JP6541012B1 - Cross-sectional shape of tsunami disaster prevention hill and wide-area refuge area and multi-purpose function prepared inside hill - Google Patents

Abstract

PROBLEM TO BE SOLVED: In a flat area near the coast, there is a problem of evacuation for a tsunami having a short arrival time. For this reason, evacuation buildings have been designated, but when a large number of people visit the beach in the summer, there is a problem that the receiving capacity is completely lacking. As a countermeasure, a large-scale coastal embankment with a concrete covering structure with reinforced foreheads was built so as not to be destroyed even if it overflows, but there was a problem that did not match the natural landscape. In addition, it is unpopular with the residents because the use of the coast is hindered, and there is a problem in the residents' agreement on construction. On the other hand, there is a problem that there is no disaster prevention effect until the full length is completed.
[Solution] As these solutions, a safe wide-area refuge site made of a concrete frame structure is prepared inside the levee. On the other hand, even if the construction of this disaster prevention hill has not been completed in the extension direction, the individual partial disaster prevention hill will realize a significant reduction of human damage by internally providing a wide-area refuge.
[Selected figure] Figure 1

Description

2E189 Theme name (disaster prevention), E02B Theme name 3/04 (Structure that protects dike, coast or harbor)
The present invention protects the coastal area from the tsunami, and also functions as a large area evacuation site inside the hills for leisure guests or people who walk or jog near the beach, as well as for surfing and swimming. It is about the tsunami disaster prevention hill which reduces human damage by a tsunami dramatically by burying the space which it has. This disaster prevention hill is a multipurpose park-type tsunami disaster prevention hill where the transportation functions such as wide area refuge, parking lot, high standard road, road station can be maintained inside. By providing a wide-area refuge area to the danger area of tsunami from the early stage of construction, it exerts a disaster mitigation function against large-scale human damage, and as construction progresses, these individual disaster prevention hills are connected and buried the above functions It is a kind of continuous multi-functional coastal levee, and the inside is a concrete large caisson (also known as cut-and-cut tunnel, similar to the submersible tunnel of submarine tunnel), so it is a structure without destruction by overflow and behind It is an invention about the tsunami disaster prevention hill with the final purpose of making it possible to protect the life and property of the whole city area from a tsunami disaster. Here, hills are relatively gentle slopes, and the overall shape in the form of a low mountain with a suitable length was imaged, and the name of the keyword for disaster prevention hills of patent application was used.

  The largest possible (Level 2) tsunami that accompanies the Great East Japan Pacific Ocean Earthquake collapses the levee body by overscouring many coastal dikes along the northeastern Pacific coast, and further by going up to land Great damage was caused to the city area. On the other hand, for the Kanto region and the west region, the city area of the region from Kanto to Kyushu for the largest earthquake when the southern Kanto earthquake and the Boso off the east and the Matsuda fault in the western region interlocked in addition to the three interlocking earthquakes of Tonankai The Cabinet Office is promoting information on disaster prevention measures and promoting preparations by disclosing information on the possibility of being attacked by a huge tsunami of 10m to 30m. In these areas, there are several cities with many residential areas and many problems that beach leisure visitors visit. Before the Great East Japan Earthquake, the magnitude of the earthquake was up to about 8 magnitude, and the upstream of the tsunami was limited, so it was possible to evacuate although the damage occurred but the human damage caused by the tsunami was limited. It was considered to be the number of people who However, it was triggered by the huge East Japan Pacific Ocean Earthquake. When the next great earthquake occurs, it is possible to go up to areas where there was no tsunami going up in the past. Many of these areas do not have coastal levees, and although evacuation buildings have been designated, it has been pointed out that there is a possibility of about 220,000 serious human damage. On the other hand, tens of thousands to over 100,000 bathers visit the tsunami attack area on the beach in the large urban area in summer season, and it is difficult to evacuate at night when the tsunami arrival time is short It has been considered that there is no adequate drastic measure because there is a serious problem or far beyond the capacity of the existing evacuation buildings. In addition, the number of foreigners visiting Japan is increasing rapidly and the land is unfamiliar, and the Olympics is approaching, and many foreigners will visit the waterfront area in areas such as yachts. Solutions to these problems are needed. On the other hand, as shown in Figure 5, the conventional coastal levee has a structure in which the main body of the earth structure is covered with a concrete block. Moreover, since the type of the conventional seawall was concrete coating, there was a problem from the beginning that the landscape should be called mineralized and killed. The deterioration of the landscape has become apparent as the coastal levee becomes higher with the increase of the assumed tsunami height, and it has been regarded as a problem by not only residents but also stakeholders. However, there is a problem that it is widely constructed as a reconstruction work of the tsunami damage area of the Great East Japan Earthquake to secure the safety of residents against the tsunami.

