foundation engineering lecture (english) - ceprofs - texas a&m

1

Jean Louis BRIAUD1

TEXAS A&M UNIVERSITY

Deeyvid SAEZ BARRIOS2

1. President of ISSMGE, Professor and Holder of The Buchanan Chair, Texas A&M University

2. PhD Graduate Student and Research Assistant, Texas A&M University

April 2010THEORY PRACTICE

1. Load Resistance Factors Design (LRFD) Approach

2. Site Investigation

3. Design of Shallow Foundation for Vertical Loads

4 P I

CONTENT OUTLINE

4. Pile Instalation

5. Design of Single Piles for Vertical Loads

6. Design of Pile Group for Vertical Loads

7. Design of Piles for Horizontal Loads

8. Special Cases (Shrink-Swell Soils, Downdrag andScour)

9 The Role of Load Testing9. The Role of Load Testing

10. Conclusion

Jean Louis BRIAUD – TEXAS A&M UNIVERSITY

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LOAD RESISTANCE FACTOR DESIGN (LRFD)

→ WORKING STRESS DESIGN

RL FS 2 0 3 0

→ LOAD RESISTANCE FACTORS DESIGN (LRFD)

γ = 1.0 to 2.0RL

FSL = FS ≈ 2.0 to 3.0


L= Load γ = Load Factor

R= Resistance Φ = Resistance Factor ϕγ

=FS

γ 1.0 to 2.0Φ = 0.30 to 0.90

RL ϕγ =

→ IMPORTANT LOAD FACTORS IN FOUNDATION ENGINEERING

∑ ∑=n n

iiii RL ϕγ


∑ ∑= =i i

iiii1 1

Σγi Li= 1.25DL + 1.75LL For Ultimate Load

Σγi Li= 1.0DL + 1.0LL For Settlement in Sand & Immediate Settlement in Clays


Σγi Li= 1.0DL Long Term Settlement in Clays

Σγi Li= 1.25DL + γEQLL+1.0EQ For Earthquake Analysis

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3

→ IMPORTANT RESISTANCE FACTORS FOR SHALLOW FOUNDATION

∑ ∑= =

=n

i

n

iiiii RL

1 1ϕγ


Σφi R= 0.35R For Friction Angle Approach ---SANDS

Σφi R= 0.45R For SPT Approach ---SANDS

Σφi R= 0.55R For CPT Approach---SANDS


Σφi R= 0.60R For Su Approach---CLAYS

Σφi R= 0.50R For CPT Approach---CLAYS

Su= Undrained Shear Strength

→ IMPORTANT RESISTANCE FACTORS FOR DRIVEN PILESUNDER COMPRESSION LOADS

∑ ∑=n n

RL ϕγ


∑ ∑= =

=i i

iiii RL1 1

ϕγ

Σφi R= 0.56R to 0.70R (Verif.) For αSu Method---CLAYS

Σφi R= 0.36R to 0.45R (Verif.) For SPT Method ---SANDS

Σ R 0 44R 0 55R (V if ) F CPT M h d SANDS


Σφi R= 0.44R to 0.55R (Verif.) For CPT Method---SANDS

Use 0.85φ(compression) for φ(uplift)


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4

→ IMPORTANT RESISTANCE FACTORS FOR BORED PILESUNDER COMPRESSION LOADS.

∑ ∑=n n

RL ϕγ


∑ ∑= =

=i i

iiii RL1 1

ϕγ

Σφi R= 0.65R For αSu Method---CLAYS SIDE

Σφi R= 0.55R For 9Su Method ---CLAY POINT

Σφ R= 0 65R For βσ’ Method SANDS SIDE


Σφi R= 0.55R For 0.057N Method---SANDS POINT

Use 0.85φ(compression) for φ(uplift)


Σφi R= 0.65R For βσ V Method---SANDS SIDE




4 P I

CONTENT OUTLINE

4. Pile Instalation



7. Design of Single Pile for Horizontal Loads



10. Conclusion


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http://www.earth-engineers.com/DSC01903.JPG

SITE INVESTIGATION – WHY IS BORING IMPORTANT?


MAYNE, P., CHRISTOPHER, B., & DEJONG, J. (2002).

