The 2011Tsunami Damage on Coastal Facilities and Countermeasures (both hard and soft) for Future Tsunamis

Transcription

1 NOSTcongress "Innovations for Global Waterchallenges" on May the 14th 2014 The 2011Tsunami Damage on Coastal Facilities and Countermeasures (both hard and soft) for Future Tsunamis Taro Arikawa Principal Researcher Port and Airport Research Institute, Japan

2 Contents Tohoku earthquake Tsunami in 2011 Tsunami characteristics and Damage of Coastal structures Future Tsunami Countermeasures How to protect and how to estimate of damage Possibility of movable breakwaters New hardware countermeasures For Evacuation

3 Tsunami characteristics and Damage of Coastal structures TOHOKU EARTHQUAKE TSUNAMI IN 2011

4 Tsunami around Japan North American plate Eurasian plate 1611 Keichou Sanriku 1854 Toukai, Nankai 1896 Meiji Sanriku 1933 Showa Sanriku 1944 Tounankai 1946 Nankai 1960 Chile 1983 Japan Sea 1993 Okushiri 2011 Tohoku Tohoku Sanriku Pacific plate Ria coast V-shape bay Philippine plate

5 Historical Earthquakes 地震調査委員会の図に加筆 Meiji Sanriku 1896/06/15 20:00 pm M8.2~8.5 (tsunami Eq.) Showa Sanriku 1933/03/03 M8.1 2:30am Keicho Sanriku 1611 Chilean Tsunami 1960/05/24

6 Ground displacement 5.3m Eastward 1.2m subsidence

7 GPS Wave guage 4.0m 青森東岸沖 6.3m 1m 岩手北部沖 岩手中部沖 6.7m 岩手南部沖 5.7m 宮城北部沖 5.8m 宮城中部沖 福島県沖 2.6 m 最大波の高さ 時刻 ( 時 ) 7

8 Disturibution of trace of tsunami height by the 2011 Tohoku earthquake tsunami joint survey group

9 All data plotted with the past events The 2011 Tohoku Earthquake Tsunami Joint Survey Group data as of Apr 30, 2011

10 Damage of Otsuchi Taken by resident

11 Destruction due to Tsunami (Shuto,1992) Tsunami Height (m) Wave Profile mild slope steep slope Wooden Houses Stone Houses Safe Steel, Concrete Buildings Community near shore rise in shallow like tide with fast speed Partially Destruction Safe(~5m) Inundation depth Like wall in offshore, 2nd wave breaking like tide with fast speed Destruction(2m~) Partially Almost same profile as 2m, Possibility of breaking is increasing at toe of tsunami Damage ratio 50% Plunging breaker Destruction(7m~) Destruction Damage ratio 100%

12 Type 1 Overflow Flooding Velocity is Low. IF the Height of Tsunami is same, then breaking is the maximum. Type 2 Bore Flooding Velocity is higher than the overflow. That is supercritical flow. Type 3 Breaking Very close to the coastline Flooding Velocity is high with the Impulsive load. Large

13 Impulsive Bore Pressure Pressure (kn/m 2 ) Type 3 Breaking Type 2 Bore Type 1 Overflow Maximum Sustainable Pressure Time (s)

14 Plan 平面図 View Unit (m) 単位 ( m) Cross Section 断面図 1:10 斜面勾配 1:10 slope or 1/10 1:30 or 1:50 勾配 12m 3. 0 Wave Paddle 造波板 In the Flume 184m

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16 Tsunami Height in front of the wall is 2.0m

17 Concrete wall Thickness=60mm

18 Kamaishi Port Kamaishi Tsunami Breakwater Harbor Side Sea Side Hirata Suga Mouth of Port Izumi Tsunami Breakwaters

19 Failure of Breakwater at North Part TOHOKU REGIONAL BUREAU MINISTRY OF LAND, INFRASTRUCTURE AND TRANSPORT Outside of Port Inside of Port

20 From video by public people 15:18 (1 st positive wave, 32 minutes after) 15:28( negative tsunami started, 42 minutes after)

21 Experimental Video under overflow tsunami 21

22 Study of failure mode based on overflow scouring (example of Port of Hachinohe) Sea side Harbor side Scouring Depth 5 to 10m Harbor Side Sea side Model Scale 1/25 Video 5 times

23 How to protect against huge tsunamis How to estimate the damage due to huge tsunamis FUTURE TSUNAMI COUNTERMEASURES

24 New Earthquake Model(Nankai Trough) the Disaster Management Council of the Cabinet Office, 2012

25 Design policy of physical countermeasures It is necessary to estimate two levels of tsunamis, and develop measures to mitigate damage for both of them. Tsunami Level High-frequency tsunami (Tsunami Prevention Level) (L1) Largest class tsunami (Tsunami Reduction Level) (L2) Definition Tsunamis that occur frequently and cause extensive damage even though they are not high The largest class of tsunami, which occurs at an extremely low frequency, but which causes enormous damage when it does Planning or design To prevent the protected lowland from being flooded, it plans and it designs. Continued mitigation through physical countermeasures It plans and it designs so that it is made easily not to destroy and to collapse, and damage should not expand though the flood of the protected lowland is permitted. That means resilient structures Disaster mitigation by evacuation

