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Standard Penetration Test SPT
Fernando SchnaidUniversidade Federal do Rio Grande do Sul
References
State-of-the-Art reviews: de Mello (1971) Nixon (1982) Decourt (1990) Clayton (1995)
ISSMGE: IRTP (Decourt et al, 1988). 1st International Symposium on Penetration
Testing
ENSAIO SPT
StandardsEquipment & ProceduresFactors affecting NSPT
Measurements & CorrectionsEnergyMean stresses
Dynamic Penetration Test Interpretation:Energy and wave propagation
Standard Penetration Test
Why?
predition of soil properties shallow and deep foundationsliquefaction potential
Applications:
most popular easy to usecheap
Standards1930: first experience in the USA1958: 1° attempt to standardised1988: ISSMGE - IRTP1991/EUA: ASTM 1586-991990/British: BS 1377-91994/Eurocode 72001/Brazil: NBR 6484
Test Procedure
EQUIPMENT
Equipment
75cm
A B C D E
F G H I
Types of hammer
- wood cussion- anvil
A: Brazilian Donut C: USA DonutE: USA SafetyF: Booros Co Ltd DarpG: British automaticH: Japanese automatic
Automatic hammer
ss1
1 2 3 4 5 n
QU
EDA
1
QU
EDA
2
QU
EDA
nPINO
SENTIDO DACORRENTE
hq
Measurements and corrections
Correct to a reference energy efficiency: 60% (N60).
International
Brazilian average energy: 72%.
60,060
icadaEnergiaAplNN SPT ⋅=
Schmertmann & Palacious (1972), Seed et al (1986), Skempton (1986)
Observation: verify the energy for which empirical interpretation methods have been devoloped
SPTSPT NNN ⋅=
⋅= 2,1
60,072,0
60
??
Energy
Measurements and correctionsDonut Safety
Energia (%)
quatidadeensaios
energia (%)
quatidade ensaios
Notas Referência
53 4 72 9 Ensaios de laboratório
Kovacs & Salomone (1982)
48
48 43
8
23 8
52 55 52
62
9 24 5
8
Várias medidas em
campo
Kovacs & Salomone (1982)
Schmertmann & Palacious (1979) Schmertmann & Palacious (1979)
Robertson et al (183) Robertson et al (183)
45 55 Valores típicos de
campo
Massa da cabeça de
bater(kg)
Eficiência (energia)
Acionamento manual Acionamento automático
Média (%)
Número de ensaios
Desvio padrão
(%)
Média (%)
Número de ensaios
Desvio padrão
(%)
1.2
66.7 51 2.73
78.5 13 2.04
3.6 75.5 195 2.95
14.0 66.4 23 1.70
13
Diaphragm wall:Shopping Centre Moinhos de Vento: Porto Alegre
x
y
AAAA
Measurements and corrections
Stress level
Sondagens – Shopping Moinhos de Vento/Porto Alegre - RS
( )60601 )( NCN N=
Measurements and corrections
Solos granulares :
( )60601 )( NCN N=
p' com varia :logo Z sptspt NN ↑↑Referência Fator de correção CN σ’v Observação
Skempton (1986) '100200
vNC
σ+= kPa
Seed et al (1983) Dr = 40 a 60%
NC Sand
Skempton (1986) '200300
vNC
σ+= kPa
Seed et al (1983) Dr = 60 a 80%
NC Sand Peck, Hamson & Thornburn (1974) ⎟⎟
⎠
⎞⎜⎜⎝
⎛
σ= '
2000log77.0v
NC kPa NC Sand
Liao & Whitman (1985) '
100
vNC
σ=
kPa NC Sand
Liao & Whitman (1985)
k
v
vNC ⎥
⎦
⎤⎢⎣
⎡
σσ
= 'ref
' )( - k = 0,4 a 0,6
Skempton (1986) '70170
vNC
σ+= kPa OC Sand
OCR = 3
Clayton (1993) '43143
vNC
σ+= kPa OC Sand
OCR = 10
Robertson et al (2000)
5.0' −
⎟⎟⎠
⎞⎜⎜⎝
⎛=
atm
voNC
σσ kPa NC Sand
Nível de Tensão
Measurements and corrections
Granular soils:
p' com varia :logo
Z
spt
spt
N
N ↑↑
Stress level
( )60601 )( NCN N=
COTA:Profun-
Nível didade Cota
d'água da em Amostra Golpescamada relação 2oe 3o
(m) RN
0
1 13
2 4
3 0
4 0
5 0
6 0
7 0
8 0
9 5
10 12
11 20
12 19
13 27
14 28
15 37
16 16 35Observações:
INICIAL
F13
Classificação do Material
Amostrador diam. Interno 34,8 mmAmostrador diam. externo 50,8 mmPeso: 65 Kg Altura de Queda: 75 cm
Gráfico
SONDAGEM:
Penetração
2,114Revestimento diam. 2,5"
Engenheiro Responsável:
Simbologia do gráficoProfundidade do nível d'água (m)
SPT 30cm finais0,00 16/02/94FINAL
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
0 10 20 30 40 50
Aterro, argila orgânica plástica com areia, cor variegada, consistência rija.
