Detailed Design of Tsunami Shelter

Takahiro Kukidome1, Shogo Otake 2, Tsutomu Takane3, Takeshi Utsunomiya4 and Shuji Onami5

1Engineer, Oriental Consultants Co., Ltd, 3-12-1 Honmachi, Shibuya-ku, Tokyo 151-0071 Japan 2Deputy General Manager, Oriental Consultants Co., Ltd, 3-12-1 Honmachi, Shibuya-ku, Tokyo 151-0071 Japan 3Deputy General Manager, Oriental Consultants Co., Ltd, 3-2-18 Nakanoshima, Kita-ku, Osaka 530-0005 Japan 4Assistant Manager, Oriental Consultants Co., Ltd, 3-12-1 Honmachi, Shibuya-ku, Tokyo 151-0071 Japan 5Manager, Oriental Consultants Co., Ltd, 3-12-1 Honmachi, Shibuya-ku, Tokyo 151-0071 Japan

ABSTRACT:Detailed design of the tsunami evacuation shelter constructed in Muroto City, Kochi Prefecture was developed. Tsunami evacuation shelters are facilities that are unique in the world. The design process, therefore, started with the clarification of the functions needed for an evacuation facility (Kukidome et al. 2013), followed by the basic plan for the shelter, the design of the main body of the shelter, and the design of incidental equipment and facilities. The basic plan for the shelter determined the location, shape, and size of the shelter from the state of existing refuges in the project area, the positions of the houses of refugees, and the parameters of expected tsunami. The design of the main body included the structural design paying attention to the safety, waterproof performance, and construction efficiency of the facility. Incidental equipment and facilities and the buildings for facilities were designed paying attention to refuge environment and evacuation activities.

1. INTRODUCTION

The 2011 off the Pacific coast of Tohoku Earthquake produced a tsunami of colossal proportion that greatly exceeded expectations, causing tremendous damage in the Tohoku region of Japan. Various measures to ensure quick and safe evacuation of people from tsunami have long been implemented in the coastal areas of the country, such as the provision of evacuation routes to embankments, construction of tsunami

evacuation towers, and arrangements to use existing buildings as refuges (Cabinet Office 2005). The 2011 earthquake triggered reinforcement of these efforts and acceleration of the measures for tsunami evacuation.

Kochi Prefecture has been developing the refuges for emergency temporary evacuation to protect people’s lives from the tsunamis expected to reach the coasts of the prefecture, and based on the estimation of tsunami height announced by the national government on March 31, 2012, it has been working for the practical implementation of tsunami evacuation shelters as a new type of refuges that are effective against larger and faster-traveling tsunamis, in addition to the improvement of existing refuges. This report describes the plan and design of the tsunami evacuation shelter (FIG. 1) being constructed at Tsuro District, Sakihama-cho, Muroto City.

FIG. 1. Tsunami Evacuation Shelter Project Outline

2. TSUNAMI EVACUATION SHELTER PROJECT OUTLINE

The project site is located in a terrain with a continuous steep cliff behind built-up residential areas along the coastline, and the arrival of a tsunami at the site is expected to be quick. Conventional measures are not effective in this situation. It was therefore decided to construct a tsunami evacuation shelter in the form of a tunnel in the cliff among the types of tsunami evacuation shelters selected in the examination of general structure (Kukidome et al. 2013). The tsunami evacuation shelter has a structure shown in FIG. 2 and is composed of the following facilities:

1. Shelter main body, 2. Shaft for outside communication, 3. Collision prevention pillars, 4. Incidental facilities (waterproof doors, lighting, ventilation, power supply

facilities) 5. Buildings and facilities (building over shaft, interior, exterior, etc.) The main body of the shelter and the shaft for outside communication were

designed considering earthquake resistance and waterproofing performance. Collision prevention pillars were designed as a protection against debris strikes.

Buildings and facilities were designed to facilitate the guiding of refugees including senior citizens and wounded persons. As construction work would be performed in a cliff, attention was given to working in small work yards and minimization of environmental impacts on nearby residences.