JP, 2015-63806, A

In the following document, it has already been stated that disaster prevention hills will be announced separately (planned after patent application).
Daijiro Kaneko, Tokuzo Hosoyada. Evaluation of refuge life risk using wooden housing rate and tsunami inundation by satellite-Development of geography and social model and application to Kamakura coast-, Proceedings of the Japan Society of Civil Engineers F6 (Safety Problem), Vol. 73, No. 1, pp 58- 70, 2017. Toshizo Hosoyama, Daijiro Kaneko, Takeshi Otake. Numerical Experiment for Evaluating Tsunami Countermeasures by Embankment Structure at Tsunami Vulnerability Beach, Proceedings of the Japan Society of Civil Engineers B1, Vol, 71, Special Issue on Hydraulics, Vol. 59, 228, 6 p, 2015.

In the case of protecting human damage, residents' property and social capital against the conventional huge tsunami (the largest possible level 2 tsunami), the conventional coastal dike (Fig. 5) is as follows: There is a problem.
<1> The problem that there is no safe area evacuation site in the coast of the flatland.
People visiting for a variety of purposes near the coast where the tsunami arrival time is short and difficult to evacuate, there is no large-scale evacuation area for safety and emergency evacuation near the coast, and it is scary in the holiday season when there are a large number of people While there is concern about the expansion of human damage of a certain scale, concrete measures can not be found at present.
<2> The problem that the tsunami overflows the embankment and structures The conventional coastal dike and tidal embankment are embankment structures, and there are many types that protect the embankment with concrete blocks, and the tsunami which overflowed these embankments is the embankment As a result of scooping the fore end which is the lower end part of the back, since the dam body is an embankment structure vulnerable to the fluid, the dam body was collapsed on a large scale and the damage was made great. For this reason, after the Great East Japan Earthquake, reinforcement measures are taken so that the lower end of the embankment (the bottom of the dam) is not scoured by the overflowing flow. That is, if partial failure starts due to cracks and overflows of the levee due to earthquake motion, the levee is an embankment and there is a part that collapses due to the tsunami, and eventually the tsunami flows even deeper to the foundation of the coastal dike, Once destroyed, there is a structural problem that it spreads to adjacent bodices one after another and loses its function as a tsunami countermeasure. As a result, large-scale turbid flow and inundation were caused in the back ground, and the land side area became turbid by the same flooding as in the case of rivers, despite the fact that human damage and economic loss became too huge disasters . There was a fundamental problem that the basic material of the coastal levee continued to use the fragile embankment for fluid.
<3> Deterioration of the landscape by concrete block coating A coating of concrete material will be applied to the entire surface of the embankment to prevent scouring of the levee, but the landscape will be astonishing and dry, as described above. It was pointed out that the landscape was deteriorated by the people and the people who visited it, and the concrete-covered coastal levee was not only unremarkable, but there was a strong criticism.
For the largest tsunami that can be envisioned, the larger the embankment, the more concrete the view will become more oppressive. It has been criticized by local residents because the landscape has become a heterogeneous view that is not compatible with the surrounding natural environment, and it has been pointed out that the scenery and the people who visit it have worsened the scenery, and that there is no convenience to use the concrete-covered coastal embankment. There is a problem to solve this current situation.
<4> The problem that there is a damage by overflowing by the tsunami more than expected It is an evacuation site that it is an appropriate evacuation site to stand on the roof, sky edge such as evacuation building, evacuation tower, hill of life at the time of tsunami warning Not exclusively. There is no guarantee that the predicted tsunami height by the Cabinet Office is considered to be an increase and convergence of the tsunami height depending on the scope of the earthquake source and the size of the fault, and it will never fall below the forecast. The reason is that observation data, which was originally a scientifically correct organization of the tsunami itself, is limited and scarce in modern Japan.
It can not be concluded that the situation beyond the largest expected tsunami can not be completely exceeded, so if the tsunami overflows the roof of the evacuation facility or the top of the evacuation facility, it is the highest in the facility conventionally People evacuate on the roof or at the sky's tip, but all those who were evacuated are swept away inland by the tsunami and will die. An unexpected life accident similar to this occurred on the roof of the evacuation building during the Great East Japan Pacific Earthquake. If there is any possibility that the tsunami will flow over the structure, it is fundamentally a collective accident that many people evacuate on the roof of the structure or the top of the bank. Therefore, the general public and leisure guests should not observe the tsunami at the heavenly end, and should not overestimate that the heavenly end of the seawall is safe for the tsunami. There are issues such as being able to evacuate further to hills like hills and mountains, or to be safe even if overflowing.
<5> A problem that does not exert its function until the full length of the coastal levee is completed The conventional coastal dike does not function as a tsunami countermeasure until the full length is completed. Because the tsunami flows from the part without the seawall and flows into the city, the seawall does not have any disaster prevention effect at all. Also, multipurpose use can not be achieved. From this, it is necessary to have the date of many years until it becomes effective, and until then there is a serious problem in terms of the effect of investment when implementing the disaster prevention measures against tsunami.

