Introduction
During bored pile construction, various issues may arise that require immediate attention from on-site technical personnel. Proper handling and timely reporting to the construction team’s chief engineer and manager are crucial to prevent Class II defects or broken piles. Below are common problems and their solutions to ensure efficient and safe construction.
1. Hole Collapse (Borehole Instability)
Cause: Common in sandy or silty soil layers.
Solution:
- Increase slurry density (1.2–1.4) to stabilize the borehole wall.
- For severe collapse, backfill with clay blocks and re-drill.
2. Hole Shrinkage
Cause: Occurs in soft or hard clay layers.
Solution:
- Raise the drill bit and ream repeatedly until the hole is straight.
- For severe deviation, backfill with a mixture of small stones and clay before re-drilling.
3. Drill Bit Burial or Jamming
Solution:
- Maintain sufficient slurry pressure to prevent further collapse.
- Use a high-power slurry pump to remove sediment around the drill bit.
- Lift the drill slowly—avoid forced extraction to prevent drill rod breakage.
4. Drill Bit Drop
Solution:
- Maintain water head and increase slurry density (1.15–1.3).
- Use an L-shaped retrieval hook attached to the drill rod to recover the bit.
5. Casing Tube Sinking
Solution:
- If detected early, backfill and reset with a longer casing.
- If near completion, increase slurry density (1.15–1.3) and support the casing with timber beams.
- Minimize cleaning time and accelerate concrete pouring.
6. Reinforcement Cage Drop
Solution:
- Maintain water head and increase slurry density (1.15–1.4).
- If no concrete has been poured, use a double L-hook for retrieval.
- If partial concrete is poured, reduce (embedment depth) and install a new cage within 2 hours.
7. Reinforcement Cage Floating
Solution:
- Stop concrete pouring immediately.
- Measure the cage and positions accurately.
- Reduce and resume pouring at a slower rate.
8. Initial Sealing Failure
Solution:
- Use a high-power slurry pump to remove unset concrete.
- Re-measure hole depth and reseal properly.
9. Pipe Blockage
Causes: Low slump, excessive foreign objects, or delayed pouring.
Solution:
- Use a threaded steel bar (Ø12–14mm) to manually clear the blockage.
10. Cage Snagging
Solution:
- Avoid forceful pulling—lower the slightly and rotate manually to adjust the position.
11. Difficulty Pouring Near Pile Top
Solution:
- Switch to a larger hopper and use a crane to increase pouring height.
- Reduce导管埋深 slightly to facilitate flow.
12. Broken Pile
Solution:
- For shallow breaks (<10m), excavate, remove weak concrete, and extend the pile with formwork.
- For deep breaks, backfill with clay, re-drill with an impact drill, and re-pour.
Conclusion
Timely detection and proper handling of bored pile issues are essential for structural integrity. Following these solutions ensures efficient construction while minimizing defects.
