Geotechnical Site Exploration in the Year 2012 and · PDF fileGeotechnical Site Exploration...
Transcript of Geotechnical Site Exploration in the Year 2012 and · PDF fileGeotechnical Site Exploration...
Geotechnical Site Exploration in the Year 2012 and Beyond
Paul W. Mayne, PhD, P.E.Georgia Institute of Technology
10 May 2012
16th Nordic Geotechnical MeetingCopenhagen
Purposes: Geotechnical Site Investigation
A must prior to all geotechnical projects
Determine geostratigraphy for site development
Information for construction and foundation selection
Collect geotechnical data for parameter evaluation
Input to analytical models and numerical FEM
Minimize surprises during construction
Mitigate potential for legal involvement
Geotechnical Site Characterization in 2012 State‐of‐the‐Art (SOA) = What we CAN do State‐of‐the‐Practice (SOP) = what we ARE doing Brief remarks on International Geotechnical Experimentation Sites (IGES) Geotech Education: overemphasis on lab Best Practices:.... small projects.... vs. medium ..... vs. large‐projects This talk = short SOA to improve current SOP
Mayne ≠ SOB
INDICES Geologic Origin Age, AG
Grain Sizes, D50
Mineralogy Plasticity, PI Shape (fractals) Sphericity, Sph Roundness, Rn
Angularity, Ang
Packing limits: emax and emin
Specific Surface, SS Particle characteristics for DEM (crushing strength, modulus, roughness, friction)
STATE Void Ratio, e0 Unit Weight, T Relative Density, DR
State Parameter, Vertical Stress, vo
Hydrostatic Pressure, uo Yield Stress Ratio, YSR Saturation, S (%) Geostatic K0 = ho’/vo’ Stiffness, G0 = Gmax
State Parameter, ψ Degree of cementation Fabric and void index, Ivo Continuity (intact or fissured)
Z
Zw
Soil Element A
Initial Conditions
CONDUCTIVITY Hydraulic: kv, kh Thermal: ke Electrical: Chemical: Df Transmissivity, Tm Permittivity, Pm
STIFFNESS Stiffness: G0 = Gmax Shear Modulus, G' and Gu Elastic Modulus, E' and Eu Bulk Modulus, K’ Constrained Modulus, D’ Tensile Stiffness, KT Poisson’s Ratio, Effects of Anisotropy (Gvh/Ghh) Nonlinearity (G/Gmax vs s) Subgrade Modulus, ks Spring Constants, kz, kx, k, kθ
COMPRESSIBILITY Recompression index, Cr Yield Stress, y' (and YSR) Preconsolidation, p’ (and OCR) Coefficient of Consolidation, cv Virgin Compression index, Cc Swelling index, Cs
STRENGTH Drained and Undrained, max
Peak (su, c’, ’) Post‐peak, ' Remolded strength Softened or critical state, su (rem) Residual (cr’, r’) Cyclic Behavior (cyc/vo')
RHEOLOGICAL Strain rate, t Time since consolidation (T) Coef. secondary compression, C Creep rate, R Time to failure, tf
Geotechnical Parameters
Jaksa (2005)
“...when you can measure what you are
speaking about and express it in numbers,
you know something about it; but when
you cannot express it in numbers, your
knowledge is of a meager and
unsatisfactory kind" Lord Kelvin (1883)
US National Geotechnical Experimentation Sites (NGES)
ASCE GeotechnicalSpecial Publication (GSP) No. 93 (2000)
Established in USA jointly by:
National Science Foundation (NSF)
Federal Highway Administration (FHWA)
ASCE Geo‐Institute
6 NGES in continental USA
NGES: Texas A&M Sand SiteUS National Geotechnical Test Site(Briaud & Gibbens, 1999; Briaud, 2007)
UpperPleistocene Clean Sands (SP)
silty Sands (SP‐SM)
Silty to Clayey Sands (SC ‐ SM)
Hard Eocene Clay Shale
0 10 20
Tip Resistance, qt (MPa)
0 500 1000 1500
Limit Pressure, PL (kPa)
0
1
2
3
4
5
6
7
8
9
10
11
12
0 10 20 30 40 50 60 70
SPT‐N value, N60 (bpf)De
pth (m
eters)
0 10 20 30 40 50
DMT Pressures (bars)
p0
p1
0 100 200 300 400
Velocity, Vs (m/s)
Crosshole 2‐1
CHTDMT
CPT
SPT
PMT
NGES: Opelika, AlabamaPiedmont residual fine sandy silts(Vinson and Brown, 1997; Mayne & Brown, 2003)
LAB TESTING Grain size Hydrometer Plasticity indices Unit weights Triaxial shear (CIUC, CIDC) Direct shear, UU, and UC Fixed wall permeameter Flex‐wall permeability Resonant column tests One‐dim consolidation
IN‐SITU TESTING and GEOPHYSICS Standard penetration tests (SPT) Full‐displacement pressuremeter (FDPMT)Menard pre‐bored pressuremeter (PMT) Flat plate dilatometer tests (DMT) Cone penetration tests (CPT) Piezocone tests with dissipations (CPTù) Seismic dilatometer tests (SDMT) Dual element piezocones (CPTu1u2) Resistivity cones (RCPTu) Seismic piezocones (SCPTu) Dielectric cones (DCPTu) Borehole shear tests (IBST) Geophysical crosshole tests (CHT) Spectral analysis of surface waves (SASW) Torque measurements following SPT Penetration rate effects studies Frequent interval Vs profiling Surface resistivity surveys
