Building structures, over some time, may have to deal with issues like wall crack development, out-of-level door and window frames, uneven floors, etc. In many cases, this is due to building foundation settlements. It is not uncommon for newly built homes to develop some minor, superficial cracks. Cracks of greater size or number, on the other hand, may indicate below-grade issues with the degree of soil compactness, voids, or the presence of water-related subsoil compromises supporting the building.
The net effect of such factors can result in “building sag” or “grade beam tilt”. Below-grade component devices may be introduced to rectify these problems or, at the very least, prevent the process from getting any worse. One example of this is foundational support piles.
Piling is the process of drilling foundations through the ground to provide more structural strength to the weak soil underneath. Piling prepares the existing ground to carry heavy loads, such as a new home or office complex. If the upper soil layers are too weak or highly compressible to support the loads transmitted by the superstructure, piles are used to transfer these loads into a stronger layer of soil or onto a bedrock. They are typically drilled deep enough to settle within these stronger layers or upon a load-transferring base like bedrock. In other cases, they are “screwed” into the soil and develop sufficient resisting torque or are driven “pushed” into the soil and develop frictional resistance. To ensure the stability and security of any building structure, pile caps/support plates, are then affixed to the top of each pile and connected to the appropriate, existing foundational support such as the grade beam.
Three common examples of these are concrete piling, helical screw piles, and steel pier piles (shown in the drawing below):
When to Use Pile Foundation?
- When you find that the groundwater table is quite high.
- When heavy or non-uniform loads from the building above are employed.
- When it is not feasible to use other types of foundation due to cost or incompatibility.
- When the soil at a shallow depth is too compressible.
- When there is a possibility of a washout due to a riverbed or seashore nearby.
- The presence of a canal or deep drainage system near the structure.
- When poor soil conditions make it impossible to excavate the desired depth.
- When it is impossible to keep the foundation trenches dry due to water seepage.
Advantages of Foundation Piles
- They can be pre-casted according to specifications.
- Can be formed into a variety of shapes and sizes for more efficient use.
- Clean, neat performance requiring minimal supervision and low storage space.
- Fit for spaces where drilling of holes is not an option.
- Able to utilize underground water tables.
A fully coordinated effort from geotechnical and structural engineers and geologists should be the procedure of choice to ensure that the result of the pile foundation analysis is properly integrated into the overall foundation design. This coordination extends through plans and specifications, preconstruction meetings, and construction.
