200 300

fS (kPa)

Dep

th (m

)

PiezoconePiezocone PenetrometersPenetrometers

Porewater Pressures Measured at Apex McClelland Penetrometer Design

CPT ProfilesCPT Profiles

Soil Soil Behavior Behavior TypeTypegg Standard Electronic Standard Electronic

Friction ConeFriction Cone

Comparison of SPT and CPTComparison of SPT and CPT

ggSPT gives physical samples for testing but SPT gives physical samples for testing but does not provide continuous profiledoes not provide continuous profile

ggCPT does not retrieve physical samples but CPT does not retrieve physical samples but gives continuous profilegives continuous profile-- Quicker (less expensive)Quicker (less expensive)

gg It is most beneficial to use CPT with another It is most beneficial to use CPT with another method that allows for retrieval of physical method that allows for retrieval of physical samplessamples

Groundwater MeasurementsGroundwater Measurements

ggGroundwater level and pore water pressure Groundwater level and pore water pressure measurements are extremely important for measurements are extremely important for geotechnical analysisgeotechnical analysis

ggSources of InformationSources of Information-- Existing wellsExisting wells-- Open boringsOpen borings-- Observation wellsObservation wells-- PiezometersPiezometers

Observation Observation WellsWells

PiezometersPiezometers

ggAdd slideAdd slide

Water Level MeasurementsWater Level Measurements

ggChalked tapeChalked tapeggTape with floatTape with floatggElectric waterElectric water--level indicatorlevel indicatorggData loggersData loggers

Learning OutcomesLearning Outcomes

ggAt the end of this session, the participant will At the end of this session, the participant will be able to:be able to:-- Describe the Standard Penetration Test (SPT)Describe the Standard Penetration Test (SPT)-- Explain energy and overburden correctionsExplain energy and overburden corrections-- Recall components of a boring logRecall components of a boring log-- Discuss the Cone Penetration Test (CPT)Discuss the Cone Penetration Test (CPT)-- Identify the differences between SPT and CPTIdentify the differences between SPT and CPT-- Identify groundwater measurement techniquesIdentify groundwater measurement techniques

Any Questions?Any Questions?

THE ROAD TOUNDERSTANDING

SOILSAND

FOUNDATIONS

Subsurface ExplorationsSubsurface Explorations

Lesson 03 Lesson 03 -- Topic 4Topic 4Minimum Subsurface Explorations, Minimum Subsurface Explorations,

Geophysical TestsGeophysical Tests(Section 3.11, 3.12)(Section 3.11, 3.12)

Learning OutcomesLearning Outcomes

ggAt the end of this session, the participant will At the end of this session, the participant will be able to:be able to:-- Locate minimum subsurface exploration Locate minimum subsurface exploration

program componentsprogram components-- Identify geophysical testing techniquesIdentify geophysical testing techniques

Minimum Guidelines for ExplorationMinimum Guidelines for Exploration

ggNumber of exploration pointsNumber of exploration pointsggDepth of exploration pointsDepth of exploration points

ggTable 3Table 3--1212-- Retaining wallsRetaining walls-- Embankment foundationsEmbankment foundations-- Cut slopesCut slopes-- Shallow foundationsShallow foundations-- Deep foundationsDeep foundations

When do you Need More than When do you Need More than Minimum?Minimum?

Group ExerciseGroup Exercise

ggWhat are the key points for determining the What are the key points for determining the extent of subsurface explorations?extent of subsurface explorations?-- Length between exploration pointsLength between exploration points-- Depth of exploration pointsDepth of exploration points-- Number of exploration pointsNumber of exploration points-- Effect of type of foundationEffect of type of foundation

Geophysical TestsGeophysical Tests

ggNon Destructive TestsNon Destructive TestsggArea coverage between exploration pointsArea coverage between exploration points

ggFHWA (2005) ManualFHWA (2005) Manual

Types of Geophysical TestsTypes of Geophysical Tests

ggSeismic methodsSeismic methodsggElectrical methodsElectrical methodsggGravity and magnetic methodsGravity and magnetic methodsggNearNear--surface nuclear methodssurface nuclear methodsggBorehole methodsBorehole methods

ggTable 3Table 3--1313

Geophysical EquipmentGeophysical Equipment

Seismograph Spectrum Analyzer

Portable Analyzer Velocity Recorder

Seismic ReflectionSeismic Reflection

Seismic RefractionSeismic Refraction

Ground Penetrating Radar (GPR)Ground Penetrating Radar (GPR)

Xadar Sensors & Software GeoRadar

Examples of Ground Penetrating Examples of Ground Penetrating Radar (GPR)Radar (GPR)

Useful in Locating Underground Utilities

Results from Ground Penetrating Results from Ground Penetrating Radar (GPR)Radar (GPR)

