Usually bored pile is used for those tall buildings or massive industrial complexes, which require foundations that can bear the load of thousands of tons, most probably in unstable or difficult soil conditions. The method of drilling bored pile is different from RC Square pile or spun pile, which is using driving method, the piling machine to be used will be different too. Bored piling works required specialist bored piling contractor to follow up instead of hiring general piling contractor. There is a simple step-by-step method on how to drill the bored pile in the construction site.
What is a Bored Pile
Bored pile is another type of reinforced concrete pile, which is used to support high building producing heavy vertical loads. Bored pile is a cast-in-place concrete pile where the bored piles have to be cast on the construction site, while other concrete piles like Spun Pile and Reinforced Concrete Square Pile are precast concrete piles. Bored piling is cast by using bored piling machine which has specially designed drilling tools, buckets and grabs, it’s used to remove the soil and rock. Normally, it can be drilling into 50 metres depth of soil. The advantage of bored piling is becuse the drilling method produces little vibration and lower noise level.
The drilling method is depending on the soil condition, so the piling contractor has to do soil investigation and decide which drilling technology has to be carried on. Piling contractor decide the correct drilling technology and minimize disturbance of the surrounding soil. For cohesion-less soils such as sands, gravels, silts, etc., whether it’s under the water table or not, the pile bore hole must be supported using steel casing or stabilizing mud such as bentonite suspension. After these, reinforcement bar will be put into the bore hole and concrete will be poured into the bore hole.
Bored Pile Advantages
The main advantages of bored piles over conventional footings or other types of piles are:
- Piles of variable lengths can be extended through soft compressible or swelling soils, into suitable bearing material.
- Piles can be extended to depths below frost penetration, and seasonal moisture variation.
- Large excavations and subsequent backfill are eliminated.
- Adjacent soil is not disturbed or remolded.
- Absence of vibration will not disturb adjacent piles or structures.
- Extremely high capacity caissons can be obtained by expanding the base of the shaft up to three times the shaft diameter, thus eliminating construction of caps over multiple pile groups.
- For many design situations bored piles offer higher capacities with potentially better economics than driven piles.
Bored piling is popular to be used in construction as a foundation, especially for bridge work and tall buildings as well. Bored piling work has to be done by specialist bored piling contractor, normal piling contractor cannot execute these type of work without experience and knowledge about bored piles.