FULL‐SCALE LOAD TESTS Drilled shaft foundations Axial tests on drilled shafts Lateral tests on drilled shafts Time and construction effects studies Driven pipe piles at varied rates De Waal piles Lateral loading testing of pile groups Shafts with self‐compacting concrete
Opelika NGES, Alabama ‐ Piedmont Residuum
Geotechnical Experimentation Sites
Volumes 1 and 2 (2003) Volumes 3 and 4 (2007)
Todate: 68 International Test Sites
Holmen Sand Site, Norway (Lunne, et al. 2003)
NGI: 1956 to 2012= 56 years testing
International Geotechnical Test Sites Each site required decades of study
Years worth of laboratory tests Many types of field testing Considerable amount of funds needed Backfigured soil engineering parameters from full-scale load tests Not have enough time ! Conclusion: Need multiple measurements
UDtube
CasedBoreholes Dynamic
PenetrationSPT: N60
'DR
Vane Shear (VST): suv = shear strengthSt = sensitivity
CrossholeVs, Vp
Gmax
FIRMCLAY
DENSESAND
CONVENTIONAL DRILLING
& SAMPLING
Drop Hammer
Oscilloscope
Pressuremeter (PMT)P0 = lateral stress G’ = shear modulussuPMT = shear strengthPL = limit pressure
SOILS LABORATORY
TX = triaxial shearCS = consolidationRC = resonant columnPM = permeameter
TX CS RC PM
Pumpingkvh
SievesHyd
Tv
Grain size analysesHydrometerWater content by ovenLiquid limit cupElectron microscopyPlastic limit threadFall cone devicePocket penetrometerTorvaneUnconfined compressionMiniature vaneDigital image analysis
Mechanical oedometerConsolidometerConstant rate of shear (CRS)Falling‐head permeameterConstant‐head permeameterFlow permeameterDirect shear boxX‐ray diffractionRing shearUnconsolidated undrained TxSimple shearDirectional shear cell
Triaxial apparatus (iso‐consols, CIUC, CKoUC, CAUC, CIUE, CAUE, CKoUE, stress path, CIDC, CKoDC, CIDE, CKoDE, constant P’)Plane strain apparatus (PSC, PSE)True triaxial (cuboidal)Hollow cylinderTorsional ShearResonant Column Test deviceNon‐resonant columnBender elements
Ppwn
CupOed
FallCone
Vst
DSB
DSS
RSPermeameters
Consolidometers
UC TTx PSC PSE
DSC
HC RCT
Iso Consol
CIUCCIDC
CKoUCCKoDC
CKoUECKoDE
CIUECIDE
BE
Pan
Geotechnical Laboratory Testing Devices
Evolution of Geotechnical Site CharacterizationModified after Lacasse (1985)
Geotechnical Methods for Site Investigation
Soils Laboratory In‐Situ Testing Geophysics
Lab Rat Field Mouse Fruit Bat
Field mouse withball penetrometer
"Typical" Intro Undergrad Geotechnical Textbook
• Soil is a 3‐phase material 1 0• Grain size distribution 1 1• Atterberg limits 1 1• Proctor compaction 1 1• Site investigation 0.5 0• Overburden stresses 1 0• Permeability 1 1• Consolidation theory 2 1• Stress‐strain behavior of soils 2 1• Triaxial testing and strength 2 1• Bearing capacity 2 0• Footing settlements 0.5 0
Table of Content Lectures Labs
OVEREMPHASIS ON LAB
Laboratory Soils Testing Limited Number (discrete points) Long Duration for Completion Expensive (Time is Money) Cost per specimen:
• Oedometer = $500 (2 weeks)• Automated Consolidation = $700 (2‐3 days)• CIUC Triaxial = $500 (2 to 3 days)• CK0UC Triaxial = $1200 ea (5 days)• Resonant Column= $2000 ea (1 week)• Permeability = $600 (1 to 2 weeks)
Large Projects
Swedish Landslides Finnish Railway System
Offshore Platforms, NorwayStorebælt Link, Denmark
Consolidation Data ‐ Burswood, Australia(courtesy of Mark Randolph, Univ. Western Australia)
0
2
4
6
8
10
12
14
16
18
20
0 50 100 150 200
Dep
th (m
)
Effective Stress, v' (kPa)
p' (lab)
vo'
0
2
4
6
8
10
12
14
16
18
20
0 1 2 3 4
Overconsolidation, OCR
erosion(OCD = 20 kPa) plus secondarycompression
n = 14
Port of Anchorage: CIUC Triaxial Tests
0
100
200
300
400
0 100 200 300 400 500 600
q =
½
(1
- 3
) (
kPa)
p' = ½(1' + 3') (kPa)
POA Triaxial Summary OC Envelope
TB 9 (138 ft)
TP11 (155 ft)
TB15 (109 ft)
TB15 (124 ft)
TB15 (149 ft)
TB25 (69 ft)
TB25 (90 ft)
TB25 (190 ft)
TB28 (95 ft)
TB31 (126 ft)
TB31 (126 ft)
TB31 (126 ft)
TB39 (115 ft)
TB39 (160 ft)
TB47 (120 ft)
TB49 (100 ft)
TB49 (115 ft)
TB56 (115 ft)
Effective Strength Envelope ' = 27o
c' = 0
n = 18
Lab‐Based Site Characterization• Expensive and time‐consuming• Predominant approach in our textbooks• Only possible on large or critical projects• For 99% of geotechnics (small‐ to medium‐size projects, insufficient funding + inadequate amount of time .......