FIG. 2. Tsunami Evacuation Shelter General View

3. BASIC PLAN FOR THE SHELTER

Of the existing tsunami refuges in the project area, Refuges 6 and 7 were considered ineffective because the passages to the refuges were narrow and fragile and the elevations were low. A tsunami evacuation shelter was therefore designed as a complement to these refuges. Considering present land use, the shelter’s entrance was planned in the position marked in FIG. 3, where open space was available. The capacity of the shelter was determined by identifying the area within the coverage of the shelter using the formula shown below incorporating the estimation based on past cases (Kochi Prefecture 2013) and the expected time to tsunami inundation (Kochi Prefecture 2012). The area to the south excluded from the coverage of Refuge 8 (201.6 m) was also added to this area. The capacities was determined as the number of inhabitants in the houses in this area with some surpluses.

D16 @300

D19 @250

Outer Vertical Bar

Outer Horizontal BarD19 @250Inner Horizontal Bar

D16 @257Inner Vertical Bar

φ2500

425

425

(3) Shaft

(2) Circumferential members of main tunnel

(1) Objects of consideration

1900

2170

1121

5192

400 3000 400

Entrance of tsunami evacuation shelter

About 165 m from community hall

About 200 m from Refuge 8

Coverage of tsunami evacuation shelter

About 165 m from community hallEarth-quake

Shock Prepare to evacuate Evacuate

Evacuation destination

① Time needed before evacuation ② Time for evacuation

(A)Time to completion of evacuation(B)Expected time of arrival of tsunami

FIG. 4. Locations of Existing Refuges and Shelter Entrance

FIG. 3. Time to Tsunami Arrival and the Time Needed for Evacuation

h

Tsunami height

Range of seismic design in crosswise direction of main tunnel

(near the entrance)

Main tunnel: 32.5m

Heavily weathered rock: 580m/s

Weathered rock: Vs=730～1130m/s

Filled soil layer: Vs=150m/s

Colluvium layer: Vs=150m/s

C

Shaft23.4m

Waterproof wall

3h

B A

C B A

Evacuation distance = Walking speed × (Predicted time to inundation ‒ Time needed before evacuation‒ Time for closing the doors of shelter (30 sec)) ‒ Distance between shelter and existing road (20 m) = 0.56 m/s × (16 min – 10 min – 0.5 min) – 20 m = 0.56 m/s × 330 s – 20 m = 184.8 m – 20 m ≒165 m

The capacity of the tsunami evacuation shelter was set at 70 persons, based on the 56 persons living in the coverage of the shelter and an allowance for the refugees from outside of the are a and the evacuation of the users of the national highway.

4. DESIGN OF SHELTER MAIN BODY

4.1. Design of the Shape of Main BodyBecause the tunnel is constructed in the sandstone rock mass categorized as soft

stone, it was decided to construct the shelter main body using a mountain tunneling method. The inside space height was set at 2.0 m, in accordance with the construction height limit for road tunnels specified for maintenance purposes. The inside space width was set at 3.0 m, considering the working space for construction machines and cost performance. The depth was determined considering the required space for evacuees (1 m2/person) and the space for toilet and washstand. The shape of the main body was designed to have a horseshoe-shaped cross-section with vertical side walls enveloping the above dimensions (FIG. 2), and pipes, cables, and lighting fixtures were planned to be installed using the surplus space above the necessary inside space height.

Considering the convenience of refugees, the cross-sectional slope in the main body was specified to be level without any gutters or notches. A longitudinal slope of 0.5% (descending toward the mouth of tunnel) was provided so that the water used for cleaning would flow down to the entrance. A drain pit was installed utilizing the space under the floor between the waterproof walls as a measure against the unexpected inundation when the waterproof doors are shut during a tsunami.

4.2. Design of TimberingBecause the shelter is a tunnel with a small cross-section in the sandstone rock mass

categorized as soft stone with the earth covering thickness from several meters to about 20 m, the part near the mouth to the point with the protective cover of 1.5D = 6.0 m (D: digging diameter 4.0 m) was designed as DIII (FIG. 5), and the part beyond this point was designed as DII. Because deposition of colluvia and heavily weathered sandstone occur in the near the mouth, long steel pipe fore-piling (all ground fasten method ) was employed for the purpose of ensuring the stability of the crown.

