sonic logging test presentation

8/12/2019 Sonic Logging Test Presentation

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Aim

The PISA-CHUM sonic pile integrity loggerwas developed to determine the integrity of

pile foundation or concrete element such as

cast in-situ piles, caisson, barrets and

diaphragm wall with pre-installed access tubes.


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Test Equipment

PISA is an acronym for Pile Integrated Sonic Analyzer. The PISA

is basically a high-performance computerized instrument, capable ofperforming both sonic and ultrasonic integrity testing.

CHUM stands for Cross-Hole Ultrasonic Monitor. The CHUM

can be used for checking integrity of deep cast insitu concretefoundations of all kinds: Bored piles, drilled shafts, caissons andbarrettes (slurry wall elements). The system uses high-frequency(ultrasonic) waves and installation of access tubes is required during

the casting stage.

PISA-CHUM meet or exceed the requirements of ASTM Standard

6760.


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PISA - CHUM

The PISA-CHUM system

consists of :i) A data logger with

pentium computer

equipped with USB.ii) A pair of pulleys with

depth meters.

iii) Ultrasonic pulse

transmitter and

receiver probes.


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On Site Testing

1) Concrete pile installed withwater-filled PVC/Steal

pipes (min.50mm diameter)

2) Ultrasonic transmitter

3) Ultrasonic receiver4) Depth encoders

5) Industrial standard rugged

field computer6) A defect in the pile and its

presentation


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METHODOLOGY1) Measure the length/depth of access tubes and distances between access tubes.

2) Make sure the access tubes filled with water. Water is the coupling medium for thetesting.

3) Lower down the transmitter and receiver into the access tubes respectively.

4) Having lower down the probes to the bottom of the access tubes, the probes are pulledupwards simultaneously while monitoring is done through the microSlate computer.

5) The transmitter will produces a continuous series of signals, sending the waves in alldirections while these travel paths do eventually reach the receiver.

6) The computer will automatically save all the data collected and then plot the traveltime between the tubes versus the depth.

7) The repetitions depend on the numbers of access tubes installed in the pile.

8) After that the data will be downloaded into the desktop for analysis.


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OUTPUTN

S

EW

15P612/08/2005

Diameter: 1.50m

NS25.7m

NE25.7m

NW25.7m

0m

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

22.0

24.0

25.7

0

0.0

12

0.2

24

0.4

36

0.6

48

0.8Arrival time [ms]

Attenuation [db]

0m

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

22.0

24.0

25.7

0

0.0

12

0.2

24

0.4

36

0.6

48


Attenuation [db]

0m

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

22.0

24.0

25.7

0

0.0

12

0.2

24

0.4

36

0.6

48


Attenuation [db]


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OTHER EQUIPMENTS

Sonic Integrity Logger TCP3 (by Fugro)

PISA (by Piletest.com)

CHA (by Pile Dynamics,Inc.)

TCP3 is the earlier equipment used for cross

hole sonic logging test. Has been substituted

by PISA and CHA.


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TCP3


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TCP3 OUTPUT


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CHA OUTPUT


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INTERPRETATIONSo As long as the FAT and attenuation are roughly constant, we can conclude

the homogeneity of the concrete for the section / profile tested.

o A local increase in FAT at certain depth of the profile means there is anobstacle / defect on the straight path between the access tubes. The sonicwaves will travel through this defect at a reduced velocity with a respectiveincrease in travel time. In such case, there will also be respective increaseof the attenuation.

o An increase of the attenuation without an increase in FAT is usually arelative rarefication of travel path outside the section between access tubes.

o The interpretation of the sonic logging test is primarily based on the FATthat give information about the homogeneity of concrete between accesstubes which also is the main objective of the test. Then it followed byattenuation value which give secondary / additional information about theconcrete homogeneity outside the section between access tubes.


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INTERPRETATIONS

o It should be recognized that sonic logging tests are intrinsically indirect andqualitative. Hence there are no simple criteria to pass or fail on the

basis of these tests alone. The sonic logging technique, however, providers

a cost-effective screening test to identify piles which have imperfectionswithin their acoustic integrity that may of structural significance. Such pilesnormally warrant further investigation and engineering evaluation.

o It is therefore recommend that the test results should be evaluated inconjunction with pile construction records and site investigation reportswhich can often indicate the possible causes and physical nature of thedetected acoustical irregularities.


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CRITERIA OF FAT &

ATTENUATION No universal accepted rules for interpretation. The determination of what

constitutes an anomaly is still arbitrary.

According to The California Department of Transportation (Caltrans), anyincrease in FAT of more than 20% indicates a significant anomaly. As forattenuation, the three Sigma rule is adopted in the interpretation.

The Chinese Codes define an anomaly if the FAT exceeds the mean by 2standard deviation and the attenuation exceeds the mean by 6dB.

As for reporting, we adopt the Caltrans rule where any increase of 20% inFAT and increase of more than 3 standard deviation in attenuation will bereported.


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POSSIBLE CAUSE OF DELAYIN FAT & ATTENTUATION

Distance between the tubes

Segregation / peripheral contamination around the tubes

Honeycomb / voids between the specific profile

Debris at the bottom of the tubes

Necking & arching of pile due to soil collapse

Bentonite slurry


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CASE OF STUDY


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CASE OF STUDY

Null FAT and attenuation signals were observed in one profile, FAT andattenuation delays were observed in the other 4 profiles during testing.

A coring was done at the center of the pile up to about 18.0m and the core

sample shows contamination of concrete (low quality concrete) at about8.8m to 9.3m below pile-top.


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CASE OF STUDYN

S

EW

Pile Name :

Date of Testing:

Diameter: 1.20m

NS33.4m NE32.9m SE32.8m

0m

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

22.0

24.0

26.0

28.0

30.0

32.0

32.8

0

0.0

12

0.2

24

0.4

36


Attenuation [db]

0m

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

22.0

24.0

26.0

28.0

30.0

32.0

33.4

0

0.0

12

0.2

24

0.4

36


Attenuation [db]

0m

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

22.0

24.0

26.0

28.0

30.0

32.0

32.9

0

0.0

12

0.2

24

0.4

36


Attenuation [db]


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CASE OF STUDYPile Name :

Date of Testing:

Diameter: 1.20m

SW33.2m

EW32.7m

NW32.8m

N

S

EW

0m

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

22.0

24.0

26.0

28.0

30.0

32.0

33.2

0

0.0

12

0.2

24

0.4

36


Attenuation [db]

0m

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

22.0

24.0

26.0

28.0

30.0

32.0

32.7

0

0.0

12

0.2

24

0.4

36


Attenuation [db]

0m

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

22.0

24.0

26.0

28.0

30.0

32.0

32.8

0

0.0

12

0.2

24

0.4

36


Attenuation [db]


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Thank you

sonic logging test presentation

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