• Therefore, as a last resort ... Overreliance on simple SPT N‐values Overuse of plasticity index correlations
Estimating Undrained Strength from Plasticity Index
0,0
0,1
0,2
0,3
0,4
0,5
0,6
0 10 20 30 40 50 60 70 80 90 100
Valu
e of
c/p
' rat
io
Plasticity Index, Ip (%)
Skempton (1957)
Raw Vane Data: c/p' = 0.11 + 0.0037 PIn = 19; r2 = 0.946: SEY = 0.028
CLAY SITES: RioGosport GrangemouthFens KopingWaterview HertenShellhaven TilburyDrammen Manglerud
Estimating Undrained Strength from Plasticity IndexRaw Vane
Estimation of Friction Angle from Plasticity Index
HomeAppliances
Note: Not to scale
TelegraphStove
Horse & Buggy
Sewing Machine
Casagrande Cup
Abacus
Split‐Spoon
OfficeEquipment
1902
HomeAppliances
Note: Not to scale
Telephone Television
Refridgerator
Gas Automobile
Washer
Casagrande Cup
Slide Rule
Split‐Spoon
OfficeEquipment
1950
Note: Not to scale
Split‐Spoon
Tablet
Liquid Limit
3‐d LED Televisionsmartphone
Refridgerator
Electric Automobile
Washer
HomeAppliances
OfficeEquipment2012
N
DR = relative densityT = unit weightLI = liquefaction index' = friction anglec' = cohesion intercepteo = void ratioqa = bearing capacityp' = preconsolidationVs = shear waveE' = Young's modulus = dilatancy angleqb = pile end bearingfs = pile skin friction
SAND
cu = undrained strengthT = unit weightIR = rigidity index' = friction angleOCR = overconsolidationK0 = lateral stress stateeo = void ratioVs = shear waveE' = Young's modulusCc = compression indexqb = pile end bearingfs = pile skin frictionk = permeabilityqa = bearing stress CLAY
Is One Number Enough???
Both Pictures from DFI European Foundations - Fall 2009
What the Public Sees and Our Image to Structural Engineers & Architects
Geotech Site Investigation New Construction Equipment
Direct Push Borehole MethodsContinuous Push Sampling
Sonic DrillingContinuous Sampling of Soil & Rock
ElectroVane Equipment torque and rotation measured downhole
Computerized DMTFlat Plate Dilatometer Systems
Computerized DMTFlat Plate Dilatometer Systems
p0p1VPVS
Menard Pressuremeter (PMT)Push‐in Pressuremeter (PiPMT)Self‐Boring Pressuremeter (SBPMT)Full‐Displacement Type (FDPMT)
Po, G, su or ', and PL
Specialty probes Vision Cone Resistivity Probes and Cone Conductivity Measurements Dielectric Piezocone Gamma and Nuclear
Hryciw (2005)
Full‐Flow Penetrometers• Plate • T‐bar • Ball penetrometer• Piezo‐ball
Randolph (2004); DeJong et al. (2010)
Applications: Very soft soils Offshore seabed Mine tailings
New Developments: Twitch TestingRandolph & Hope (2004); Randolph (2004)
DrainedUndrainedPartially‐drained
SPT
TxPT LPTVST
PMT
CPMT
DMT
SPLT
K0SB
SWS
HF
BST
TSC
FTSCPT
CPTu
RCPTu
SCPTu
SDMT
TBPTBPT
Full Flow PenetrometersSPTT
SCPMTù
SPT = Standard Penetration TestTxPT = Texas Penetration TestVST = Vane Shear TestPMT = Pressuremeter TestCPMT = Cone PressuremeterDMT = Dilatometer TestSPLT = Screw Plate Load TestISB = Iowa K0 Stepped BladeSWS = Swedish Weight SoundingHF = Hydraulic FractureBST = Borehole Shear Test
TSC = Total Stress Cell (spade cell)FTS = Freestand Torsional ShearPV = PiezovaneMPT = Macintosh Probe TestCPT = Cone Penetration TestCPTu = Piezocone PenetrationRCPTu = Resistivity PiezoconeSCPTu = Seismic ConeSDMT = Seismic Flat DilatometerTBPT = T‐Bar Penetrometer TestBPT = Ball Penetrometer
PPT = Plate Penetration TestPLT = plate load testHPT = Helical Probe TestPBPT = piezoball penetration testRapSochs = Rapid soil characterization systemCPTù = piezodissipation testDMTà = Dilatometer with A‐reading dissipationsSPTT = Standard Penetration Test with TorqueLPT = Large Penetration TestDEPPT = Dual Element PiezoProbe TestSCPMTu = Seismic Piezocone Pressuremeter
PLTDEPPT
HPT
Field Geotechnical In‐Situ Testing Methods
PPT
MPT
PV PBPT
RapSochs
CPTù
DMTà
Manly BeachSydney, Australia
Cone Penetration Tests (CPT) ‐ Portsmouth, VA
0
20
40
60
80
100
120
140
0 100 200 300 400
Cone Tip Resistanceqt (tsf)
Dep
th (f
eet)
-10 0 10 20 30 40
Porewater Pressure u2 (tsf)
0 1 2 3 4
Sleeve Frictionfs (tsf)
qt
u2
fs
CPT• Current Phase Tranformer• Cross Product Team• Cellular Paging Teleservice• Chest Percussion Therapy• Crisis Planning Team• Consumer Protection Trends• Computer Placement Test• Current Procedural Terminolgy• Cost Per Treatment• Choroid Plexus Tumor• Cardiopulmonary Physical