4.3. Design of LiningBecause the structure is a tsunami evacuation shelter, the lining on the main body

was designed as a waterproof structure. Because it is difficult to estimate the drop of ground water level during a tsunami, the structure was designed to withstand the water

pressure from the tsunami height of 1.91 m plus the run-up height of 5.81 m (three times the tsunami height) as shown in FIG. 6. The two waterproof walls on which the waterproof doors are attached near the mouth was designed to have the same 400 mm thickness as the lining, based on the analysis using the two-dimensional finite element method considering wave pressure.

4.4. Design of Waterproofing WorkA tsunami evacuation shelter must have a high reliability in terms of waterproofing.

It is therefore decided to cover the outside of the main frame with waterproof sheets. Thick chemical adhesive sheets (t = 2.0 mm) adhering to the surface of the lining were used so that any damage to the sheets may not result in water intrusion or leakage. Thick long-fiber unwoven fabric (t = 5.0 mm) was used as the back cushioning material to prevent sheet damage during installation of the lining.

4.5. Design of PortalThe portal was designed as a wall-type portal on the cliff face in the direction

perpendicular to the propagation of tsunami. The back of the portal was covered with 90-cm thick sand as a protective blanket against falling rocks, and was further lined with concrete (t = 200 mm) considering the erosion by tsunami.

4.6. Construction Plan and Temporary Work PlanBecause the area around the project site was densely built up with houses,

construction was conducted using machine excavation generating low vibration and noise. Considering the maneuverability in a small cross-section and the treatment of locally occurring hard stone, a 0.8-t class breaker was used as the percussion boring machine. Considering the narrow and long space and other site restrictions, construction was conducted using a wheel loader (2.3 m3 class) for mucking, a concrete mobile and a small gun for spraying, and a hydraulic crawler drill (150 kg class) for rock bolt installation.

FIG. 5. Pattern of Timberwork in Tunnel

Fig. 6. Concept of Structural Design of Tunnel

t=100

Lining Concrete

Sprayed Concrete

1500

400 100

2170

753

400

100 Invert Concrete

Leveling Concrete

t=100

R1=1500

(σck=18N/mm2)

t=400(RC Structure

(σck=18N/mm2)

400100

2000

R2=2600

R3=50

0

400

100

SL

3423

5423

28°26'13"

Rock Bolt L=2000Deformed Bar, Proof Stress

Wire Mesh

φ5×150×150

330 670

1000

500

Wire Mesh

L=10466120°

=1350

3@450

φ114.3×6.0×9500Long Steel Pipe Forepiling

1000

(24-15-25 C=270kg/m3)

t=400(RC Structure)(24-8-25)

117.7 kN or More

5. SHAFT FOR OUTSIDE COMMUNICATION

5.1. Position of the ShaftThe slope of the shelter site was steep as shown in FIG. 7, and had many boulders

and multiple tiers of rockfall safety fences. A field inspection of the boulders and the existing rockfall protection fences up to the top of the slope and the survey of past slope failures were therefore conducted. Based on the information obtained, the location of the shaft was determined to be behind the second-tire rockfall protection fence, considering the safety of the tunnel mouth, the movement of materials and construction machines, and the availability of land for the work yard.

5.2. Structural DesignBecause work was to be performed in the small work yard on the slope, timbering was achieved using liner plates (FIG. 8). The liner plates were those with

reinforcement ring structures to deal with unsymmetrical earth pressure resulting from the front-to-back inclination of the slope. The lining (FIG. 8) was designed assuming that water pressure would act on it through the liner plates. For waterproofing, the outside of the lining was treated with waterproof sheets and cushioning materials similarly to the shelter main body.

5.3. Rockfall Protection of the ShaftAs the slope behind the shaft was scattered with many boulders, there was a

concern that the rocks falling during an earthquake might damage the electricity room and the shaft. Large rocks exceeding a certain size were split, and a combination of a passive protection fence at the mid-slope height and a rockfall protection net near the shaft was designed.

5.4. Construction Plan for the ShaftAs for the excavation of the shaft, the Monorack carrying soil had a carrying

capacity of only 2 t, and the use of blasting might trigger rockfall. It was therefore decided to perform hand-tool excavation assisted by simple construction machines. Mucking was planned to be hoisted by a motor winch (0.5 t capacity) and dropped via a chute onto the temporary muck pile in the work yard.

