Case Studies Linking Foundation Performance and In-Situ Tests in the Appalachian Piedmont

Paul W. Mayne, PhD, P.E. Georgia Institute of Technology

01 October 2013

Appalachian Piedmont Geologic Province

Surficial Extent of Appalachian Piedmont

VA-MD-DC

GA-AL-SC-NC

Piedmont Geologic Province

AL

GA SC

NC

VA

MD DE

PA NJ

"Georgia Red Clay"

Stone Mountain Red Top Mountain

North Lake Lanier

Primary Rock Types by Geologic Origin

Grain

Aspects

Clastic Carbonate Foliated Massive Intrusive Extrusive

Coarse Conglomerate

Breccia

Limestone

Conglomerate

Gneiss Marble Pegmatite

Granite

Volcanic Breccia

Medium Sandstone

Siltsone

Limestone

Chalk

Schist

Phyllite

Quartzite Diorite

Diabase

Tuff

Fine-

Grained

Shale

Mudstone

Calcareous Mudstone

Slate Amphi-bolite

Rhyotite Basalt

Obsidian

Sedimentary Types Metaphorphic Igneous Types

PIEDMONT

Geologic Time Scale

Geologic Time Scale Era Period Epoch Time Boundaries (Years Ago) Holocene - Recent Quaternary 10,000 Pleistocene 2 million Pliocene 5 million Cenozoic Miocene 26 million Tertiary Oligocene 38 million Eocene 54 million Paleocene 65 million Cretaceous 130 million Mesozoic Jurassic 185 million Triassic 230 million Permian 265 million Pennsylvanian Carboniferous 310 million Mississippian 355 million Paleozoic Devonian 413 million Silurian 425 million Ordovician 475 million Cambrian 570 million Precambrian 3.9 billion

Earth Beginning 4.7 billion

Piedmont Gneiss

and Schist

Piedmont Granite

Z-Age ≈ 1 billion years ago

Major Rock Formations in USA

Piedmont

Piedmont Subsurface Profile

"Georgia Red Clay" (CL - ML)

RESIDUUM (ML to SM)

SAPROLITE

Partially-Weathered Rock (PWR)

Intact Rock: Gneiss

Schist, Granite

GT Load Test Site, West Campus

0

10

20

30

40

50

60

70

80

0 10 20 30 40 50 60 70 80 90 100

SPT N-values (bpf)Dep

th (fe

et)

GRANITIC GNEISS

Piedmont Residuum:

Silty Fine Sand (SM)

PWR

0

10

20

30

40

50

60

0 10 20 30 40 50

In-Situ Testing in the Piedmont • SPT = standard penetration testing

• PMT = pressuremeter testing

• DP = dynamic penetrometers

• percussive soundings (air-track)

• VST = vane shear testing

• DMT = flat plate dilatometer

• CPT = cone penetration testing

• CPTu = piezocone testing

• Vs = shear wave velocity

• SCPTu = seismic piezocone

• SDMT = seismic dilatometer

Miller & Sowers (1967). Shear characteristics of

Piedmont soils using rotating vanes

SCPTU in Piedmont residual silts Winston-Salem, NC

0

2

4

6

8

10

12

14

16

18

0 500 1000

Modulus ED (atm)

0

2

4

6

8

10

12

14

16

18

0 1000 2000 3000 4000

Dep

th (

mete

rs)

Pressure (kPa)

Po

P1

0

2

4

6

8

10

12

14

16

18

0 1 10

Material Index ID

Clay Silt Sand0

2

4

6

8

10

12

14

16

18

0 5 10 15

Horiz. Index KD

Fairfax Hospital, Northern Virginia (1984) Case Study: Drilled shaft (L = 65' and d = 3') in Piedmont residuum

Axial Pile Influence Factors (Rigid Pile)

Randolph & Wroth (1979); Poulos & Davis (1980)

