foundation engineering lecture (english)
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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
1
2
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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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
LOAD RESISTANCE FACTOR DESIGN (LRFD)
∑ ∑= =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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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
LOAD RESISTANCE FACTOR DESIGN (LRFD)
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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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
LOAD RESISTANCE FACTOR DESIGN (LRFD)
∑ ∑= =
=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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
Σφi R= 0.44R to 0.55R (Verif.) For CPT Method---SANDS
Use 0.85φ(compression) for φ(uplift)
Su= Undrained Shear Strength
3
4
→ IMPORTANT RESISTANCE FACTORS FOR BORED PILESUNDER COMPRESSION LOADS.
∑ ∑=n n
RL ϕγ
LOAD RESISTANCE FACTOR DESIGN (LRFD)
∑ ∑= =
=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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
Σφi R= 0.55R For 0.057N Method---SANDS POINT
Use 0.85φ(compression) for φ(uplift)
Su= Undrained Shear Strength
Σφi R= 0.65R For βσ V Method---SANDS SIDE
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 Single Pile 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
4
5
http://www.earth-engineers.com/DSC01903.JPG
SITE INVESTIGATION – WHY IS BORING IMPORTANT?
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
MAYNE, P., CHRISTOPHER, B., & DEJONG, J. (2002).
SITE INVESTIGATION – STANDARD PENETRATION TEST (SPT)
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
MAYNE, P., CHRISTOPHER, B., & DEJONG, J. (2002)
SITE INVESTIGATION – CONE PENETRATION TEST (CPT)
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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Advantages1) Fast and continuous
profile
Disadvantages1) Required skill
operator to run
MAYNE, P., CHRISTOPHER, B., & DEJONG, J. (2002)
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.
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
MAYNE, P., CHRISTOPHER, B., & DEJONG, J. (2002)
SITE INVESTIGATION – SEISMIC PIEZOCONE TEST
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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MAYNE, P., CHRISTOPHER, B., & DEJONG, J. (2002).
SITE INVESTIGATION – PRESSUREMETER TEST (PMT)
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
Advantages
1) Theoretically sound in determination of soil parameters
MAYNE, P., CHRISTOPHER, B., & DEJONG, J. (2002)
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.
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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 Single Pile 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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→ 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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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THE STATIC LOAD TEST FOR THE FOOTINGS
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
LOAD SETTLEMENT CURVE RESULTS
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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G.B.C.E vs STRENGTH EQUATION
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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+=)(
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
c f y
From The Standard Penetration Test (SPT)
KN=40DNKP NkPau γ+=)(
ZONE OF INFLUENCE IN SHALLOW FOUNDATION
BZi B
Zi
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
(SOWER, G. 1961 ; MURTHY, 2002)
PRESSURE BULB CHART
STRESS INCREASED UNDER THE FOUNDATION
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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2:1 METHODQ
STRESS INCREASED UNDER THE FOUNDATION
∆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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
(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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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--CONSOLIDATION THEORY--
σ'eo
e
σvo' σvo
'+∆σ'
C
Normally Consolidated Clays
SETTLEMENT OF SHALLOW FOUNDATION
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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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--ELASTIC SOLUTION--Q
SETTLEMENT OF SHALLOW FOUNDATION
( )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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
⎠⎝ B
PLAN VIEWB
B B
L D
--LOAD SETTLEMENT CURVE METHOD--SETTLEMENT OF SHALLOW FOUNDATION
PMT
P
2Ro
∆R
P P
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
∆R/Ro
PL
Limit Pressure
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0 . 2 4
O
s RB R
Δ=
SETTLEMENT OF SHALLOW FOUNDATION
--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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
SETTLEMENT OF SHALLOW FOUNDATION
--LOAD SETTLEMENT CURVE METHOD--
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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SETTLEMENT OF SHALLOW FOUNDATION
--LOAD SETTLEMENT CURVE METHOD--
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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FIVE LARGE SPREAD FOOTINGS TESTS IN SANDS
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
LABORATORY TESTS
→Water Content & Unit Weight
→Atterberg Limits
IN-SITU TESTS
→Borehole Shear Test & Cross-Hole
Wave Tests
FIVE LARGE SPREAD FOOTINGS TESTS IN SANDS
→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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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FIVE LARGE SPREAD FOOTINGS TESTS IN SANDS
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
FIVE LARGE SPREAD FOOTINGS TESTS IN SANDS
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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FIVE LARGE SPREAD FOOTINGS TESTS IN SANDS
n
tt
SS
⎟⎟⎠
⎞⎜⎜⎝
⎛=
11
Creep Model
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
FIVE LARGE SPREAD FOOTINGS TESTS IN SANDS
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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FIVE LARGE SPREAD FOOTINGS TESTS IN SANDS
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
IMPORTANT FINDING
Pu (kPa) = 75 N
THE GENERAL BEARING CAPACITY DOES NOT WORK IN THIS CASE
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
DEVELOP ED THE LOAD SETTLEMENT CURVE METHOD
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Comparison between Bearing Capacity Predictions and Measured Pressure at 150 mm of Se.
