Solutions for Common Bored Pile Construction Issues: Prevention and Treatment Measures

1. Dealing with Deviated Drilling Holes

Quality Problems and Phenomena

1. Non-vertical holes after completion with deviation exceeding the specified L/100

2. Difficulty in inserting reinforcement cages

Causes

1. Unlevel drilling rig or an uncompacted construction site causing uneven settlement

2. Unstable underwater drilling platform foundation

3. Bent drill pipes or loose connections are causing excessive drill bit movement

4. Obstacles near existing structures are pushing drill bits sideways

5. Uneven soil hardness or encountering boulders

Preventive Measures

1. Level and compact the site before rig positioning; regularly check levelness during drilling

2. Align the pulley groove, the drill pipe chuck, and the centerline vertically

3. Conduct pre-construction surveys near existing structures; use impact drilling if obstacles are found

4. Regularly inspect and replace bent drill pipes

5. For impact drilling, use appropriate stroke and consider two-stage hole forming

Treatment Methods

1. Use impact drilling for boulders

2. For excessive deviation, backfill with clay and redrill after compaction

2. Handling Hole Shrinkage During Drilling

Quality Problems

• Difficulty in lowering the hole detector due to diameter reduction

Causes

1. Weak soil layers compress inward

2. Water-expanding plastic soil layers

3. Worn drill bits are not repaired timely manner

Prevention

1. Frequently ream holes when encountering weak/plastic soils

2. Regularly inspect and repair drill bits

Treatment

• Ream hole repeatedly until the design diameter is achieved

3. Managing Hole Collapse During Drilling

Quality Problems

• Wall collapse during/after drilling

Causes

1. Inadequate mud density or leaking casing

2. Low mud pressure on walls

3. Fast advancement in sandy layers

4. Long drilling interruptions

5. Equipment vibration near the site

Prevention

1. Avoid heavy equipment near the site

2. Properly install and seal casings

3. Adjust mud properties according to geology

4. Maintain continuous operation

5. Handle reinforcement cages carefully

Treatment

• For severe cases, redrill after proper backfilling

4. Addressing Stuck Drill Bits

Quality Problems

• Immobilized drill bit during operation

Causes

1. Irregular hole shapes

2. Improper bit lowering

3. Falling debris

4. Over-sized repaired bits

Prevention

1. Use proper drilling techniques

2. Ensure the bit size matches the hole diameter

3. Control impact energy

Treatment

1. Try gentle maneuvering

2. Use jacks or pulley systems for extraction

3. Consider controlled blasting in hard strata

5. Preventing Casing Bottom Collapse

Quality Problems

• Casing wall collapse and rig tilting

Causes

1. Improper clay backfilling

2. Inadequate geological data

3. Undersized casing

4. Water infiltration

Prevention

1. Backfill with ≥50cm of clay around the casing

2. Extend casing through weak layers

3. Use properly sized casings

4. Seal casing properly

Treatment

1. For underwater cases, sink casing deeper

2. For bottom collapse, reposition and reinforce the casing

6. Preventing Reinforcement Cage Deformation

Quality Problems

• Excessive twisting/bending during handling

Causes

1. Lack of temporary supports

2. Improper lifting points

3. Insufficient stiffener rings

Prevention

1. Add stiffeners every 2-2.5m

2. Use proper lifting techniques

3. Install temporary supports for long cages

Treatment

• Severely deformed cages must be remade

7. Securing Positioned Reinforcement Cages

Quality Problems

• Cage sinking or displacement

Causes

1. Improper fixation

2. Measurement errors

3. Reference point movement

Prevention

1. Secure cages to the casing with wooden blocks

2. Compact backfill around casing

3. Verify measurements carefully

Treatment

• Use cranes to reposition before concreting

8. Preventing Reinforcement Cage Flotation

Quality Problems

• Upward cage movement during concreting

Causes

