Tunnel Boring MachinesIMIA WGP 60

Michael Spencer, Zurich London (Chairman) Alessandro Stolfa Generali Heiko Wannick Munich ReRonan Gallagher Allianz John Forder Willis Beat Guggisberg Allianz Eric Bentz SCOR Steve Cross Zurich Chris Blueckert Zurich

Presented by Michael SpencerIMIA Conference, Istanbul 29th Sep. 2009

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History

1825Sir Marc Isambard BrunelTunnelling ShieldRotherhithe Tunnel5 floods in all

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Early Soft Soil Tunnels

Early Soft Soil TunnelsLondon Underground late 19th Century

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Hard Rock Machines

Henri-Joseph Maus ‘Mountain Slicer ‘ 1845 failedWilson Patented Stone Cutting Machine 1853 failedJames Robbins 1950 first successful machine used in Shale and worked 10 times faster than conventional methods

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Soft Rock Machine

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Hard Rock Machine

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Hard Rock Machine

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Largest Machines To Date

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Trailing Equipment

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Start of the Art

Maximum diameters Slurry Machine 15.43 M EPB 15.2 MMaximum Water Head above 4.5 bars (45m head of water)

Marmaray 8 barsHallandsas 8 bars

Maximum Speeds Closed Mode 0-8cm/min

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Operational Parameters

Speed of the ShieldTorque of the cutter headThrust of the jacksPumping flows in a slurry machineViscosity of excavated soil in an EPBQuantity of soil excavatedChanges in the chracteristics of the soil granularity/ viscosity colour

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Loss Exposures

TBM Fabrication and delivery to siteTBM Assembly at siteExcavation of the tunnelDisassembly and reshipment

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Manufacture / Fabrication

Manufacturing and delivery time up to 12 months new less for refurbished machinesMain perils fire flood cat natTransport marine, air , land is it covered in the Car policy ?Land routes to some site especially hydro projects are often difficultSuppliers extensions

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Assembly and Testing At site

Up to 3 months, storage much longer in case of delaysLifting and lowering into positionFlooding fire and theftLandslide and collapse of ground around the machinesFaulty workmanship skilled technicians (preferably from the suppliers especially during testing)OFTA Onsite first Time AssemblySupplier Gurarantee for 50 or 100m

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TBM Before excavation

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Excavation Works

FloodFire and ExplosionTunnel CollapseUnexpected ground conditionsWrong MachineInexperience of the operatorMachinery BreakdownBreakthrough

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Loss Prevention

Mechanical and electricalBreakdownHydraulic OilsMaterials non toxic and flammableContact surfaces sharp edges and hot surfacesRupturing of pipes and hosesSafe access to the cutter headHandling of heavy loadsPumping equipmentControl systems

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TBM Launch and Arrival

Launch normally into a diaphragm wall or secant bored pile wall

Sealing Ring gasket system (lip seals) and soil/rock sealing block (jet grouting or lean concrete secant bored piles)

Arrival the most critical as the whole tunnel can be flooded

Flying launch steel structure and a hydraulic unit with hollow piston jacks faster and safety advantages

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Launch and Arrival

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TBM Affect of Third Party exposures

Damage Category Severity Typical Damage

0 Negligible Hairline Cracks

1 Very Slight Fine Cracks 1mm

2 Slight Cracks to 5mm

3 Moderate Cracks 5-15mm

4 Severe Cracks 15-25mm

5 Very severe Major repairs

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TBM Prediction of Settlement

For TBMs zone of influence is centred along the centreline of the tunnel = depth of the invert below ground level on either side of the centreline Damage caused by rotation, angular strain, relative deflection, tilt , horizontal strain extent depends on the condition of the existing buildings and structures

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Insurance recommendations

Period Of Cover Check whether cover is required only on site or for storage transport and fabricationExcavation cover Check equipment is adequately protected against fire. Are there adequate safety measures in place taking into account the ground conditions? Ancillary covers: Is cover for abandonment and recovery expenses included? What is the cover for consumables?Is cover required for machinery breakdown? What is the basis of indemnity?

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Losses

1987 Tooting BecOpen face boring machines compressed air

Inundation requiring ground freezing to repair

1990 Great belt LinkFlood to closed face machine left open for maintenance to the face 2 machines underwater

Fire to one machine at the end of the drive

Socatop fire aboard a service train for the TBM

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Socatop

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Great Belt Link

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Machinery Breakdown

Main losses are to

Main bearingMotorBreakerGripper and Pad

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Conclusion

The TBM has revolutionised the construction industryDevelopments in new machines may present challengesTBMs are varied and must match the conditions in which they need to workCommercial considerations may affect the risk levels an underwriter may faceThere is a lack of information about lossesCloser cooperation between tunnelling machine suppliers contractors and the insurance industry The very nature of these machines and the conditions in which they work means these should only be underwritten by specialist underwriters