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THE PRESSUREMETER:THE PRESSUREMETER:
SOME CONTRIBUTIONS TO SOME CONTRIBUTIONS TO FOUNDATION ENGINEERINGFOUNDATION ENGINEERING
JeanJean--Louis BRIAUDLouis BRIAUD
President of ISSMGEPresident of ISSMGE
Jean-Louis Briaud – Texas A&M University
President of ISSMGEPresident of ISSMGE
Professor, Texas A&M University, USAProfessor, Texas A&M University, USA
•• TEXAM TEXAM vsvs Menard PressuremeterMenard Pressuremeter
•• PMT results PMT results vsvs Other Tests ResultsOther Tests Results
•• ShalShal Found : Scale & Embedment Effect?Found : Scale & Embedment Effect?•• ShalShal. Found.: Scale & Embedment Effect?. Found.: Scale & Embedment Effect?
•• ShalShal. Found.: Load. Found.: Load--Settlement CurveSettlement Curve
•• Deep Found.: Lat. Load, Reference CaseDeep Found.: Lat. Load, Reference Case
•• Deep Found.: Lat. Load, Complex CasesDeep Found.: Lat. Load, Complex Cases
Jean-Louis Briaud – Texas A&M University
Deep Found.: Lat. Load, Complex CasesDeep Found.: Lat. Load, Complex Cases
•• Deep Found.: Vert. Load, DowndragDeep Found.: Vert. Load, Downdrag
•• Future WorkFuture Work
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Jean-Louis Briaud – Texas A&M University
THE TEXAMTHE TEXAMPRESSUREMETER1981
SimpleSafeVersatile
Jean-Louis Briaud – Texas A&M University
Versatile
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Jean-Louis Briaud – Texas A&M University
USEFUL CORRELATIONS
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SAND (36 sites)
Jean-Louis Briaud – Texas A&M University
CLAY (44 sites)
Jean-Louis Briaud – Texas A&M University
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VERY POOR CORRELATIONS
Jean-Louis Briaud – Texas A&M University
SHALLOW FOUNDATIONS: SCALE & EMBEDMENT EFFECT?
Jean-Louis Briaud – Texas A&M University
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THIS BEARING CAPACITY EQUATIONTHIS BEARING CAPACITY EQUATIONRARELY WORKSRARELY WORKS
12u c qp cN BN DNγγ γ= + +
1p BNγ=
Jean-Louis Briaud – Texas A&M University
12up BNγγ=
Jean-Louis Briaud – Texas A&M University
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3mx3m Footing Load Tests up to 1200 tonsTexas A&M National Site
Jean-Louis Briaud – Texas A&M University
3mx3m Footing Load Tests up to 1200 tonsTexas A&M National Site
Jean-Louis Briaud – Texas A&M University
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Jean-Louis Briaud – Texas A&M University
THIS BEARING CAPACITY EQUATIONTHIS BEARING CAPACITY EQUATIONRARELY WORKSRARELY WORKS
12u c qp cN BN DNγγ γ= + +
1p BNγ=
Jean-Louis Briaud – Texas A&M University
12up BNγγ=
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Jean-Louis Briaud – Texas A&M University
Jean-Louis Briaud – Texas A&M University
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THIS BEARING CAPACITY EQUATIONTHIS BEARING CAPACITY EQUATIONALWAYS WORKSALWAYS WORKS
up kr=
Jean-Louis Briaud – Texas A&M University
, , ,L C Ur p q N s=
Jean-Louis Briaud – Texas A&M University
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SHALLOW FOUNDATIONS: LOAD SETTLEMENT CURVE
Jean-Louis Briaud – Texas A&M University
Jean-Louis Briaud – Texas A&M University
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Jean-Louis Briaud – Texas A&M University
LOAD SETTLEMENT CURVE METHODLOAD SETTLEMENT CURVE METHOD
pf = Γ pp
Jean-Louis Briaud – Texas A&M University
s/B = 0.24 ΔR/R