Therapy• Corrugated Plastic Tubing• Cumulative Price Threshold
• Certified Proctology Technologist• Cell Preparation Tube• Central Payment Tool• Cockpit Procedures Trainer• Cone Penetration Test• Color Picture Tube• Critical Pitting Temperature• Certified Phelbotomy Technician• Control Power Transformer• Cost Production Team• Channel Product Table• Conditional Probability Table• Command Post Terminal
Cone Penetrometers
• 10-cm2
• 15-cm2
• mechanical• electric• cabled• piezo-• electronic• seismic-• digital• wireless
Cone Penetrometers
33- 15- 10- 5- 1-cm22- 10- 15- 40-cm2
• US Navy XDP• Canadian FFCPT• German MARUM
100-cm2 Harpoon CPT
Mini-CPTs for Centrifuge0.5 cm2
Micro-Cone PenetrometersKim, Choi, Lee & Lee: Korea University
(GeoFlorida 2010)
FBG = Fibre Bragg Grating sensor
Cone Penetrometer Rigs
AutoCoson - Robotic CPTby A.P. van den Berg, Holland
PROD = Portable Remotely Operated Drill
by Benthic Geotech Australia
Cone Penetrometer Testing
Chinese CPT Equipmentwww.madeinchina.com
圆锥贯入试验
Interpretation Methods for In-Situ TestsEmpirical Analytical
Statistical Dislocation Theory
)/1(
2
'195.112
vo
t uqM
OCR
Interpretation Methods for In-Situ TestsFinite Elements Strain Path Method
Finite Differences Discrete Elements
Cone Penetrometer TestingHand-held electronic cone penetrometers
Rimik CP40
Measured Penetration Resistance
Excellent Repeatability
SpectrumScout SC 900
Eijkelcamp
Recent Economic Losses in PensionsNON SEQUITURBy Wiley Miller The NEW GeoRETIREMENT PLAN
Georgia Tech
Natural Clean Siliceous Sands
Georgia Tech
Friction Angle of Sands CIDC Triaxial Tests
1
2
3
4
5
6
0 5 10 15 20 25 30 35
Axial Strain, a (%)
Stre
ss R
atio
, 1'/ 3
'
DR = 82.6 %DR = 74.5 %DR = 59.3 %DR = 38.5 %DR = 22.3 %
1)'/'(1)'/'('sin
31
31
41.5º41.0º
38.8º
36.7º35.2º
33.7º cv'
P' = peak friction angle
Data on SaturatedQuartz Sand(Koerner, 1970)
Georgia Tech
Undisturbed vs. Reconstituted Sands• Reconstituted: Artificial Air Pluviation Moist Tamped Water Sedimented Slurried Compacted Vibration
• Undisturbed: Natural 1‐d Freezing (tubes or coring) Agar Injection
SPT SCPTu
N60
Vs
fsub
qtEstimatedRelativeDensity, DR
UndisturbedFrozenSpecimens
YoungArtificialSpecimens
In‐Situ e0In‐place DRFabricOCAnisotropyStructureAge
EstimatedNC e0DR
dwn
Triaxial Testing
Interpreted Friction Angle: Preparation Methods
AirPluviation
MoistTamped
WaterSedimentation
Slurry
Vibration
CompactionCoolantSystem
1‐dGroundFreezing
LiquidNitrogen(‐20º)Coring
Disturbed SoilAugeringRotary DrillTube SampleDrive Sample
CLASS A METHOD METHOD B
Georgia Tech
Silty Sand (Høeg, Dyvik, & Sandækken, 2000)
0
100
200
300
400
500
600
0 5 10 15 20 25
Axial Strain, a (%)
Shea
r Str
ess,
1 -
3)
Undisturbed
Pluviated
Slurried
e0 (consolidated) = 0.71 vc' = 500 kPa; hc' = 250 kPa
SOA-1: 17 ICSMGE - Egypt 2009
Silty Sand (Høeg, Dyvik, & Sandbækken, 2000)
Undrained Behaviour: Undisturbed vs. Reconstituted Sands
-200
-100
0
100
200
0 5 10 15 20 25
Axial Strain, a (%)
Pore
wat
er P
ress
ure,
u
(kPa
)
UndisturbedPluviated
Slurried
CAUC Triaxial Tests
Bad News
SOA-1: 17 ICSMGE - Egypt 2009
Data from Høeg, Dyvik, & Sandækken (ASCE JGGE, 2000)
Undrained Behavior: Undisturbed vs. Reconstituted Sands
0
200
400
600
800
1000
0 200 400 600 800 1000 1200
Shea
r Str
ess,
q =
0.5
(1
-3)
Average Stress, p' = 0.5(1' + 3')
Undisturbed
Pluviated
Slurried
sin'
' = 36.5ºc' = 0
Good News
Undisturbed vs Reconstituted SandDrained Triaxial Compression Tests (Mimura 2003)
SOA‐1: 17th ICSMGE 2009 ‐ Alexandria
0
100
200
300
400
0 2 4 6 8 10 12 14 16
Axial Strain, a (%)
Dev
iato
r Str
ess
= (
1 -
3) k
Pa
Reconstituted (air pluviation)
Undisturbed (1-d freezing)
Edo River Sand (Mimura, 2003)CIDC Triaxial TestsDepth = 3.7 to 4.0 m c ' = 49 kPa
D 50 = 0.29 mm UC = 2.2e 0 = 1.04 G s = 2.68e max = 1.227 e min = 0.812D R = 45%
Undisturbed vs Reconstituted SandDrained Triaxial Compression Tests (Mimura 2003)
SOA‐1: 17th ICSMGE 2009 ‐ Alexandria
0
50
100
150
0 50 100 150 200
Ave Stress, p' = 0.5(1' + 3') (kPa)
Shea
r Str
ess,
s =
0.5
( 1 -
3)
(kPa
)
Undisturbed
Pluviated
(q/p')f
' = 41.4o
c' = 0 kPa
sin' = 0.661
Edo River Sand
Good News
30
35
40
45
50
0 50 100 150 200 250 300
Normalized Tip Resistance, qt1 = (qt/atm)/(vo'/atm)0.5
Tria
xial
Fric
tion
Ang
le,
' (de
g.)
