JGL Corporate brochure - Flipbook - Page 42
06.
Case studies, our projects
HS2 WORKS, MANDEVILLE ROAD
A major shaft and underground infrastructure package delivered as part of
the HS2 programme, comprising deep shaft sinking, sprayed concrete lined
(SCL) tunnelling, and reinforced concrete structural works.
Client:
Main contractor:
SCS Railways
HS2
Sector:
Rail infrastructure
Project duration:
2023-2026, 3+ years
Scope of works
Joseph Gallagher undertook the full delivery of two deep
shafts and associated subsurface structures, including
excavation, primary and secondary lining systems, and
structural concrete works.
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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
The works also include construction of the ventilation
basement headhouse and associated below-ground
infrastructure.
Technical overview
»
Main shaft: 23m internal diameter, 38m depth
»
Satellite shaft: 14m internal diameter, 21.5m depth
Key elements
»
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
»
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
»
Primary support: Fibre-reinforced sprayed concrete (SCL)
»
»
Underground connections: Excavation and formation of
cross passage and maintenance adit linking shaft structures
Secondary lining: Cast in-situ reinforced concrete designed
for long-term loading, durability, and watertightness
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»
Permanent works: Construction of RC base slabs, walls,
intermediate slabs, and headhouse superstructure
Concrete volume: 21,000m³+ (including SCL and in-situ
structural concrete)
»
»
Waterproofing systems: Installation of fully bonded and/or
drained waterproofing membranes to shafts and SCL tunnels
Excavation (arisings): 35,000m³+ removed under controlled
logistics
»
Reinforcement: 2,800+ tonnes
»
Waterproofing coverage: 5,800m² across shafts and tunnel
interfaces
Joseph Gallagher Group | CORPORATE PORTFOLIO | 2026