The present invention has been made in view of the above problems, and the object of the present invention is to provide a built-in type wide-area refuge site as a countermeasure against tsunami and a structure that enables multipurpose use according to the construction stage. To realize the tsunami disaster prevention hills.
<1> In the case of the tsunami disaster prevention hill which was built and maintained partially about the place where construction is relatively easy By constructing the disaster prevention hill from the area where construction is possible, significant improvement of human damage to the tsunami from early It is possible to It is possible to realize a structure with a function to provide a large area evacuation area for safe emergency evacuation to people visiting with various purposes near the coast where the tsunami arrival time is short and evacuation is difficult To do. This should be a fundamental measure to prevent the spread of human damage of a terrible scale even during a large-scale vacation season.
<2> In the case of continuous disaster prevention hills Not only people visiting around the coast for various purposes, but also continuous disaster prevention hills prepared near the coast, life and houses of all people on the inland side, factories, It will be possible to make strong disaster prevention measures to protect public goods as hospitals or social capital from tsunami.

<1> Maintain a wide-area refuge inside a disaster prevention hill Inside a tsunami disaster prevention hill, it is a large area for safe evacuation for people who are visiting for various purposes near the coast where evacuation time is short because the tsunami arrival time is short Create a concrete caisson structure with the function of providing a large area evacuation site, and make it possible to safely evacuate a large number of people in the disaster prevention hills even during the outing vacation season.
By this measure, even if it overflows to a tsunami that exceeds the largest possible tsunami (Level 2), the disaster prevention hill will not collapse to such an extent that it can not keep its shape due to scouring, and the inside of the disaster prevention hill A design that enables a wide area evacuation area to maintain a safe structure.
<2> Realization of a structure that prevents the levee from tipping over by the wave power of the tsunami Waves caused by the tsunami rather than the cross section of the tsunami breakwater whose height is similar to that of the breakwater and the cross-sectional width of the break is short In order to prevent the upper part of the conventional coastal levee from being overturned and destroyed by the force (impact force by flow and fluid force close to the flow), the shape of the hill is made into a wide cross section and concrete is not broken inside In order to strengthen the stability to the wave power of the tsunami at each stage by burying the caisson.
<3> Improving the landscape of disaster prevention hills The cross section of the disaster prevention hills is wider with respect to the height and the hills become loose not only because it is stable to the tsunami force, but also in conjunction with planting, which will be described later To improve the conventional bad image concrete landscape.
<4> It is essential that the cross-sectional shape of the seaside park disaster prevention hill is gentle and wide as a place of rest, in order to use it as a seaside park from the beach area, and it is planted with rest (Fig. 3) Providing a desirable shade for swimming and beach leisure.
<5> Slope protection and reduction effect by planting against tsunami tsunami planting on hills is not only covered by grass as a beach park, but also pine forest well-known as coastal landscape (white sand and blue pine) and root system Deep planting Shii, one of the primitive ecosystems in the area (Recommendation by a plant ecologist Miyawaki Akira, Professor Emeritus of the Yokohama National University), and saving energy to protect the slopes of the disaster prevention hills from the tsunami velocity It also works as a workman. The cherry tree Somei Yoshino tends to wither in about 80 years, but it is easy to make a hollow on the ground, but since many mountain cherry trees are grown naturally in some areas, it is also good to incorporate long-lived mountain cherry trees inside the beach park.
<6> Securing sufficient receiving capacity and traffic capacity as a large-area refuge area Widely secure the width of the cross section of the disaster prevention hill, and realize a sufficient space (receiving capacity) as a large-area refuge area. In large-area refuge areas, a bulkhead will be provided to prevent the spread of fire and flood damage. In addition, by using high-standard roads in the lower part of the hills, space utilization inside the hills will be realized as trunk roads in the coast. The shape of the high-standard road is three lanes of one way similar to the seabed sunk tunnel and the size of all six lanes, and secures a large traffic capacity and spare space for a tunnel fire (car accident).
<7> Suppression of sinking due to own weight Generally, when a structure is built near an estuary or soft ground, it sinks under its own load due to lack of supporting capacity. Therefore, in the case of the necessary area, we will try as shown in the explanatory drawing of the basic structure (Figure 2) among various ground improvement methods, and think that it is good for ground improvement by cheap displacement sand or sand compaction or injection method . The disaster prevention hill itself is also designed to reduce the contact pressure by making the concrete frame (caisson) horizontally long and to control the sinking.
<8> Prevention of subsidence by split rock stone For the foundation construction, split the split stone under concrete caisson (Figs. 1 and 2) and disperse the load to reduce the ground contact load to the ground and prevent sinking. Settlement is due to the problem of decreasing the design height of disaster prevention hills over time. This technology is widely adopted as a port construction technology and is applied to the land section.
<9> Realization that disaster prevention hills show disaster prevention effect at discontinuous construction time disaster prevention hills become a long coastal embankment at the time of completion, and many months are required until completion, but the said disaster prevention hills is the construction period Even at any stage, discontinuous individual hills serve as a large-scale refuge site, so the tsunami disaster prevention function is exhibited at summer bathers, fireworks or major events such as the Olympics. In addition, it can be used as a parking lot in the coastal area for transportation planning for urban problems, in preparation for the project day when there are many crowds. From these functions, it is effective to establish a discontinuous disaster prevention hill on the famous seaside beach by priority.
<10> Use of the slope and sky edge of the disaster prevention hill The disaster prevention hill is designed to be a cross section with a gentle slope because it plans planting etc. assuming a pine forest in consideration of its use as a beach park and the landscape. doing. In addition, it is appropriate to flatten the upper end of the hill in consideration of maintenance and use of recreation such as walk, jogging, wheelchair etc. in the upper part of the dam body (sky end) of the disaster prevention hill.
<11> Reinforcement disaster prevention hill top of the sky end in wave convergence part The overflow T-retaining wall at the center, L-shaped retaining wall (including tie rods etc.) to the left and right When applied, it can reinforce hilly cross sections. In particular, it is effective as a reinforcement measure to cope with the possibility of overflow in the area where the tsunami converges and the mountain foot attachment area due to the shape of the bay.
<12> A candidate for planting and landscape As providing a shade as a beach park, when planting trees that improve the landscape, it is also good to use a primordial vegetation-type evergreen forest that is strongly rooted and resistant to tsunami. In addition, it is excellent in view of landscape as a white sand blue pine, which is a pine forest which has been a coastal landscape from the Middle Ages to the modern times. It is reported that the area has long been a pine forest, and some of those pines are still in existence today, so it is locally superior to restore the old pine forest. On the other hand, it is also effective to reproduce vegetation, which is the primitive ecology of sand dunes that existed in the past. We combine these potential solutions to plant and cover planting in field trials, and identify the merits and demerits in each area and correct the planting.
<13> A disaster prevention hill with a traffic center and leisure facility function in a disaster prevention hill The height of a levee that does not overflow to the largest possible tsunami that may occur can usually be seen on the inland side It is possible to maintain facilities such as slopes to the second floor, connections to existing roads, transportation facilities including buses and trams, road stations, and other leisure-related facilities on the beach. There is basically no hindrance to disaster prevention even if it is a simple facility or a semi-permanent structure taking into consideration a tsunami on the coast side, there is no problem even if it is maintained in consideration of convenience as a seaside park on disaster prevention hills . In principle, on the inland side and within the bank. It is because the safety against the tsunami is secured.
<14> Securing of the project cost If a high-standard road can be maintained inside the disaster prevention hill, local public can be used if it is possible to utilize the road budget of the country which is a budget scale outstanding in public construction as a merger. It is thought that the budgetary path to realize the disaster prevention hill will be greatly opened and the early realization will be facilitated when the group is commercialized.