SITE INVESTIGATION – STANDARD PENETRATION TEST (SPT)


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Advantages

1) Sampling Is Possible

MAYNE, P., CHRISTOPHER, B., & DEJONG, J. (2002)

SITE INVESTIGATION – STANDARD PENETRATION TEST (SPT)

2) Simple

3) Suitable in many soil types

Disadvantages

1) Sample Disturbance

2) Not applicable for very soft or very loose soils

3) High Variability



SITE INVESTIGATION – CONE PENETRATION TEST (CPT)


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Advantages1) Fast and continuous

profile

Disadvantages1) Required skill

operator to run


SITE INVESTIGATION – CONE PENETRATION TEST (CPT)

profile.

2) Applicable for soft soils.

3) Strong Theoretical basis in interpretation.

operator to run

2) No soil sample can be obtained.

3) Unsuitable for very hard or dense soils and large particles.



SITE INVESTIGATION – SEISMIC PIEZOCONE TEST


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MAYNE, P., CHRISTOPHER, B., & DEJONG, J. (2002).

SITE INVESTIGATION – PRESSUREMETER TEST (PMT)


Advantages

1) Theoretically sound in determination of soil parameters


SITE INVESTIGATION – PRESSUREMETER TEST (PMT)

soil parameters.

2) Applicable for larger zone of soil mass than any other in-situ test.

3) Develop complete stress vs strain curve

Disadvantages

1) It requires trained personel .

2) Time consuming (8 tests per day).

3) Delicate equipment.


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1. Clays and Silts:

LABORATORY TESTS

• Classification Tests,

• Undrained Shear Tests,

• Drained Shear Tests,

• Consolidation Tests

2. Sands and Gravels:• Classification Tests





4 P I

CONTENT OUTLINE

4. Pile Instalation






10. Conclusion


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→ BEHAVIOR OF SANDS AND CLAYS UNDER LOAD CONDITIONS

DESIGN OF SHALLOW FOUNDATION

FSQu Qu Q (Load)

CLAYS

FSQu

SANDS

Q(Load)Qu

allSS >FS Q

allSS <

0.1B 0.1B


B=Foundation WidthS(Settlement)

Ultimate Load Controls Settlement Controls

S(Settlement)

Q

D1γD1γ D

GENERAL BEARING CAPACITY EQUATION (G.B.C.E)

2γfs

fs Pp Pp

B

qqccu DNSBNScNSP 121 γγ γγ ++=

Sc, Sγ, Sq= Correction Factors (shape, inclination, eccentricity and inclined loads)Nc, Nγ, Nq= Bearing Capacity Factors (function of the friction angle, φ)

qqccu 122γγ γγ

THE G.B.C.E RARELY WORKS


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THE STATIC LOAD TEST FOR THE FOOTINGS


LOAD SETTLEMENT CURVE RESULTS


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G.B.C.E vs STRENGTH EQUATION


THE STRENGTH EQUATION ALWAYS WORKS

IN SANDS

From The Pressuremeter Test (PMT)

K 1 0 f f iDpKP Lpu γ+=

Kp = 1.0 for square footing

From The Cone Penetrometer Test (CPT)

Kc ≈ 0.20 for sands.

From The Standard Penetration Test (SPT)

K 75

DqKP ccu γ+=

DNKP NkPau γ+=)(


Pl= Limit Pressure from PMT

N=blows/ft from the SPT

qc= Cone Point Resistance

KN = 75

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THE STRENGTH EQUATION ALWAYS WORKS

IN CLAYS

From the Undrained Shear Strength, Su

N ≈ 6 0 for square footingu c uP N S Dγ= +

Nc ≈ 6.0 for square footing.

From The Pressuremeter Test (PMT)

Kp = 1.0 for square footing

From The Cone Penetrometer Test (CPT)

Kc ≈ 0.40 for clays .

DpKP Lpu γ+=

DqKP ccu γ+=

Pl= Limit Pressure from PMT N=blows/ft from the SPT

qc= Cone Point ResistanceSu= Undrained Shear Strength


c f y

From The Standard Penetration Test (SPT)

KN=40DNKP NkPau γ+=)(

ZONE OF INFLUENCE IN SHALLOW FOUNDATION

BZi B

Zi


SQUARE FOOTING STRIP FOOTING RECTANGULAR FOOTING

BLBZ i ⎟⎠⎞

⎜⎝⎛ −=

24BZ i 2= BZ i 4=

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NEWMARK’S INFLUENCE CHART(MURTHY, 2002)

STRESS INCREASED UNDER THE FOUNDATION


(SOWER, G. 1961 ; MURTHY, 2002)