Final Location Selected

Candidate Shaft

φ2500φ3500

425

425

Waterproof Sheet

Lining Concretet=425(σck=24N/mm2)

Sprayed Concretet=50(σck=18N/mm2)

Liner Plate

FIG. 7. Candidate Shaft Locations FIG. 8. Cross-Section of the Shaft

6. SEISMIC DESIGN

6.1. Design ConditionsFrom the standpoint of ensuring waterproofing during evacuation, target

performance and limit levels were defined for earthquake resistance and waterproofing performance (Table 1, Table 2). Because the shelter main body must have particularly high waterproofing performance, the response of rebar during a level 2 earthquake was specified to remain within the elastic ranges. It was also specified that the area near the tunnel mouth must not have structural joints, which could be susceptible to water leakage. As for the shaft, the response of rebar to the bending in the longitudinal direction, which could cause through cracks in the walls, was specified to remain within the elastic range.

The design earthquake considered in the design were level 1 and level 2 earthquake ground motions. The definition is shown in Table 3, and the input earthquake ground motions are shown in FIG. 9 to FIG. 11.

Table 2. Response Limit Levels (Level 2 Earthquake)

Table 1. Target Performance of Tsunami Evacuation Shelter

Table 3. Definition of Design Earthquake

Earthquake Definition of design earthquake

Level 1Bedrock waveform in the model based on the focus of Ansei NankaiEarthquake, as defined in damage prediction for Kochi Prefecture (KochiPrefecture 2002)

Level 2Type I

Bedrock waveform in the earthquake focus model examined in "ModelStudy of Very Large Earthquake in Nankai Trough" (Cabinet Office 2012)

Level 2Type II

Bedrock waveform based on Type II seismic motion defined forunderground structures using the waves observed during the 1995Southern Hyogo Prefecture Earthquake (Metropolitan Expressway 2008),adjusted with the regional correction factor of 0.85 given in Specificationsfor Highway Bridges (Japan Road Association 2012b).

Earthquakeresistance

Design earthquake (estimated Nankai earthquake (anearthquake corresponding to "Seismic Intensity Distributionfrom a Very Large Earthquake in Nankai Trough, March31, 2012, Cabinet Office, Government of Japan") or anearthquake occurring directly beneath the area) does notcause cracks or other damage leading to inundation.

Watertightness

Water tightness is guaranteed against the water pressurefrom expected tsunami (Announcement for KochiPrefecture No. 2, Tsunami Inundation Prediction for a VeryLarge Earthquake in Nankai Trough, December 2012).

(1) Level 1 (2) Level 2 Verificationmembers

Verificationitems

Limit level Verificationmembers

Verificationitems

Limit level

Bending Yield curvature x 1.15 safety factor Bending No more than yield curvatureShear No more than permissible shear stress Shear No more than shear strengthCompressivestress intensity

No more than compressive strength of concrete Bendingcompressive

No more than compressive strength of concrete

Tensile stressintensity

No more than tensile strength of concrete Bending tensile No more than yield strength of rebar

Bendingcompressive

No more than permissible compressive stress ofconcrete

Bendingcompressive

No more than compressive strength of concrete

Bending tensile No more than tensile strength of concrete Bending tensile No more than tensile strength of concreteBending No more than cracking moment Bending No more than yield curvatureShear No more than permissible shear stress Shear No more than shear strengthOpening Use of joint appropriate for opening Opening Use of joint appropriate for openingShift Use of joint appropriate for shift Shift Use of joint appropriate for shiftShear No more than shear yield strength of dowel bars Shear No more than shear yield strength of dowel barsBendingcompressive

No more than permissible compressive stress ofconcrete

Bending No more than ductile capacity

Bending tensile No more than permissible tensile stress of rebar Shear No more than shear strength

Shear No more than permissible shear stress

Main frame

Waterproofwall

Crosswiseof theshelter

Crosswiseof theshelter

Main frame

Waterproofwall

Lengthwiseof theshelter andshaft

Main frame

Structuraljoint

Lengthwiseof theshelter andshaft

Main frame

Structuraljoint

* Permissible compressive stress intensity and permissible shear stress intensity areaccording to Specifications for Highway Bridges IV (Japan Road Association 2012a).