By planning and designing the present invention so as to have the following multi-purpose functions, it exerts a multi-purpose effect of alleviating drastic improvement and urban problems by hardware such as hill built-in wide area refuge as a disaster prevention measure against tsunami be able to.
<1> Providing a safe evacuation area in the coast of flatland.
A disaster prevention hill structure internally equipped with a function to provide a large-scale evacuation area for safe emergency evacuation to people visiting for a variety of purposes near the coast where evacuation time is short and evacuation is difficult To do. In this way, it is an effective drastic measure by hardware that prevents the expansion of human damage of a terrible scale even during a large-scale vacation season, and it is a disaster prevention measure that demonstrates the investment effect by multipurpose use.
<2> Tsunami disaster prevention hills The tsunami disaster prevention hills do not overflow even if it overflows It realizes that tsunami disaster prevention hills are the height of the scale that the tsunami does not overflow, even if it overflows, even if it is a conventional coastal dike Concrete caisson is buried in the disaster prevention hill so as not to destroy it, and the wide-area refuge in the hill is safe. In addition, if disaster prevention hills are continuously completed, the whole land side will not be flooded by the tsunami, and in principle it will be possible to completely prevent human damage to residents of the residential area and there will be no need to evacuate. Demonstrate the investment effect of preserving property and social capital throughout the city.
<3> Planting and landscape improvement and function as a beach park It is not only that the cross-sectional shape of the disaster prevention hill widens its width relative to its height and the hill is not only stable to the tsunami force, it will be described later To improve the traditional concrete landscape that you want to avoid in conjunction with In addition, it can be used as a beach park, and the cross-sectional shape of the disaster prevention hill is a gentle gradient and designed to be wide, which promotes its use as a seaside park from the beach area. It also functions as a place of rest by providing shade for sea bathing and beach leisure by planting. These properties are considered to have nothing in the conventional coastal dike, and are made possible because the concrete caisson structure, which will be a large area evacuation site, is embedded inside.
<4> Even if the disaster prevention hill is discontinuous, the disaster prevention function is exhibited Even if the disaster prevention hill is in the process of construction and in a discontinuous situation, the upper floor of the embankment is the original disaster prevention as a wide area refuge It can be used for measures. It is an advantage that existing disaster prevention measures do not have the existing evacuation measures for many current seaside cities, and that it is a necessary property for urgent measures to be taken as a disaster prevention measure, and that it is extremely effective. Think.
<5> Measures against urban traffic problems In the coast of a city with a large population, coastal roads are often constructed as measures against traffic congestion in the city area behind, this expressway is incorporated inside the embankment, high As a standard road, traffic congestion in the city area can be alleviated. In addition, even if the disaster prevention hill is discontinuous, the lower part of the dike can be effectively used as a scarce parking lot for coastal cities in the coastal area. These functions exert complex improvement effects on serious daily traffic jams in the inland area, and are effective measures for alleviating urban environmental problems in the area.
<6> Measures for securing the budget The tsunami disaster prevention hill is a hard project, so the project cost is large, but because it can develop high-standard roads inside the disaster prevention hill, it has been extremely prominent among public works in the country A road is opened to utilize the road project, which is a budget scale. In addition, since the local government is responsible for primary disaster prevention measures, it is recommended that the bond issuance supported by the Cabinet Office be used in conjunction with sharing of business in the disaster prevention hills and maintenance of related facilities.