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Jean-Louis Briaud – Texas A&M University
Jean-Louis Briaud – Texas A&M University
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Jean-Louis Briaud – Texas A&M University
Q (t)/Q (t ) = (t/t )-n
LONG TERM VERTICAL LOAD
Qu(t)/Qu(to) = (t/to) n
s(t)/s(to) = (t/to)n
Jean-Louis Briaud – Texas A&M University
n = 0.01 to 0.03 in sandsn = 0.02 to 0.08 in clays
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ΔR(t)/ΔR(t ) = (t/t )-n
n VALUES FROM PMT TESTS
ΔR(t)/ΔR(to) = (t/to) n
n = -log(ΔR(t)/ΔR(to) / log(t/to)
Jean-Louis Briaud – Texas A&M University
n = 0.01 to 0.03 in sandsn = 0.02 to 0.08 in clays
Jean-Louis Briaud – Texas A&M University
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Jean-Louis Briaud – Texas A&M University
s(t)/s(to) = (t/to)n
LONG TERM SETTLEMENT
o o
t = 50 yearsto = 5 minutesn = 0.03
Jean-Louis Briaud – Texas A&M University
s(t)/s(to) = (50x365x24x60 / 5) 0.03
s(50 years)/s(5 minutes) = 1.59
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The San JacintoMonument
Jean-Louis Briaud – Texas A&M University
PL=2.7 MPa, Py=1.6 Mpa, E0=54 MPaEr=145 MPa, n=0.022
Jean-Louis Briaud – Texas A&M University
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Jean-Louis Briaud – Texas A&M University
Ultimate Bearing Capacity
PL = 680 kPa at 5 m depth
Su = 100 kPa at shallow depth
Total pressure at 5 m = 224 kPa
Jean-Louis Briaud – Texas A&M University
pNet pressure at 5 m = 141 kPa
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Elastic SettlementE0 = 30 Mpa, B = 38 m, p = 141 kPa, γ = 0.35
S(t0) = 0.88(1 – 0.352)x141x38/30000 = 138 mm
Long Term Settlements(t)/s(to) = (t/to)n
s(to) = 138 mm, t = 70 yrs, to = 5 min, n = 0.045
Jean-Louis Briaud – Texas A&M University
S(70 years) = 138 (70 x 365 x 24 x 60 / 5) 0.045S(70 years) = 325 mm
Jean-Louis Briaud – Texas A&M University
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LATERAL LOAD ON PILES : REFERENCE CASE
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LATERAL LOAD-DEFLECTION CURVE
Jean-Louis Briaud – Texas A&M University
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Jean-Louis Briaud – Texas A&M University
Jean-Louis Briaud – Texas A&M University
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Jean-Louis Briaud – Texas A&M University
ULTIMATE HORIZONTAL LOAD, Hou
Hou = ¾ pl B Dvpl = limit pressure from PMTB = projected pile widthDv = (π/4) lo with lo = (4EI / K)1/4 for L > 3 loDv = L/3 for L < loE = modulus of pile materialI = moment of inertia of pile
Jean-Louis Briaud – Texas A&M University
I moment of inertia of pileK = 2.3 EoEo = PMT first load modulus of soilL = pile length
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Jean-Louis Briaud – Texas A&M University
HORIZONTAL DISPLACEMENT yo @ Hou/3
y = 2 H / l K for L > 3lyo = 2 Ho / lo K for L > 3loyo = 4 Ho / L K for L < lo
Ho = Hou/3 = horizontal load at ground surface
Jean-Louis Briaud – Texas A&M University
K = 2.3 Eo = horizontal modulus (line load/deflection)
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Jean-Louis Briaud – Texas A&M University
INTERACTION DIAGRAM FOR COMBINED HORIZ. LOAD AND OVERTURNING MOMENT
Jean-Louis Briaud – Texas A&M University
ANY COMBINATION OF H AND M ON THE DIAGRAM GIVES THE SAME DEFLECTION
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LATERAL LOAD ON PILES : COMPLEX CASES
Jean-Louis Briaud – Texas A&M University
H (t)/H (t ) = (t/t )-n
LONG TERM LATERAL LOAD