AdvantagesAdvantages

ggNonNon--invasiveinvasive-- Beneficial at contaminated sitesBeneficial at contaminated sites-- Useful in gravelly and talus deposits where Useful in gravelly and talus deposits where

drilling is difficultdrilling is difficultggCovers large geographical areas quicklyCovers large geographical areas quicklyggSmall strain measurements possibleSmall strain measurements possibleggRelatively inexpensive considering the large Relatively inexpensive considering the large

area covered by the testsarea covered by the tests

DisadvantagesDisadvantages

ggWorks best in cases where there is large Works best in cases where there is large change in property being measuredchange in property being measured

ggEach method has some limitationEach method has some limitation-- Equipment, noise, processing, etc.Equipment, noise, processing, etc.

ggResults can be nonResults can be non--uniqueuniqueggSpecialized equipment is requiredSpecialized equipment is required

Examples of Uses of Geophysical Examples of Uses of Geophysical TestsTestsggHighly variable subsurface conditionsHighly variable subsurface conditions

-- KarstKarst, buried gravel deposits, etc., buried gravel deposits, etc.ggRegional studiesRegional studies

-- Depth to Depth to rippablerippable rockrock-- Selection of alternative alignmentsSelection of alternative alignments

ggSettlement sensitive structuresSettlement sensitive structures-- Evaluation of inEvaluation of in--situ deformation situ deformation modulimoduli

Learning OutcomesLearning Outcomes

ggAt the end of this session, the participant will At the end of this session, the participant will be able to:be able to:-- Locate minimum subsurface exploration Locate minimum subsurface exploration

program componentsprogram components-- Recall geophysical testing techniquesRecall geophysical testing techniques

Any Questions?Any Questions?

THE ROAD TOUNDERSTANDING

SOILSAND

FOUNDATIONS

Interstate 0 Interstate 0 –– Apple FreewayApple FreewayNote: Scale shown in Station FormNote: Scale shown in Station Form

Baseline Stationing

Baseline Stationing

S.B. Apple Frwy

N.B. Apple Frwy

Proposed Toe of SlopeProposed Toe of Slope

Existing Ground SurfaceExisting Ground Surface

12

Proposed Final GradeProposed Final GradeProposed AbutmentProposed Abutment

Interstate 0Interstate 0

9090 9191 9292 9393

Apple Freeway Apple Freeway ExerciseExercise

Site Exploration Basic Soil Properties

Terrain Reconnaissance Site Inspection Subsurface Borings

Laboratory Testing

Slope Stability

Embankment Settlement

Spread Footing Design

Pile Design

Construction Aspects

ggAppendix AAppendix A-- Section A.2Section A.2

Plan a subsurface exploration Plan a subsurface exploration program given the following:program given the following:ggExamination of USGS Examination of USGS topotopo and geology and geology

maps and USDA soil map indicates delta maps and USDA soil map indicates delta landformlandform

ggField inspection showed wet area with Field inspection showed wet area with cattails in the vicinity of east abutmentcattails in the vicinity of east abutment

Develop a Boring Location PlanDevelop a Boring Location Plan

Baseline Stationing

Baseline Stationing

S.B. Apple Frwy

N.B. Apple Frwy

Proposed Toe of SlopeProposed Toe of Slope

Existing Ground SurfaceExisting Ground Surface

12

Proposed Final GradeProposed Final GradeProposed AbutmentProposed Abutment

Interstate 0Interstate 0

9090 9191 9292 9393

Proposed Boring LayoutProposed Boring Layout

Final Exploration LayoutFinal Exploration Layout

CPT-BAF-2 CPT-BAF-4

CPT-BAF-3CPT-BAF-1

Boring LogsBoring Logs

ggAppendix AAppendix A-- Section A.2Section A.2

CPT Logs CPT Logs –– Appendix A, Section A.2Appendix A, Section A.2

Hand Auger Hand Auger LogsLogsggEast AbutmentEast Abutment

Summary of Exploration PhaseSummary of Exploration Phase

gg Terrain ReconnaissanceTerrain Reconnaissance-- Delta landformDelta landform-- Possible buried clay depositPossible buried clay deposit

gg Site InspectionSite Inspection-- Unsuitable soil near east approach embankmentUnsuitable soil near east approach embankment-- Easy access for drilling and CPT equipmentEasy access for drilling and CPT equipment

gg Borings, Borings, CPTsCPTs, Hand Auger Holes, Hand Auger Holes-- SPT show sand over clay over gravel and rockSPT show sand over clay over gravel and rock-- CPT indicates thin silt seams in clay layerCPT indicates thin silt seams in clay layer-- Hand auger holes define unsuitable organicsHand auger holes define unsuitable organics-- Undisturbed samples and vane shear tests in clayUndisturbed samples and vane shear tests in clay

Any Questions?Any Questions?

THE ROAD TOUNDERSTANDING

SOILSAND

FOUNDATIONS