It is a figure explaining the basic cross-sectional shape of the disaster prevention hill concerned with invention. Example 1 It is the figure that represents the most comprehensive basic form when the ground improvement of the disaster prevention hill in the estuary etc. is necessary. (Example 2) It is a figure explaining planting for pine or land endemic species (primitive ecology) and planting work for scouring protection. It is an explanatory view in which the multipurpose use of the sky end and the reverse T-shaped retaining wall work for protection against overflow are installed. This is an example of a new seawall embankment with concrete scouring measures at the end of the forehead, and is an example of construction for the largest tsunami that can be assumed. However, the embankment is a traditional embankment. It is a conceptual diagram of the general shape supposing the level 2 normal tsunami and high tide from old times. An example of similar terrace type construction for protection work to prevent wave reflection and scour in the area where the tsunami converges is shown. This is an example showing a completed landscape assumed to be realized in a step-like manner using retaining walls on the slopes of a disaster prevention hill.

Figure 1 shows the whole cross section of the tsunami disaster prevention hill. On the second floor of a wide-width concrete frame structure (usually called caisson) inside a disaster prevention hill, a space to be a wide-area refuge will be maintained. This cross section structure makes the evacuation zone more secure against tsunami. We have realized a stable cross-section that does not collapse against external force and tsunami wave force, and a structural form with cross-sectional shape, weight, and strength that withstands the wave force of the tsunami wave and overflow caused by the tsunami more than expected. The height of the disaster prevention hills changes depending on the tsunami wave height, which is the design wave height, and this figure is the case of the tsunami wave height of 15 m.