Yodo River Natori RiverTone River Edo RiverMildred Lake MasseyKidd J-PitLL-Dam HighmontHolmen W. KowloonGioia Tauro K&M'90
)/'()/q(
log116.17(deg)'atmvo
atmt
Sands with mica, smectite, illite, and other minerals
DuncanDam
DuncanDam
HiberniaHibernia
Friction Angle of Quartz‐Silica Sands from CPTClean silica toquartz sands
Sandbox
Why was the sand wet ?
Because the sea weed
Friction Angle ' from CPTU for clays & silts
1
10
100
20 25 30 35 40 45
' (degrees)Res
ista
nce
Num
ber,
Nm
Bq
0.1 0.2 0.4 0.6 0.8 1.0
Bq = 0 Notes for NTNU Method:
1. Define Cone Resistance Number: Nm = (qt-vo)/(vo'+a')
2. Attraction: a' = c'cot' where ' = effective friction angle andc' = effective cohesion intercept.
3. For case where a' = c' = 0: NM = Q = (qt-vo)/vo'
4. Define Porewater Pressure Parameter: Bq = u2/(qt-vo)
5. Approximate Expression Given for Ranges: 0.1<Bq < 1.0and 20º < ' < 45º
Robertson & Campanella (1983) for Sands
Approx: ' ≈ 29.5º Bq0.121[0.256 + 0.336·Bq + logQ ]
NTH: (Senneset, et al 1989; Sandven, et al. 1995)
Qt
6. Plastification angle, p = 0
CPTu Sounding, Sandpoint, Idaho
0
10
20
30
40
50
60
70
80
0 2 4 6 8 10
Tip Resistance, qt (MPa)D
epth
(met
ers)
0 50 100 150
Sleeve Friction, fs (kPa)0 1 2 3
Pore Pressure, u2 (MPa)
Evaluating ’ at Sandpoint, Idaho (NTH Method)
0
500
1000
1500
2000
2500
3000
0 100 200 300 400 500 600
Effective Vertical Stress, vo' (kPa)
Net
Con
e R
esis
tanc
e, q
t -
vo (k
Pa)
Nm = Q = 4.2
Evaluation of ’ at Sandpoint, Idaho (NTH Method)
0
500
1000
1500
2000
2500
0 1000 2000 3000
Net Cone Resistance, qt - vo (kPa)
Exce
ss P
ress
ure,
u2 -
u0 (
kPa)
Bq = 0.75
Evaluation of ’ by CPTu (NTH Method)
1
10
100
20 30 40 50' (degrees)
Resist
ance
Num
ber,
Nm
Bq = 0.1 0.2 0.4 0.6 0.8 1.0
Bq = (u2-u0)/(qt-vo)
NM = (qt-vo)/vo'
= 32.30
Triaxial Data ‐ Sandpoint IdahoMaximum q Criterion - TRIAXIAL DATA SUMMARY - IDAHO
0
50
100
150
200
250
0 100 200 300 400 500
p' = (1' + 3')/2
q =
( 1'-
3')/2
' = 32.3 deg
c' = 0 kPa
Triaxial Data from Sandpoint, Idaho(courtesy of Dean Harris, CH2M‐Hill)
q = 0.546 p'r2 = 0.996
n = 30
0
100
200
300
0 100 200 300 400 500
q =
(
1'- 3
')/2
(k
Pa)
p' = (1' + 3')/2 (kPa)
Max. (q/p') ratio criterion - IDAHO Triaxial Data
' = 33.1 deg
c' = 0 kPa
Georgia Tech
Evaluation of OCR in Clays by Piezocone TestsHybrid Cavity Expansion‐Critical State Model
Soil Properties:M = 6 sin’/(3‐sin’)
’ = effective friction angle
Cc = compression index
Cs = swelling index
= 1 – Cs/CcIR = G/su = Rigidity Index
G = shear modulus
su = undrained shear strength = (M/2)(OCR/2)vo'
’, Cc, Cs
Hybrid SCE‐CSSM Theory)/1(
234
2
1)1)(ln('/))((2
R
vovotM
IqOCR
For = 1
)]ln(1[)('
31
R
votP IM
q
’ = 30º → M = 1.2IR = 100
)(33.0' votP q First‐Order Approximation
Profiling Yield Stress in Clays by Cone Penetrometer
10
100
1000
10000
100 1000 10000Net Cone Resistance, qt - vo (kPa)
Yiel
d St
ress
, p
' (k
Pa)
Fissured
Intact Clays: p' = 0.33 (qt - vo) qt
Calcareous
Intact
9 Swedish clays (Larsson & Mulabdic 1991)
22 Canadian Clays (Demers & Leroueil 2002)
Pisa clay (Jamiolkowski and Pepe 2001)
Clays: Lateral Stress Coefficient, K0
0
1
2
3
4
1 10 100
Late
ral S
tress
Coe
ffici
ent,
K 0
Overconsolidation Ratio, OCR
BothkennarBrent CrossMadingleyOnsoyTarantoPorto TolleDrammenMassenaHamiltonBandas AbbasMontalto403020DrammenCowden TillSaint AlbanCanons ParkGrangemouthStrong PitLower 232rd StBritish Library
SBP = Self-Boring PressuremeterTSC = Total Stress Cell
'sin0 )'sin1( OCRK
= '
Sel
f-Bor
ing
Pre
ssur
emet
erTo
tal S
tress
Cel
l
Sands: Lateral Stress Coefficient, K0
0
1
2
3
4
1 10 100
Overconsolidation Ratio, OCR
Late
ral S
tres
s C
oeffi
cien
t, K
0Triaxial: n = 121Oedometer: n = 307Chambers: n=597Po River: n = 28Stockholm: n = 33Holmen: n = 2Thanet Sands: n =20304050
0
= ' (deg)
'sin0 )'sin1( OCRK
Kp
Georgia Tech