PRESSURE BULB CHART



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2:1 METHODQ


∆σ2

12

1

B

z

Strip Footing

( )BzQ+

=Δ'σ

Square Footing

( )2BzQ+

=Δσ

Rectangular Footing

( )( )LzBzQ

++=Δσ

Circular Footing

( )24

DQ

=Δσ∆σ(2:1)

B z/2z/2

( )Bz + ( )2Dz +π


(2:1)

Q’ = load per unit of length ∆σ=actual pressure distribution∆σ(2:1)= average pressure from the 2:1 method

σ'

σ'+∆σ’

σ' Stress-Strain Curve from a suitable test

SETTLEMENT OF SHALLOW FOUNDATION

--GENERAL METHOD--

Hi σv uo σ'v ∆σ’ εb εa ∆H=∆εxHi

H1

εεb εa

a suitable test

∑ =Δ=

n

i iT HH1

H2

H3

H4

Zi


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--CONSOLIDATION THEORY--

σ'eo

e

σvo' σvo

'+∆σ'

C

Normally Consolidated Clays


σp'

⎞⎛ ΔH ''e1

e2

Cr1

Overconsolidated Clays If σ’

vo+Δσ’ < σ’p

⎟⎟⎠

⎞⎜⎜⎝

⎛ Δ++

=o

o

v

vvcc e

HCs '

0

0 log1 σ

σσ

⎟⎟⎞

⎜⎜⎛ Δ+

=o vv

rcHCs '

''0 log

1

σσ

e

Cc

1


If σ’vo+Δσ’ > σ’

p

σ'p=maximum past pressure experience by the soil

⎟⎠

⎜⎝+ ov

rc e '0

g1 σ

⎪⎭

⎪⎬⎫

⎪⎩

⎪⎨⎧

⎟⎟⎠

⎞⎜⎜⎝

⎛ Δ++⎟⎟⎠

⎞⎜⎜⎝

⎛

+=

p

vvc

v

prc

oCCe

Hs '

''

'

'

0

0 loglog1

0σ

σσσσ

--TIME RATE OF SETTLEMENT--SETTLEMENT OF SHALLOW FOUNDATION

v

drv

CHTt

2

= ( )

maxHH

U tave Δ

Δ=

H1

H2

HZi

50% 90% Time, t

Hdr=Smallest Drainage Path

Uave= Average Degree of Consolidation

H3

H4

Settlement, ΔH

∆Hmax


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--ELASTIC SOLUTION--Q


( )21;

I q BS

Eν−

= BLQq =

B

E≈100 Su for clays E≈750 N(SPT) for clean sands E≈450 N(SPT) for silty sands

I=0.88 I=π/45.0

88.0 ⎟⎠⎞

⎜⎝⎛=

BLI

SHAPE FACTOR


⎠⎝ B

PLAN VIEWB

B B

L D

--LOAD SETTLEMENT CURVE METHOD--SETTLEMENT OF SHALLOW FOUNDATION

PMT

P

2Ro

∆R

P P


∆R/Ro

PL

Limit Pressure

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0 . 2 4

O

s RB R

Δ=


--LOAD SETTLEMENT CURVE METHOD--

pdeBLf PffffP .... ,/ Γ= βδ

( )Bef e /33.01 −= Eccentricity

( ) 1.0, /18.0 BDf DB += Slope Proximity

( )LBf BL /2.08.0/ += Shape

( ) 21

90/tan1 ⎥

⎦

⎤⎢⎣

⎡−=

−vh FFf δ Inclination





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FIVE LARGE SPREAD FOOTINGS TESTS IN SANDS


LABORATORY TESTS

→Water Content & Unit Weight

→Atterberg Limits

IN-SITU TESTS

→Borehole Shear Test & Cross-Hole

Wave Tests


→Atterberg Limits

→Relative Density

→Triaxial Test

→Resonant Column Test

→PiezoCone Penetration Test

→Dilatomer Test

→Pressuremeter Test

→Step Blade Test

→Standard Penetration Test & Cone

Penetration TestPenetration Test


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22


n

tt

SS

⎟⎟⎠

⎞⎜⎜⎝

⎛=

11

Creep Model




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IMPORTANT FINDING

Pu (kPa) = 75 N

THE GENERAL BEARING CAPACITY DOES NOT WORK IN THIS CASE


DEVELOP ED THE LOAD SETTLEMENT CURVE METHOD

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Comparison between Bearing Capacity Predictions and Measured Pressure at 150 mm of Se.