Figure 2 is a general cross-sectional view of a multi-functional disaster prevention hill where ground improvement is generally performed in the vicinity of an estuary or a soft ground area. When a structure is built, it is because it sinks under its own load due to lack of supporting power in some places. In the case of the area necessary for this measure, we will improve the ground to support the upper structure by various ground improvement methods. It is the second of a comprehensive example that realized the basic structure.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<1> Maintenance and repair due to earthquake motion Damage such as cracks of the levee due to seismic motion is expected, but because there is a concrete caisson (Fig. 1) as a wave protection structure against tsunami, it is stronger than the conventional coastal dike and the levee There is no problem with the tsunami safety of After the tsunami strikes, we will be able to repair it on the day after. As for bridges, there are large-scale collapses and collapses at the time of earthquake, but there is no example of large-scale destruction at the time of earthquake disaster in the tunnel structure in the project.
<2> The foundation disaster prevention hill of maintenance management establishes a foundation for maintenance because it is long, and management of equipment and storage as a large area refuge area, space fee, lease income, income and maintenance of parking lot Organizations that share management, maintenance and management of hilly dams, maintenance of planting, etc., or management organizations such as cooperative councils are required.
<3> Storage function as a wide area refuge area Because a wide area refuge area is maintained inside in the coastal area, large-scale equipment and storage of food, beverages, medicines, etc. over ordinary wide area refuge areas according to the standard It is necessary to maintain the warehouse. It is desirable to maintain the heliport for relief work in the disaster prevention hill.
<4> Operation of traffic terminal With the purpose of alleviating the city traffic jam on a daily basis, we established consultation body such as bus terminal (or tram station), road station, etc. Tsunami disaster prevention hill where city planning consideration was considered It is necessary to manage Since these are large projects, they need to be separate organizations and have a forum for operation.
<5> Management system of parking lot About management of a large-scale parking lot (figure 1) in a levee body, many uses such as a bather, a tourist, a beach leisure visitor are considered, and a management system of only a parking lot It is considered necessary. It is conceivable to make extensive use of existing organizations.
<6> Planting of hills and use of parks for disaster prevention planting on hills (Fig. 3) is a good natural environment that citizens want, judging from the scale of the hills from the viewpoint of conservation of natural environment It is thought that it will be one of the important points in commercialization by making efforts in consideration. In addition to the above-mentioned lawn protection as a beach park, we planted a pine forest well-known as a coastal landscape (white sand and blue pine) and Shii (Shii) which is one of the primitive ecosystems of the local area. Akira Miyawaki, a plant ecologist, recommended by Professor Emeritus of the Yokohama National University), and will also work as an energy-saving work to protect the surface of the disaster-prevention hill from the flow velocity of tsunami. For example, since many mountain cherry trees are naturally grown in the hilly area on the coast of the Pacific coast where many tsunamis occur, and it becomes a Taoyuan Town where the whole mountain is covered, including incorporating long-lived mountain cherry trees into the beach park In addition to adapting to the landscape of the city, it is also necessary to have a perspective on creating an environment for disaster prevention hills.
<7> Ground improvement and maintenance When a structure is built near the estuary or soft ground, it sinks under its own load. Therefore, if necessary, the ground will be improved as shown in Figure 2 (the second comprehensive map). However, even if a concrete body (caisson) is made long horizontally and the contact pressure is reduced to suppress sinking by its own weight, in the case of a large estuary like in the case of a first grade river, sand compaction or substituted sand Not only that, it is necessary to prevent the sinking of the top of the disaster prevention hill by ground improvement methods such as full-scale injection solidification and deep mixing treatment. The height of the sky end is below the design, and it is necessary to prevent overflow problems in advance. In addition, if it sinks, it will be maintained and managed by recovery by bulking.
<8> Settlement regular observation and maintenance repair Since concrete caisson is the main component of the structure, the load is distributed on the average by spreading the cobble stone on the foundation to reduce the ground contact load to the ground, and the settlement of the hill prevent. This technology, which is widely used for port construction, is applied to land construction for disaster prevention hills. Periodical observation of the crest height for settlement, and maintenance / restoration of hill height by the reverse T-shaped retaining wall described in the construction area in question are necessary to prevent overflow Become.
<9> Drainage Management of Rainwater Because the area occupied by disaster prevention hills is large, it is necessary to maintain drainage facilities (U-shaped ditch, drainage channel, etc.) sufficient for rainfall on both slopes. In addition, since rainwater is concentrated at the lower end of the levee through the drainage ditch, it is necessary to design the section and slope of the drainage channel appropriately.
