Innovation in Shaft Design & Construction

This category recognises projects that are driving use of innovative methods and smart technologies within the industry to improve design and construction of shafts for tunnelling schemes and other deep excavations.

FLI Precast Solutions
Thames Tideway Carnwath Road Shaft Mass Benching

FLI Precast Solutions were invited by BMBJV to design and manufacture precast elements for for proposed shaft mass benching works at the Thames Tideway Carnwath Road. This included: • The 3D modelling of the complex shapes required. • The engineering required to combat the vertical stresses and horizontal pressures during installation. • The fabrication of special moulds and transport and handling frames for the benching blocks which were up to 27t each.

Hewson Consulting Engineers
DfMA and Offsite Methods for Rapid Shaft Construction

Tideway, a £4.5bn initiative to modernise London’s sewer system, is a 25km ‘super sewer’ under the city and River Thames. The Carnwath Road shaft in Fulham, 25 meters in diameter and 42 meters deep, was initially used to launch a TBM and later to extract spoil. The shaft connects three tunnels and includes a mezzanine level for plant equipment. Hewson Consulting redesigned the upper shaft structure to accelerate the schedule and enhance safety by integrating temporary works into the permanent design. Utilizing precast concrete elements, Hewson eliminated the need for traditional falsework. Their approach shaved 6 months off the programme, reduced risks, and decreased carbon footprint, and was the first time encasement of multistorey structural steel transfer trusses in reinforced concrete has been used in a tunnel shaft. It showcases how offsite methods traditionally used on above-ground structures can drive cost and time savings when applied to below ground projects.

Mott MacDonald
Innovative solutions to improve buildability at Bromford tunnel intermediate shaft

The Bromford intermediate shaft on the HS2 Birmingham section is a 18.1m diameter 46m deep circular shaft innovative solutions were used to reduce the cost and speed up construction. these included the use of the observational method to inspect the bentonite filter cake on the d walls during excavation to reduce d wall lengths. the use of large transfer beams part way down the shaft to reduce programme duration and decoupling of the 3.2m thick base slab from the walls to improve buildability

Skanska Costain Strabag Joint Venture
Groundwater Management of the Greenpark Way Vent Shafts

Building deep ventilation shafts for the HS2 Greenpark Way project faced major hurdles due to high groundwater pressure and permeable ground. Traditional methods used in isolation wouldn't suffice. An innovative, multi-faceted approach addressed the issue. First, grouting techniques like fissure grouting and jet grouting significantly reduced dewatering demands. Second, a phased dewatering system with various well types (ejector, deep, wellpoint & passive relief) tackled water from different levels. Finally, a sealed steel can was developed for safe TBM reception, preventing water ingress during tunnel connection. The project's strength lies in its adaptability. Additional wells and grouting were implemented as challenges arose, allowing construction to proceed safely. This approach, with continuous monitoring and collaboration, successfully addressed the groundwater challenge and offers a valuable case study for future complex tunnelling projects.