Comparison between Predicted and Measured Load at 25 mm of Settlement


San Jacinto Monument Houston (1936)

LOADING:

Gross Pressure = 224 kPa

Max Pressure (Dead + Wind) = 273 kPa

EXAMPLE - SAN JACINTO MONUMENT

Excavation= - 83 kPa

Net Pressure=141 kPa

Net Pressure after Mat Poured = 10 kPa

Pressure from Terraces = 34 kPa & 84 kPa


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STRATIGRAPHY - SAN JACINTO MONUMENT


SOIL INDEX PROPERTIES


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CONSOLIDATION CHARACTERISTICS


STRESS DISTRIBUTION


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CONSOLIDATION CHARACTERISTICS


ACTUAL SETTLEMENT


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ACTUAL SETTLEMENT

DESCRIPTION S(m)

CASE 8 (I l di R b d) 0 607CASE 8a (Including Rebound) 0.607

CASE 7a (Not including rebound) 0.370

DAWSON’S PREDICTION 0.187


MEASURED SETTLEMENT 0.329




4 P I

CONTENT OUTLINE

4. Pile Instalation






10. Conclusion


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BORED PILES → Concrete (dry drilling

or mud drilling), timberor steel piles.

Use in harder soils or

DRIVEN PILES → Timber , Concrete, and

Steel.

→ Use in softer soils.

DESIGN OF DEEP FOUNDATION-TYPES OF PILES

→ Use in harder soils orfor high loads.

→ Nominal diametersranging from 0.40 to 4.0m.

→ Typical length rangingfrom 3 m to 45 m.

→ Nominal diametersranging from 0.30 to 3.0m.

→ Typical length rangingfrom 3.0 m to 60 m.

END BEARING PILES FRICTION PILES


WW

DRIVING ANALYSISN (bpf)

Set-Up

ΣN (bpf)

W

I-II-

s

s

III-

End of Driving


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http://www.vibropile.com.auhttp://www.coastalcaisson.com

DRILL DRY

INSTALATION OF BORED PILES

DRILL DRY

DRILL WET

USING CAISINGUSING CAISING


http://www.moretrench.com/~moretren/cmsAdmin/uploads/thumb2/Drilled_Shafts_001.jpg

DRILL DRY - BORED PILE INSTALLATION


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http://www.kbtech.com/images/photos/Anderson%2022%20Cobble%20on%20Auger%20Pilot.jpg

DRILL WET - BORED PILE INSTALLATION


INSTALLATION OF BORED PILE WITH CAISING

http://www.agrafoundations.ca/images/large/3.0-Bored-Piles/Thumb-2.jpg


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WAK

BULB, STRONG LAYER ≈ FIXED END

V

NON-DESTRUCTIVE TESTING FOR BORED PILES

time

cLt 2

=

at A

FL

A

COMP. COMP.

time

cLt 2

=

at A


NECKING, WEAK LAYER ≈ FREE END

VWAK

NON-DESTRUCTIVE TESTING FOR BORED PILES

F

time

cLt 2

=

at A

L

A

COMP. TENS.

time

cLt 2

=

at A


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PILE DRIVINGhttp://images.google.com/imgres?imgurl=http://www2.dot.ca.gov/hq/esc/geotech/projects/t


h

W

PILE DRIVING ANALYSIS FOR DRIVEN PILES

( )3 0 0( ) 2

U De W h m mR c

N b p f

=+

L R

st

st

Load, Q

sb


Settlement, s

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PILE DRIVING ANALYSIS FOR DRIVEN PILES

RUD

RUD

RUDTotal

EnergyElastic Energy

max( )

2.5UDeWh mmR =

Np(bpf)75e=efficiency of the hammerW= hammer weight

Scs


gh= drop heightNp= number of blow per footC= elastic compression (5mm?)RUD= ultimate resistance of the pileat the end of driving.

