Pier Foundation

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The Pier Foundation is preferred in a location where the top level consists of the decomposed rock overlying strata of sound rocks.

The difference between a cast-in-situ pile and a pier is arbitrary, a cast-in-situ pile exceeding 0.6 m in diameter which is commonly referred to as a pier.

Pile foundations transfer loads through friction and bearing and pier foundation transfer loads only through bearing.

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Typically, the pier foundation is deeper than the pile foundation.

pier foundation

Introduction to pier foundation:

A pile is a vertical column of a relatively large cross-section than the pile, which is installed in a dry area by digging a large diameter cylindrical hole to the desired depth and then backfilling from the concrete.

In some situation, it becomes difficult to move the bearing pile through the decomposed rock.

In the case of rigid clays, which offer large resistance to the driving of a bearing pile, the pier foundation can be easily built.

Types of pier foundation:

Masonry or concrete pier:

When a good bearing stratum exits upto 5 m below ground level, brick masonry or concrete foundation piers may be used in excavated pits.

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The size and spacing of the pier is dependent on the depth of the hard bed, the nature of the soil dependent and the super-imposed load.

The concrete pier is made up of concrete, it is precast as well as cast in situ pie.

Precast concrete pier are manufactured in a factor then driven into the ground at the place required.

The precast concrete pier generally reinforces with steel wires generally 30 cm to 50 cm in cross-section and up to 20 m in length.

A cast steel shoe is provided at the bottom of the pier.

Drilling caisson:

Drilled caisson are foundation holes or sub pier and interchangeably used to represent a cylindrical foundation.

An axial load at the top and a drilled caisson is large compressed member subject to reaction at the bottom.

Drilled caissons are usually drilled with mechanical means, it can be of three types as follows:

  • Concrete caisson with increased bottom.
  • Steel pipe with concrete filled in pipe.
  • Cassion with concrete and steel core in steel pipe.

Advantages of Pier Foundation:

  1. This method is easy and requires a small amount of material and labor.
  2. The necessary material is easily available here.
  3. It has a wide range of design variations.
  4. We can also use different materials here to enhance the beauty and it remains in our budget.
  5. The Pier Foundation saves money and time because it does not require extensive excavation and much concrete.
  6. This causes minimal disruption to the soil environment.
  7. A shovel can be used for excavation, existing roots and soil organisms remain mostly undivided.
  8. The space between the house and the ground is sufficient to install utilities such as plumbing and electrical wiring between them.
  9. Workers can easily find the space between the house and the ground to solve issues related to plumbing and electrical as there is enough space to crawl.
  10. It is comfortable for walking on the floor, which does not rest on a solid surface and it is good for those who have stiffness and back pain.
  11. Inspection is possible because the diameter of the shaft is large.
  12. Ground vibration that is normally associated with driven piles is absent in the case of drilled pier construction.
  13. Bearing capacity can be increased by under-reaming the bottom (in non-caching material).

Disadvantages Pier Foundations:

  1. The installation of drilled piers requires careful supervision and quality control of all materials used in construction.
  2. The method is bulky so adequate storage space is required for all materials used in construction.
  3. The construction of piers, where there is a heavy flow of groundwater flow due to the pressure of the artesian is very difficult.

RELATED ARTICLES:

PILE FOUNDATION | CAISSON FOUNDATION | PIER AND BEAM FOUNDATION

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Conclusion:

The Pier Foundation is preferred at a location where the top layer consists of the decomposed rock leveling.

In such a situation, it becomes difficult to move the bearing pile through the decomposed rock.

In the case of rigid clays, which offer large resistance to the driving of a bearing pile, the pier foundation can be easily built.

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