seismic behaviour of tunnels in urban areas - btsym 2017 conference

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BTSYM Conference 2017Seismic Behaviour of Tunnels in Urban AreasAndrea Leanza, COWI UK Ltd

BTSYoungMembers@BTSYM

Introduction Case histories Analysis methodsNumerical SimulationConclusion

Seismic behaviour of tunnels in urban areastable of contents10 March 20172


Seismic behaviour of tunnels in urban areasintroduction10 March 20173


Seismic behaviour of tunnels in urban areasintroduction10 March 20174

BTSYoungMembers@BTSYMRectangular StructureDaikay Metro Station (Japan, Kobe Earthquake 1995)Circular StructureBolu Tunnel (Turkey, Izmit Earthquake 1999)Soil InstabilityChi-Shue Tunnel (Taiwan, Chi-Chi Earthquake 1999) Introduction Case histories Analysis methodsNumerical SimulationResults and conclusions

Seismic behaviour of tunnels in urban areascase histories10 March 20175



Daikay subway station (Japan, Kobe earthquake 1995)(racking effect)


Daikay subway station (Japan, Kobe earthquake 1995)(racking effect)



Bolu tunnel (Turkey, Izmit earthquake 1999)(ovalling effect)




Chi-Shue tunnel (Taiwan, Chi-chi earthquake 1999)(soil instability)

Chi-Shue Tunnel before Chi-Chi Earthquake; Chi-Shue Tunnel after Chi-Chi Earthquake; Slope failure induced tunnel collapseSketch of damage pattern.

BTSYoungMembers@BTSYMForced-Based Method (Rectangular Structure)F-R method for rectangular structuresDisplacement-Based Method (Circular Structure)Simplified solutions - Free field approachSimplified solutions - Soil-Structure InteractionSimplified equivalent static analysisNumerical MethodDetailed equivalent static analysisFull dynamic time history analysis

Introduction Case historiesAnalysis methodsNumerical simulationResults and conclusions

Seismic behaviour of tunnels in urban areasanalysis methods10 March 201710

BTSYoungMembers@BTSYMFull dynamic time history analysisCity systemsMechanical propertiesSeismic inputModellingResultsGraphical OutputsHorizontal acceleration (time history)Vertical displacement (time history)Tunnel force (time history)Tunnel force around the perimeter (maximum envelope)Soil accelerationSoil displacement

Introduction Case historiesAnalysis methodsNumerical simulationConclusionsSeismic behaviour of tunnels in urban areasnumerical simulation10 March 201711

BTSYoungMembers@BTSYMCity systems

a) Free-field, b) tunnel, c) tunnel + 1 above ground structure, d) tunnel + 2 above ground structures Seismic behaviour of tunnels in urban areasnumerical simulation10 March 201712

BTSYoungMembers@BTSYMCity systems

a) Free-field, b) tunnel, c) tunnel + 1 above ground structure, d) tunnel + 2 above ground structures Seismic behaviour of tunnels in urban areasnumerical simulation10 March 201713

BTSYoungMembers@BTSYMMechanical properties

Seismic behaviour of tunnels in urban areasnumerical simulation10 March 201714

Soil Type CSoil Type BSoil Shear Wave Velocity Profiles

BTSYoungMembers@BTSYMSeismic input

a) Ricker Wavelet a(g)=0.1g, a=0.1x9.81=0.981m/sec2 b) Associated displacement response spectra



Modelling


Beam elements Plain strain elements Lumped masses

Structure AStructure BStructure A

a) Rectangular tunnel onlyb) Rectangular tunnel + 1 above ground structurec) Rectangular tunnel + 2 above ground structuresa)b)c)


a)

Modelling

Seismic behaviour of tunnels in urban areasnumerical simulation10 March 201717Static SupportsStructure AStructure BStructure Aa) Circular tunnel onlyb) Circular tunnel + 1 above ground structurec) Circular tunnel + 2 above ground structuresb)c)Dynamic Supports

Displacement constraints


Graphical output horizontal acceleration


Visco ElasticElasto Plastic

BTSYoungMembers@BTSYMGraphical output horizontal acceleration


Visco ElasticElasto Plastic


Horizontal acceleration (time history) check point "A"


TunnelTunnel + Structure ATunnel + Structure A & B


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Vertical displacement (time history) check point "B"


TunnelTunnel + Structure ATunnel + Structure A & B


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Tunnel force (time history) corner "A" - bending moment

Seismic behaviour of tunnels in urban areasnumerical simulation10 March 201722TunnelTunnel + Structure ATunnel + Structure A & B


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Tunnel force around the perimeter (maximum envelope) bending moment



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Tunnel force around the perimeter (maximum envelope) axial force"



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Tunnel force around the perimeter (maximum envelope) shear stress



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Tunnel force around the perimeter (maximum envelope) dynamic soil pressure



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Soil acceleration tunnel array



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Soil displacement tunnel array



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Introduction Case historiesAnalysis methodsNumerical simulationConclusionsSeismic behaviour of tunnels in urban areasconclusions10 March 201729


Simplified methods cannot take in consideration the presence of the above ground structures and the soil-structure interaction is neglected.The best performance is given by a Full Time History Numerical Analysis.The elastic analyses revealed an increase of the dynamic vertical displacements at the middles of the tunnels slabs, up to 120%. The introduction of the soil non-linearity reveals large increase of the permanent settlements.Aboveground structures caused a slight reduction of the acceleration at all check points. The differences were found to be smaller for the elasto-plastic analyses.Above ground structures can significantly affect the seismic behaviour of the tunnels with a general increase of the forces in the lining of 40-60%. For non-linear soil, residual values are reported.The presence of the above ground structures increase the soil pressure applied to the tunnel of about the 30%. For non-linear soil, residual values are reported.

Seismic behaviour of tunnels in urban areasconclusions10 March 201730


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Thank you for your attentionAndrea Leanza, Structural & Earthquake Engineer, Cowi UK Ltd



seismic behaviour of tunnels in urban areas - btsym 2017 conference

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