PURPOSE OF TIP CORING
Tip coring test’s purpose is to verify concrete strength of pile toe and thickness of soft soil layers under pile toe after pile construction. Tip coring test results in combination with other testing methods help Designer decide the transfer of construction phase. The acceptable thickness of soft soil layers is less than 10cm (TCVN 9395: 2012).
METHOD OF TIP CORING
The test piles must be installed D114mm tube to depth of 1.0- 1.5m from pile tip.
For each pile to be cored, the coring work shall be completed before the concrete in the pile has reached an age of 28 days to allow the cores to be tested at 28 days.
Testing procedure was performed as follows:
- Preparing: test pile location, pile name, drilling machine installation, data recording sheet and acceptance minutes;
- After installing drilling machine in accordance with the technical requirement, drilling and sampling concrete pile tip with diameter 90mm, contained in sample tube length 1.0m.
- After drilling and taking off concrete drilling at pile tip, clearing hole bottom. Concrete samples will be compressed to test strength (if necessary).
- Then using the split tube (diameter tip is 73mm, split section length is 0.3m, total split tube is 0.56m) to drill pressly without pump to take and pull up sample. Finally, opening split tube to check the thickness and condition of humus layer.
- TCVN 9395:2012 “Bored pile – Construction, check and acceptance”.