Calibration Chamber Testing Mineralogy Grain Distribution Angularity Index Parameters Age Origin Dry or Saturated Stress History hc'
vc'
DR
eo
T
qc and fs
p0 and p1
N60
PL
ArtificialSandDeposit
BC1, BC2, BC3BC4, and BC5
CPT Calibration Chamber DatabaseAnisotropically-Consolidated Sands
10
100
1000
10 100 1000
ho' = 0.30 qc0.22vo'0.69 OCR0.27
App
lied
Late
ral St
ress
, h
c' (kP
a)NC Sands
1 < OCR < 4
4 < OCR < 6
6 < OCR < 10
10 < OCR < 15
Note: stresses in kPa
26 Seriesn = 636
Earlston Edgar Erksak Frankston Hilton Mines Hokksund Hostun Lanchester Leighton Buzzard LB #2 Light Castle Sand Oosterschelde Lone Star Monterey #0 Montery #60 Ottawa Reid‐Bedford South Oakleigh Ticino Ticino #2 Toyoura Washed Mortar Sand
SAND SERIES
CPT Method for Ko and OCR in Silica Sands
Regression from CPT Calibration Chamber Database (n = 705 data points; r2 = 0.871): Ko = 0.192(qt/atm)0.22 (vo’/atm)‐0.31 OCR 0.27
Relationship between Ko and OCR a priori: Ko = (1‐sin’) OCRsin ’
Evaluate Effective Stress Friction Angle: ’ = 17.6+11log(qt1)
where: qt1 = (qt/atm)/(vo’/atm)0.5
CPT Method for Clean Quartz‐Silica Sands Combine Ko equations
Overconsolidation Ratio, OCR:
where KoNC = 1 ‐ sin’ = 1 ‐
Tip Stress in MPa and vo’ in kPa
Effective Friction Angle from CPT
27.01
31.0
22.0
)'(33.1
vo
t
oNC
qK
OCR
Rhymes with Orange by Hilary Price "THE LAB"
CPT Methodology in Clean Quartz Sands Overconsolidation Ratio, OCR:
Assume characteristic value: ’ = 35 Sands: qt ≈ (qt ‐ vo) Simplified:
Preconsolidation Stress:
27.0'sin1
31.0
22.0
)/'()/(
)'sin1(192.0
atmvo
atmtqOCR
''
)/'(8.13]/)[(
02.1
22.0
vo
p
atmvo
atmvotqOCR
7.0)(3.0)(' votp qkPa
CPT methodology for all soil types Reduced expression from SCE‐CSSM model for clays:
Simplified regression equations from chamber tests data on clean sands:
General form:
Exponent m' varies: clay m' = 1.0; sand m' = 0.72
7.0)(3.0)(' votp qkPa
)(33.0' votp q
')(33.0)(' mvotp qkPa
Generalized Pc' Method for CPTs in all soil types
10
100
1000
10000
10 100 1000 10000 100000Net Cone Resistance, qt - vo (kPa)
App
aren
t Yie
ld S
tres
s,
p' (
kPa)
General Trend:p' = 0.33(qt-vo)m
Intact clays: m = 1.00 Organic clays: m = 0.90 Silts: m = 0.85 Silty Sands: m = 0.80Clean Sands: m = 0.72
'1' )100/()(33.0' matm
mvotp q Amherst, MA
Washington DCAtchafalyala LABoston Blue Clay, MAColebrook Road BCEmpire LAEvanston ILSF Bay Mud, CALower 232rd St BCPort Huron MISt. Alban, QuebecNRCC, OntarioYorktown VASt.Jean Vianney, QESurry, VABaton Rouge, LAStrong Pit, BCOttawa STP, OntarioVarennes, QETaranto, ItalyBrent Cross UKMadingley UKSurrey UKCanons Park UKCretaceous DCBothkennarTrendStockholm SandPo River SandHolmen SandNorth Sea SandHibernia SandTrend 2Opelika Sandy SiltTrend 3Rio de JaneiroAtlanta Silty SandPentre SiltDutch PeatEuripides Silty SandTrend 4Trend
m'
Stockholm, Sweden (Dahlberg, ESOPT 1974)
• Original 24 m natural sand
• 16 m of sand quarried for construction
• Calculated OCR = (v+vo’)/vo’ from excavated quantity
• SPT, CPT, in-place density tests, PMT, triaxials
• Screw-Plate Load Test (SPLT) or field compressiometer to obtain in-situ p’
Stockholm Sand, SwedenStockholm Sand, Sweden
Bedrock
8 meters remained
16 meters quarried
Preloaded Natural Sand Deposit
D50 (av) = 0.9 mm
DR (av) = 60 %qcqc
Stockholm Sand, Sweden
0
1
2
3
4
5
6
7
8
0 50 100 150 200 250
Dep
th (m
eters)
Cone Tip Stress, qt (bars)
CPT 12
CPT 03
CPT 11
CPT 06
0
1
2
3
4
5
6
7
8
30 35 40 45 50 55
Friction Angle, ' (deg)
DrainedTriaxialTests
CPT Eqn
Stockholm Sand
0
1
2
3
4
5
6
7
8
0 1 2 3 4 5 6 7 8D
epth
(met
ers)Preconsolidation Stress, p' (kg/cm2)
Screw Plate Tests(interpretation by Prof. Dahlberg)
Calculated from quarried overburden
CPT Evaluation:p' = 0.33 qtnet
0.75
(stresses in kPa)vo'
Stockholm Sand
0
1
2
3
4
5
6
7
8
0 5 10 15 20 25D
epth
(m)Overconsolidation Ratio, OCR
Calculated from quarried overburden:OCR = (v'+vo')/vo'
CPT Evaluation:
OCR = 0.33 (qtnet)0.75 /vo'
