Tsunami Bore Uplift Effects on Coastal Structures

Computational Analysis and Experimental Comparison

Ben Anderson (University of Minnesota)Huiquing Yao (University of Hawaii)

Advisor: Dr. Ian Robertson (University of Hawaii)HARP REU Program

8/3/2011

Introduction Computational Models 2D vs. 3D Computational data comparison with

experimental data Conclusions and Recommendations

Overview

A blocked tsunami wave under a slab can caused a large uplift force –– piers, harbors, and building floor slabs

As a tsunami wave approaches the shore, it transform into a turbulent bore –– Turbulence model

Introduction

Potential gap designs

Example pier structure -- Ryan Takakura

The Samoa Tsunami on September 29, 2009

Failure of new ferry dock caused by 2009 Samoa tsunami (Robertson, et al, 2010)

Simulating tsunami waves with a dam break

In the Lab

Plan drawing of wave flume -- Ryan Takakura

Slab and wall setup --Ryan Takakura

Dam break swing gate

Dam break flume

http://www.youtube.com/watch?v=DIxqe1FSPbk-- “The Effects of Tsunamis on Coastal Structures”

Experimental Video

Back

Dimensions Mesh Size k-ε and k-ω SST 3D and 2D Comparison

Computer Modeling

Dimensions

5.7404m 6.286m

Total length : 12.02637mGap : 0m2D model extended to equate extra volume at the end of the flume

Mesh Size• Area surrounding the slab and tank

floor were designed with a smaller cell size

Back

k-ε◦ based on model transport equations for the

turbulence kinetic energy (k) and its dissipation rate (ε)

k-ω SST◦ based on model transport equations for the

turbulence kinetic energy (k) and the specific dissipation rate (ω)

◦ “Shear-stress transport” (SST) accounts for the transport of the turbulent shear stress

k-ε and k-ω SST Comparison

k-ε Side View

k-ω SST Half Speed

k-ω SST Side View

-incorporates standing water

k-ω SST has a more realistic bore and pressure results

Used k-ω SST for our simulations

The biggest issue with the two dimension model is the air that gets trapped under the slab

3D may give a more realistic representation of what actually happens

3D and 2D Comparison

3D Side View

2D Slab (k-ω SST)

3D Slab

3D View of Slab

Chose to use 2D model 2D has a faster computational speed

Software: OpenFoam Focused on the maximum uplift force (N) k-ω SST for all cases 2D Graphs: 0 cm gap

Comparing Experimental and Computer Models

Slab height : 14cmUpstream : 60cmDownstream: 5cm

Load cell measured net load Computational model only measured

integral of the uplift load on the slab

Computational and Experimental Measurement Differences

Slab height : 14cmUpstream : 60cmDownstream: 5cm

Slab height : 5cmUpstream : 60cmDownstream: 2.5cm

Slab height : 10cmUpstream : 45cmDownstream: 2.5cm

Slab height : 14cmUpstream : 45cmDownstream: 5cm

Slab height : 14cmUpstream : 45cmDownstream: 2.5cm

Slab height : 14cmUpstream : 60cmDownstream: 2.5cm

Recommend making mesh finer to eliminate variances due to mesh size

Extend fine mesh out in front of the slab Different cases use different mesh sizes Try more simulations in 3D

Conclusions and Recommendations

"This material is based upon work supported by the National Science Foundation under Grant No. 0852082. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation."

Christy Allison, Taylor Dizon, Deanna Quickle . “The Effects of Tsunamis on Coastal Structures” REU, University of Hawaii at Manoa, summer 2010

Ge, Ming. “Uplift Loading On Elevated Floor Slab Due To A Tsunami Bore.” Thesis for Master’s Degree, Dept of Civil Engineering, University of Hawaii at Manoa, December 2010

Robertson, Ian, et al. “Reconnaissance Following the September 29, 2009 Tsunami in Samoa.” Research Report, Dept of Civil Engineering, University of Hawaii at Manoa, January 20 2010

Takakura, Ryan. “Reducing Tsunami Bore Uplift Forces By Providing A Breakaway Panel.” Thesis for Master’s Degree, Dept of Civil Engineering, University of Hawaii at Manoa, December 2010

Works Cited

Any Questions?