<10> Slope protection against rain water The large cross-sectional area of the disaster prevention hill, even if the cross-sectional shape of a single unit discontinuous in the length direction, at the time of partial completion, by planting grass for seed spraying or covering, etc. Therefore, we must suppress the topsoil erosion by rainwater.
About tsunami protection estuary in cooperation with <11> Kawaguchi Pass and its flood, it is known that the upstream of a tsunami is remarkable. Based on strong criteria such as increase of strength and safety factor of used steel materials, securing of basic operation, securing of high-level power supply and securing of multiple protection, etc., in accordance with the design criteria of new fences revised after tsunami earthquake caused by East Japan Pacific Ocean earthquake Maintain at the same time. If a weir vulnerable to the tsunami is destroyed by the tsunami run-up, the tsunami will go over the levee from the vicinity of the weir to the back of the tsunami disaster prevention hill, and human damage and economic loss will increase It is because.
<12> Securing embankment materials and constructing earthworking and tsunami disaster prevention hilly areas require a large amount of embankment materials for hilly dams (Fig. 1) excluding caisson parts. The design height of the disaster prevention hill is the height from the average sea level, and the height can be reduced in the natural sand dune-like height, but considering the storm surge, natural drainage, etc. It is possible to excavate the area left with a certain degree of elevation and use it as the fill material. It is necessary to shorten the transportation distance of the embankment material which is the construction principle of the earthwork. In other words, we try to collect soil from near area.
<13> It is necessary to spread load on the ground while spreading the stone on the foundation of the concrete caisson in preparation for the presence of the soft ground of the silt system as in the vicinity of the estuary of the stone foundation of the base split stone and the estuary of the split stone There is (Figure 2). This is because the caisson sinks for many years and the height of the top of the levee becomes low due to this, and the height at the time of design against the tsunami is not satisfied, resulting in the deformation to the dangerous side. As a stone material necessary for this foundation work, it is necessary to carry sea urchin from the rocky area near the seashore on a considerable scale by sea, and land it in the construction area, and then level the unevenness. This is because it is easy to prevent the subsidence of the concrete caisson and damage to the bottom of the caisson due to the protrusion of rock. However, the amount of work is not as large as the earthwork of the embankment, but the geographical position and distance of the quarry from which stone material is cut becomes important. In addition, for the construction work, stone landing facilities will be needed on the shore near the construction site.
<14> Use of the ruins of quarry and improvement of profitability of disaster prevention hill construction In securing fracture stone of foundation of disaster prevention hill on soft ground, it is the scale to flatten the mountain even if it is small scale, usually land construction It is appropriate to improve the profitability of disaster prevention hill construction by using the ruins which combines the quarry with the land preparation for residential area. Therefore, it is desirable to be consistent with the city plan of the city concerned.
<15> Securing displacement sand for ground improvement With regard to displacement sand under broken stone used for ground improvement (Fig. 2), it is necessary to secure insufficient high-quality mountain sand. For example, since there is a large amount of sand resources in the Boso peninsula in the metropolitan area, it is relatively easy to secure sand by transporting it to the shore of the construction site by means of a conveyor belt and a cargo ship.
<16> Concrete caisson production method Concrete caisson is built in the field or built in a floating dock or a caisson yard in an existing port, poured into a crane or this yard, placed on a boat or raised the caisson to the sea Towing and transport to the site will be adopted.
The difficulty of the <17> construction method and improvement and reinforcement after completion The construction method of the disaster prevention hill concerned is that the basic structure is a concrete caisson (Fig. 1, a frame with a square grid-like wall structure). Is a method of construction where there is an already experienced structure. In addition, it is noted that there are many construction examples for ground improvement with crushed stone that is laid on the foundation of caisson for load distribution, and further substitution sand at the lower part, and the method is easy. On the other hand, the tsunami height in the coastal area of the tsunami is not uniform along the length of the disaster prevention hill, and depends on the location and size of the epicenter, and the shape of the bay. Therefore, based on the trace or partial damage left on the sea-side bank surface of the relevant tsunami disaster prevention hill due to the newly generated tsunami, the maintenance of the terrace terrace garden shown in FIG. In the future, it is conceivable that the sea side hill surface of the disaster prevention hill will be reinforced by adopting a method to prevent reflection and overflow. The problem of uneven tsunami height is the highly difficult reinforcement and improvement method in the maintenance and management of disaster prevention hills after completion.
Measures to the hill edge in the case of <18> discontinuous simple substance If the said disaster prevention hill is discontinuous single substance, according to the plan, the landscape measures by the embankment and scooping prevention etc. and planting are carried out about the hill edge part .

