When the bearing capacity of upper level soil is not enough to resist the load then pile foundation is designed. It is a deep foundation (See: Type of Foundations).
The basic function of pile is to transfer loads to hard layer of soil under ground.
On top of piles, pile-cap is constructed to spread the loads among piles. On a pile cap, there can be one or more columns.
Where a pile should be and distance among piles under a pile cap, all these things are considered and designed by structural engineer. As per pile location, a structural engineer designs the reinforcement of that pile cap. If a pile is misplaced the reinforcement of pile cap will lose its functionality. So, care should be taken during locating the piles.
Locating pile is easy. You just have to be cautious so that no pile is misplaced.
Process of locating piles on plot
In foundation layout of structural drawing, there will be grids on both directions. These grids are shown in the drawing like 1, 2, 3... and A, B, C... etc. Mark these grid points on each sides of plot as shown on drawing. Make these marks unmoveable.
When we completed marking grid-line points on plot now it is easy to locate the pile locations. In drawing you'll see every pile distance is shown either from grid line or from another pile.
- Now locate the pile on plot as shown on drawing. Put a steel peg on the centre of pile. Steel peg can be 10 mm or 12 mm diameter bar and 6 to 8 inch long.
- Fix the steel peg by pouring concrete around it. So that it can't be displaced.
- Do the same for rest of the piles.
Locating piles after construction is started
Under a pile cap, there can be many piles and one technical term we should always remember that within minimum 10 feet distance we shouldn't bore another pile in same day. But one or more pile can exist within 10 feet as designed. So after casting one pile we maintain minimum 10 feet distance for starting another piling work for the same day. That's why, there is a possibility of missing in-between pile/piles if you don't track properly.
How do we track piles during construction?We make a copy of pile-layout drawing.
Numbering all pile from 1st one to last one by 1, 2, 3... Like this if not numbered previously on drawing.
After casting one pile just mark the pile number on that drawing (see the image above). In this way we can easily find out which pile have been completed and which one not as well as how many piles have been completed at a glance.
If you follow this tactics no pile has been left uncompleted.
How do you track pile during construction? Please share...