LABOUR SUPPLY brochure - Flipbook - Page 34
Case studies: HS2, Mandeville Road
HS2 WORKS, MANDEVILLE
ROAD, MIDDLESEX
Sector Rail infrastructure
Client HS2 with SCS Railways as end-user / client
Location Mandeville Road, Greenford
Scope of works
JGL undertook the full delivery of two deep shafts
and associated subsurface structures, including
excavation, primary and secondary lining systems,
and structural concrete works.
The works also include construction of the
ventilation basement headhouse and associated
below-ground infrastructure.
Key elements
Shaft sinking: Sequential excavation of main and
satellite shafts using staged excavation dig and
spray method.
Primary lining (SCL): Application of sprayed
concrete lining to form initial ground support to
shaft including cross passages and maintenance
tunnels
Secondary lining: In-situ reinforced concrete
lining to achieve final structural and durability
requirements
Underground connections: Excavation and
formation of cross passage and maintenance adit
linking shaft structures
Permanent works: Construction of RC base
slabs, walls, intermediate slabs, and headhouse
superstructure
Waterproofing systems: Installation of fully
bonded and/or drained waterproofing membranes
to shafts and SCL tunnels
34
MEP interface integration: Coordination and
installation of cast-in items, penetrations, and
drainage infrastructure
Temporary works: Design and implementation of
shaft support systems, working platforms, lifting
arrangements, and access/egress solutions
Technical overview
Main shaft: 23m internal diameter, 38m depth
Satellite shaft: 14m internal diameter, 21.5m depth
Excavation methodology: Top-down sequential
excavation in London Clay with controlled face
advance and temporary support installation
Ground conditions: Predominantly stiff to very
stiff London Clay with low permeability, requiring
localised groundwater management
Primary support: Fibre-reinforced sprayed
concrete (SCL)
Secondary lining: Cast in-situ reinforced concrete
designed for long-term loading, durability, and
watertightness
Concrete volume: 21,000m³+ (including SCL and
in-situ structural concrete)
Excavation (arisings): 35,000m³+ removed under
controlled logistics
Reinforcement: 2,800+ tonnes
Waterproofing coverage: 5,800m² across shafts and
tunnel interfaces
Joseph Gallagher Limited | Specialist, technical workforce supply
