THE PRESSUREMETER: SOME CONTRIBUTIONS TO FOUNDATION … · 2020. 10. 14. · 8/26/2010 1 THE...

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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


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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THE TEXAMTHE TEXAMPRESSUREMETER1981

SimpleSafeVersatile


Versatile

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USEFUL CORRELATIONS


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SAND (36 sites)


CLAY (44 sites)


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VERY POOR CORRELATIONS


SHALLOW FOUNDATIONS: SCALE & EMBEDMENT EFFECT?


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THIS BEARING CAPACITY EQUATIONTHIS BEARING CAPACITY EQUATIONRARELY WORKSRARELY WORKS

12u c qp cN BN DNγγ γ= + +

1p BNγ=


12up BNγγ=


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3mx3m Footing Load Tests up to 1200 tonsTexas A&M National Site


3mx3m Footing Load Tests up to 1200 tonsTexas A&M National Site


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THIS BEARING CAPACITY EQUATIONTHIS BEARING CAPACITY EQUATIONRARELY WORKSRARELY WORKS

12u c qp cN BN DNγγ γ= + +

1p BNγ=


12up BNγγ=

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THIS BEARING CAPACITY EQUATIONTHIS BEARING CAPACITY EQUATIONALWAYS WORKSALWAYS WORKS

up kr=


, , ,L C Ur p q N s=


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SHALLOW FOUNDATIONS: LOAD SETTLEMENT CURVE



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LOAD SETTLEMENT CURVE METHODLOAD SETTLEMENT CURVE METHOD

pf = Γ pp


s/B = 0.24 ΔR/R

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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


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)




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s(t)/s(to) = (t/to)n

LONG TERM SETTLEMENT

o o

t = 50 yearsto = 5 minutesn = 0.03


s(t)/s(to) = (50x365x24x60 / 5) 0.03

s(50 years)/s(5 minutes) = 1.59

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The San JacintoMonument


PL=2.7 MPa, Py=1.6 Mpa, E0=54 MPaEr=145 MPa, n=0.022


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Ultimate Bearing Capacity

PL = 680 kPa at 5 m depth

Su = 100 kPa at shallow depth

Total pressure at 5 m = 224 kPa


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


S(70 years) = 138 (70 x 365 x 24 x 60 / 5) 0.045

S(70 years) = 325 mm


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LATERAL LOAD ON PILES : REFERENCE CASE


LATERAL LOAD-DEFLECTION CURVE


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ULTIMATE HORIZONTAL LOAD, Hou

Hou = ¾ pl B Dv

pl = 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


I moment of inertia of pileK = 2.3 EoEo = PMT first load modulus of soilL = pile length

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HORIZONTAL DISPLACEMENT yo @ Hou/3

y = 2 H / l K for L > 3lyo = 2 Ho / lo K for L > 3lo

yo = 4 Ho / L K for L < lo

Ho = Hou/3 = horizontal load at ground surface


K = 2.3 Eo = horizontal modulus (line load/deflection)

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INTERACTION DIAGRAM FOR COMBINED HORIZ. LOAD AND OVERTURNING MOMENT


ANY COMBINATION OF H AND M ON THE DIAGRAM GIVES THE SAME DEFLECTION

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LATERAL LOAD ON PILES : COMPLEX CASES


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



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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)




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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


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


PMT only applicable to one way cyclic loading

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LATERAL LOAD NEAR A TRENCH


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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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72

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Pile Ult. CapacityQu = 706 + 1000

Q = 1706 kNQu 1706 kNAssume Neutral Pt.

wp = wsFind Load Distrib.Qt + Qd = Qp +Qf


t d p fCalculate Pile Mmt.

wp # ws

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TIEBACK WALLS


EARTH PRESSURE COEF. Vs MOVEMENT / HEIGHT


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So what !So what !

Too complicated !


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


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


Q y pQ y p•• Laterally loaded pilesLaterally loaded piles•• Shallow foundationsShallow foundations•• End bearing pilesEnd bearing piles

THE PRESSUREMETER: SOME CONTRIBUTIONS TO FOUNDATION … · 2020. 10. 14. · 8/26/2010 1 THE...

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