(stresses in kPa)
Yield stress in soils from CPT22 )log22.1()log47.3(: FQIindexmaterialCPT c
Bernie Bott’sEvery Flavor Bean
Field Geophysics ‐Mechanical Wave Methods
SRFS = Surface Refraction SurveySFLS = Surface Reflection SurveySASW = Spectral Analysis of Surface WavesMASW = Modal Analysis (Rayleigh Waves)CSW = Continuous Surface WavesPSW = Passive Surface Wave TestingReMi = Reflection MicroSeisSLP = Suspension Logger ProblngCHT = Crosshole TestRCHT = Rotary CrossholeDHT = Downhole TestUHT = Uphole TestSCPTu = Seismic Piezocone TestSDMT = Seismic Flat Dilatometer TestBTSD = Borehole Torsional Shear Device
Seismograph+ Source
Receivers Geophones
SFLS SFRS
RotarySource
VerticalSource
TorsionalSource
Cased Boreholes
VsHV
VsHH
VsHH
VsHH
Oscilloscope+ Source
Vp
VsVH
SpectralAnalyzer+ Source
SASW MASW CSW PSW ReMi
Rayleigh Wave Methods
CHT
RCHT
BTSD SLP
VsVV
high frequencies
medium frequencycontent
lowfrequencycontent
VsRW
DHT
UHT
Cone Penetration Tests (CPT)Piezocone Penetration Test (CPTu)Seismic Piezocone Penetration Testing (SCPTu)
D 7400
SCPTu Sounding – Memphis, TN
0
5
10
15
20
25
30
35
0 10 20 30 40
Dep
th (m
)
qt (MPa)
0
5
10
15
20
25
30
35
0 100 200 300
fs (kPa)
0
5
10
15
20
25
30
35
0 1000 2000 3000
u2 (kPa)
0
5
10
15
20
25
30
35
0 100 200 300 400
Vs (m/sec) d = 35.7 mm
qt
fs
u2
Vs
Seismic Piezocone Test in New Orleans East
Economy of S‐Wave Velocity Measurements
Cost to Profile Vs to 30 m depth:
Crosshole $ 15,000 to $18,000
Downhole $ 8,000 to $ 9,000
SASW / MASW $ 3,000 to $4,500
ReMi survey $ 2,500 to $3,000
*SCPTu $ 1,500 to $2,000
*includes 5 readings: qt, fs, ub, t50, Vs
100-m SCPTu in Fraser River, British Columbia
V
Qsu = (fp dAs)
Qt = Qs + Qb
Qbu = qb Ab
} fp = fctn ( fs and u)
Clays: qb = qt ‐ ub Sands: qb 0.1 qt
RIGID PILE RESPONSERandolph Solution
qb = unit end bearing
unit side friction, fp
CPT
qt
ub
fs
Vs → Emax = 2 t Vs2 (1+)
Top Displacement, wt
])/(1[ 3.0max tut
tt QQEd
IQw
Load Transfer
)]1)(/(5ln[)/(
)1(11
1
2 vdLdL
I
21
IQQ
t
b}
PILE
Summary Seismic Piezocone TestsOpelika NGES, Alabama
Axial Load Tests: Opelika, Alabama (Brown 2002)
Drilled Shaft (cased method)d = 0.91 mL = 11.0 m
Qt (total)
Qs shaft
Qb base
104
www.hindu.com www2.dot.ca.gov
www.statnamiceurope.com
Reaction FrameDead Weight
Osterberg CellStatnamic Load Testwww.fhwa.dot.gov
Pile Load Tests
O-Cell Elastic Solution
01
1
111o1s
1
rL2
wrGP
P = applied forceL = pile lengthro = pile radiusEp = pile modulusGs = soil side shear modulus = Poisson's ratio of soil
2o
2
222o2s
2
rL2
)1(4
wrGP
Rigid pile under compression loading
Rigid pile shaft under upward loadingupper
segment
lower segment
O-Cell
w = pile displacementl = Ep/GsL = soil-pile stiffness ratio = Gs2/Gsb (Note: floating pile: = 1)Gsb = soil modulus below pile base/toe = ln(rm/ro) = soil zone of influencerm = L{0.25 + [2.5 (1-) – 0.25]}
P1 = P2
Diameterd1 = 2r1Length
L1
Diameterd2 = 2r2Length
L2
Seismic Piezocone Tests Calgary Medical Center, Alberta
0
2
4
6
8
10
12
14
16
18
20
22
24
0 10000 20000 Tip Stress, qt (kPa)
Dep
th (met
ers)
0 200 400 600Sleeve Friction, fS (kPa)
-500 0 500 1000Porewater, u2 (kPa)
u2
uo-hydro
0 100 200 300 400 500 600Shear Wave, VS (m/s)
DrilledShaft O-CellLoad Test
Dimensionsd = 1.4 mL = 14 m
O-Cell 10m
14m
Evaluation of Calgary O-Cell Shaft Response by Seismic Piezocone Tests
-40-30-20-10
01020304050607080
0 1000 2000 3000 4000 5000 6000 7000 8000
O-Cell Load, Q (kN)
Displac
emen
t, w
(mm)
Loading Down Measured Below O-CellMeasured Above O-Cell Loading Up
d = 1.4 m
L = 10 m
L = 4 m
Frequent-interval Vs profiling Charleston, South Carolina
0 0.1 0.2 0.3 0.4 0.5
0
5
10
15
20
25
30
Time (sec)
Dep
th (m
) GT AutoSeis
SDMTà = Seismic Dilatometer TestVenice
Frequent‐Interval SCPTu, Aiken, SC
02468
1012141618202224262830323436384042444648
0 10 20 30 40 50
Dep
th (m
)
qT (MPa)Cone Resistance
-500 0 500 1000 1500 2000
