riverside county - orange county

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Riverside County - Orange County MISRiverside County - Orange County MIS

Riverside County - Orange County


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Fifth level

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Riverside County - Orange County Riverside County - Orange County

Major Investment StudyMajor Investment Study

Tunneling Considerations in the Tunneling Considerations in the

Santa Ana MountainsSanta Ana Mountains

MIS Policy CommitteeMIS Policy Committee

April 29, 2005April 29, 2005

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Riverside County - Orange County MISRiverside County - Orange County MISRiverside County - Orange CountyClick to edit Master title style



Fifth level

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Design and Construction Challenges:Design and Construction Challenges:

• GroundwaterGroundwater

• Landfill sitesLandfill sites

• Active and non-active faultsActive and non-active faults

• VentilationVentilation

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Groundwater IssuesGroundwater Issues : :

• Groundwater levels affect surface ecologyGroundwater levels affect surface ecology

• Tunneling should not affect groundwater levelsTunneling should not affect groundwater levels

• Watertight linings required Watertight linings required

• Linings designed for water pressure plus ground Linings designed for water pressure plus ground loadsloads

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Watertight Lining Options:Watertight Lining Options:

• Cast in place, waterproof permanent Cast in place, waterproof permanent lininglining

• Segmented pre-cast concrete lining Segmented pre-cast concrete lining

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Drill & Blast Tunnel with Waterproof Permanent Lining

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TBM with Segmented, Pre-cast Concrete Lining

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Watertight Segmental Concrete Tunnel

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Groundwater Design Challenges: Groundwater Design Challenges:

• Groundwater pressures impact approach to Groundwater pressures impact approach to constructionconstruction

• Tunnel diameter of 46 feet limits allowable Tunnel diameter of 46 feet limits allowable groundwater pressure to a tunnel depth of 700 groundwater pressure to a tunnel depth of 700 feet below groundwater surface feet below groundwater surface

• Practical limit of 32 inches for segmental liner Practical limit of 32 inches for segmental liner thickness thickness

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Influence of Tunnel Diameter & Depth of Groundwater

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Challenges of Tunneling Challenges of Tunneling

Near Landfill SitesNear Landfill Sites• Face stability problems in tunnel excavationFace stability problems in tunnel excavation

• Potential of encountering contamination Potential of encountering contamination

• Potential damage to landfill liningPotential damage to landfill lining

• Long term durability and contamination risksLong term durability and contamination risks

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Active and Non-active Faults:Active and Non-active Faults:

• Non-active faults characterized by stability or Non-active faults characterized by stability or water ingress problemswater ingress problems

• Active faults characterized by potential for large Active faults characterized by potential for large movementsmovements

• Elsinore fault active, last movement in 1910Elsinore fault active, last movement in 1910

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VentilationVentilation Design Considerations:Design Considerations:

• Smoke control in case of fireSmoke control in case of fire

• Air quality within the tunnelAir quality within the tunnel

• Quality of air dischargedQuality of air discharged

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VentilationVentilation OptionsOptions

• Longitudinal (Nozzles, Central or Jet Fans)Longitudinal (Nozzles, Central or Jet Fans)

• Fully Transverse (supply and exhaust)Fully Transverse (supply and exhaust)

• Semi-Transverse (supply or exhaust)Semi-Transverse (supply or exhaust)

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Longitudinal VentilationLongitudinal Ventilation

Longitudinal Ventilation with Central Fans & Saccardo Nozzle

Longitudinal Ventilation with Jet Fans

Longitudinal Ventilation with Saccardo

Nozzle & Shaft

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Fully Transverse VentilationFully Transverse Ventilation

Fully Transverse Ventilation with Supply and Exhaust Fully Transverse Ventilation with Supply and Exhaust SystemsSystems

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Semi - Transverse VentilationSemi - Transverse Ventilation

Semi-Transverse Supply Ventilation SystemSemi-Transverse Supply Ventilation System

Semi-Transverse Exhaust Ventilation SystemSemi-Transverse Exhaust Ventilation System

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Possible Ventilation System for Deep Tunnel

Air supply

Air exhaust

Fresh air route

Vitiated air route

Exhaust duct Exhaust duct

Service tunnel & fresh air supply

Ø 44’ Ø 20’ Ø 44’

Jetfan

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Possible Ventilation System for Deep Possible Ventilation System for Deep

TunnelTunnel

Possible Ventilation Shaft Layout

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