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ADVANCED NON DESTRUCTIVE TESTING PRACTICES
FOR PILE FOUNDATIONS
By: Ravikiran Vaidya Principal, Geo Dynamics (India)
HIGH STRAIN DYNAMIC PILE TESTING
DYNAMIC PILE TESTING EQUIPMENT
APPARATUS
• Compact Pile Driving Analyzer
• Sensitive Transducers• Signal Cables• Output Device
PRINCIPLE OF DYNAMIC PILE TESTING
STRAIN GAUGES
STRAINS
STRESS
FORCE
ACCELEROMETERS
ACCELERATION
VELOCITY
DISPLACEMENT
Rs = ( 1 – Jc )[ P1+ Z.v1 ]/2 + ( 1 + Jc )[ P2 – Z.v2 ]/2
Pile Resistance = Function (Force, Velocity)
Here,
Jc = soil damping
P1 & v1 = Force and Velocity at Time T1
P2 & v2 = Force and Velocity at Time T2
TEST SET-UP ARRANGEMENTS
PREPARATION FOR FIXING SENSORS
•Drilling holes diametrically on either side
Sensors fixed on the pile
USE OF TRIPOD/CRANE FOR TESTING
PDA TEST IN PROGRESS
TEST SET-UP ARRANGEMENTS
• HAMMER WEIGHT = 1% - 2% OF TEST LOAD
• BUILD PILE HEAD = 1.6 x PILE DIAMETER
• PLYWOOD CUSHION = 25mm - 50mm
• STEEL PLATE = 25mm - 50mm
• GUIDE TO ENSURE VERTICAL FALL (Optional)
• MINIMUM WAIT PERIOD = 7 – 10 DAYS
PDA INPUT PARAMETERS
•Pile Properties (at Sensor Location)• Area • Length below sensors and in soil
• Material Properties• Density SP•Wave Speed WS• Elastic Modulus EM• EM = c2 = (SP/g) WS2
• Damping Factor Jc = 0.5 to 0.9
PDA OUTPUT GRAPHSGEO DYNAMICS Pile Driving Analyzer ®
TP1
TS: 204.8
TB: 0.0
F1 (60000)
F2 (60000)
A12 F12
TS: 204.8
TB: 0.0
V1 (4.76)
V2 (4.76)
68 @ 66.5 m
Project InformationPROJECT: PILE NAME: TP1DESCR: 1300MMOPERATOR: GEO DYNAMICSFILE: TP1.w019/4/2010 6:35:31 PMBlow Number 4
Pile PropertiesLEAREMSPWSEA/C2L/CJCLP
mcm^2MPakN/m3m/skN-s/mms[]m
71.513273.23
3607624.5
3800.01260137.620.7070.3
Quantity ResultsCSXCSITSXEMXFMXDFNRMXRSUDMX
MPaMPaMPakN-mkNmmkNkNmm
16.019.73.8
146.321197
36780
1222910
SensorsF1: [6346] 97.6 (1)F2: [B474] 92.5 (1)A1: [24207] 1035 g's/v (1)A2: [24209] 1050 g's/v (1)CLIP: OKF1/F2: HIGH 1.60V1/V2: OK 1.10
Version 2008.098.031
PILE INFORMATION / RESULTS
GEO DYNAMICS Pile Driving Analyzer ®
TP1
TS: 204.8
TB: 0.0
F1 (60000)
F2 (60000)
A12 F12
TS: 204.8
TB: 0.0
V1 (4.76)
V2 (4.76)
68 @ 66.5 m
Project InformationPROJECT: PILE NAME: TP1DESCR: 1300MMOPERATOR: GEO DYNAMICSFILE: TP1.w019/4/2010 6:35:31 PMBlow Number 4
Pile PropertiesLEAREMSPWSEA/C2L/CJCLP
mcm^2MPakN/m3m/skN-s/mms[]m
71.513273.23
3607624.5
3800.01260137.620.7070.3
Quantity ResultsCSXCSITSXEMXFMXDFNRMXRSUDMX
MPaMPaMPakN-mkNmmkNkNmm
16.019.73.8
146.321197
36780
1222910
SensorsF1: [6346] 97.6 (1)F2: [B474] 92.5 (1)A1: [24207] 1035 g's/v (1)A2: [24209] 1050 g's/v (1)CLIP: OKF1/F2: HIGH 1.60V1/V2: OK 1.10
Version 2008.098.031
SOLUTION FOR SOIL PARAMETERSFrom Field Data, we obtain
F measured V measuredF = V x Z, Fm = Vm x Z
Here, Zp = Pile Impedance = EA/C, Rs = Soil Resistance
Consider, Fcomputed (Fc) = Vm x Zp
Hence Fm = Fc + (Vm x Rs)
• Only unknown is Rs, which is computed
• Discretize the pile into series of elements toobtain Rs at various distances from top
Fm = Vm x (Zp + Rs)= (Vm x Zp) + (Vm x Rs)
