seismic design of tunnels - tunneling short course

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Mike Wongkaew, PhD, PE, SEAssociate Vice PresidentNational Tunnel Practice Lead – NW

Seismic Design of Tunnels

Tuesday 9/10/2019, 3:30 p.m. – 4:15 p.m.

2 12th Annual Breakthroughs in Tunneling Short Course – Seismic Design of Tunnels and Shafts – Mike Wongkaew, PhD, PE, SE

Seismic Environment

Source: https://earthquake.usgs.gov/hazards/hazmaps/conterminous/index.php#2014

3 12th Annual Breakthroughs in Tunneling Short Course – Seismic Design of Tunnels and Shafts – Mike Wongkaew, PhD, PE, SE

Seismic Performance of Above Ground Structures - Inertia Effects

4 12th Annual Breakthroughs in Tunneling Short Course – Seismic Design of Tunnels and Shafts – Mike Wongkaew, PhD, PE, SE

Seismic Performance of Underground Structures

Source: Dean et al (2006), Power et al (1998)

5 12th Annual Breakthroughs in Tunneling Short Course – Seismic Design of Tunnels and Shafts – Mike Wongkaew, PhD, PE, SE

Seismic Effects on Underground Structures – Imposed Deformation

Source: Shamsabadi et al (2001) Source: JSCE (2008)

6 12th Annual Breakthroughs in Tunneling Short Course – Seismic Design of Tunnels and Shafts – Mike Wongkaew, PhD, PE, SE

Seismic Effects on Underground Structures – Imposed Deformation

Source: JSCE (2008)

Source: Iida et al (1996)

7 12th Annual Breakthroughs in Tunneling Short Course – Seismic Design of Tunnels and Shafts – Mike Wongkaew, PhD, PE, SE

Work Flow for Seismic Design of Underground StructuresDetermine Seismic Environment

• Design Criteria• Maximum Design

Earthquake (MDE)• Operating Design

Earthquake (ODE)• Seismic Hazard

Analysis• Deterministic SHA• Probabilistic SHA

• Ground Motion Parameters• Acceleration,

velocity, displacement

• Response spectra, motion time history

• Spatial incoherence of ground motion

Evaluate Ground Response to Shaking

• Ground Failure• Liquefaction• Slope instability• Fault displacement

• Ground Shaking and Deformation• Longitudinal

extension/compression

• Longitudinal bending• Racking / Ovaling

Evaluate Underground Structure Response to Seismic Shaking

• Seismic design loading criteria• Loading criteria for

MDE• Loading criteria for

ODE• Underground Structure

Response to Ground Deformation• Free-Field

Deformation Approach

• Soil-Structure Interaction Approach

• Special Seismic Design Issues

Polic

ySe

ism

olog

y

Geo

tech

nica

l Ear

thqu

ake

Engi

neer

ing

Tunn

el S

truct

ural

Eng

inee

ring

8 12th Annual Breakthroughs in Tunneling Short Course – Seismic Design of Tunnels and Shafts – Mike Wongkaew, PhD, PE, SE

Determine Seismic EnvironmentDetermine Seismic Environment

• Design Criteria• Maximum Design

Earthquake (MDE)• Operating Design

Earthquake (ODE)• Seismic Hazard

Analysis• Deterministic SHA• Probabilistic SHA

• Ground Motion Parameters• Acceleration,

velocity, displacement

• Response spectra, motion time history

• Spatial incoherence of ground motion

Evaluate Ground Response to Shaking

• Ground Failure• Liquefaction• Slope instability• Fault displacement

• Ground Shaking and Deformation• Longitudinal

extension/compression

• Longitudinal bending• Racking / Ovaling

Evaluate Underground Structure Response to Seismic Shaking

• Seismic design loading criteria• Loading criteria for

MDE• Loading criteria for

ODE• Underground Structure

Response to Ground Deformation• Free-Field

Deformation Approach

• Soil-Structure Interaction Approach

• Special Seismic Design Issues

Polic

ySe

ism

olog

y

Geo

tech

nica

l Ear

thqu

ake

Engi

neer

ing

Tunn

el S

truct

ural

Eng

inee

ring

Design return periods for recent major mass transit projects:

MDE = 2,500 years (4% in 100 years)ODE = 150 years (50% in 100 years)

9 12th Annual Breakthroughs in Tunneling Short Course – Seismic Design of Tunnels and Shafts – Mike Wongkaew, PhD, PE, SE

Determine Surface Ground Motion Parameters - Acceleration

Source: https://earthquake.usgs.gov/hazards/hazmaps/conterminous/index.php#2014

10 12th Annual Breakthroughs in Tunneling Short Course – Seismic Design of Tunnels and Shafts – Mike Wongkaew, PhD, PE, SE

Determine Surface Ground Motion Parameters – Velocity & Displ.

Source: FHWA-NHI-09-010 Road Tunnel Manual (2009)

11 12th Annual Breakthroughs in Tunneling Short Course – Seismic Design of Tunnels and Shafts – Mike Wongkaew, PhD, PE, SE

Evaluate Ground Response to ShakingDetermine Seismic Environment

• Design Criteria• Maximum Design

Earthquake (MDE)• Operating Design

Earthquake (ODE)• Seismic Hazard

Analysis• Deterministic SHA• Probabilistic SHA

• Ground Motion Parameters• Acceleration,

velocity, displacement

• Response spectra, motion time history

• Spatial incoherence of ground motion

Evaluate Ground Response to Shaking

• Ground Failure• Liquefaction• Slope instability• Fault displacement

• Ground Shaking and Deformation• Longitudinal

extension/compression

• Longitudinal bending• Racking / Ovaling

Evaluate Underground Structure Response to Seismic Shaking

• Seismic design loading criteria• Loading criteria for

MDE• Loading criteria for

ODE• Underground Structure

Response to Ground Deformation• Free-Field

Deformation Approach

• Soil-Structure Interaction Approach

• Special Seismic Design Issues

Polic

ySe

ism

olog

y

Geo

tech

nica

l Ear

thqu

ake

Engi

neer

ing

Tunn

el S

truct

ural

Eng

inee

ring

12 12th Annual Breakthroughs in Tunneling Short Course – Seismic Design of Tunnels and Shafts – Mike Wongkaew, PhD, PE, SE

Ground Shaking and Deformation – Seismic WavesEvaluate Ground Response to Shaking

• Ground Failure• Liquefaction• Slope instability• Fault displacement

• Ground Shaking and Deformation• Longitudinal

extension/compression

• Longitudinal bending• Racking / Ovaling

Evaluate Underground Structure Response to Seismic Shaking

• Seismic design loading criteria• Loading criteria for

MDE• Loading criteria for

ODE• Underground Structure

Response to Ground Deformation• Free-Field

Deformation Approach

• Soil-Structure Interaction Approach

• Special Seismic Design Issues

Geo

tech

nica

l Ear

thqu

ake

Engi

neer

ing

Tunn

el S

truct

ural

Eng

inee

ring

Source: Kawashima

13 12th Annual Breakthroughs in Tunneling Short Course – Seismic Design of Tunnels and Shafts – Mike Wongkaew, PhD, PE, SE

Directions of Seismic Wave Propagation – Design Implications

14 12th Annual Breakthroughs in Tunneling Short Course – Seismic Design of Tunnels and Shafts – Mike Wongkaew, PhD, PE, SE

Free-field Strains and Curvatures - Simplified Harmonic Waves

Source: Hashash et al (2001) and St John and Zahrah (1987)

15 12th Annual Breakthroughs in Tunneling Short Course – Seismic Design of Tunnels and Shafts – Mike Wongkaew, PhD, PE, SE

Site Response Analysis (e.g. SHAKE, Opensees, DeepSoil)

16 12th Annual Breakthroughs in Tunneling Short Course – Seismic Design of Tunnels and Shafts – Mike Wongkaew, PhD, PE, SE

Evaluate Underground Structure Response to Seismic ShakingDetermine Seismic Environment

• Design Criteria• Maximum Design

Earthquake (MDE)• Operating Design

Earthquake (ODE)• Seismic Hazard

Analysis• Deterministic SHA• Probabilistic SHA

• Ground Motion Parameters• Acceleration,

velocity, displacement

• Response spectra, motion time history

• Spatial incoherence of ground motion

Evaluate Ground Response to Shaking

• Ground Failure• Liquefaction• Slope instability• Fault displacement

• Ground Shaking and Deformation• Longitudinal

extension/compression

• Longitudinal bending• Racking / Ovaling

Evaluate Underground Structure Response to Seismic Shaking

• Seismic design loading criteria• Loading criteria for

MDE• Loading criteria for

ODE• Underground Structure

Response to Ground Deformation• Free-Field

Deformation Approach

• Soil-Structure Interaction Approach

• Special Seismic Design Issues

Polic

ySe

ism

olog

y

Geo

tech

nica

l Ear

thqu

ake

Engi

neer

ing

Tunn

el S

truct

ural

Eng

inee

ring

17 12th Annual Breakthroughs in Tunneling Short Course – Seismic Design of Tunnels and Shafts – Mike Wongkaew, PhD, PE, SE

Underground Structure’s Response to Ground DeformationEvaluate Underground Structure Response to Seismic Shaking

• Seismic design loading criteria• Loading criteria for

MDE• Loading criteria for

ODE• Underground Structure

Response to Ground Deformation• Free-Field

Deformation Approach

• Soil-Structure Interaction Approach

• Special Seismic Design IssuesTunn

el S

truct

ural

Eng

inee

ring

18 12th Annual Breakthroughs in Tunneling Short Course – Seismic Design of Tunnels and Shafts – Mike Wongkaew, PhD, PE, SE

Rectangular Section

Source: Wang (1993)

19 12th Annual Breakthroughs in Tunneling Short Course – Seismic Design of Tunnels and Shafts – Mike Wongkaew, PhD, PE, SE

Ratio of Underground Structure Deformation vs Free Field

Tunnel deformation could be up to 2.4x free field deformation

Dependent on stiffness ratio

Additional reference for circular and rectangular sections:− Penzien, 2000, Seismically

Induced Racking of Tunnel Linings

Closed form approximation for longitudinal (snaking) deformation

20 12th Annual Breakthroughs in Tunneling Short Course – Seismic Design of Tunnels and Shafts – Mike Wongkaew, PhD, PE, SE

Work Flow for Seismic Design of Underground StructuresDetermine Seismic Environment

• Design Criteria• Maximum Design

Earthquake (MDE)• Operating Design

Earthquake (ODE)• Seismic Hazard

Analysis• Deterministic SHA• Probabilistic SHA

• Ground Motion Parameters• Acceleration,

velocity, displacement

• Response spectra, motion time history

• Spatial incoherence of ground motion

Evaluate Ground Response to Shaking

• Ground Failure• Liquefaction• Slope instability• Fault displacement

• Ground Shaking and Deformation• Longitudinal

extension/compression

• Longitudinal bending• Racking / Ovaling

Evaluate Underground Structure Response to Seismic Shaking

• Seismic design loading criteria• Loading criteria for

MDE• Loading criteria for

ODE• Underground Structure

Response to Ground Deformation• Free-Field

Deformation Approach

• Soil-Structure Interaction Approach

• Special Seismic Design Issues

Polic

ySe

ism

olog

y

Geo

tech

nica

l Ear

thqu

ake

Engi

neer

ing

Tunn

el S

truct

ural

Eng

inee

ring

21 12th Annual Breakthroughs in Tunneling Short Course – Seismic Design of Tunnels and Shafts – Mike Wongkaew, PhD, PE, SE

Example #1 – Cut and Cover Subway Station (Los Angeles)

22 12th Annual Breakthroughs in Tunneling Short Course – Seismic Design of Tunnels and Shafts – Mike Wongkaew, PhD, PE, SE

Example #1 – Seismic Soil-Structure Interaction Analysis

Source: Tsai et al (2015)

23 12th Annual Breakthroughs in Tunneling Short Course – Seismic Design of Tunnels and Shafts – Mike Wongkaew, PhD, PE, SE

Example #2 – Pump Station (Portland, OR)

220 MGD pump station 135 ft dia. X 162 ft

deep Subsurface:

− Fill 25 ft− Alluvium 115 ft− Troutdale formation

185 ft− Mudstone

Avg. shear wave velocity = 550 ft/s

PGA = 0.34 g

24 12th Annual Breakthroughs in Tunneling Short Course – Seismic Design of Tunnels and Shafts – Mike Wongkaew, PhD, PE, SE

Example #2 – Seismic Soil Structure Interaction Analysis

FEA model Solid elements for

soils, 9x shaft diameter wide

Shell elements for shaft walls and slabs

Free field deformation applied to the side boundaries

25 12th Annual Breakthroughs in Tunneling Short Course – Seismic Design of Tunnels and Shafts – Mike Wongkaew, PhD, PE, SE

Example #2 – Seismic Soil Structure Interaction Analysis

1.2” differential displacement (top vs bottom of shaft)

Principal stresses in shaft walls (psi) well within concrete capacity

X

YZ

-29.

-25.

-20.

-15.

-10.

-5.

0.

5.

10.

15.

20.

25.

29.

-31.

-30.

-24.

-18.

-12.

-6.

0.

6.

12.

18.

24.

30.

31.

Use of simple 3D model helped us understand seismic performance (and reduce wall thickness & cost)

Source: Wongkaew and Owyang, 2004

26 12th Annual Breakthroughs in Tunneling Short Course – Seismic Design of Tunnels and Shafts – Mike Wongkaew, PhD, PE, SE

Example #3 – SEM Tunnel Adjacent to Building Basement (Wash.)

Soil-tunnel-building FEA model Free field displacement applied at left

and right boundaries Evaluated seismic deformation and

interaction of basement and tunnel

Photo 1Source: Yang and Penrice (2014)

27 12th Annual Breakthroughs in Tunneling Short Course – Seismic Design of Tunnels and Shafts – Mike Wongkaew, PhD, PE, SE

Key Takeaways

• “Ground Displacement Problem”

• NOT “Inertial Problem”

• Consider Soil-structure Interaction

• Design underground structures to accommodate displacement demand

Determine Seismic Environment

Evaluate Ground Response to Shaking

Evaluate Underground Structure Response to Seismic Shaking

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