FIVE LARGE SPREAD FOOTINGS TESTS IN SANDS
Comparison between Predicted and Measured Load at 25 mm of Settlement
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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STRATIGRAPHY - SAN JACINTO MONUMENT
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
SOIL INDEX PROPERTIES
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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CONSOLIDATION CHARACTERISTICS
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
STRESS DISTRIBUTION
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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CONSOLIDATION CHARACTERISTICS
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
ACTUAL SETTLEMENT
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
MEASURED SETTLEMENT 0.329
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 Single Pile 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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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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
WW
DRIVING ANALYSISN (bpf)
Set-Up
ΣN (bpf)
W
I-II-
s
s
III-
End of Driving
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
http://www.moretrench.com/~moretren/cmsAdmin/uploads/thumb2/Drilled_Shafts_001.jpg
DRILL DRY - BORED PILE INSTALLATION
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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http://www.kbtech.com/images/photos/Anderson%2022%20Cobble%20on%20Auger%20Pilot.jpg
DRILL WET - BORED PILE INSTALLATION
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
INSTALLATION OF BORED PILE WITH CAISING
http://www.agrafoundations.ca/images/large/3.0-Bored-Piles/Thumb-2.jpg
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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PILE DRIVINGhttp://images.google.com/imgres?imgurl=http://www2.dot.ca.gov/hq/esc/geotech/projects/t
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
Np
L
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WAVE EQUATION ANALYSIS
WAK WAK
D D
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
ACCELERATIONsb
time
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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 Single Pile 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
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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
(Nq from API)
Short and Long TermULTIMATE FRICTION FOR DRIVEN PILES IN CLAY
uu Sf α=max'
max vuf βσ=
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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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)
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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≤ ≤ ≤
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
Pu(kPa)=57 NSPT for 0≤ NSPT≤75 blows per foot
Pu= 4300 kPa for NSPT≥ 75 blows per foot
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39
FOR MORE INFORMATION ON DOWNDRAG VISIT:
PILNEG, free software
http://ceprofs.tamu.edu/briaud/
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
( )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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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41
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 Single Pile 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
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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
( ) 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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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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43
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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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
43
44
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 Single Pile for Horizontal Loads
8. Special Cases (Shrink-Swell Soil, Downdrag andScour)
9 The Role of Load Testing9. The Role of Load Testing
10. Conclusion
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
DESIGN OF SINGLE PILE FOR HORIZONTAL LOADS
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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45
DESIGN OF SINGLE PILE FOR HORIZONTAL LOADS
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
DESIGN OF SINGLE PILE FOR HORIZONTAL LOADS
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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46
DESIGN OF SINGLE PILE FOR HORIZONTAL LOADS
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
ULTIMATE HORIZONTAL LOAD
oov lLforlD 34
>⎟⎠⎞
⎜⎝⎛=π
DESIGN OF SINGLE PILE FOR HORIZONTAL LOADS
vlou BDpH43
=ov lLforLD <=
34/14
⎟⎠⎞
⎜⎝⎛=
KEIl o
Pl = limit pressure from PMT L=length of the pile
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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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47
FIXED HEAD BEHAVIOR FREE HEAD BEHAVIOR
Hou
yo
M
Hou
yo
M
DESIGN OF SINGLE PILE FOR HORIZONTAL LOADS
Ly'o=0
L
0' ≠oy
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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
DESIGN OF SINGLE PILE FOR HORIZONTAL LOADS
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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
Pl = limit pressure from PMT
B = projected pile width
E = modulus of pile material
I = moment of inertia
M = moment at the top
L = length pile
Hou = ultimate horizontal load
lo = transfer length
Ho = applied horizontal load
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48
HORIZONTAL DISPLACEMENT @Hou/3
DESIGN OF SINGLE PILE FOR HORIZONTAL LOADS
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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
Pl = limit pressure from PMT
B = projected pile width
E = modulus of pile material
I = moment of inertia
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.