CAPWAP METHODCAPWAP METHOD
1 Set up pile model and assumesoil model for RRshaftshaft and RRtoetoe
RRshaftshaft
RRtoetoe
5 Go to step 2
4 Adjust RRshaftshaft and RRtoetoe
3 Compare FFcc with measured FFmm
2 Apply one measured curve ((vvmm));Calculate complementary FFcc
vvmmFFcc
FFmm
Repeat until match Repeat until match is satisfactoryis satisfactory
20 100
-15000
0
15000
30000
ms
kN
4 L/c
Force MsdForce Cpt
20 100
-15000
0
15000
30000
ms
kN
4 L/c
Force MsdVelocity Msd
Pile
0
200
400
600
800
kN
/m
0
3750
7500
11250
15000
kN
Shaf t ResistanceDistribution
Pile Forceat Ru
0 3750 7500 11250 150000.000
5.000
10.000
15.000
20.000
Load (kN)
Dis
pla
ce
me
nt
(mm
)
Pile TopBottom
Ru = 12624.5 kNRs = 10752.1 kNRb = 1872.4 kNDy = 15.0 mmDx = 17.0 mm
Pile: TP1; 1300MM; Blow: 2 (Test: 04-Sep-2010 18:35:) 23-Oct-2010GEO DYNAMICS CAPWAP(R) 2006-2
CAPWAP(R) 2006-2 Licensed to GEO DYNAMICS
SAMPLE OUTPUT OF CAPWAP
OUTPUT QUANTITIES OF CAPWAP
• Static Capacity At Time Of Testing.
• Static Load Test Curve.
• Total Skin Friction And End Bearing.
• Skin Friction Variation Along The Pile Length.
• Compressive And Tensile Stresses Developed During Testing.
• Net And Total Displacement Of The Pile.
• Pile Integrity And Changes In Cross-Section.
RELIABILITY STUDIES END-BEARING PILES
KURLA FLYOVER , MUMBAIPILE DETAILS
Pile Type R.C.Bored
Pile Dia. 1200mm
Pile Depth 20.80m
Design Load 339.3Tons
Test Load 509.0Tons
Soil Type Weathered Rock
PDA Test 28.09.98
Static Test 12.09.98
0 100 200
300 400 500 600
Load in Tons
0.0
1.0
2.0
3.0
Pile
top
settl
emen
t in
mm --Static Load Test Curve
--Dynamic Load Test Curve
JJ URBAN VIADUCT , MUMBAI
PILE DETAILS
Pile Type R.C.Bored
Pile Dia. 1200 mm
Pile Depth 7.0 m
Design Load 550.0 T
Test Load 1375.0 T
Soil Type Fresh Basalt
PDA test 21.05.99
Static Test 14.05.99
0 200 400 600 800 1000 1200 1400 1600
Load in Tons
0.0
1.0
2.0
3.0
4.0
5.0
Pile
top
settl
emen
t in
mm --Static Load Test Curve
--Dynamic Load Test Curve
BORIVALI NATIONAL PARK FLYOVER, MUMBAI
PILE DETAILS
Pile Type R.C.Bored
Pile Dia. 1000 mm
Pile Depth 8.6 m
Design Load 235 T
Test Load 352.5 T
Soil Type Fresh Basalt
PDA test 23.05.99
Static Test 15.07.99
0 100 200 300 400 500
Load in Tons
0.0
0.5
1.0
1.5
2.0
Pile
top
settl
emen
t in
mm
--Static Load Test Curve
--Dynamic Load Test Curve
0
2
4
6
8
10
12
14
16
0 200 400 600
800 1000 1200
Load in tons
Pile
Top
Set
tlem
ent i
n m
m
PILE DETAILS
Pile Type R.C.Bored
Pile Dia. 1200 mm
Pile Depth 18.0 m
Design Load 675 T
Test Load 1012.5 T
Soil Type Indeterminate Weathered Rock
PDA test 24.01.08
Static Test 06.11.07-07.11.07
ELEVATED HIGHWAY PROJECT, BANGALORE
RELIABILITY STUDIESFOR FRICTION PILES
AHMEDABAD-VADODARA EXPRESSWAYPHASE -II
PILE DETAILS
Pile Type R.C.Bored
Pile Dia. 500mm
Pile Depth 20.50m
Design Load 90.0Tons
Test Load 105.0Tons
Soil Type Silty Clay
Dynamic test 16.01.02
Static Test 31.01.02
0
1
2
3
4
5
6
0 20 40 60 80 100 120 140 160 180Load in tons
Pile
Top
Set
tlem
ent
in m
m
--Static Load Test Curve
--Dynamic Load Test Curve
CHENNAI BYPASS PROJECT