Sedimento argiloso orgânico plástico, cor preto, consistência muito mole.
Sedimento argiloso orgânico plástico, cor cinza, consistência média a rija.
Sedimento arenoso, granulometria fina, cor amarela a cinza, medianamente compacto a compacto.
1,60
7,95
9,30
REF.DATA:COTA:
Profun-
Nível didade Cota
d'água da em Amostra Golpescamada relação 2oe3o
(m) RN0 0
1 2
2 2 0
3 0
4 0
5 0
6 0
7 0
8 0
9 0
10 0
11 0
12 0
13 0
14 14.5 0
15 0
16 16 0
17 7
18 5
19 30
20 21
21 21 28
22 22.3 25Observações:
Argila siltosa orgânica, com pouco areia fina e fragmentos de
Areia fina, argilosa, com frag. de marisco, cinza,pouco compacta
Engenheiro Responsável:
Simbologia do gráficoProfundidade do nível d'água (m)linha azul SPT 30cm finais1,00 16/08/72
0,3 20/08/72FINAL
Areia fina, pouco argilosa, com frag. de marisco, cinza, compacta
LIMITE DE SONDAGEM
Areia fina,pouco argilosa,frag. de marisco,cinza,muito compacta
marisco, cinza, escura, muito mole.
9/1/1972-0.45
Recanto de Portugal
Revestimento diam. 76,2 mm
FIRMA C
Aterro- areia fina, com material variado, fofa.
Amostrador diam. Interno 34,9 mmAmostrador diam. externo 50,8 mmPeso: 65 Kg Altura de Queda: 75 cm
Gráfico
OBRA:
SONDAGEM:
Penetração
INICIAL
CLIENTE:
F7 / 72LOCAL:
Classificação do Material0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
0 10 20 30 40 50
SONDAGEM SPT PRÉ-ESCAVAÇÃOUFRGS - Universidade Federal do Rio Grande do Sul
CLIENTE:OBRA: SHOPPING MOINHOS DE VENTO REF. RS.7660/7LOCAL: DATA: Jul-98SONDAGEM: S1 COTA: 11,90 m
Profun-Nível didade Penetração
d'água da Gráfico Observações:camada
(m)0 0 0 0,20 cm de piso de concreto1 4 4 Até 1,5m aterro de argila siltosa2 27 27 c/ areia fina média, vermelha,3 22 30 mole.4 25 355 11 26 De 1,5 a 8m argila siltosa, 6 24 29 vermelha escura, dura7 40 408 11 43 De 8 a 11m silte argiloso c/ areia9 25 30 fina morrom claro, duro
10 23 3111 9 12 De 11 a 15m silte argiloso c/ 12 9 12 areia de textura variada, rijo a 13 10 16 duro14 14 2015 12 1716 15 1717 12 18 De 15 a 20m silte argiloso c/18 15 19 areia de textura variada, micaceo19 16 21 variegado, rijo a duro20 18 4521 32 42 De 20 a 22,39m argila siltoda c/22 28 areia de textura variada, micacea23 cinza, dura - solo residual24252627282930
Não
loca
lizad
o
1º e 2º
Nº de Golpes para 30cm
2º e 3°0
5
10
15
20
25
30
0 10 20 30 40
Interpretation
CharacterizationClassification;Soil properties:
Granular;Clay;Cohesive-frictional soils: hard soils, residualSoft rocks
Classification
modified from Clayton (1993)
Sand
(N1)60 0 - 3 Very loose
3 – 8 Loose
8 – 25 Medium
25 – 42 Dense
42 – 58 Very dense
Clay
(N)60 0 – 4 Very soft
4 – 8 Soft
8 – 15 Firm
15 – 30 Stiff
30 – 60 Very stiff
> 60 Hard
Residual soils*