Hou = ultimate horizontal load
lo = transfer length
HORIZONTAL DISPLACEMENT @Hou/3
DESIGN OF SINGLE PILE FOR HORIZONTAL LOADS
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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
Pl = limit pressure from PMT
B = projected pile width
E = modulus of pile material
I = moment of inertia
L = length pile
Hou = ultimate horizontal load
lo = transfer length
Ho = applied horizontal load
48
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DESIGN OF SINGLE PILE FOR HORIZONTAL LOADS
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
( )( )
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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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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50
( )( )
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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
∆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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
50
51
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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
aN NRR
=Δ
RR
a
Nlog1⎟⎟⎠
⎞⎜⎜⎝
⎛ΔΔ
“a” FROM THE PRESSUREMETER TEST
PMT ONLY APPLICABLE FOR ONE WAY
R 1 ( )Na
log⎠⎝=
CYCLIC LOADING
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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52
THE PRESSUREMETER TEST
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
THE PRESSUREMETER TEST
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
52
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LATERAL LOAD NEAR A TRENCH
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
trenchnotrench HH λ=LATERAL LOAD NEAR A TRENCH
λ
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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FUTURE WORK IN RETAINING WALLS
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
EARTH PRESSURE COEFFICIENT VS MOVEMENT/HEIGHT
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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Hou Hou
FIXED HEAD BEHAVIOR
DESIGN OF PILE GROUP FOR HORIZONTAL LOADS
L L
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
( ) ( )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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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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
8 DIAMETER PENETRATION AND 1.0- DIAMETER CLEAR SPACING
0.21 0.17 0.17 0.18 0.26
8 DIAMETER PENETRATION AND 2.0- DIAMETER CLEAR SPACING
0.19 0.19 0.19 0.19 0.24
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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 Single Pile 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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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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
Shrink-Swell SoilShrinking
Qu
SwellingQu
FOUNDATION ON SHRINK SWELL SOILS
L
h=active zoneLOAD
Qu
Qp
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
Shrinking
Swelling )( hLDfL uLOAD −= π
DhfL uLOAD π=
4)(
2DphLDfL uuLOADππ +−=
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STIFFENED SLAB ON PIERS
FOUNDATION ON SHRINK SWELL SOILS
ELEVATED STRUCTURAL SLAB ON PIERS
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
THIN POST TENSIONED SLAB ON GRADE
FOUNDATION ON SHRINK SWELL SOILS
STIFFENED SLAB ON GRADE
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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59
DOWNDRAG ON PILES
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
PILE POINT BEHAVIOR
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
EXAMPLE OF DOWNDRAG ON SINGLE PILES
Pile Ultimate Capacity
Qu = 706 + 1000
Q = 1706 kNQu 1706 kN
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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EXAMPLE OF DOWNDRAG ON SINGLE PILES
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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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)
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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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
32% Observed Occurrence
Case 3 - Loss of Deck
5% Observed Occurrence
Case 4 - Loss of Pier
37% Observed Occurrence Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
OBSERVED FAILURE MODES OF BRIDGE DUE TO SCOUR(based on failure photos in Briaud’s files)
126
Case 1 - Big Scour Hole
26% Observed Occurrence
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
63
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Courtesy of the University of Kentucky at Louisville
OBSERVED FAILURE MODES OF BRIDGE DUE TO SCOUR(based on failure photos in Briaud’s files)
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
OBSERVED FAILURE MODES OF BRIDGE DUE TO SCOUR(based on failure photos in Briaud’s files)
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
64
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OBSERVED FAILURE MODES OF BRIDGE DUE TO SCOUR(based on failure photos in Briaud’s files)
129
Case 2 – Settlement of Pier
32% Observed Occurrence
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
OBSERVED FAILURE MODES OF BRIDGE DUE TO SCOUR(based on failure photos in Briaud’s files)
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
65
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OBSERVED FAILURE MODES OF BRIDGE DUE TO SCOUR(based on failure photos in Briaud’s files)
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
OBSERVED FAILURE MODES OF BRIDGE DUE TO SCOUR(based on failure photos in Briaud’s files)