Crosswiseof the shaft Main frame

Crosswiseof the shaft

Main frame

* Ductility capacity and shear strength are according to Specifications for Highway BridgesV (Japan Road Association 2012b).

FIG. 9. L1: Asperity I FIG. 11. L2TIIFIG. 10. L2 TI: East Side Case

6.2. Design Method and Results(1) Seismic Design of Shelter Main Body in Cross-Sectional Direction

Seismic design in cross-sectional direction was developed for the area near the mouth of the main body tunnel containing loose ground (FIG. 1). Three cross-sections were considered: Cross-Sections A-A and B-B with different ground conditions in the area near the mouth and Cross-Section C-C, where the main frame is totally located in the bedrock (FIG. 1). Because all these cross-sections were situated in unprepared ground, the ground and the shelter were modeled using two-dimensional nonlinear FEM (FIG. 12), and design was developed based on dynamic analysis.

The objects of verification were the circumferential members of the main frame and waterproof walls. Because the shear capacity was exceeded in some members in response to level 2 earthquake ground motion when only concrete was used, shear reinforcement bars were added. (2) Seismic Design of Main Body Tunnel and Shaft in Longitudinal Direction

Seismic design in the longitudinal direction was developed focusing on the points where ground rigidity changes near the mouths of the shelter main body and the shaft, as well as the points where the structure changes in the shelter main body and the shaft. Seismic analysis was performed using a frame model for the entire structural system (FIG. 13) in the time-history response analysis with the seismic deformation method, considering the seismic motions along the axis of the shelter main body and the in the direction perpendicular to the axis.

Based on the results of seismic analysis, structural joints were added at the position where ground rigidity changes in the shaft and the position where it is connected to the shelter main body, and the waterproofing rubber according to the response displacement was installed. In addition, dowel bars were used in the structural joints in the upper part of the shaft, where large shear displacement was expected.

The steel diameter in the main frame was increased, because the shear capacity was exceeded in some members near the mouth of the main body and the crown of the shaft. (3) Seismic Design of Shaft in Cross-Sectional Direction

The seismic design of the shaft in cross-sectional direction was verified for the main frame. FIG. 14 shows the analytical model. The working load was defined as the maximum reaction force of the soil spring obtained from the analysis in the longitudinal

FIG. 12. Seismic Design Model for Main Body in Cross-Sectional Direction

(B-B Cross-Section)

(2) With Waterproof Wall

Horizontal roller

Horizontal roller Circumferential members of main frame: non-linear beam needed

(1) Without Waterproof Wall

Viscous boundary

Waterproofing wall: shell element

Viscous boundary

Ground: plane strain element

Circumferential members of main frame: non-linear beam needed

Horizontal roller

Horizontal roller

Ground: plane strain element

FIG. 13. Seismic Design Model for Main Body and Shaft in

Longitudinal Direction

Soil springMain body tunnel

Rigid area

Shaft

Structural joint (joint material only)

Structural joint (with dowel bars)

longitudinal direction, and this load was applied statically on the main frame. Based on the results of seismic analysis, steel diameter was increased and shear reinforcement bars were added in the part with loose layers (colluvial layers) near the crown of the shaft (FIG. 15).

7. COLLISION PREVENTION PILLARS

7.1. Design of Dimensions and ShapeCollision prevention pillars were designed for the purpose of protecting the shelter

main body and doors from the collision of drifting houses and other objects. The shape and dimensions were determined so that they would not reduce the visibility of the shelter entrance, would not block traffic lines, and would not impede restoration and rescue activities.

7.2. Structural Design of Collision Prevention PillarsThe colliding load was calculated using the maximum flow rate and the maximum

water depth in the tsunami simulation analysis, assuming that driftage consists of buildings in the vicinity. The weight of facility buildings was assumed to be 0.6 t/m2, based on past study (National Institute for Land and Infrastructure Management 2008). The structural design of collision prevention pillars was developed by a method considering the energy absorption due to the deformation of the ground and the pillars (Coastal Development Institute of Technology and Cold Region Port and Harbor Engineering Research Center 2009) (FIG. 16).