Hou(t)/Hou(to) = (t/to) n
y0(t)/yo(to) = (t/to)n
Jean-Louis Briaud – Texas A&M University
n = 0.01 to 0.03 in sandsn = 0.02 to 0.08 in clays
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ΔR(t)/ΔR(t ) = (t/t )-n
n VALUES FROM PMT TESTS
ΔR(t)/ΔR(to) = (t/to) n
n = -log(ΔR(t)/ΔR(to) / log(t/to)
Jean-Louis Briaud – Texas A&M University
n = 0.01 to 0.03 in sandsn = 0.02 to 0.08 in clays
Jean-Louis Briaud – Texas A&M University
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CYCLIC LATERAL LOAD
yN = y1 N a
a averages 0.1 for clays (one way and two way)
a averages 0 08 for sands under one way loading
Jean-Louis Briaud – Texas A&M University
a averages 0.08 for sands under one way loading
a averages 0 for sands under two way loading
ΔR /ΔR = N a
a FROM PMT TESTS
ΔRN/ΔR1 = N a
a = log (ΔRN/ΔR1) / log N
Jean-Louis Briaud – Texas A&M University
PMT only applicable to one way cyclic loading
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Jean-Louis Briaud – Texas A&M University
Jean-Louis Briaud – Texas A&M University
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Jean-Louis Briaud – Texas A&M University
LATERAL LOAD NEAR A TRENCH
Jean-Louis Briaud – Texas A&M University
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Htrench = λ Hno trench
λ
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Acceleration of truck
20Vehicle Acceleration
‐30
‐20
‐10
0
10
Acceleration (g)
‐50
‐40
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40
Time (sec)
Raw acc
50ms
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Impact Force (X ,Y and Z directions)
300
500
50ms Vehicle Force
‐700
‐500
‐300
‐100
100
Force (kN)
‐1500
‐1300
‐1100
‐900
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40
Time (sec)
X‐dir
Y‐dir
Z‐dir
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Full‐scale K‐12 Test and Numerical simulation(LS‐DYNA ) Drucker‐Prager γ= 21 kN/m3, E= 50 MPa, c=20 kPa, φ=40 ˚, ψ=20˚
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3m embedded Single Post in Very Dense SandDrucker‐Prager γ= 22 kN/m3, E= 32 MPa, c= 4 kPa, φ= 40 ˚, ψ= 15˚
Soil pressure (x‐drection)Drucker‐Prager γ= 22 kN/m3, E= 32 MPa, c= 4 kPa, φ= 40 ˚, ψ= 15˚
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Numerical Simulation Matrix‐ Single post in sandNum Energy level Soil Strength E (Mpa) γ (kN/m3) φ ψ c (kPa) Depth Remark Results
1 K-12 V.Dense+ 50 21 40 20 15 3m Akram OK2 K-12 V.Dense 32 22 40 15 4 3m OK3 K-12 V.Dense 32 22 40 10 4 3m OK4 K-12 V.Dense 32 22 40 5 4 3m OK5 K-12 V.Dense 32 22 40 0 4 3m OK6 K-12 V.Dense 32 22 40 -5 4 3m contact v1 NG7 K-12 V.Dense 32 22 40 5 4 3m contact v1 OK8 K-12 V.Dense 32 22 40 10 4 3m contact v3 B9 K-12 V.Dense 32 22 40 10 4 4m contact v3 OK10 K-12 V.Dense/Dense 20 20.6 37 6 3.3 6m contact v2 OK11 K-12 V.Dense/Dense 20 20.6 37 6 3.3 5m contact v2 OK12 K 12 V Dense/Dense 20 20 6 37 6 3 3 5m contact v3 B12 K-12 V.Dense/Dense 20 20.6 37 6 3.3 5m contact v3 B13 K-12 V.Dense/Dense 20 20.6 37 6 3.3 4m contact v2 OK14 K-12 V.Dense/Dense 20 20.6 37 6 3.3 4m contact v3 NG15 K-12 V.Dense/Dense 20 20.6 37 6 3.3 3m contact v2 OK16 K-12 V.Dense/Dense 20 20.6 37 6 3.3 3m contact v3 NG17 K-12 Dense 16 20 36 5 3 6m contact v2 NG18 K-12 Dense 16 20 36 5 3 5m OK19 K-12 Dense 16 20 36 5 3 5m contac v1 NG20 K-12 Loose 1.8 17 27 -15 1 6m Error NG21 K-12 Loose 1.8 17 27 -15 1 3m NG22 K-08 Dense 16 20 36 5 3 3m OK23 K-08 Dense 16 20 36 5 3 3m contact v2 Ok24 K-08 Dense 16 20 36 5 3 3m