Rigid Pile in an Infinite Elastic Medium

0.01

0.10

1.00

0 10 20 30 40 50 60 70 80 90 100

Slenderness Ratio, L/d

Infl

uen

ce F

acto

r, I

o

Boundary Elements

Closed Form v = 0.5

Closed Form v = 0.2

Closed Form v = 0s

pt

tEd

IPw

Poulos & Davis (1980) Solution vs. Randolph Solution

Pt = load at top = Ps + Pb

Homogeneous Soil: Es = Elastic modulus n' = Poisson's ratio

RIGID PILE RESPONSE Length L and diameter d

Side Load, Ps

= Pt - Pb

Top Displacement, wt

s

tt

Ed

IPw

Load Transfered to Base:

)]1)(/(5ln[

)/(

)1(1

1

1

2 vdL

dLI

21

I

P

P

t

bPb = Base load

Ground Surface

Randolph Solution

Fairfax Hospital, Northern Virginia

0

1

2

3

4

5

6

7

8

9

10

0 500 1000 1500 2000 2500 3000 3500 4000

Dis

pla

cem

en

t, w

t(m

m)

Axial Load, Q (kN)

Elastic Soln: Qtotal = Qs + Qb

Elastic: Pred. Qs

Elastic Pred. Qb

Measured Load Test

s

pt

tEd

IPw

E' ≈ ED (ave. 64 DMTs) = 35 MPa = 364 tsf L = 65 feet and d = 3 feet Ratio L/d = 21.7 gives Ip = 0.076

Buildings on Piedmont - Northern Virginia and Washington DC

0

100

200

300

400

500

600

700

800

0 10 20 30 40 50 60

Ela

sti

c M

od

ulu

s, E

' (b

ars

)

SPT N60 value (bpf)

DMT-SPT Relationship in Piedmont Residuum

TRR 1169 (1988)

ADSC/ASCE

Opelika NGES

NCSU Site

Olympic Stadium

Northern Piedmont

Building Foundations

ED = 22 ∙satm∙N60 0.82

DMT-SPT Correlation in Piedmont Residuum (Mayne & Frost, TRR 1988) Also EPRI Manual (1990)

Foundation Systems in the Piedmont Spread footings

Mat foundations

Augercast pilings

Drilled shafts

Micropiles

Driven pipe piles

H-pilings

Monotubes

Step-taper piles

Franki piles (PIFs)

First American Bank Mat

22-story Bank Building - Mat Foundation Tysons Corner, Virginia

0

50

100

150

200

0 50 100 150 200

West Side (feet)

No

rth

Sid

e (

feet)

Structural Reinforced

Concrete Mat

Foundation:

t = 4.5 feet

Foundation Perimeter

Bank Tower: Total Q = 73,400k

Bearing Elev = +495 feet msl Mat Thickness, t = 4.5 ft Applied Stress: q = 3.47 ksf

Georgia Tech

Wachovia/Wells Fargo Tysons Corner, VA

-4.0

-3.5

-3.0

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

0.5

0 50 100 150 200 250 300 350

Dis

pla

ce

me

nts

(in

ch

es

)

Time (days)

FAB Measured Displacements

Corner (pt 13)

Edge (pt 4)

Edge (pt 14)

Center (pt 7)

Center (pt 9)

PREDICTED

Corner

Edge

Center

Georgia Tech

Settlements: GSU Dormitory, Atlanta

0

1

2

0 1 2 3 4 5 6

Finite Layer Thickness, h/d

Inf

luenc

e F

act

or, IH

d

c

c/d

10

5

3

2

1.5

1

Harr (1966)

Approximation

s

Hc

E

IdqDeflectionCenter

)1(:

2n

c

Dormitory B Settlement Contours

0

5

10

15

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105

Breadth Distance (m)

Width

Dista

nce (m)

100 mm 120 mm 140 mm 160 mm

180 mm 200 mm 220 mm 240 mm

North

Reinforced Concrete Mat Foundation: c = 105 m; d = 18.3 m, thickness t = 1.07 m

-0.64

-0.54

-0.44

0

50

100

150

200

250

300

0 10 20 30 40 50 60 70 80 90 100

Distance (meters)

Se

ttle

me

nt

(mm

)

SW-NE Diagonal

NW-SE Diagonal

DMT Calculated (h = 12 m)