925 D19@250

→D22@250

400

D16@250

→D19@125

2475

D19@250

→D19@125

D19@250

→D25@125

6300

6100 7162D16@150ctc250

D16@150ctc250

6300

FIG. 15. Range of Reinforcement

(1) Arrangement of Main Bars and Joints (2) Shear Reinforcement Bars (for Transverse Cross-Section)

Range of reinforcement

Flexible joint

Range of reinforcementFlexible joint + dowel bars

Shift: 10.2mm Opening: 0.9mm

Opening: 0.0mmShift: 0.3mm

FIG. 14. Seismic Design Model for Shaft in Cross-Sectional Direction

Soil spring

X

Y

X direction: freeY direction: fixedRotation: fixed

X direction: fixedY direction: free Rotation: fixed

Opening: 0.1mmShift: 0.2mm

D16

@15

0ctc

250

D16@150ctc250

8. FACILITY DESIGN

Waterproof doors, lighting fixtures, ventilation facilities, power supply facilities, and spiral staircase were installed as shown in FIG. 8.

Waterproof doors open to the outside so that they are closed by the action of water pressure, and two doors are arranged in series. Each door has an automatic closing device, which allows opening by hand and closes the door when it is released. The doors would be hard to open under water pressure.

The luminous intensity of lighting fixtures was specified to be 100 Lx, referring to the Standard for Facility Design, JIS Standards, etc. (Table 4). The supply of air to the inside of the shelter is provided by ventilation fan via the shaft. Because grid power is likely to be cut off during the use of the tsunami evacuation shelter, lighting fixtures and ventilation facilities in the shelter are operated using a power generator. The power generator is located in the aboveground building at the top of the shaft, so that it would not be stopped by tsunami.

The staircase in the shaft is a spiral staircase (steel) fixed to the side walls. This

FIG. 16. General Drawing of Collision Prevention Pillar

FIG. 17. Conceptual Drawing of Incidental Facilities in the Shelter

enables the porion of the shaft along its center to be used for air supply and exhaust ducts, electric cable conduits, and introduction of light.

Table 4. Lighting Conditions Facility Luminous intensity Remarks Garage 75Lx Standard for Building Facility Design Hall, elevator 100Lx JIS Z9110 Entrance (foyer), entrance hall (night) 100Lx JIS Z9110 Because the tsunami shelter is a facility to be used by the refugees themselves, an

operating manual (draft) instructing the use of facilities during evacuation was prepared, so that they can become familiar with the tsunami shelter on occasion such as regular evacuation drills.

Table 4. Lighting Conditions

Facility Luminous intensity Remarks Garage 75Lx Standard for Building Facility DesignHall, elevator 100Lx JIS Z9110 Entrance (foyer), entrance hall (night) 100Lx JIS Z9110

9. ARCHITECTURE AND FACILITY DESIGN

9.1. Interior Space of the ShelterTo satisfy the minimum needs of refugees who use the shelter for 24 hours, it is

equipped with toilet and washstand (FIG. 18), wall handrails, and power outlets (FIG. 19), in addition to the waterproof doors, lighting fixtures, ventilation facilities, power supply facilities, and staircase mentioned in Facility Design. In addition, stockpiles of food, water, emergency camping mat, etc. are maintained in the inner part of the shelter main body. No walls or doors are installed between the shaft and the shelter main body, so that natural light enters from the shaft.

The toilet is a temporary toilet in which excreta are solidified by a coagulant. Each user dispose of the excreta into the waste pit in the toilet booth. The toilet is located in the side of the shaft near the exhaust port, where odor is less likely to spread in the tunnel (FIG. 11).

FIG. 19. Interior of the Shelter

FIG. 18. Plan of Toilet and the Area Near the Shaft

Toilet

Underground Passage

Floor: Dustproof Paint Finish

Floor Hatch 600×600

Floor Plan Detail　S=1/30

1WD

Up

1

2

3

45 6

7

8

9

10

11

Lighting and ventilation facilities Handrail

Power outlet

9.2. Building at the Top of the ShaftThe building at the top of the shaft was designed as shown in FIG. 20 and FIG. 21.

This building serves as the place for the power generator, the access to and from the This building serves as the place for the power generator, the access to and from the spiral staircase, a lookout platform, air intake and exhaust ports, and intake natural light for the tunnel. Due to the location atop the seaside cliff, special attention was paid to the prevention of salt damage and minimum maintenance. The building is made of reinforced concrete, and doors are stainless steel. A top-light at the top of the shaft send light to the interior of the shelter. A sound-proof door is installed between the generator room and the shaft.