contact v3 Ok25 K-08 Dense/Medium 12 19.1 35 0 2.5 3m contact v2 OK26 K-08 Dense/Medium 12 19.1 35 0 2.5 3m contact v3 OK27 K-08 Medium 8 18 33 -5 2 6m contact v2 OK28 K-08 Medium 8 18 33 -5 2 5m contact v2 OK29 K-08 Medium 8 18 33 -5 2 5m contact v3 OK30 K-08 Medium 8 18 33 -5 2 4m contact v2 OK31 K-08 Medium 8 18 33 -5 2 4m contact v3 NG32 K 08 Medium 8 18 33 5 2 3m contact v2 NG32 K-08 Medium 8 18 33 -5 2 3m contact v2 NG33 K-04 Loose 2 17 27 -10 1 3m contact v2 NG34 K-04 Medium 8 18 33 -5 2 3m contact v2 OK35 K-04 Medium 8 18 33 -5 2 3m contact v3 OK36 K-08 Medium/Loose 4 17.3 29 -8 1.3 6m contact v3 NG37 K-04 Medium/Loose 4 17.3 29 -8 1.3 5m contact v3 OK38 K-04 Medium/Loose 4 17.3 29 -8 1.3 4m contact v2 OK39 K-04 Loose 2 17 27 -10 1 6m contact v3 OK40 K-04 Medium/Loose 4 17.3 29 -8 1.3 4m contact v3 NG41 K-04 Medium/Loose 4 17.3 29 -8 1.3 3m contact v3 NG42 K-04 Loose 2 17 27 -10 1 5m contact v3 NG43 K-04 Loose 2 17 27 -10 1 4m contact v3 NG44 K-04 Dense/Medium 12 19.1 35 0 2.5 2m contact v3 NG45 K-04 Dense 16 20 36 5 3 2m contact v3 NG46 K-04 V.Dense/Dense 20 20.6 37 6 3.3 2m contact v3 OK47 K-08 Dense 16 20 36 5 3 2m contact v3 NG48 K-08 V.Dense/Dense 20 20.6 37 6 3.3 2m contact v3 NG49 K-08 V.Dense 32 22 40 10 4 2m contact v3 OK50 K-04 Medium/Loose 4 17.3 29 -8 1.3 4.5m contact v3 OK
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Design chart for single post
Design Chart For Single Post in Sand
1
2
3
4
Post Embe
dmen
t (m)
K12
K8
K4
K12 Est
K8 Est
K‐12 OK
K‐12 NG
K‐8 OK
0
1
1 1.5 2 2.5 3 3.5 4
Sand Strength
K‐8 OK
K‐8 NG
K‐4 OK
K‐4 NG
E (MPa) 2 4 8 12 16 20 32
N (bpf) 0 10 20 30 40 50 50+
PL (kPa) 200 500 1000 1500 2000 2500 2500+
* W14‐109 Post 68
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69
70
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71
72
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73
74
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Pile Ult. CapacityQu = 706 + 1000
Q = 1706 kNQu 1706 kNAssume Neutral Pt.
wp = wsFind Load Distrib.Qt + Qd = Qp +Qf
Jean-Louis Briaud – Texas A&M University
t d p fCalculate Pile Mmt.
wp # ws
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TIEBACK WALLS
Jean-Louis Briaud – Texas A&M University
EARTH PRESSURE COEF. Vs MOVEMENT / HEIGHT
Jean-Louis Briaud – Texas A&M University
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So what !So what !
Too complicated !
Jean-Louis Briaud – Texas A&M University
p
THE PREBORING PRESSUREMETERTHE PREBORING PRESSUREMETER
DISADVANTAGESDISADVANTAGES
•• Influence of borehole qualityInfluence of borehole quality
•• Uncontrolled drainageUncontrolled drainage
•• Limited use for slopes and wallsLimited use for slopes and walls
Jean-Louis Briaud – Texas A&M University
Limited use for slopes and wallsLimited use for slopes and walls
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THE PREBORING PRESSUREMETERTHE PREBORING PRESSUREMETER
ADVANTAGESADVANTAGES
CC i ii i• Can be doneCan be done in many soilsin many soils•• Gives in situ stress strain curveGives in situ stress strain curve•• In situ “load test”In situ “load test”•• Inexpensive Inexpensive equipmentequipment•• Quality of test from shapeQuality of test from shape of curveof curve
Jean-Louis Briaud – Texas A&M University
Q y pQ y p•• Laterally loaded pilesLaterally loaded piles•• Shallow foundationsShallow foundations•• End bearing pilesEnd bearing piles
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