Promoters Tunnel

Presentation

Tim Smart

Head of Engineering & Operations

20th October 2014 1

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Tunnel Briefing Agenda

1. Why tunnel? 2. Operational aspects of tunnels 2.1 Safety requirements 2.2 Noise and vibration 2.3 Aerodynamics and porous portals 2.4 Vent shafts and smoke control 2.5 Energy requirements

3. Construction 3.1 Tunnelling techniques 3.2 Shaft construction 3.3 Settlement 3.4 Rate of tunnelling 3.5 Construction aspects 4. Costs implications 4.1 Costs of tunnelling 4.2 Land costs 4.3 Impact on programme

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Tunnels Location

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1. Why Tunnel? Terrain

• Chiltern Tunnel

• Long Itchington

Surface Disruption

Cost effective

• Euston

• Northolt

• Bromford

Connectivity

• South Heath

• Wendover

• Burton Green

• Greatworth

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Terrain Example: Chiltern Tunnel

Chalfont St Peter

Chalfont St Giles

Amersham

Little Missenden

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Terrain Example: Chiltern Tunnel

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Surface Disruption Example: Northolt Tunnel

OOC Station

Northolt

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Surface Disruption Example: Northolt Tunnel

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Connectivity Example: Burton Green Plan View

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Connectivity Example: Burton Green Plan View

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Tunnels Phase One

• 7.4km

• London Clay Euston

• 14km

• London Clay/Lambeth/Chalk Northolt

• 13.4km

• Chalk Chilterns

• 1.5km

• Penarth Group/Mercia Mudstone

Long Itchington Wood

• 2.8km

• Penarth Group/Mercia Mudstone

Bromford

• 1.1km

• Chalk South Heath

• 1.3km

• Chalk Wendover

• 2.1km

• Glacial Till/Oolite/Whitby Mudstone

Greatworth

• 2.5km

• Low Jurassic Marlstone/Mudstone

Chipping Warden

• 0.4km

• Penarth Group/Mercia Mudstone

Long Itchington Wood

• 0.5km

• Lower Carboniferous Mudstone

Burton Green

Twin Bored Tunnel Cut & Cover

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2. Operational Aspects of Tunnelling

2.1 Safety Arrangements

2.2 Noise and Vibration

2.3 Aerodynamics and Porous Portals

2.4 Vent Shafts and Smoke Control

2.5 Energy Requirements

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2.1 Minimum Safety Requirements (TSI)

Safe Area

• to the surface every 1 km or

• adjacent to independent tunnel tube every 500m

Fire Fighting Points - Applies to all tunnels over 1 km and rolling stock dependent

• Tunnel Length 1 to 5 km - portals with minimum standing area 550 sq m

• Tunnels Length over 5km - every 5km depending on rolling stock characteristics

Fire Fighting Point defined as

• Location inside or outside tunnel where fire fighting equipment can be used and passengers can evacuate

• Water supply capacity requires a minimum of 800 l/min for 2 hrs.

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Tunnel Cross Passage

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Emergency Train Evacuation

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Evacuation Walkway

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Tunnel Cross Passage Opening HS1

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Typical Cross passage Door

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2.2 Vibration

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1. Noise/ vibration of rail caused by train 2. Attenuation through trackform 3. Attenuation through tunnel and ground 4. Attenuation through building foundations 5. Attenuation through structure building 6. Possible amplification from resonance of

building structure

INDICATIVE

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Vibration mitigation via “booted sleeper” track

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Tunnel Operational Noise

HS2 vent shafts are designed, constructed, operated and maintained along with associated stationary equipment so that noise in the worst affected residential receptors, conforms to British Standard Guidance and achieves the aims of the Noise Policy Statement for England.

Mechanical equipment within the vent shaft is only operated under the following circumstances:

• During an emergency;

• During maintenance when required to maintain an acceptable air quality environment; and

• During tunnel congestion when required to maintain an acceptable air quality environment.

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2.3 Tunnel Aerodynamics

Tunnel aerodynamics are a function of the interaction of key infrastructure and rolling stock parameters such as:

• Diameter and roughness of tunnel • Length of tunnel • Provision of tunnel draught relief • Portal design • Train speed and length • Train aerodynamic profile

The primary controlling factors are the train speed and the “blockage ratio” (i.e. train area/tunnel area).

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Tunnel Aerodynamics

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Propagation of pressure wave

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Porous Portal Slide

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Porous Portal

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Porous Portal

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2.4 Vent Shafts

Primary Purpose • Smoke extract and control • Pressure relief • Access for emergency services • Passenger comfort to keep air quality and temperature

within acceptable limits

Secondary Uses • Tunnel boring machine maintenance intervention • Access for railway maintenance

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Vent Shafts along Bored Tunnels

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DOWN TUNNEL

UP TUNNEL

FANS

DAMPERS

DAMPERS

DAMPERS ARE NORMALLY CLOSED

FANS ARE FIXED PITCH, VARIABLE SPEED, REVERSIBLE

UP TUNNEL

Shaft Fans

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DOWN TUNNEL

UP TUNNEL

FANS

DAMPERS

DAMPERS

Shaft Fans

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DOWN TUNNEL

UP TUNNEL

FANS

DAMPERS

DAMPERS

Shaft Fans

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In Line Tunnel Fan

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Fans for portal arrangement via “Saccardo Nozzle”

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“Saccardo Nozzle” viewed from the tunnel

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2.5 Increased energy use in Tunnels

Traction power • Energy required for the traction power of the trains increases in tunnels. • In the open air 80% of the energy used by the train goes into overcoming air

resistance. This increases to 90% in a tunnel.