9.3. Exterior Shape and ColorTo support evacuation in an emergency, the area around the entrance is equipped

with lighting and signage as shown in FIG. 22. The doors are painted in green, a color implying safety, to improve visibility and to provide a sense of security. The arch-shaped mouth of the tunnel makes the entrance to stand out and provides a sense of security.

10. CONCLUSION

This article reported the detailed design of a tsunami evacuation shelter, which is a facility that is unique in the world. The design was developed focusing on the safety and security during the expected evacuation period of 24 hours. After determination of the size of the facility, structural design was developed paying attention to safety and waterproofing performance, and then incidental equipments and facilities were designed considering the refuge environment. It is hoped that the present design example will help the development of tsunami evacuation facilities in the areas with difficulty in evacuation to high ground, tsunami evacuation buildings, tsunami

50

1010

180

20

Power Generator

Stainless Steel Hood Stainless Steel Hood

Stainless Steel Hood

Down

103

102

101

100

92

93

94

95

9697 98

99

106

105

104

107

Control Panel

▽　31,413

Earthwork

Skylight Dome: Polycarbonate

Outer Wall: Exposed Concrete　　　Clear Finish

Roof: Concrete (Steel Trowel)Polyurethane Coating Waterproofing (X-2)

FIG. 20. Plan of Generator Room FIG. 21. Elevation of Generator Room

FIG. 22. Appearance of the Shelter Entrance Area from the Refugee’s Eyes

evacuation towers, and other conventional facilities.

REFERENCES Cabinet Office of Japan(2005): 津波避難ビル等に係るガイドライン

(Guidelines for Tsunami Evacuation Buildings). Cabinet Office (2012):南海トラフの巨大地震による震度分布・津波浸水予測

(第2次報告) ‒強震断層モデルと震度分布について (Study Committee on the Models for Very Large Earthquake in Nankai Trough (Second Report) ‒ On the Major Earthquake Fault Line Model and Seismic Intensity Distribution).

Coastal Development Institute of Technology (2009):津波漂流物対策施設設計

ガイドライン(案)(Design Guidelines for Tsunami Driftage Control Facilities (Draft)) Japan Road Association (2012a): Specifications for highway bridges, Part IV

Substructures. Japan Road Association (2012b): Specifications for highway bridges, Part V

Seismic design. Kochi Prefecture (2002):第2次高知県津波防災アセスメント調査事業 (The

Second Survey Project on Tsunami Disaster Prevention Assessment in Kochi Prefecture).

Kochi Prefecture (2012):高知県版第2弾 南海トラフの巨大地震による震度分

布・津波浸水予測(Announcement for Kochi Prefecture No. 2, Prediction of Seismic Intensity Distribution and Tsunami Inundation from a Very Large Earthquake in Nankai Trough, December 2012).

Kochi Prefecture (2013): 高知県津波避難計画策定指針 (中間とりまと

め )(Kochi Prefecture Guidelines for Formulation of Tsunami Evacuation Plans (Interim Compilation))

Kukidome, T., Hotta, Y., Yosioka, S., Otake, S., Kurata, M., and Utsunomiya T. (2013): 津波避難シェルターの技術検討(Technical Study on Tsunami Evacuation Shelters.”)Proceedings of the 68th Annual Scientific Meeting of Japan Society of Civil Engineers, VI-253, pp. 505-506.

Metropolitan Expressway (2008): トンネル構造物設計要領 (開削工法

編)(Design Manual for Tunnel Structures (Cut and Cover Method)). National Institute for Land and Infrastructure Management (2008): 公共土木施設

の地震・津波被害想定マニュアル(案)(Manual for Earthquake and Tsunami Damage Estimation for Public Civil Engineering Facilities (Draft)). Technical Note of National Institute for Land and Infrastructure Management No. 485, pp. 22-29.