1. Fast concrete placement near the cage bottom

2. Hanging on a rising pipe

Prevention

1. Slow placement near the cage

2. Center pipes properly

3. Anti-snag measures

Treatment

• Apply downward pressure if flotation begins

9. Avoiding Broken Piles in Underwater Concreting

Quality Problems

• Mud inclusion or discontinuous piles

Causes

1. Pipe blockages

2. Improper pipe positioning

3. Over-extraction

4. Leaking pipes

Prevention

1. Test pipes before use

2. Maintain proper embedment depth (2-4m)

3. Control concrete workability

4. Have backup equipment

Treatment

• Various unblocking techniques for clogged pipes

10. Ensuring Pile Head Quality

Quality Problems

• Premature cracking or irregular surfaces

Causes

1. Early demolition

2. Inadequate overpour

3. Mud contamination

Prevention

1. Allow proper curing (≥70% strength)

2. Overpour by ≥80cm

3. Demolish carefully

4. Prohibit blasting methods

Treatment

• Continue demolition until sound concrete is reached

11. Correcting Pile Center Deviation

Quality Problems

• Misaligned pile positions

Causes

1. Positioning errors

2. Improper casing

3. Cage misplacement

Prevention

1. Careful measurement verification

2. Proper casing installation

3. Accurate cage positioning

12. Ensuring Quality in Dug Pile Concreting

Quality Problems

• Segregation or low strength

Causes

1. Poor materials/mixing

2. Improper placement

3. Water presence

4. Nearby dewatering

Prevention

1. Use proper mixes

2. Employ tremie pipes

3. Control water conditions

4. Coordinate nearby work

Treatment

• Additional piles if the strength is inadequate

13. Preventing Waterlogged Foundations

Quality Problems

• Softened base from water

Causes

1. Rainfall

2. High water table

3. Insufficient dewatering

Prevention

1. Time excavation carefully

2. Perimeter drainage

3. Adequate pumping

4. Cutoff trenches

Treatment

• Replace softened material with granular fill

14. Stabilizing Foundations on Uneven Strata

Quality Problems

• Sliding or tilting foundations

Causes

1. Uneven bearing capacity

2. Hillside locations

3. Synclinal strata

Prevention

1. Create stepped foundations

2. Ground improvement

3. Full excavation

4. Rock anchoring

Treatment

• Grouting to strengthen weak zones

15. Mass Concrete Quality in Pile Caps

Quality Problems

• Surface or through cracks

Causes

1. Ground movement

2. Thermal stress

3. Plastic shrinkage

Prevention

1. Uniform foundation preparation

2. Thermal control measures

3. Proper curing

4. Construction joints, if needed

Treatment

• Crack injection or reinforcement

16. Quality Control for Pier Concreting

Quality Problems

• Honeycombing, poor finish

Causes

1. Improper materials

2. Segregation

3. Poor vibration

Prevention

1. Avoid slag cement

2. Control slump

3. Use tremie pipes

4. Proper vibration

Treatment

• Patch minor defects

17. Preventing Horizontal Cracks at Pier Tops

Quality Problems

• Cracking near the top

Causes

1. Low pressure

2. Over-vibration

Prevention

1. Secondary vibration

2. Remove top ties

3. Apply surcharge

Treatment

• Epoxy injection or reconstruction

18. Accurate Bearing Plate Installation

Quality Problems

• Misaligned plates

Causes

1. Measurement errors

2. Poor fixation

3. Voids underneath

Prevention

1. Careful positioning

2. Secure welding

3. Center hole technique

Treatment

• Reinstallation with proper anchoring

19. Addressing Local Collapse in Slipforming

Quality Problems

• Edge failures

Causes

1. Improper segmentation

2. Fast lifting

3. Uneven jacks

4. Poor vibration

Prevention

1. Proper segmentation

2. Controlled lifting

3. Jack synchronization

4. Thorough vibration

Treatment

• Patching or reconstruction

20. Correcting Template Deviation in Slipforming

Quality Problems

• Twisting/misalignment

Causes

1. Uneven jack speed

2. Uneven loading

3. Improper concreting

4. Wind effects

Prevention

1. Synchronized jacks

2. Balanced loads

3. Proper placement

Treatment

• Adjust jack speeds differentially

• Correct tilt before twist