(N)60 0 – 5 Completely weathered
5 – 10 Very weathered (lateritic)
10 - 15 Weathered
> 15 Moderately weathered
(saprolitic)
Weak rock
(N)60 0 – 80 Very weak
80 – 200 Weak
Classification
Go/N60 vs (N1)60
( )60160
60
0 )(Np
NN
pG
vo
aa ασ
α =′
=
Schnaid (1999) e Schnaid et al (2004)
Total stress – Δu ≠ 0
Disturbed soil -
Soil propertiese
Granular soils
5<sptN
Effective stress – no Δu
Nspt reflects stiffness and strengthE & φ
E &u SHard soils (including residual soils)
Composit materials (lime, fibers…)c+φRobust test
Nspt reflects stiffness and strengthE &cσ
Soft rocks
Cohesive soil
Cohesive-frictional
Is one measurement sufficient? (Mayne, 2001)
Su= undrained shear strength;γg= unit weight;Ir = rigidity index;φf = friction angle;OCR = over-consolidation;Ko = earth pressure coefficienteo= voids ratio;Vs= shear wave velocity;E = Young’s modulus;Cc = consolidation coefficient;qb= pile bearing capacity;K = permeability;Qb= ultimate stress
dr= relative density;γg= unit weight;LI= liquefaction index;φf = friction angle;Su= undrained shear strength;eo= voids ratio;Ko = earth pressure coefficient;Vs= shear wave velocity;E = Young’s modulus;Ѱ = dilation angleqb= pile bearing capacity;
CLAY SANDNSPT
Granular soils
7.1minmax
2601
)(7.11)(eeD
N
r −=
φ →→ rspt DN
5,0
0 16'23,0 ⎟⎟⎠
⎞⎜⎜⎝
⎛+⋅
=v
rNDσ
5,0
0 27'28,0 ⎟⎟⎠
⎞⎜⎜⎝
⎛+⋅
=v
rNDσ
Gibbs e Holtz (1957)
Skempton (1986)
Cubrinovski & Ishihara (1999)
Friction angle –
Granular soils
φ →→ rspt DNFriction angle –
Granular soils
φ →→ rspt DNFriction angle –
( )[ ]RpQDm rcvp −−=− ''' lnφφBolton (1986)
( ) 712,0'tan49,1 =− φrDMello (1971)
φ = 30° + 15 Dr - areias purasφ = 25° + 15 Dr - areias com mais de 5% de finos
Meyerhof (1956)
Granular soils
φ →→ rspt DNFriction angle –
Material
Bolton
(1979)
Bolton
(1979)
Robertson &
Hughes (1986)
Dense well-graded sand or gravel 55o 35o 40o
Uniform medium dense/coarse sand 40o 32o 34-37o
Dense sandy silt with some clay 47o 32o
Fine sand and sandy-silty-clay 35o 30o 30-34o
Clay-shale, or partings 35o 25o
Clay 25o 15o
p'φ cv'φ cv'φ
Granular soils
Friction angle –
Mayne (2006)34.0
'60'
)/(2.12arctan ⎥
⎦
⎤⎢⎣
⎡+
≈atmvo
pN
σσφ
601' )(4.1520 Nop +≈φ
Hatanaka & Uchida (1996)
φ →sptN
Mello (1967, 1971)
7.824
124
4.2015.00.4 22 ±⎟⎠⎞
⎜⎝⎛ ++⎥
⎦
⎤⎢⎣
⎡−⎟
⎠⎞
⎜⎝⎛ +∗+= φπφπ φπσφπ
φtgtg etgetg
tgSPT
°+= 15*20' Nφ
Teixeira (1996)
0q (t/m²)
5 10 15 20 25 30
10
20
30
40
50
60
70
25°
25°
30°
50°
50°
45°
45°
40°
40°
40°
40°
30°
40°
35°
30°
25°
SPT
As retas fornecem os valores de Ø
Areia FinaAreia GrossaConjunto
de Mello (1971)
Granular soils
Granular soilsFriction angle – φ →sptN
Granular soils
Stiffness - large strains, high shear stresses, insensitive to stress history.