( )3 0 0( ) 2

U De W h m mR c

N b p f

=+

WAVE EQUATION ANALYSIS

2

2

2

2

tU

ER

AED

zU

∂∂

=−∂∂ ρπ

Ecρ

= Wave Velocity

WAK

ρ

RUD

ρ=mass density of the pile

E=elastic modulus

A=cross sectional area of the pile

RUD= ultimate resistance of the pile at the end ofdriving

D


Np

L

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WAVE EQUATION ANALYSIS

WAK WAK

D D


L L

+-

+

+

Soft Hard

Software: CAPWAP

Driving ProcessPile CapacityPil I i

PILE DRIVING ANALYZER

h

W

Pile IntegrityStresses along the Pile

STRAINL R

Strain and

AccelerationTransducers

st


ACCELERATIONsb

time

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4 P I

CONTENT OUTLINE

4. Pile Instalation






10. Conclusion


pufuu QQQ +=

ApAfQ +

Qu

Qu

Working

ULTIMATE BEARING CAPACITY OF A SINGLE PILE

pusuu ApAfQ +=

fu= Ultimate Skin Friction (kPa)

As= Surface Area

L fu Qfu

Ultimate Load

Working Load

pu= Ultimate Point Pressure (kPa)

Ap= Point Areapu Qpu


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Short and Long TermULTIMATE POINT RESISTANCE FOR DRIVEN PILES

For Clays -Short Term.uSq 9max =

For Clays Long TermN'

( ) ( ) 5.0max 1000 NkPaq = For Sands (Short & Long Term)

For Clays -Long Term (Nq from API)

For Sands -Short & Long Term

qvo Nq max σ=

qvo Nq 'max σ=

Others Methods are based on Pressuremeter and Cone Penetration Test

Frank, R. (1997), Calcul des Fondations Superficielles et Profondes, Presses de L’Ecole Nationale des Ponts et Chaussees, pp141


(Nq from API)

Short and Long TermULTIMATE FRICTION FOR DRIVEN PILES IN CLAY

uu Sf α=max'

max vuf βσ=


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ULTIMATE FRICTION FOR DRIVEN PILES IN SAND

For Piles in Sand

Short and Long Term'

max vuf βσ=

( ) ( ) 7.0max 5 NkPafu =

N=SPT blow count

For Bored Piles Usefumax=0.75fumax (Driven)


For Clays:KPaSSuf 275550 ≤=

Reese & O’NeilNc

S

Square

ULTIMATE BEARING CAPACITY OF A BORED PILE

KPaSSuf uu 27555.0 ≤=

92.016; ≤⎥⎦

⎤⎢⎣

⎡⎟⎟⎠

⎞⎜⎜⎝

⎛+==

bcucu B

LNSNP

0.5' ; 1 .5 0.135( ( )) ;f z ftβσ β= = −

D/B

Strip

For Sands:; 1 .5 0.135( ( )) ;

0.25 1.2; 200u v

u

f z ftf kPa

βσ ββ≤ ≤ ≤


Pu(kPa)=57 NSPT for 0≤ NSPT≤75 blows per foot

Pu= 4300 kPa for NSPT≥ 75 blows per foot

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FOR MORE INFORMATION ON DOWNDRAG VISIT:

PILNEG, free software

http://ceprofs.tamu.edu/briaud/


http://ceprofs.tamu.edu/briaud/

Briaud J.-L., Tucker L.M., 1998, “Design guidelines for downdrag on uncoated and bitumen coated piles”, NCHRP Report 393, National Academy of Sciences.

Qu

Qu

CRITICAL DEPTH OF A SINGLE PILE

Nc

St i

Square9.0

SKEMPTON’S CHART

L1 fu

Dc=4B

LAYER 1

D/B

Strip7.0

4.0Jean Louis BRIAUD – TEXAS A&M UNIVERSITY

pu

B

4B LAYER 2

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40

Qtop

Stop

SETTLEMENT FOR SINGLE PILES

GENERAL APPROACH

L

Stop

fu

AELPSS ave

bottomtop +=

0 .6 (? )a v e to pP Q=

q Sbottom


( )EBpIs bottom

21 υ−=

Qtop

QQwT f1

1111 21

sp AfAqP += AEPLww += 12

SETTLEMENT FOR SINGLE PILES

P3

Qtop

P2

L1 f1

L2

w3

wT

f2

w

f

f2

w

w q1

P1

q

L3

w1

w2

f3f1

w

q


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4 P I

CONTENT OUTLINE

4. Pile Instalation






10. Conclusion


Qusingle

Qugroup

ULTIMATE LOAD CAPACITY OF A PILE GROUP

L L

Zone of Influence

gleuugroup enQQ sin=

e=overall efficiency factor ≈1.0Jean Louis BRIAUD – TEXAS A&M UNIVERSITY

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BLOCK FAILUREANALYSIS OF A PILE GROUP FOR CLAYEY SOILS

Qugroup

L

D


( ) BLSNDLBSQ ucuublock ++= 2

( )min ,ugroup usingle ublockQ nQ Q=

B L

LOAD TRANSFER FOR A PILE GROUP ANALYSIS

Qugroup Qugroup

2/3L L L

Hard Layer


Transfer the Load to 2/3 L if the Soil is uniform (Friction Piles)

