Frequently Asked Questions
- How should I prepare the pile head for PDA Test (on Bored Piles)?
The pile should be cast up to near ground level, with at least 1m – 2m of pile head exposed for working space. The pile should be encased with steel casing (for this 1m – 2m) and with steel cage reinforcement inside all the way to the top level of pile. This is to provide protection to the pile head for the dynamic pile test.
- What hammer weight should I use for the PDA Test for impact?
As a general guidance, you should use a hammer with a weight that is about 1% – 2% of the test load. For example, for a pile with test load of 1000 tons, you should use a hammer with a weight of about 10 tons – 20 tons.
- What are some results that I can expect to get from the output for PDA Test?
Some of the common output from PDA Test includes: RMX – Maximum resistance (Geotechnical Capacity of the pile), DMX – Maximum settlement (includes the temporary compression during the hammer blow), CSX – Maximum compressive stress (To evaluate whether the pile has been over-stressed from the impact).
- Can I know what’s the skin friction for this pile tested?
We will need to run a program call CAPWAP to tell the accurate skin friction distribution along the pile shaft from PDA Test.
- How should I prepare the pile head for PIT Test?
The pile head should be hacked to desired level (usually at cut off level) ensure there is sound concrete, as loose concrete might give false result on the pile. No hacking is required if the pile is cast with flat and sound concrete.
- How do you detect any defect from the pile tested?
We base our analysis on the assumption that wave traveling at a constant speed inside the pile, and any change in pile impedance, which is a function of Elastic Modulus, Cross‑sectional Area and Wave speed, would cause an early reflection before the pile toe.
- How do you check the pile integrity from Sonic Logging Test?
Wave travel at a certain wave speed inside the concrete pile. If there is any defect in between the tubes, the wave would take a longer time to travel from the transmitter to the receiver probe. This would be indicated on the “waterfall profile” that we are logging on the screen.
- Can we conduct Sonic Logging Test on piles that are not pre-selected?
No. For Sonic Logging Test, we will need to have GI tubes pre-installed (cast-in-situ). However, we will recommend PIT test for those who need to check the pile integrity.