(Jamiolkowski et al., 1991)
Uncemented unaged sands (after Eslaamizaad & Robertson, 1997
Western Australia sands (after Schnaid et al,2004)
Classification
Go/N60 vs (N1)60
( )60160
60
0 )(Np
NN
pG
vo
aa ασ
α =′
=
Schnaid (1999) e Schnaid et al (2004)
Granular soils
Stiffness - large strains, high shear stresses, insensitive to stress history
bNaMPaG ).()( 600 =
200 3 2600 av pNG σ ′=
Schnaid (1999) e Schnaid et al (2004)
450 3 2600 av pNG σ ′=
Upper boundary: uncemented sands
Lower boundary: uncemented sands
Granular soils
Stiffness - large strains, high shear stresses, insensitive to stress history.
)(160
'MPaN
E =Stroud (1989):Lower bound
E/N60 (MPa) Resistência à penetração N60 média Limite inferior Limite superior
4 1,6 - 2,4 0,4 - 0,6 3,5 - 5,3 10 2,2 - 3,4 0,7 - 1,1 4,6 - 7,0 30 3,7 - 5,6 1,5 - 2,2 6,6 - 10,0 60 4,6 - 7,0 2,3 - 3,5 8,9 - 13,5
Granular soils
Stroud (1988)Clayton (1993)
Cohesive soils
Mello (1971):Su/N ranges from 0,4 a 20 (sensitive clay);Su stress path dependent
Décourt (1989): Su = 10,5 N60 (kN/m2);Stroud (1979)
Pre-consolidated non-sensitive: Su = 4,5 N60 (kN/m2)
Undrained shear strength -
uspt SN →
SOLOS COESIVOSUndrained shear strength
uspt SN →
Cohesive-frictional materials
σ′= 1200 3 2600 av pNG( )no pS
eFG '
)(=
eeeF
+−
=1
)17.2()(2
σ′= 200 3 2600 av pNG
Schnaid et al, (2004)σ′= 4503 2
600 av pNG
Cohesive-frictional materialsYoung modulus - E
6,10,1 −=a
)(MPaaNE =
)(MPabNE c=
(Sandroni, 1991).
(Barksdale e Blight, 1997).