Claims (7)

Concrete caisson with lattice structure,
An inverted T-shaped retaining wall having an inverted T-shape provided on top of the concrete caisson,
The concrete caisson and an embankment in which the retaining wall is embedded;
The above-mentioned concrete caisson has a high standard road on the first floor and a wide area refuge on the second floor .
The width of the bottom surface of the concrete caisson in the land direction is set to be greater than the height from the bottom surface,
A part of the slope of the embankment in the first half is composed of a step-like L-shaped retaining wall. The slope for the entrance and exit connected to the said wide area refuge place is provided in the slope by the side of the land of the said embankment, The disaster prevention hill of Claim 1 characterized by the above-mentioned. At least two or more reverse T-shaped retaining walls are installed,
The said reverse T-shaped retaining wall is mutually connected by the tie rod , The disaster prevention hill of Claim 1 and 2 characterized by the above-mentioned. The disaster prevention hill according to any one of claims 1 to 3 , wherein planting is carried out on the slope of the embankment . An L-shaped retaining wall is provided on the slope of the embankment,
The slope of the said embankment is formed in step shape , The disaster prevention hill of any one of the Claims 1-4 characterized by the above-mentioned. The disaster prevention hill according to any one of claims 1 to 5 , wherein a part of the slope on the land side of the embankment is provided with a facility connected to the high standard road . It is further equipped with a foundation department that includes a stone cobble stone ,
The said concrete caisson is installed on the said foundation part, The disaster prevention hill of any one of Claims 1-6 characterized by the above-mentioned.