Engineering & Innovation

Morgan Est has been responsible for all of the major innovations in the tunnelling industry in the last 15 years including:

• Lasershell^TM method of tunnelling
• Tunnelbeamer^TM
• Sprayed waterproof membrane
• Computerised shaft jacking system
• Use of a multi-mode TBM to construct the Airside Road Tunnel at Heathrow Terminal 5
• Largest Mixshield TBM used in UK
• Development of EPDM gasketted caisson shaft rings with integral bentonite injection system
• Tunnel lining with self cleansing profile
• Steel fibre reinforced tunnel linings
• Combishell^TM method of tunnelling
• Inverted Dome Base
• First UK use of Earth Pressure Balance TBM.

In 2004 Morgan Est was awarded the prestigious “Quality in Construction Award for Innovation” for the development of innovative techniques including the Lasershell^TM method of tunnelling. We were also highly commended in the “Research and Development (Plant and Equipment)” section.

 

The Lasershell™ method was developed in association with Beton- und Monierbau of Austria with the main purpose of eliminating the risk to tunnel workers in exposed ground situations. However, there are many other benefits to be derived from the system:

• Improved ring closure time to reduce settlement
• Inclined face to reduce settlement (demonstrated by numerical simulation and confirmed by monitoring)
• The use of high specification shotcrete in conjunction with the Tunnelbeamer™ system, which allows the removal of lattice girders and mesh thus eliminating the durability issues caused by shadowing
• Removal of lattice girders and mesh, providing safety benefits by reducing manual handling and the need for specialist plant
• Reduction in construction costs, both material and time related
• Reduction in construction time, further reducing settlement
• Total quality control on lining shape, thickness and position.
  

The method has been used very successfully on the Terminal 5 Project in the construction of cross passages, machine rooms, sumps and connecting tunnels.

 

Developed to facilitate the Lasershell™ technique, the patented Tunnelbeamer™ system is a laser based tunnel profile surveying package that allows real-time monitoring of excavation and shotcrete profiles.

 

The waterproofing of sprayed concrete tunnel linings has traditionally been carried out using sheet membrane followed by a cast in-situ secondary lining.  Whilst this method is acceptable for linear construction, installation of a sheet membrane system becomes difficult when dealing with complex geometrical shapes such as junctions.

Morgan Est has worked in close co-operation with the UK's leading waterproofing company, to develop an effective sprayable waterproofing system which can significantly improve productivity, particularly on complex geometry projects.

 

Morgan Est Tunnelling Division has developed experience on over 100 jacked wet and dry caisson shafts since pioneering the technique.  The largest diameter caisson sunk to date is 21m.  In order to guarantee full control over the shaft sinking process, a computer controlled jacking system has been developed.  Each jacking ram position includes an extensometer that is linked to a central control unit.  This enables the steering load at each ram to be selected automatically and records the applied loads.

 

To limit ground movements in sensitive urban environments, sophisticated Slurry and EPB TBMs are now commonly used. Both of these techniques can significantly alter the physical properties of the tunnel spoil making disposal or re-use difficult. In 1996, Morgan Est was awarded the contract for the construction of the Airside Road Tunnel (ART) at Heathrow Airport.

To ensure stability of the tunnel face under the airfield and to minimise difficulties conditioning the London Clay, a new TBM concept was developed.  The machine utilises compressed air face support with a novel piston displacement pump to maintain the seal.

The use of the MultiMode TBM was successful, with negligible disruption to surface structures (face loss limited to less than a measured 0.5%) and with minimal spoil conditioning required leading to lower spoil disposal costs.

 

Value Engineering of the client's design resulted in:

• Refinement of the geotechnical parameters (creep and in-situ stress) for the design of the lining.  This enabled the inverted arch lining to be redesigned over the majority of the tunnel to a flattened invert.  This led to a reduction in excavation volumes and therefore backfill concrete, resulting in a programme and cost benefit.

• Alternative waterproofing design (replacing crack control reinforcement and water bar with waterproof membrane over the vault of the tunnel over its entire length).  Removal of the reinforcement resulted in safer and faster construction of the secondary lining resulting in cost benefits.

• Installation of a permanent quality shotcrete primary lining, which was designed to work in combination with the secondary cast in-situ lining to accommodate the long term loads (this concept is referred to as concentric shell).  This allowed a thinner secondary lining leading to programme and cost benefits.

As a result of these changes the tunnel was finished five months ahead of schedule and delivered £10m of construction savings.

 

• Largest Mixshield TBM used in UK
• Development of EPDM gasketted caisson shaft rings with integral bentonite injection system
• Tunnel lining with self cleansing profile

 

First developed at the Bolton Water Street storage shaft following involvement of Morgan Est in value engineering of the client's earlier storage shaft design.  This resulted in significant savings and has since been used on other contracts at Folkestone, Dunstable and Hastings.

Bolton - Shaft re-design offering 30% saving on original design.

Use of dome base design to value engineer client's design at Folkestone, resulting in shallower diaphragm walls and a reduced slab design.

 

In 1994, on the Design and Construct project to build the Heathrow Baggage Transfer Systems project, Morgan Est (then Miller Tunnelling) designed and constructed the world's first steel fibre reinforced concrete tunnel linings. These resulted in an Ultra Thin High Strength Lining with significant reduction in damage during construction. The use of steel fibres has since become commonplace in tunnel lining design.

 

Developed for the Heathrow Baggage Transfer Systems project in 1994, the patented Combishell™ method of tunnelling is a composite sprayed concrete lining method that allows benefit to be taken from the primary lining when designing the secondary lining. Significant benefits have been demonstrated over more traditional SCL methods.

 

Morgan Est introduced the first EPB TBM to the UK on the Thames Water Ring Main leading to Thames Water completing the rest of the Ring Main tunnels using this technology, resulting in record producing productions for segmental tunnelling.