1,4c 6,0 ==b
(Jones e Rust, 1989)
Soft rocksUnconfined compression
strength Degree of weathering
N60 < 200 )(10 60 kPaNc =σ
Stroud (1988)
)(0.25.0 60' MPaNE −=
Stroud (1988)
Energy conceptsPrinciples of soil dynamics
:New interpretation
Wave propagation analysis
∫∞
=0
)( )( dttVtFE
Timoshenko & Goodier, (1970)
Condicionador e Amplificador
com 3 canais
Osciloscópio
Bateria
Borneira
Micro Computador com Placa A/D PCM-DAS 16D/16 da ComputerBoards para 350kHz
Wave propagation analysis
3.34
2.43
HASTE DE SONDAGEM
HASTE DE SONDAGEM
CÉLULA DE CARGA
3.34
FURO PARA PARAFUSO 6mm
2.50
2.503.152.69
4.26
3.34
2.43
0.46
3.34
30.00
10.00
Wave propagation analysis
Acelerômetros Brüel & Kjaer
Modelo = 4375S
(indicado para altas freqüências)
Faixa de aceleração 100μG a 10 kG
Danifica com 16kG
Wave propagation analysis
Extensômetros
Marca Excel
Tipo PA-06-125TG-350-LEN
Roseta dupla 90o
A B C Dsaida saidaentrada entrada
Wave propagation analysis
Wave propagation analysis
)()()()( SDI tftftftf =++
where: ƒΙ = inertial forces;
ƒD = damping forces
ƒS = reconstitutive forces
Mechanism of dynamic penetrationFinite difference analyisis - D’Alembert’s principle
i = 1
2 3 4
: :
r
j = 1 2
3 4
: :
: :
s
MARTELO
HASTE
mj
EA
mi
Δ
Vo
R
Ru
Ru J VQ
Reação (R)
Deformação
O
A
B
C
RDeslocamento
Damping (J)Constante de mola K'Deformação permanente
EA
LUVAS
Wave propagation analysis
Mechanism of dynamic penetration
Wave propagation analysis
35,8 m rod length
35,8 m rod length: typical measurements
Wave propagation analysis
35,8 m rod length: typical measurements
Wave propagation analysis
Numerical simulation
SPTLPT
0 5 10 15 20 25 30
Average penetration per blow300/Nref (mm)
20
18
16
14
12
10
8
6
4
2
0
Dep
th (m
)MeasuredSimulated
SPT - Ladner 06
0 5 10 15 20 25 30
Average penetration per blow300/Nref (mm)
20
18
16
14
12
10
8
6
4
2
0
Dep
th (m
)
MeasuredSimulated
SPT - Ladner 09
0 10 20 30 40
Average penetration per blow300/Nref (mm)
20
18
16
14
12
10
8
6
4
2
0
Dep
th (m
)
MeasuredSimulated
RLPT - Ladner 08
0 10 20 30 40
Average penetration per blow300/Nref (mm)
20
18
16
14
12
10
8
6
4
2
0
Dep
th (m
)
MeasuredSimulated
RLPT - Ladner 11
H1m
0,75
Δρ
H1h
ΔρRef
0,75+Δρ
H2h
H2m
Δρ
ΔEPm = Mm (0,75+Δρ) g
ΔEPh = Mh Δρ g
(1) (2)
Hamiltons’s principle
ΔEPGm+hsystem = Ws + Wnc
ΔEPGm+hsystem – Wnc = Esampler
Esampler = Ws = Fd Δρ
New interpretation method
0,75
Instrumentação Instrumentação
Instrumentação
Δρ
t1 = 0 t2 = t t3 = Martelo = 65 kg
g = 9,806 m/s2
Amostrador
Haste
0,75
ΔρΔρ
hm(t
1)
hh(t
1)
hh(t
3)
hm(t
3)
Referência
Centro de massa da HASTE
Centro de massa do MARTELO
Dynamic force- Fd:
New interpretation method
ρΔ+ρΔ+=Δ •+ gMgMEEPG hm
sistemahm
where: - E• = Theoretical potential energy = 478J
- Mm = Hammer mass = 65kg
- Mh = Rod mass = 3,23kg/m
- g = gravity acceleration
- Δρ = permanente sampler penetration
Dynamic force- Fd:
New interpretation method
ρΔ==Δ + dncsistema
hm FWEPG
Dynamic force- Fd: CALIBRATION
ρρηηρηηηη
ΔΔ+Δ+
=)( )()75,0( 231313 gMgMgMF rhh
d
Sistema do Eficiênica Haste da Eficiência