DMT Calculated (h = 18 m)

DMT Calculated (h = 24 m)

10" mat settlements DMT ED = 85 tsf www.geoengineer.org

ADSC-ASCE-FHWA Load Test Program Georgia Tech, Atlanta

Load Tests

End-bearing drilled shaft: d = 0.76 m L = 19.2 m

Friction-type drilled shaft: d = 0.76 m L = 16.9 m

Deep plate load test: d = 0.61 m z = 16.9 m

GT End-Bearing Shaft C1: d = 2.5' by L = 70'

Axial Load Transfer Distribution

0

10

20

30

40

50

60

70

80

0 200 400 600 800 1000

Axial Load, Q (tons)

Dep

th (

feet)

50 tons

100 tons

200 tons

300 tons

400 tons

500 tons

600 tons

700 tons

800 tons

900 tons

1000 tonsBas

LOAD Q

Base

Vibrating Wire Strain Gages

Elastic Continuum Response - GT Shaft C1

0

10

20

30

0 2000 4000 6000 8000 10000

Axial Load, Q (kN)Top D

eflection,

wt (m

m)

Qtotal = Qs + Qb Pred. Qs Pred. Qb

Meas. Total Meas. Shaft Meas. Base

Using DMT ED Modulus in Elastic Solution

Elastic Continuum Response - Shaft C2

0

50

100

150

200

0 1000 2000 3000 4000 5000 6000

Axial Load, Q (kN)Top D

eflection,

wt (m

m)

Qtotal = Qs + Qb Pred. Qs Pred. Qb

Meas. Total Meas. Shaft Meas. Base

Using DMT ED Modulus

in Elastic Solution

Cone Penetration Tests (CPT) at GT West Campus

0

2

4

6

8

10

12

14

16

18

20

0 2 4 6 8 10

Dep

th (

m)

qt (MPa)

0

2

4

6

8

10

12

14

16

18

20

0 100 200 300

fs (kPa)

0

2

4

6

8

10

12

14

16

18

20

0 1 2 3 4 5 6

FR = fs/qt (%)

qt

fs

Continuous Readings at 20 mm/s

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

• Cell Prepartion Tube

• Central Payment Tool

• Certified Proctology Technologist

• 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

Piezocone Response in the Piedmont

0

0

0

1

2

3

4

5

6

7

8

9

10

0 2 4 6 8 10

De

pth

(m

ete

rs)

Cone Tip Resistanceqt (MPa)

0

1

2

3

4

5

6

7

8

9

10

0 100 200 300 400

Sleeve Frictionfs (kPa)

0

1

2

3

4

5

6

7

8

9

10

-100 0 100 200

Porewater Pressureu2 (kPa)

0

1

2

3

4

5

6

7

8

9

10

0 500 1000 1500

Porewater Pressureu1 (kPa)

qt

u1

u2

fs

Height of Capillarity

CPTu in Piedmont PWR- Atlanta, GA

SPT

N60

23

34

71

34

56

67

50/6"

50/6"

50/2"

50/3"

0

2

4

6

8

10

12

14

0 10 20 30 40 50 60

qT (MPa)

Dep

th (

m)

0 0.2 0.4 0.6 0.8 1

fs (MPa)

-0.1 -0.05 0 0.05 0.1

u2 (MPa)

Partially-

Weathered

Rock

(gneiss)

Saprolite

(hard fine

sandy silt)

Residuum:

silty fine

sand

SCPTU in Piedmont residual silts Winston-Salem, NC

Geotechnics 2013 in the Piedmont

More Measurements

is

More Better

Mas Mejor

Seismic Piezocone (SCPTu) Piedmont silts in Marietta, GA

Tip Resistance

0

2

4

6

8

10

12

14

16

18

20

22

24

0 10 20 30

qT (MPa)

Dep

th (

m)

Sleeve Friction

0 200 400 600

fs (kPa)

Porewater Pressure

-100 0 100 200

u2 (kPa)

0

5

1

0

1

5

2

0

Shear Wave Velocity

0 100 200 300 400 500

Vs (m/s)