u2 (kPa)Porewater Pressure
0 1 2 3 4 5 6
FR (%)Friction Ratio
0 100 200 300 400 500 600 700 800
Vs (m/s)Shear Wave Velocity
Roto CH4 P-I
Continuous Vs profilingto 45 meters
GT AutoSeis
0
10
20
30
40
m
0 100 200 300 ms
Continuous‐Interval Seismic Piezocone, BC
0
5
10
15
20
25
30
35
40
45
50
0 10 20 30
Dep
th (m
)
qt (kPa)
0
5
10
15
20
25
30
35
40
45
50
0 100 200
fs (kPa)
0
5
10
15
20
25
30
35
40
45
50
0 1000 2000
u2 (kPa)
0
5
10
15
20
25
30
35
40
45
50
0 100 200 300 400 500
Vs (m/sec)
Freq. Domain
ConventionalDHT
113
Continuous‐interval SCPTu at Norfolk, VAContinuous‐interval SCPTu at Norfolk, VA
NorfolkFormation(Holocene)
YorktownFormation(Miocene)
CPT User = "Conehead"
ConeHeads arefrom ...FRANCE
No Confirmationby the French
If you come home from the garbage dump with more than you went in with.......
....You might just be a redneck
Comedian defines "redneck" as "a person who gloriously lacks of sophistication"
Geotechnical Parody - - -You might just be a ConeHead
Parody on "You might just be a redneck"
If you believe that the best means to evaluate N60 is from CPT data.......
...then you just might be a ConeHead
Geotech Parody on "You might just be a redneck"
If you think our professional image may be improved using CPT rather than SPT
....then you just might be a ConeHead
Geotech Parody on "You might just be a redneck"
If you believe in..... Fast
Economical
Efficient
Continuous
Collection of digital data
from multiple readings
Logged directly to your computer
qt
u2
fs
VstGmaxE’’’OCRPc'kvh
suK0
}
t50
...then you just might be a ConeHead
If you would like more high tech used in our geotechnical practice......
....then you just might just be a ConeHead
If you think the Washington Monument is a tribute to cone penetration testing
....then you just might just be a ConeHead
Geotech Parody on "You might just be a redneck"
High‐Frequency Geophysics
Electromagnetic methods
(dielectric, resistivity, conductivity)
Ground penetrating radar
Electromagnetic conductivity
Electrical resistivity
Permittivity
Magnetometer surveys
15 m squareSouth Carolina
15 m square
PWO4‐49U
PWO4‐49UNew Orleans 99/100 surveys
1/100 surveys
MASW Arrays for MappingSubsurface Heterogeneity
Surface Distance (m)Shear Wave, Vs (m/s)
Depth (m
)
FIRMCLAY
DIRECT‐PUSH TECHNOLOGY
SDMTàVpVstflexp1p0
NON‐INVASIVE GEOPHYSICS
(Resistivity, Radar, Conductivity)
SCPTùVs fst50u2qt
DENSESAND
loosesand
softclay
Types of Piezo‐Dissipation Responses
7
Piezo-Dissipations at Evergreen, North Carolina
0
100
200
300
400
500
600
700
800
900
1000
0.01 0.1 1 10 100
Time (minutes)
Mea
sure
d u 2
(k
Pa)
02D at 13.8 feet (4.2 m)
01D at 24.9 feet (7.6 m)
07D at 27 feet (8.3 m)
08D at 18 feet (5.5 m)
MONOTONIC
DILATORY
SCPTù at Atlanta Airport Runway 5
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
0 5 10 15 20
qT (MPa)
Dep
th (m
)
0 200 400 600
fs (kPa)
-100 0 100 200 300
ub (kPa)0 100 200 300 400
Vs (m/s)t50 (seconds)1 10 100 1000
Five Independent Readings of Soil Behavior: qt, fs, ub, t50, Vs
Danish Sonic Multi‐Sensor Probe(DSMSP) for hard ground, glacial till, and cemented geomaterials
Enlargement
Hydraulic Rig
SquareRods
Square Wedge Penetrometer
Tip Stress, qd
Lateral Stress, L
Resistivity,
Shear WaveVelocity, VS
Dynamic Driver Module (Impact, Sonic)
DSMSPdesign
will provide4 continuousreadings with
depth
Summary and ConclusionsGeotechnical Site Exploration in 2012 and Beyond
Best practice: drilling + sampling + lab testing + in‐situ + geophysics = $$$$ + Only possible on large projects Small‐ to medium‐size projects ‐ stop relying so much on single‐numbered tests (i.e. SPT‐N) and plasticity index correlations Routine explorations:
• Quick mapping by non‐invasive geophysics• Multi‐channel SCPTu or SDMT
Conetec ‐ Vancouver, BC
US Dept of Energy ‐ SRS, SC
S&ME ‐ Charleston, SC
thanks
Organizing Committee 16th NGM