PILE DETAILS
Pile Type R.C.Bored
Pile Dia. 1200mm
Pile Depth 23.70m
Design Load 375.0Tons
Test Load 875.0Tons
Soil Type Dense Silty Sand
PDA test 17.09.05
Static Test 14.08.05
0
2
4
6
8
10
0 100 200 300 400 500 600 700 800 900 1000
Load in tons
Pile
Top
Set
tlem
ent i
n m
m
--Static Load Test Curve
--Dynamic Load Test Curve
GCPTCL JETTY, DAHEJ
PILE DETAILS
Pile Type R.C.Bored
Pile Dia. 1200mm
Pile Depth 34.70m
Design Load 275.2Tons
Test Load 412.8Tons
Soil Type Dense Sand
PDA Test 17.09.05
Static Test 14.08.05
0
1
2
3
4
5
0 100 200 300 400 500
Load in tons
Pile
Top
Set
tlem
ent i
n m
m
--Static Load Test Curve
--Dynamic Load Test Curve
HEBBAL GRADE SEPARATOR, BLR
0
2
4
6
8
10
0 100 200 300 400 500 600
L o a d i n t o n s
P i l
e T
o p
S e
t t l
e m
e n
t i
n m
m
PILE DETAILS
Pile Type R.C.Bored
Pile Dia. 1200mm
Pile Depth 34.70m
Design Load 275.2Tons
Test Load 412.8Tons
Soil Type Murum & W.D. Rock
PDA test 17.09.05
Static Test 14.08.05
--Static Load Test Curve
--Dynamic Load Test Curve
DMRC PROJECT, NEW DELHI
Delhi Metro Rail Corporation Project, New Delhi
0
2
4
6
8
0 100 200 300 400 500 600 700 800L o a d i n t o n s
mm
--Static load test curve--Dynamic load test curve
0
2
4
6
8
0 100 200 300 400 500 600 700 800
L o a d i n t o n s
P I l
e T
o p
S e
t t l
e m
e n
t i
nm
m
PILE DETAILS
Type of Pile R.C.Bored
Dia of the pile 1500mm
Pile Depth 37.15m
Design Load 289.7Tons
Test Load 434.6Tons
Soil Type
Dynamic test 20.03.02
Static Test 17.02.02
--Static Load Test Curve
--Dynamic Load Test Curve0
5
10
15
20
25
30
0 100 200 300 400 500 600 700 800 900
L o a d i n t o n s
P i l
e T
o p
S e
t t l
e m
e n
t i
n m
m
--Static Load Test Curve
--Dynamic Load Test Curve
PILE DETAILS
Pile Type R.C.Bored
Pile Dia. 1000mm
Pile Depth 43.5m
Design Load 360.0 Tons
Test Load 520.0 Tons
Soil Type
PDA test 11.05.07
Static Test 18.028.07-19.02.2007
PEEVEES COCHIN MALL PROJECT
0
1
2
3
4
5
6
7
8
9
10
0 100 200 300 400 500 600 700Load in tons
Pile
Top
Set
tlem
ent i
n m
m
Static Load Test CurveDynamic Load Test Curve
BENEFITS & APPLICATIONS
• Both PDA / PIT Have Proven Application Worldwide
• Applicable both Offshore & Onshore for Bored, Driven Concrete, Steel, Timber Piles
• Generates Useful Information other than pile capacity
• More tests can be conducted & hence Better Quality Assurance
• Tests conducted by Independent Agency
• Requires Less space compared to Static Tests
• More Safety Compared to Static Testing
• Evaluates Pile Integrity Incl. Extent & Location of Damage
• Determines if Problem is Pile, Soil or Hammer
• Confirms Capacity, Even at Large Loads
• Expertise essential for interpretation and data collection CAPWAP mandatory for all bored piles and atleast first few initial driven piles
• Reliability studies important to assess knowledge of testing company and in some cases to calibrate with soil.
• Method can be used for almost all pile types
• Technology is a part of IRC and various code provisions.
• Recommended on 2%-10% of total piles at the project site
CONCLUSIONS