Vs

fs

u2

qt

u0

Piezo-Dissipation in Piedmont Residuum

-100

0

100

200

300

400

500

600

1 10 100 1000

Pore

wate

r P

ressu

re (

kP

a)

Time (seconds)

5.59 m

6.57 m

7.47 m

8.38 m

10.45 m

13.53 m

u1 dissipations

u2 dissipationsu0

u1

u2

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)

De

pth

(m

)

0 200 400 600

fs (kPa)

-100 0 100 200 300

ub (kPa)

0

5

10

15

20

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

Equivalent Elastic Modulus for Static Loading

Gmax = t Vs2

t = gt/g

Emax = 2Gmax(1+n)

Modulus Reduction Scheme (Fahey & Carter 1993)

0.15

0.17

0.19

0.21

0.23

0.25

0.27

0.29

0.31

0.33

0.35

0.37

0.39

0.41

0.43

0.45

0.47

0.49

0.51

0.53

0.55

0.57

0.59

0.61

0.63

0.65

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Mo

du

lus R

ed

uctio

n, G

/G0

Mobilized Strength, q/qmax = 1/FS

Resonant Column, Torsional Shear,and Triaxial Data

g = 0.2 0.3 0.4 0.5 = exponent

Algorithm: G/G0 = 1 - (q/qmax)g

Randolph Compressible Pile

sL

pt

tEd

IPw

:]1[

d

L

L

Lx

nn

)tanh(

)1(

811)1(41

d

L

L

Lx E

n

)tanh(4

)1(

43

[2] Ip = x1/x3

The proportion of load transferred from the top to base:

[3] Pb/Pt = x2/x3

The proportion of load carried in side shear is:

[4] Ps/Pt = 1 - Pb/Pt

The displacement at the pile toe/base is given by:

[5] wb = wt/cosh(L)

[6] = db/d = eta factor (Note: db = base diameter, so that = 1 for straight shaft piles)

[7] = EsL/Eb = xi factor (Note: = 1 for floating pile; < 1 for end-bearing pile)

[8] E = Esm/EsL = rho term. The parameter can be evaluated from: E = ½(1+Es0/EsL).

[9] = 2(1+n)Ep/EsL = lambda factor

[10] = ln{[0.25 + (2.5 E(1- n) - 0.25)] (2L/d)} = zeta factor

[11] L = 2(2/)0.5 (L/d) = mu factor

)cosh(

1

)1(

42

Lx

n

Es = Equivalent Elastic

Soil Modulus

AXIAL PILEDISPLACEMENTS

LengthL

Diameter d

Eso(surface)

EsM (mid-length)

EsL (along side at tip/toe/base)

Eb (base geomaterial

Modulus of layer 2)

sL

t

tEd

IPw

Pt Where Ip = displacement

Influence factor from

elastic continuum theory

z = Depth

Soil Layer 1

Soil or Rock Layer 2

National Geotechnical Experimentation Site Opelika, Alabama

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

Mean SCPTu Profiles Opelika NGES, Alabama

Opelika NGES in the Piedmont

Drilled Shaft Load Tests: Opelika, Alabama (Brown 2002)

4 Drilled Shafts d = 0.91 m L = 11.0 m

Q (total)

Q shaft

Q base

0

20

40

60

80

100

120

0 1000 2000 3000 4000

Dis

pla

ce

me

nt,

s (

mm

)

Applied Load, Q (kN)

Opelika NGES

Shaft S02

Shaft S04

Shaft S07

Shaft S09

Load Test at I-85 Bridge, Coweta County, GA

GDOT Drilled Shaft Load Test: D = 0.91 m L = 20.1 m Load Test Directed by Mike O'Neill

SCPTu at I-85 Bridge, Newnan, GA

0

2

4

6

8

10

12

14

16

18

0 2 4 6 8

qT (MPa)

De

pth

(m

)

0

2

4

6

8

10

12

14

16

18

0 100 200 300

fs (kPa) Ub (kPa)

0

2

4

6

8

10

12

14

16

18

-100 0 100 200

0

2

4

6

8

10

12

14

16

18

0 100 200 300 400

Vs (m/s)

Drilled Shaft Response, Coweta County, GA

0

10

20

30

40

50

0 2000 4000 6000 8000

Dis

pla

cem

ent,

wt(m

m)

Axial Load, Q (kN)

Qtotal = Qs + Qb

Pred. Qs

Pred. Qb

Meas. Total

Meas. Shaft

Meas. Base

RHYMES WITH ORANGE by Hilary Price

Rock → Stone → Sand = Formation of Residuum

Saprolitic

Class “A” Prediction of Axial Pile Response Jackson County, Georgia

Gmax from SCPTu for dynamically-loaded block foundations

Switched to driven 273 mm diameter closed-ended steel pipe piles: 8 < L < 18 m.

CPT qt, fs and u2 used for axial capacity and Vs for initial stiffness.

Turbine Foundations,

Plant Dahlberg Power Station

Southern Companies

Courtesy Marty Meeks

Seismic Piezocone Sounding, Jackson County, GA

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

0 2 4 6 8 10

De

pth

(m

)

qt (MPa)

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

0 100 200 300 400

fs (kPa)

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

-100 0 100 200

u2 (kPa)

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

0 100 200 300 400 500

Vs (m/sec)

fs

qt

Vs

u2

Axial Pile Response from SCPTu, Jackson County, GA

Driven Steel Pipe Pile No. P22 (L = 9.45 m)

0

2

4

6

8

10

12

14

0 200 400 600 800 1000 1200

Axial Load, Q (kN)

Deflect

ion,

w t

(m

m)

Predicted by SCPTu

in Advance

Measured

Axial Pile Response from SCPTu, Jackson County, GA

Driven Steel Pipe Pile No. P33 (L = 17.8 m)

0

2

4

6

8

10

12

14

0 200 400 600 800 1000 1200

Axial Load, Q (kN)

Deflect

ion,

w t

(m

m)

Predicted in advance

from SCPTU data

Measured from Load Test

51

www.hindu.com www2.dot.ca.gov

www.statnamiceurope.com

Reaction Frame Dead Weight

Osterberg Cell Statnamic Load Test www.fhwa.dot.gov

Pile Load Tests

GDOT O-Cell Load Test for Viaduct at CNN

2.9 m

11.8 m

6.2 m

d = 1.68 m

d = 1.59 m

d = 1.44 m

Residual Soils

(ML/SM)

Partially-Weathered

Rock (PWR)

Stage 1 O-cell

Stage 2 O-cell

Constructed Dimensions

of Drilled Shaft

GT Seismic Piezocone Sounding (SCPTu) GDOT - International Blvd.

Notes: Electronic data lost from 15.70 m to 16.70 m due to computer malfunction.

Tip Resistance

0

2

4

6

8

10

12

14

16

18

20

22

0 10 20 30

qT (MPa)

De

pth

(m

)

Sleeve Friction

0 200 400 600 800

fs (kPa)

Porewater Pressure

-100 0 100 200

u2 (kPa)

0

5

1

0

1

5

2

0

Shear Wave velocity

0 100 200 300 400 500 600

Vs (m/s)

Class A Prediction - GDOT Bridge at CNN

GDOT International Blvd. at CNN

0

10

20

30

40

50

0 1 2 3 4 5 6 7 8 9 10 11 12

Axial Load, Q (kN)

Top

Deflect

ion,

wt (m

m)

Qt Predicted

O-cell top down

O-cell Creep Limit

(MN)

Elastic Continuum Solution with SCPTu data input

LoadTest

O-cell load tests in Piedmont rocks Drilled shafts - Lawrenceville, GA (2011)

O-Cell Elastic Solution

01

1

111o1s

1

r

L2

wrG

P

P = applied force

L = pile length

ro = pile radius

Ep = pile modulus

Gs = soil side shear modulus

n = Poisson's ratio of soil

2o

2

222o2s

2

r

L2

)1(

4

wrG

P

Rigid pile or plate under compression loading

Rigid pile shaft under upward loading upper

segment

lower segment

O-Cell

w = pile displacement

l = 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 influence

rm = L{0.25 + [2.5 (1-n) – 0.25]} = magic radius

P1 = P2

Diameter d1 = 2r1

Length L1

Diameter d2 = 2r2

Length L2

O-cell tests - ADSC/ASCE Lawrenceville, GA

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

0 1000 2000 3000 4000 5000 6000

Dis

pla

cem

en

t, w

(in

che

s)

Applied Load, Q (tons)

Upper Segment Base Response

Elastic Pred Upward Elastic Down Pred

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

0 200 400 600 800 1000 1200

Dis

pla

cem

ent,

w (

inch

es)

Applied Load, Q (tons)

Upper Segment Base Response

Elastic Pred Upward Elastic Down Pred

E' = 3500 tsf E' = 1050 tsf

Test Shaft 1 in Rock Test Shaft 2 in PWR

Application of Randolph Elastic Solution

Recommendations to Geotechnical Practice

Site Characterization

in the Piedmont

FIRM CLAY

DIRECT-PUSH TECHNOLOGY

SDMTà Vp

Vs

tflex

p1

p0

NON-INVASIVE GEOPHYSICS

(Resistivity, Radar, Conductivity)

SCPTù Vs

fs

t50

u2

qt

DENSE SAND

loose sand

soft clay

Direct Push Borehole Methods Continuous Push Sampling Steel mandrel with inner plastic lining (d = 35 to 70 mm) Hydraulic and/or percussive push in 3-m strokes

www.geoprobe.com www.ams-samplers. com boartlongyear.com

Sonic Drilling

Vibrations at resonant frequency of drill pipe Fast and continuous sampling of soil and rock

Calibration of SPT Energy - Auto Hammers

Manufacturer Type ID No. Mean Energy Ratio (%) Reference

Diedrich D-120 ID 26 46 UDOT Diedrich D-50 321870551 56 GRL CME 850 ID 21 62.7 UDOT BK-81 w/ AW-J rods B2 68.6 ASCE Mobile B-80 ID 18 70.4 UDOT SK w/ CME hammer B6 72.9 ASCE Diedrich D50 UF5 76 UF CME 55 UF2 78.4 FDOT CME 850 296002 79 GRL CME 45 UF1 80.7 UF CME 85 UF4 81.2 UF CME 75 w/ AW-J rods A3 81.4 ASCE CME 75 UF3 83.1 UF CME 750 ID 4 86.6 UDOT Mobile B-57 DR-35 93 GRL CME 75 rig ID 10 94.6 UDOT

Factor of 2.1

O-cell load tests in Piedmont rocks Drilled shafts - Lawrenceville, GA (2011)

Methods for Rating Rock Masses

Core Recovery (CR) Rock Quality Designation (RQD); Deere et al. (1966) Rock Mass Rating (RMR); Bieniawski (1976, 1989) Q-System by NGI; Barton et al. (1976, 1991) Geological Strength Index (GSI); Hoek (1995, 2009)

Uniaxial Compressive Strength, qu

Rock Quality Designation (RQD) Spacing of Joints Condition of joints and/or infilling Groundwater conditions

Rock Mass Rating (RMR)

Shear Wave Velocity Profile in Piedmont VC Summer Power Station, South Carolina

Intact Rock

CR = 98 - 100%

RQD = 97 - 100%

Vs = 10,100 fps = 3078 m/s

qu = 25 ksi = 170 MPa

gt = 180 pcf = 28 kN/m3

Shear Wave, Vs (fps) Shear Wave, Vs (fps)

Elev

atio

n (

feet

msl

)

Vs from suspension logging in boreholes

Geotechnics 2013 in the Piedmont

• Beyond conventional SPT and PMT, showed advent and value of DMT, CPT, + SCPTu, SDMT

• Elastic continuum solution for pile foundations

Static top down loading

Bi-directional O-cell load tests

• Fundamental soil stiffness: Gmax = Vs2

• Presented case studies in Piedmont

• Use of Rock Mass Rating (RMR)

• Recommended more use of geophysics for site characterization, particularly Vs profiling

thanks