Transfer the Load to the bottom if there is a hard layer

(End Bearing Pile)

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CASE HYSTORY – NEW ORLEANS HOSPITAL10000 Timber Piles0.3 m diameter (average)16 Story-Building15 m Long

1500 MN

15 m LongSoft Clay at the top2m thick dense sand at 14.5 m

Su=20 kPa

H

H=2 m

H=14.5 m

SandLOAD

Load Test for a Single Pile


Su=30 kPa

H1

H2

H3

H4

H=83.5 m

H5

L

Weight of the Hospital=1500 MN

Ru for one pile = 300 kN

10000 x Ru=3000 MN ----FS=2.0 ok.1500 MN

CASE HYSTORY – NEW ORLEANS HOSPITAL

Hi σv ∆σ Uo ∆σ’ εb εa ∆H=∆εxHi

Ultimate Block Capacity= 1200 MN (PROBLEM)

∆Htotal = 0.50 m

H

H=2 m

H=14.5 m

H1

H2

H3

H4

H=83.5,

H5

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4 P I

CONTENT OUTLINE

4. Pile Instalation




8. Special Cases (Shrink-Swell Soil, Downdrag andScour)


10. Conclusion


DESIGN OF SINGLE PILE FOR HORIZONTAL LOADS


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ULTIMATE HORIZONTAL LOAD

oov lLforlD 34

>⎟⎠⎞

⎜⎝⎛=π


vlou BDpH43

=ov lLforLD <=

34/14

⎟⎠⎞

⎜⎝⎛=

KEIl o

Pl = limit pressure from PMT L=length of the pile


l p

B = projected pile width

E = modulus of the pile material

I = moment of inertia

K = 2.3 Eo

L length of the pile

Dv=(π/lo) with Io=(4EI/K)1/4 for l>3lo

Dv=L/3 for l<lo.

Hou=ultimate horizontal load

lo =transfer length

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FIXED HEAD BEHAVIOR FREE HEAD BEHAVIOR

Hou

yo

M

Hou

yo

M


Ly'o=0

L

0' ≠oy


L =length pile

Hou =ultimate horizontal load

M =moment at the top of the pile

yo = horizontal displacement at the top of the pile

y'o =deflection at the top of the pile

HORIZONTAL DISPLACEMENT @Hou/3


GENERAL CASE

oo lLfMH 322 L d Fl ibl

P li it f PMT

yo

oEK 3.2=

oo

o

o

oo lLfor

klKly 32 >+=

( )2

2 2 3o oo o

H L My for L l

KL− +

= <

Long and Flexible

Short and Rigid


Pl = limit pressure from PMT


E = modulus of pile material


M = moment at the top

L = length pile

Hou = ultimate horizontal load

lo = transfer length

Ho = applied horizontal load

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48



FREE HEAD

o lLforHy 32>= L d Fl ibl

P li it f PMT

oo

o lLforKl

y 3>=

oo

o lLforLKHy <−=

4

oEK 3.2=

yo

Long and Flexible

Short and Rigid






K =2.3 Eo

L = length pile

Dv = (π/lo) with Io=(4EI/K)1/4 for l>3lo

Dv = L/3 for l<lo.





FIXED HEADo lLforHy 3>= L d Fl ibl

P li it f PMT

yo

oEK 3.2=

oo

o lLforKl

y 3>=

oo

o llforKLHy <−= 2

Long and Flexible

Short and Rigid






L = length pile



Ho = applied horizontal load

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( )( )

n

ooou

ou

tt

tHtH

−

⎟⎟⎠

⎞⎜⎜⎝

⎛=

( )( )

n

ooo

o

tt

tyty

⎟⎟⎠

⎞⎜⎜⎝

⎛=

LONG TERM LATERAL LOAD

n=0.01 to 0.03 in sands

n=0.02 to 0.08 in clays


Hou= ultimate horizontal load at time t

Hou= ultimate horizontal load at time to

yo = lateral deflection at time t

yo = lateral deflection at time to

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( )( )

n

tt

tRtR

−

⎟⎟⎠

⎞⎜⎜⎝

⎛=

ΔΔ

( )( )⎞⎛

⎟⎟⎠

⎞⎜⎜⎝

⎛ΔΔ

−= o

ttRtR

nlog

“n” VALUES FROM THE PRESSUREMETER TEST

n=0.01 to 0.03 in sandsn=0.02 to 0.08 in clays

( ) oo ttR ⎟⎠

⎜⎝Δ

⎟⎟⎠

⎞⎜⎜⎝

⎛

ottlog


∆R(t)= change in the radius of the cavity at time t

∆R(t0)= change in the radius of the cavity at time to

“n” VALUES FROM THE PRESSUREMETER TEST


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aN Nyy 1=

a averages 0.1 for clays (one way and two way)

CYCLIC LATERAL LOADING

a averages 0.08 for sands under one way loading

a averages 0 for sands under two way loading

Ho

ONE WAY CYCLIC Ho

TWO WAY CYCLIC

y

LOADING

y

TWO WAY CYCLIC LOADING


aN NRR

=Δ

RR

a

Nlog1⎟⎟⎠

⎞⎜⎜⎝

⎛ΔΔ

“a” FROM THE PRESSUREMETER TEST

PMT ONLY APPLICABLE FOR ONE WAY

R 1 ( )Na

log⎠⎝=

CYCLIC LOADING


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THE PRESSUREMETER TEST


THE PRESSUREMETER TEST


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LATERAL LOAD NEAR A TRENCH


trenchnotrench HH λ=LATERAL LOAD NEAR A TRENCH

λ


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FUTURE WORK IN RETAINING WALLS


EARTH PRESSURE COEFFICIENT VS MOVEMENT/HEIGHT


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Hou Hou

FIXED HEAD BEHAVIOR

DESIGN OF PILE GROUP FOR HORIZONTAL LOADS

L L


( ) ( )gleougroupou enHH sin=n= number of piles

e=efficiency factor

Direction of the Load

4 DIAMETER PENETRATION AND 0.5- DIAMETER CLEAR SPACING

GROUP EFFICIENCY FOR HORIZONTALLY LOADED PILES

0.33 0.360.31

Fraction of the Load


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0.20 0.18 0.14 0.20 0.28

8 DIAMETER PENETRATION AND 0.5 DIAMETER CLEAR SPACING

GROUP EFFICIENCY FOR HORIZONTALLY LOADED PILES


0.21 0.17 0.17 0.18 0.26


0.19 0.19 0.19 0.19 0.24





4 P I

CONTENT OUTLINE

4. Pile Instalation






10. Conclusion


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Soil Movement

FOUNDATION ON SHRINK-SWELL SOILS

h=active zoneShrink Swell Soil ∆w

Water Content Profile

d

w

i

wi

i

i

i wE

wfHH

γγ

εΔ

=Δ

=Δ

=33.0


Shrink-Swell SoilShrinking

Qu

SwellingQu

FOUNDATION ON SHRINK SWELL SOILS

L

h=active zoneLOAD

Qu

Qp


Shrinking

Swelling )( hLDfL uLOAD −= π

DhfL uLOAD π=

4)(

2DphLDfL uuLOADππ +−=

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STIFFENED SLAB ON PIERS


ELEVATED STRUCTURAL SLAB ON PIERS


THIN POST TENSIONED SLAB ON GRADE


STIFFENED SLAB ON GRADE


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DOWNDRAG ON PILES


PILE POINT BEHAVIOR


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2(1 )4

ppunch

s

Q Dv

AEπω = −

PILE POINT BEHAVIOR

ωpunch = Pile point movement

ν = Poisson’s ratio

Qp= Point resistance

A= Area of pile pointA= Area of pile point

D= Diameter of pile point

Es= Soil modulusFor clays = Es = 100 Su = EPMT

For sands=Es (kPa) = 750 N = 2 EPMT


EXAMPLE OF DOWNDRAG ON SINGLE PILES

Pile Ultimate Capacity

Qu = 706 + 1000

Q = 1706 kNQu 1706 kN


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EXAMPLE OF DOWNDRAG ON SINGLE PILES


Qfn(group)Qfn(single)

DOWNDRAG FOR A GROUP OF UNCOATED PILES

LL

s s sCorner Piles

Side Piles

Internal Piles

( ) ( )glefngroupfn QQ sin5.0=

( ) ( )glefnsidefn QQ sin40.0=

( ) ( )glefnernalfn QQ sinint 15.0=

5.2=dsfor


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SCOUR TYPES

Probable Flood Levelys(Abut) Applies ys(Cont) Applies

CL

Normal Water Level

ys(Abut)

y s(pier)y s(Cont)


is Abutment Scour Depthis Contraction Scour Depthis Pier Scour Depth

Where, ys(Abut)

y s(Cont)

y s(pier)

( )0.7( )1 ( ) ( )2.2 2.6

's Pier

w L sp pier c pier

yK K K K Fr Fr

a= ⋅ ⋅ ⋅ ⋅ ⋅ ⋅ −

0.331 10.89 , for 1.43' 'w

y yK a a

⎧ ⎛ ⎞ <⎪ ⎜ ⎟= ⎨ ⎝ ⎠⎪

MAXIMUM PIER SCOUR (Oh, 2009)

Where,1.0 , else⎪⎩

1

1.0 , for 30Value in following Table , else

Kθ > °⎧

= ⎨⎩1.0, for whole range of /LK L a=

0.91

2.9 , for 3.42' '

1 0 elsesp

S SK a a

−⎧ ⎛ ⎞ <⎪ ⎜ ⎟= ⎨ ⎝ ⎠⎪⎩1.0 , else⎩

Shape of pier nose Shape of pier noseSquare nose 1.1 Circular cylinder 1.0Round nose 1.0 Sharp nose 0.9

1K1K


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OBSERVED FAILURE MODES OF BRIDGE DUE TO SCOUR(based on failure photos in Briaud’s files)

Case 1 - Big Scour Hole

26% Observed Occurrence

Case 2 – Settlement of Pier


Case 3 - Loss of Deck


Case 4 - Loss of Pier

37% Observed Occurrence Jean Louis BRIAUD – TEXAS A&M UNIVERSITY


126

Case 1 - Big Scour Hole



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Courtesy of the University of Kentucky at Louisville





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65


129

Case 2 – Settlement of Pier





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134

Case 3 - Loss of Deck



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Hatchie River Bridge, Tennessee



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138

Case 4 - Loss of Pier



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72





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This distance should be made larger to decrease

the risk of collapse

145Jean Louis BRIAUD – TEXAS A&M UNIVERSITY

STRUCTURAL

and

GEOTECHNICAL

THE ROLE OF SOIL STRUCTURE-INTERACTION

Qu Q

S

k1


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4 P I

CONTENT OUTLINE

4. Pile Instalation




8. Special Cases (Shrink-Swell Soils and Downdrag)

9. Example Problems

0 T T10.The Role of Load Testing

11. Conclusion


→Laboratory testing brings the problem of sampledisturbance . However, its application is valuable for theunderstanding of some properties that can not bedetermined using In-Situ Tests.

THE ROLE OF LABORATORY TESTING


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THE ROLE OF IN-SITU TESTINGMAYNE, P., CHRISTOPHER, B., & DEJONG, J. (2002).

→In-situ testing gives a good estimation of the soil properties byreducing the problem of sample disturbance.

→Its application depends on the project magnitude and importance.


http://images.google.com/imgres?imgurl=http://

THE ROLE OF LOAD TESTING: SONIC INTEGRITY TEST

→SONIC-INTEGRITY: is an in-situ test that helps to locatepotential problems in bored piles.


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Hydraulic

Jack and Gauges

Q(Load)

Qu Qu

LOAD

RXRX

THE ROLE OF LOAD TESTING: STATIC LOAD TEST FOR PILES

Q(Load)

0.1B

QuQu

AEL

L

RX

SANDS

S(Settlement)

CLAYS

AEQLBS e += 1.0

L

Reaction Piles


http://www.earth-engineers.com/Pile%20Load%20Test%20%281%29.jpg

THE ROLE OF LOAD TESTING: STATIC LOAD TEST FOR PILES

→ It provides the load curve of an installed pile. From that,the ultimate load resistance of the pile can be determined.


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STATIC LOAD TEST FOR SHALLOW FOUNDATION(Texas A&M University Load Tests)


THE ROLE LOAD TESTING: STATNAMIC TEST

www.statnamiceurope.com/

→ The Statnamic is another load test that provides a loadSettlement curve of an installed pile.


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foundation engineering lecture (english) - ceprofs - texas a&m

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