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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OBSERVED FAILURE MODES OF BRIDGE DUE TO SCOUR(based on failure photos in Briaud’s files)
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
OBSERVED FAILURE MODES OF BRIDGE DUE TO SCOUR(based on failure photos in Briaud’s files)
134
Case 3 - Loss of Deck
5% Observed Occurrence
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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OBSERVED FAILURE MODES OF BRIDGE DUE TO SCOUR(based on failure photos in Briaud’s files)
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
Hatchie River Bridge, Tennessee
OBSERVED FAILURE MODES OF BRIDGE DUE TO SCOUR(based on failure photos in Briaud’s files)
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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OBSERVED FAILURE MODES OF BRIDGE DUE TO SCOUR(based on failure photos in Briaud’s files)
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
OBSERVED FAILURE MODES OF BRIDGE DUE TO SCOUR(based on failure photos in Briaud’s files)
138
Case 4 - Loss of Pier
37% Observed Occurrence
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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OBSERVED FAILURE MODES OF BRIDGE DUE TO SCOUR(based on failure photos in Briaud’s files)
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
OBSERVED FAILURE MODES OF BRIDGE DUE TO SCOUR(based on failure photos in Briaud’s files)
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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OBSERVED FAILURE MODES OF BRIDGE DUE TO SCOUR(based on failure photos in Briaud’s files)
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
OBSERVED FAILURE MODES OF BRIDGE DUE TO SCOUR(based on failure photos in Briaud’s files)
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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OBSERVED FAILURE MODES OF BRIDGE DUE TO SCOUR(based on failure photos in Briaud’s files)
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
OBSERVED FAILURE MODES OF BRIDGE DUE TO SCOUR(based on failure photos in Briaud’s files)
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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OBSERVED FAILURE MODES OF BRIDGE DUE TO SCOUR(based on failure photos in Briaud’s files)
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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
73
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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 Single Pile for Horizontal Loads
8. Special Cases (Shrink-Swell Soils and Downdrag)
9. Example Problems
0 T T10.The Role of Load Testing
11. Conclusion
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
→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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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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.
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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.
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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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
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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.
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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STATIC LOAD TEST FOR SHALLOW FOUNDATION(Texas A&M University Load Tests)
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
THE ROLE LOAD TESTING: STATNAMIC TEST
www.statnamiceurope.com/
→ The Statnamic is another load test that provides a loadSettlement curve of an installed pile.
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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STATNAMIC LOAD TEST FOR SINGLE PILES
Q(Top Load)
BANGQ( p )
ChargeBIG MASSLASER
Calibrated
Dynamic
stop
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
S(Top Settlement)
Ly
Load Cell
Sbottom
O’CELL INSTALLATIONFROM: HTTP://WWW.LOADTEST.COMTransducers
HC
THE ROLE OF LOAD TESTING: OSTERBER CELL TEST
L
Load Cell
Hydraulic Control
Steel Plates
Tested Area
Load Cell
Reaction Area
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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79
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 Single Pile for Horizontal Loads
8. Special Cases (Shrink-Swell Soils and Downdrag)
9. Example Problems
0 T T10.The Role of Load Testing
11. Conclusion
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
Foundation engineering requires:
1. A good understanding of site conditions including Geology
CONCLUSION
2. Proper use of theory in design
3. Safety against ultimate capacity
4. Allowable movements
5. Good experience and engineering judgementjudgement
6. Appropriate specifications
7. Quality control during construction
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
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MORE REFERENCES
BRIAUD, J.L., “SALLOP: Simple Approach for Lateral Loadson Piles,” Journal of Geotechnical and GeoenvironmentalEngineering, Vol. 123, No. 10, pp. 958-964, ASCE, NewYork, October 1997.
BRIAUD, J.L., The Pressuremeter, A. A. Balkema, Rotterdam,Netherlands, 1992.
ASSHTO LRFD (Load Resistance Factor Design).
BRIAUD J L GIBBENS R “B h i f Fi S d
Jean Louis BRIAUD – TEXAS A&M UNIVERSITY
BRIAUD J.-L., GIBBENS R., “Behavior of Five SpreadFootings in Sand,” Journal of Geotechnical andGeoenvironmental Engineering, Vol. 125, No.9, pp. 787-797,September 1999, ASCE, Reston, Virginia.
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