Increased power for Mechanical and Electrical plant and equipment • Increase in energy costs for the railway due to the plant necessary for safety

arrangements, for example: ― fans ― lifts ― fire mains ― emergency lighting plus tunnel integrity plant (e.g pumps, cooling

arrangements)

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3. Construction

3.1 Types of Tunnelling Techniques Applicable to HS2

Bored Tunnels

• Shield type machines with precast segmental tunnel lining.

• Used when surface access is very limited at depths typically below one tunnel diameter.

• Longer tunnel lengths where economical to use machine.

Cut & Cover Tunnels (“Green Tunnels”)

• Typically concrete box structures constructed in excavated ground.

• Used at shallower depths where there is good surface access.

Mined/Sprayed Concrete Lining Tunnels

• Mechanically excavated with sprayed concrete lining.

• Used in shorter drives or more complicated shapes, also in soft rock ground conditions.

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Bored Tunnels Earth Pressure Balance Tunnel Boring Machine (EPBM)

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Bored Tunnels HS1 EPBM in factory showing back up arrangements

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Bored Tunnels Cutter Head

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Bored Tunnels Slurry or “Hydroshield” Tunnel Boring Machine

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Precast Tunnel Lining Manufacture

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50m

100m

Size Length - 300m Width - 100m Scale Length - 3 football pitches Width - 2 foot ball pitches

100m

280m

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Bored Tunnels Tunnel Ring Segments

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Segment Yard & Drive Site Locations

Old Oak Common

M25

Northolt tunnel Harvil Road

Washwood Heath

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Mined tunnel

Excavator

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Sprayed Concrete Lining

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Cut & Cover “Green Tunnel”

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Construction of tunnels where all the ground above is cleared

Cut and Cover Cross Section

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Cut and Cover Construction Methodology 1

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Cut and Cover Construction Methodology 2

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HS1 Cut and Cover Under Construction

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HS1 Cut and Cover Completed

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Diaphragm Wall Construction

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Diaphragm Wall Construction

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Typical Plant for Cut & Cover Tunnel

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3.2 Shaft Construction

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Completed Shaft

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Shaft Construction

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Completed Shaft

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Shaft Construction

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Adit Construction

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3.3 Settlement

INDICATIVE 61

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Settlement Protective Measures • The primary form of settlement mitigation will be by good tunnelling

practice, including continuous working. Where required additional measures (e.g. grouting and structural solutions) will be carried out based on a three stage assessment as set out in Information Paper C3: Ground Settlement.

• Phase 1 Assessment: A preliminary assessment based on “green field” conditions will be undertaken. Where the predicted settlement is less than 10 mm or less than 1/500 slope, no further assessment is required.

• Phase 2 Assessment: In the case of predicted settlement of more than

10mm or 1/500 slope, an individual building assessment will be carried out. If the potential damage classification is Category 2 (slight) or below - no further assessment is required.

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Settlement Protective Measures • Phase 3 Assessment: Where predicted settlement indicates potential

damage classification of 3 (moderate) or higher, a detailed evaluation will be carried out with the aim to reduce the effects to acceptable levels. Where this is not possible further protective measures will be implemented.

• Settlement Deed. Properties within 30 metres of tunnels may apply for a Deed (as set out in information paper C3) to ensure that protective measures are implemented in accordance with the assessment criteria.

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3.4 Rate of Tunnelling

• The rate of tunnelling is important in minimising settlement. This is achieved by operating tunnel boring machines appropriately (such as using Earth Pressure Balance machines in “closed” mode).

• In order to keep settlement to acceptable limits, HS2 has specified a maximum of 1% volume loss for bored tunnels.

• Continuous 24 hour tunnelling also minimises settlement as it does not allow time for the ground to fully relax.

• Other methods of controlling settlement include grouting techniques, particularly compensation grouting.

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3.5 Construction Aspects

(1) Construction Sites

(2) 24 hours/ 7 days working

(3) Supporting logistics – including excavated material

(4) Noise and Vibration

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Construction Noise - Tunnel Drive Sites

• Tunnel drive sites generate similar noise levels to other large construction sites.

• Tunnelling activities and the associated local site material handling will be operated 24 hours a day.

• Noise mitigation is provided by the standard means such as hoarding, muffling, baffles and noise suppression on plant and equipment.

• Tunnel sites will be subject to the same HS2 procedures set out under the Code of Construction Practice and will be subject to Local Authority Approval under Section 61 of Code of Pollution Act 1974.

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Construction Noise - Tunnel Boring

• Sound and vibration from the tunnel boring machine will be perceptible inside properties for a few days either side of the TBM as it passes beneath them.

• The effects of ground‐borne sound and vibration

from the TBM on building occupants will be short‐term and hence they are not considered to be significant.

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4. Costs of Tunnelling Factors

• Tunnel Size • Ground Conditions (rate of progress) • Groundwater/aquifers • Material disposal methodology • Number of shafts • Cross Passages • Ground treatment • Settlement monitoring.

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Costs of Tunnelling

Fixed Costs • TBM typically £15 to £20m • Back up material handling similar costs order.

Linear Costs • Labour • Lining materials • Excavated material disposal

Incremental Cost dependent on • Surface arrangements for drive sites, reception sites, portal arrangements. • Increase in shafts, cross passages, shaft M&E systems. • Number of logistics vehicles

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Cost vs. Length

0 0 0

£

km

CO

ST

LENGTH

Shaft + M&E plant for vent & smoke control

INDICATIVE

Additional Shafts + M&E plant for vent & smoke control

Increase in cost per metre due to distance travelled by tunnel logistics requiring more spoil transport.

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Tim Smart

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