Martelo do Eficiência 0,0042-1,00 1,00 764,0
3
2
1
321
===
===
ηηη
ηηη lSoil properties
Bearing capacitySoil properties
Bearing capacity
Granular soils
Friction angle - φ d →F
Vésic (1972)
e d 1 FFAreias ≅∴=→ ν
)tan () ( slσocpe δγσ LKANNcAF ++=
Odebrecht et al (2005) ρ
ρρηΔ
Δ+Δ+=
] ) 75,0([ m2m13 gMngMnFd
Hermansson e Gravare (1978) Sand
Granular soils
Friction angle
φ d →F
(Odebrecht et al, 2004 e Schnaid et al, 2004; 2005)
Sand: case study
-32
-30
-28
-26
-24
-22
-20
-18
-16
-14
-12
-10
-8
-6
-4
-2
00 2000 4000 6000 8000 10000
qc (KPa)
Prof
undi
dade
(m)
-32
-30
-28
-26
-24
-22
-20
-18
-16
-14
-12
-10
-8
-6
-4
-2
025 30 35 40 45
(graus)
Prof
undi
dade
(m)
-32
-30
-28
-26
-24
-22
-20
-18
-16
-14
-12
-10
-8
-6
-4
-2
00 5 10 15 20 25 30
NSPT
Prof
undi
dade
(m)
φ graus
φ SPT
φ R&C
Areia
Areia
Areia
Itajaí - SC
Cohesive soils
Undrained shear strength - u d S →F
Vésic (1972)
0,6 6,0 e
d
FFArgilas ≅∴=→ ν
)tan () ( slσocpe δγσ LKANNcAF ++=
Odebrecht et al (2005)
lbc
bd
AANLAF
Suαγ+−
=6,0
Hermansson e Gravare (1978)
Clays: case study
-13
-12
-11
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
00 500 1000 1500
qt (KPa)
Prof
undi
dade
(m)
-13
-12
-11
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
00 100 200 300
U, Uo (KPa)
Prof
undi
dade
(m)
-13
-12
-11
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
00 10 20 30 40
Su (KPa)
Prof
undi
dade
(m)
-13
-12
-11
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
00 25 50 75 100
w (%)
Prof
undi
dade
(m)
-13
-12
-11
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
00 500 1000 1500
NSPT
Prof
undi
dade
(m)
7
0/70
0/65
0/80
0/100
0/70
0/90
0/60
0/60
0/70
0/50
3 Vane
Sampler: open Sampler: pluggedBR 101 – Garopaba - SC
Challanges
complete standardisation is not likely to be achieved: reference value of 60% of the potential energy observation of recommended codes of practice and better workmanship.incorporate energy and wave propagation concepts to interpretation methods
Nota:a Norma Brsileira NBR 6484.b ASTM D 156-84.c [(Kaito et al. (1971); Yoshida et al. (1988)] d [Koester et al. (2000); Daniel (2000)] e seção transversal de aço
Detalhes SPTa SPTb JLPTc NALPTd
Massa do Martelo (kg) 65.0 62.3 98.1 133.5
Altura de queda (m) 0.75 0.762 1.50 0.762
Comprimento do Martelo (cm) 0.23 0.533 0.368 0.699
Diâmetro do Martelo (cm) 0.20 14.0 21.1 17.8
Seção transversal de área (cm2) 4.1 8.0 10.1 9.3
Massa linear - haste (kg/m) 3.230 6.304 7.959 7.328
Velocidade de impacto do martelo (m/s) 3.836 3.866 5.425 3.866
Comprimento de haste (m) 11.8 11.8 11.8 11.8
Seção transversal - amostrador e (cm2) 10.807 8.800 18.800 13.900
Comprimento do amostrador (m) 0.45 0.45 0.45 0.45
Massa linear - amostrador (kg/m) 8.516 6.934 14.814 10.953
Presente Simulação
Q Propriedades do solo J
Ru (N)
0.0010.656000
0.0010.656000
0.0010.656000
0.0010.656000
Penetração por golpe - Δρ (m) 0.031 0.030 0.080 0.068
E (J) 510 507 1601 1149
Detalhes do ensaio SPT e LPT (Daniel, 2000)
OUTROS ENSAIOSDINÂMICOS
LPT x SPT: