Wongkaew – Seismic Design of Tunnels

Seismic Design of Tunnels

Mike Wongkaew, PhD, PE, SE Associate Vice President National Tunnel Practice Lead – NW

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

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

2 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

3 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)

4 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)

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: JSCE (2008)

Source: Iida et al (1996)

6 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 Structures

Determine Seismic Evaluate Ground Response Evaluate Underground Environment to Shaking Structure Response to Seismic Shaking

• Design Criteria • Ground Failure • Seismic design loading • Maximum Design • Liquefaction criteria Earthquake (MDE) • Slope instability • Loading criteria for • Operating Design • Fault displacement MDE Policy Earthquake (ODE) • Ground Shaking and • Loading criteria for • Seismic Hazard Deformation ODE Analysis • Longitudinal • Underground Structure • Deterministic SHA extension/compressi Response to Ground • Probabilistic SHA on Deformation • Ground Motion • Longitudinal bending • Free-Field Deformation Parameters • Racking / Ovaling Approach • Acceleration, Seismology velocity, • Soil-Structure displacement Interaction Approach Tunnel Structural Tunnel Engineering • Response spectra, • Special Seismic Design motion time history Issues • Spatial incoherence Geotechnical Earthquake Engineering of ground motion

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

Determine Seismic Evaluate. DesignGround Response return periods for recentEvaluate major Underground mass transit Environment to Shaking Structure Response to projects: Seismic Shaking MDE = 2,500 years (4% in 100 years) • Design Criteria • Ground Failure • Seismic design loading ODE = 150 years (50% in 100 years) • Maximum Design • Liquefaction criteria Earthquake (MDE) • Slope instability • Loading criteria for • Operating Design • Fault displacement MDE Policy Earthquake (ODE) • Ground Shaking and • Loading criteria for • Seismic Hazard Deformation ODE Analysis • Longitudinal • Underground Structure • Deterministic SHA extension/compressi Response to Ground • Probabilistic SHA on Deformation • Ground Motion • Longitudinal bending • Free-Field Deformation Parameters • Racking / Ovaling Approach • Acceleration, Seismology velocity, • Soil-Structure displacement Interaction Approach Tunnel Structural Tunnel Engineering • Response spectra, • Special Seismic Design motion time history Issues • Spatial incoherence Geotechnical Earthquake Engineering of ground motion

8 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

9 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)

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

Determine Seismic Evaluate Ground Response Evaluate Underground Environment to Shaking Structure Response to Seismic Shaking

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

Evaluate Ground Response Evaluate Underground to Shaking Structure Response to Seismic Shaking

• Ground Failure • Seismic design loading • Liquefaction criteria • Slope instability • Loading criteria for • Fault displacement MDE • Ground Shaking and • Loading criteria for Deformation ODE • Longitudinal • Underground Structure extension/compressi Response to Ground on Deformation • Longitudinal bending • Free-Field Deformation • Racking / Ovaling Approach • Soil-Structure Interaction Approach

Tunnel Structural Tunnel Engineering • Special Seismic Design Issues

Source: Kawashima Geotechnical Earthquake Engineering

12 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

13 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)

14 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)

15 12th Annual Breakthroughs in Tunneling Short Course – Seismic Design of Tunnels and Shafts – Mike Wongkaew, PhD, PE, SE Evaluate Underground Structure Response to Seismic Shaking

Determine Seismic Evaluate Ground Response Evaluate Underground Environment to Shaking Structure Response to Seismic Shaking

16 12th Annual Breakthroughs in Tunneling Short Course – Seismic Design of Tunnels and Shafts – Mike Wongkaew, PhD, PE, SE Underground Structure’s Response to Ground Deformation

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 Tunnel Structural Tunnel Engineering Issues

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

Source: Wang (1993)

18 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

19 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 Structures

Determine Seismic Evaluate Ground Response Evaluate Underground Environment to Shaking Structure Response to Seismic Shaking

20 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)

21 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)

22 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

23 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

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

-31. -29. -30. . 1.2” differential displacement -25. -24. -20. (top vs bottom of shaft) -18. -15. -12. -10. . Principal stresses in shaft -5. -6. 0. 0. walls (psi) well within concrete 5. 6. capacity 10. 12. 15. 18. 20. 24. 25. 30. 29. 31. Z Y X

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

Source: Wongkaew and Owyang, 2004

25 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

Source: Yang and Penrice (2014) Photo 1

26 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 Evaluate Underground Determine Seismic Evaluate Ground Structure Response Environment Response to Shaking to Seismic Shaking

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