PIL/General/TBT-PIL-015

Contiguous Pile Wall Installation

Piling & Foundations › General › Contiguous Pile Wall Installation

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Contiguous pile walls are formed from closely spaced bored piles used to retain earth for basements and excavations.
Unlike secant walls, contiguous piles do not overlap — small gaps remain between adjacent piles.
The piling rig must be set up on a designed and approved piling platform with adequate bearing capacity.
Pile installation involves boring, reinforcement cage placement, and tremie concreting in sequence.
Spoil arisings from boring may be contaminated and must be assessed before disposal.
Reinforcement cages are heavy and require planned lifting operations with exclusion zones.
The work is often carried out close to existing structures, live services, and site boundaries.
Ground movement and vibration during piling can affect adjacent buildings and buried infrastructure.
BS EN 1536 and BS 8004 set the standards for bored pile design and construction in the UK.
A temporary works design is required for the piling platform, guide walls, and propping sequence.

Prevent collapse	Retaining walls must be correctly constructed to prevent ground collapse that could bury workers or damage structures.
Protect adjacent structures	Vibration and ground movement from piling can crack foundations and damage nearby buildings and services.
Legal duty	CDM 2015 requires temporary works to be designed, checked, and inspected by competent persons.

Don't

Ensure the piling platform is designed, constructed, and inspected before any rig setup
Verify all buried services are located and marked before boring any pile position
Establish and enforce exclusion zones around the piling rig during all operations
Use a planned lifting operation for placing reinforcement cages into the bore
Monitor adjacent structures for movement using pre-installed survey points
Check bore alignment and depth against the design at each pile position
Manage spoil arisings safely and test for contamination before disposal
Confirm concrete supply and tremie arrangements before starting each pile bore
Maintain communication between the rig operator, banksman, and site supervisor
Record as-built pile positions, depths, and concrete volumes for every pile installed

DON'T set up the piling rig on ground that has not been assessed for bearing capacity
DON'T enter the exclusion zone while the piling rig is operating or moving
DON'T leave open bore holes unguarded — they are a fall hazard to personnel
DON'T lift reinforcement cages without an approved lift plan and exclusion zone
DON'T ignore signs of ground movement or cracking on adjacent structures
DON'T bore near live services without hand-dug trial holes confirming their positions
DON'T pour concrete into a bore without verifying the cage is at the correct depth
DON'T allow spoil to accumulate around the rig where it obstructs safe access
DON'T carry out piling without the temporary works design approval in place
DON'T operate the rig near overhead power lines without a safe approach distance

See also: Piling Safety Awareness | Piling Platform Requirements

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