Pile Design
In my experience, it’s worth taking the time to understand what you think is going to take place using drawings and documents, then watch it happen on site to see if you were right.
I recommend printing out/viewing digitally any relevant project drawings and specifications for a section of works before they start and ask yourself:
What am I expecting to see?
What are we trying to build?
In what order will things happen?
The key documents for Piling are listed below. These are usually drawn by the Structural Engineer and should be available on the online drawing platform used by most companies.
1. Piling General Arrangement Drawing
Example piling layout drawing
The Piling General Arrangement (GA) drawing shows the location of the piles and gives each a reference.
Roughly how many are there? About 40 in example below, how many can be done in a day?
Where are they in relation to the site boundary? Some are close, can the piling rig still get to these piles?
What number of piles are in clusters together on average? 3/4..
Are there any close to neighbouring properties? Check on site, are there any potential issues with neighbours?
2. Piling Schedule
Example piling schedule
A piling schedule accompanies the general arrangement drawing and includes information on the diameter of the piles and what loadings they have been designed to take.
They should include setting out and pile cut off levels which will be covered in the build sequence post.
Exactly how many piles are there?
What loadings are higher than others for each pile?
Do we have the co-ordinates so they can be set out?
What diameter are the piles?
3. Piling Specification: Defines what British Standards the design and installation should be in accordance with and any other relevant things to look out for.
Sometimes the Piling Specification is included as a section within the main Structural Specification.
What are the installation tolerances for the pile?
Is there any specific mention on hazards? Ground water?
What grade of concrete is to be used?
Other considerations
The ground conditions on your site dictate what length and diameter piles are required as each ground type can take different loading.
Structural Engineers and Piling Subcontractors will consider this but they will need a Site Investigation Report to tell them what ground is present on site.
The worse the ground, the longer and larger diameter the piles will need to be
It is common for the Piling Subcontractors to take the initial design intent drawings from the Structural engineers and produce final working drawings. This is known as a Contractor Design Proposal (CDP).
Subcontractors have expertise within their field and in some cases they can take the loadings given by the Structural Engineers and justify shorter or slimmer piles based on their experiences with the ground conditions. This proposal needs to be approved by the Structural Engineers before it can be implemented.
Bonus question: Can you visualise what reinforcement steel will look like by reading the pile cage fabrication drawings? What size are the bars? How many are there?
Definitions
Loadings – how much force from the weight of the building, anything designed to go in it and wind
Setting out – how the positions of the piles will be transferred from the drawings to the actual construction site
British Standards – UK guidelines ensuring quality, safety, and consistency in various industries including construction
Tolerance – acceptable differences from the planned measurements. An example of this is according to British Standards tolerance for piles vertically at any level is 1 in 100
Contractor Design Proposal (CDP) – to present the contractor’s ideas and plans for executing certain design elements or portions of the project.
Posts to Follow
We plan to go into more details about piling and add sections on:
- Piling Methods
- Logistics
- Temporary Works
- Build Sequence
- Health, Safety & Environment
- Quality
- Programme
- Commercial
Please let us know if you found this post useful using the chat function. We’d love to hear from you – is there anything in particular you’d like for us to focus on next?