Advantages and Disadvantages of Drilled Pier Foundations

Advantages

1. Pier of any length and size can be constructed at the site.
2. Construction equipment is normally mobile and construction can proceed rapidly.
3. Inspection of drilled holes is possible because of the larger diameter of the shafts.
4. Very large loads can be carried by a single drilled pier foundation thus eliminating the necessity of a pile cap (in case of a pile foundation).
5. The drilled pier is applicable to a wide variety of soil conditions.
6. Changes can be made in the design criteria during the progress of a job.
7. Ground vibration that is normally associated with driven piles is absent in case of drilled pier construction.
8. Bearing capacity can be increased by under-reaming the bottom (in non caving materials).

Disadvantages

1. Installation of drilled piers needs a skillful supervision and quality control.
2. The method is incommodious. Sufficient storage space is needed for all the equipments and materials used in the construction.
3. In case of driven pile, there is an added advantage of increased bearing capacity due to compaction in granular soil, which cannot be obtained by drilled pier construction.
4. Construction of drilled piers is very difficult at places where there is a heavy current of ground water flow due to artesian pressure.