26 Effect of breakwater (Tomita et. al, 2012) Water surface elevation (m) Without Breakwater Arrival time 6 minutes delay (tsunami height of 4 m) with breakwater without Tsunami height 13.7 m 8.0 m With Breakwater Tsunami height (m) Time after earthquake (min) 26

27 Resilient structure (for hardware) The Image of resiliency Caisson Armor block Erosion protection mat Armor rock Rubble mound

28 Relationship of Tsunami External Force Damage with Damage Hard Countermeasure No Hard Countermeasure Hard Countermeasure + resiliency Tsunami Level for design of protective structures Tsunami Level (Return Period) Tsunami Level for planning of evacuation

29 Resilient city against Tsunami "hardware" (disaster prevention facilities, etc.) and "software" (disaster prevention training, etc.) measures Largest class tsunami Image of Coastal Area High-frequency tsunami Buildings as Residential tower, hotel and so on Seawall Breakwater Office building as Evacuation tower multiple protective structure

30 How to estimate the damage due to large tsunamis In order to evaluate the damage due to giant tsunamis, influence of destruction of structures, debris, etc. is required. The power of the tsunami is greatly different depending on the place and the condition 3 dimensional numerical simulator should be required to analyze overflow, scour, flood into buildings and so on. The system which connects tsunami propagation simulator and 3-D numerical simulator should be developed.

31 The STOC-CADMAS system Quasi-3D model (multi-level model) Assumes hydrostatic pressures at each level Computation load: light STOC-ML 3D model Estimates the free water surface with the VOF method Computation load: heavy CADMAS-SURF/3D Tsunami source STOC system (Tomita et. al., 2005) CADMAS system (Arikawa et. al., 2005) STOC-IC Coupled with DEM 3D model Calculates the free water surface with a vertically integrated continuity equation Computation load: moderate

32 Layer Domain for STOC-IC Domain for CADMAS-SURF

33 STOC-ML

34 Tsunami source: Takagawa, Tomita(2012) CADMAS-SURF/3D

35 Comparison of wave profile measured by GPS Buoy (Tsunami Source: Central Disaster Prevention Council (2011)

36 Comparison of Maximum Inundation height (Tsunami Source: Central Disaster Prevention Council (2011) measured

37 Calculated Wave Force This building was washed away by tsunami Building specification: width 7.1m, depth 5.3m, height 13.8m Assuming that weight of the Building per unit area : 12kN/m2 Weight in the air:2019 kn Weight in the water:1177 kn(14/24) From the video analysis, this building withstood against Tsunami under at least 7 to 8 meter tsunami height It indicates that this building was washed away when the tsunami height became maximum. t(s)

38 New hardware countermeasures POSSIBILITY OF MOVABLE BREAKWATERS

39 Protection of harbour against tsunami/storm At ordinary: Installation of breakwater below seabed for free navigation Tsunami Storm At tsunami/storm: Raising breakwater to protect harbour Shipway Harbour Marina Container Terminal Ferry Terminal Fishing Port 39

40 Flap-gate Breakwaters (Japanese Type) Flap Type Tsunami/Surge Barrier Hitachizosen Corporation Toyo Construction Co., Ltd. Penta-Ocean Construction Co., Ltd - The flap type tsunami barrier lies down on the bottom of sea usually. - When tsunamis or storm surges occur, it rises up above the sea surface with its buoyancy and seals entrances of ports or channels, and then It stands up utilizing water elevation of outside. - The lying gate has buoyancy in normal circumstance, and mooring systems keep it lying position. Offshore side Onshore side Offshore side Onshore side 2. Standing 1. Rising 3. Falling Operation room Mooring Systems Stoppers against backrush Gates Tension rods Substructure

41 Buoyancy-Driven Vertical Piling System New type breakwater against tsunami and storm Double piles set below seabed Raising upper pile by air in case of tsunami or storm Upper steel pile Lower steel pile Before raising Raising Completion of raising Air Deadweight>Buoyancy Air Deadweight<Buoyancy Deadweight< Buoyancy 41

42 Structural configuration of breakwater Sea side Port side Exhaust valve Inner air Sea bed Overlapped part Upper pile (movable) To compression tank Rubble Stabiliser Air inlet pipe Lower pile 42

43 Wakayama-shimotsu port

44 Protect effectiveness at Wakayama- Shimotsu Port in Japan

45 Wakayama- Shimotsu Port

46 Case Studies Vertical Pile Breakwaters Earthquake Model: Tokai/ To-Nankai/ Nankai Earthquake

47 Maximum Tsunami height Comparison Not installed Installed Opening Rate10%

48 FOR EVACUATION

49 Mortality in Different Municipalities Maximum Onagawa Natori Rikuzentakada Minamisankriku Otsuchi Kamaishi Higashimatsushma Kesennuma Sendai Ofunao Minumum Yono Fudai

50 For Safety

51 Inundation depth 50cm Inundation height is about 50cm, Inundation speed is about 4.0m/s

52 Probability of falling or sliding sliding Probability of falling or sliding 確率 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Inundation depth 浸水深 (m) Men 転倒等確率 ( 男性 ) Women For falling only (men) 転倒等確率 ( 女性 ) 転倒率 ( 男性 ) falling Tsunami Warning in Japan * Tsunami Height is 50cm

53 Thank you for your attention!