Dynamic Testing Services (Singapore) Pte Ltd
1 Pemimpin Drive #05-12 One Pemimpin, Singapore 576151  Tel: 63378212  Fax: 66945926  Email: info@dtsspl.com
 
 
 
  PIT (PiIe Integrity) Test  
         
 
1.0 PIT Test (Pile Integrity Test)
1.1 Dynamic Testing Services (Singapore) Pte Ltd, provides specialist testing works in “Pile Integrity Test'' (PIT) using low strain impact method. The test is also called sonic echo method.
1.2 In today's deep foundation industry, this inexpensive and reliable non-destructive test for pile integrity offers a practical and cost-effective solution.
   
   
2.0 Why Need Pile Integrity Test?
2.1 Deep foundations are the major components of buildings which are subjected to high loads. Defects in deep foundations can be unknown till foundation problems arise. Pile Integrity Test is not expensive but foundation problems are. As a responsible contractor, engineer or owner representative you cannot afford to simply assume that your foundation is safe without proof from adequate testing.
 
a) Driven piles - may be damaged by high driving stresses.
b) Bored piles or angered shafts - may suffer from separation of concrete, necking, inclusions, voids, contamination of concrete, etc.
c) After installation of plies, shafts may he damaged by construction equipments, lateral soil movement, slope or retaining wall failure or temporary struts failure.
d) Impractical to statically test each pile.
e) Gives estimate of pile length.
   
   
3.0 To Conduct PIT Test
3.1 Pile Integrity Test is performed using highly sensitive accelerometer, special conditioned hammer and a precision instrument and analysts system called PIT Corrector.
3.2 Testing involves the attachment of accelerometer to the pile top. After attachment, pile is impacted with specially conditioned hammer to generate a low strain compressive wave into the pile. The acceleration and velocity records versus time is graphically displayed with subsequent reflections from either pile toe or pile defects. Please refer to attached.
3.3 The integrity test method is also able to give average records of several impacts cancelling any random signals in any particular blow. Another option is exponential amplication of the signal with time which is not normally available in other systems. This function allows detection of integrity of even long piles with high action by amplifying the signal at deep depths.
3.4 Requirement for PIT test are as follows: -
a) Pile top to be approximately flat and free from debris, soil and water.
b) Pile top is accessible for hammer impact.
c) Pile top concrete should be sound.
   
   
4.0 Data Interpretations & Analysis
4.1 Once data are collected, they will be analyzed thoroughly using the PIT Collector's reprocessing and signal enhancement facilities and plots will be made of all records.
4.2 Data interpretations is based on wave propagation theory. When a hammer impacts the pile top, an acoustic wave with propagate down through the pile. When the downward travelling compression wave encounters a change in pile stiffness (eg: cross-sections change) or concrete quality, it generates an upward traveling wave (tension wave) which is tater observed at pile top. If no change in pile stiffness or pile is good, no earth tension reflection will be detected.
4.3 The location of defects can be estimated from the velocity reflection and size of defects can he estimated from the magnitude of early reflection. Refer to Figure 1 for typical example of test results.
   
   
5.0 Test Report
5.1 On completion of all field work a final report covering all aspects of the pile monitoring and analysts work will be prepared. This report will incorporate results of the PIT test and computer analysts.
   
   
6.0 Test Recognition
6.1 PIT Test is recognised and specified in various international engineering standards and codes of practice such as: -
a) ASTM (American Standard of Testing Materials) D5882-96
b) 858004 (British Standard - Foundation Code)
c) ICE (Institute of Civil Engineers) Piling Specifications
d) Canadian Foundation Engineering Manual (1992 – Canadian Geotechnical Society)
   
   
7.0 DTS Experiences
7.1 Dynamic Testing Services (Singapore) Pte Ltd has been in operation in Singapore since early 1990 providing pile integrity testing services to the local construction industry. More than 500 over piles (RC piles and bored piles) are tested for integrity each year as a supplement to static load test to serve as quality control program.
   
8.0 Advantages of PIT Test
8.1
a) Gives immediate fast results to check pile integrity.
b) Simple and cheap method to investigate integrity problem and gives quality control on site.
c) Detects the location and severity of defects for quick decision making and suspect piles can be subjected to further test and if necessary replaced or repaired.
d) Check pile length instated.
 

 

 

 

 
 
 
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