1.8m — 25m
Shaft Diameter
WHAT WE OFFER
B&W offer the facility to construct pre-cast concrete segmental shafts from 1.8m to 25m in diameter, in a wide variety of ground conditions.
Shafts are installed by underpinning or caisson methods depending on the ground conditions and size of shaft. Where a segmental shaft isn’t required, B&W also install sheet piled pits and cofferdams giving clients a single point of contact for every shaft solution.
B&W CAPABILITY
Sheeted Pits & Frames
B&W delivers safe and efficient installation of sheeted pits with frames, using proven shoring systems to ensure ground stability and protect surrounding assets. The team ensures accurate frame installation to required levels and tolerances, with strong focus on safety, coordination, and programme efficiency.
TWO INSTALLATION METHODS
One technique rarely fits every scheme.
The ground decides the method. We assess the geology, groundwater and site constraints then select underpinning or caisson construction to deliver the shaft safely and on programme.
01
METHOD ONE
Underpinning
Excavation progresses in stages, with pre-cast concrete segmental rings installed and underpinned as material is removed beneath them. Suited to cohesive ground and tight urban sites where surface disturbance must be kept to a minimum.
Typical use
Cohesive / stable ground / stiff clay and rock
Diameter
1.8m — 25m
Footprint
Minimal surface impact
02
METHOD TWO
Caisson
The shaft structure is pre-built at surface level and sunk under its own weight or with jacking assistance as material is excavated from inside. Suited to running sands, high water tables and larger-diameter installations.
Typical use
Soft / water-bearing ground
Diameter
3m — 25m
Footprint
Pre-assembled at surface
BY THE NUMBERS
Shaft sinking specs
1.8m
MIN. DIAMETER
Smallest PCC segmental
25m
MAX. DIAMETER
Largest PCC segmental
2
METHODS
Underpinning & caisson
0.15m
CLEARANCE
From a 30m listed chimney
APPLICATIONS
Where B&W shafts are put to work.
A B&W shaft is rarely just a hole in the ground. Most double as launch and reception points for our own trenchless operations, so the shaft and the tunnel it serves are delivered by one coordinated team.
All Services01
Storage & Pumping Stations
Permanent structures for utility networks
02
Pipejacking Launch & Reception
In place of deep sheeted pits
03
TBM Launch Shafts
For tunnel boring machine drives
04
Micro Tunnelling Shafts
Launching remotely operated MTBMs
05
Guided Auger Boring Pits
For guided boring installations
06
Timber Headings Access
Entry shafts for traditional techniques
PLANT & EQUIPMENT
Specialist shaft sinking kit, owned, maintained, on the yard.
01
SPECIALIST JACKS
Hydraulic jacking systems sized for every shaft diameter.
02
ACCESS & LADDER BAYS
Certified vertical access systems for crews and inspection.
03
MAN RIDERS
Powered personnel hoists for safe descent on deep shafts.
04
GROUTING SYSTEMS
Annulus and contact grouting to seal the finished shaft.
05
VENTILATION PLANT
Forced ventilation maintained throughout excavation.
06
SHEET PILING & COFFERDAMS
Alternative shoring where a segmental shaft isn’t required.
NOTABLE INSTALLATION
8.5m
Deep
A shaft sunk 0.15m from a 30m listed chimney.
One such notable shaft was 8.5m deep, installed just 150mm from the foundations of a 30m-tall listed chimney. The structure required continuous 24/7 monitoring for movement throughout excavation a job that demanded the right method, the right plant and an experienced crew.
Depth
8.5m
Clearance
0.15m from foundations
Adjacent structure
30m listed chimney
Monitoring
24/7 movement survey
“From a 1.8m utility chamber to a 25m TBM launch the ground is different every time. The answer is always knowing which method to reach for.”
YOUR NEXT SHAFT
Tell us about the ground.
Send us your ground investigation and shaft requirements and we’ll come back with a method, a programme and the right plant for the scheme.
Or call direct
1.8m
25m
SHAFT DIAMETER RANGE