Tidal Wall

Abstract

To provide a tide embankment which comprises both high earthquake resistance and strong tsunami resistance, which has reuse property against repeating tsunami, and which can secure further higher safety even though a severe load such as a load in a giant earthquake, a load in huge tsunami, and a superimposed load in an aftershock and a huge tsunami wave force applies.SOLUTION: A tide embankment comprises a plurality of groups of support piles also used as tide barriers which are formed by integrally joining support piles 2 also used as tide barriers that are for both a tide barrier structure and a support pile structure and that become a basic structure skeleton common to an upper structure and a lower structure with each other by joints 10 to continuously arrange, in which neighboring groups of support piles also used as tide barriers are connected by water cutoff joints 20 having water cutoff property, pressure resistance, and relative displacement followability.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a seawall. [Background technology]

[0002] Seawalls are required to have high earthquake resistance and strong tsunami resistance, be reusable against repeated tsunamis, and continue to ensure safety even when subjected to severe loads such as earthquake loads caused by a huge earthquake before the huge tsunami strikes, tsunami loads accompanying the strike of a huge tsunami, and loads caused by the superposition of aftershocks and the wave forces of a huge tsunami (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-143439 A Summary of the Invention [Problem to be solved by the invention]

[0004] The conventional seawall in Patent Document 1 is characterized by having a seawall section made up of a plurality of steel pipe sheet piles connected at the top, and a support pile section made up of every few steel pipe sheet piles that make up the seawall section, which is extended to the supporting ground and embedded in the ground. Therefore, in the above-mentioned conventional seawall, the seawall section made up of short steel pipes at the top and the support pile section made up of long steel pipes that are extended to the supporting ground and embedded in the ground at every few steel pipes that make up the seawall section have different vertical lengths, and therefore have different natural frequencies. When a major earthquake or aftershock occurs, depending on the natural vibration characteristics of the flood wall section made of short steel pipes and the support pile section made of long steel pipes in the above-mentioned conventional seawall, they may each exhibit behavior in a different natural vibration mode, and the flood wall section made of short steel pipes and the support pile section made of long steel pipes may each exhibit different displacement time histories, which may result in an increase in stress inside the pile due to a phase difference. In addition, the above-mentioned conventional seawalls are structured to support severe external forces such as the weight of the entire structure, which consists of the upper seawall section and the support piles, which are extended from the seawall section to the supporting ground and embedded in the supporting ground at intervals of several pipes, the weight of snow, wind load, inertia forces due to huge earthquakes, dynamic earth pressure and ground reaction forces, tsunami loads due to huge tsunamis, drifting object loads and ground reaction forces, tsunami loads due to the superposition of aftershocks and huge tsunami wave forces, inertia forces, dynamic water pressure, dynamic earth pressure and ground reaction forces, and combinations of these, by the support piles, which are made of long steel pipes that are extended from the upper seawall section made of short steel pipes to the supporting ground at intervals of several pipes and embedded in the supporting ground. Therefore, it is expected that the above-mentioned conventional seawalls will be subjected to the above-mentioned severe external forces during massive earthquakes, huge tsunamis, and when aftershocks and the wave forces of a huge tsunami are superimposed. Such severe external forces on the above-mentioned conventional seawalls will be transmitted in a concentrated manner to the supporting pile section made of long steel pipes that are extended from the upper short steel pipe seawall section to the supporting ground and embedded therein, and to the supporting ground. Then, depending on the scale and vibration characteristics of a mega-earthquake specific to the target site, or the scale of the mega-tsunami wave force, as well as the scale and vibration characteristics of the drifting object load or aftershocks that are taken into account when superimposed with the mega-tsunami wave force, the load transmitted to the supporting pile section, which is made of long steel pipes that are extended and embedded in the supporting ground every few pipes from the upper short steel pipe seawall section of the above-mentioned conventional seawall, and to the supporting ground, may be concentrated and transmitted significantly.

[0005] In view of the above problems, the present invention aims to provide a seawall that prevents or suppresses an increase in stress inside the piles due to the phase difference in the natural vibration characteristics of the seawall structure and the supporting pile structure, and maximizes the load distribution effect of the basic structural body and the local load distribution effect of the supporting ground, thereby maximizing the load capacity that can be borne by the structural body as a whole, thereby providing a seawall that combines high earthquake resistance and strong tsunami resistance, and is reusable against repeated tsunamis, even when subjected to severe loads such as loads during a massive earthquake, loads during a massive tsunami, and loads when aftershocks and the wave forces of a massive tsunami are superimposed. This allows for an even higher level of safety to be ensured. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides the following means.

[0007] The invention described in claim 1 relates to a flood wall / support pile structure, which is used for both the flood wall structure and the support pile structure and has a basic structural frame common to the upper structure and the lower structure. Integrate with joints Joint Continuously A group of parallel seawalls and support piles multiple Prepare and a connecting portion of adjacent groups of flood wall and support piles is provided with a plurality of water stop joints on the inner side of the bank from the center line of the flood wall and support pile related to the connecting portion in the cross section in the direction perpendicular to the pile axis, one side of each of the water stop joints is installed on a first end flood wall and support pile which is the flood wall and support pile connected to the end side of the flood wall and support pile group, and the other side of each of the water stop joints is installed on a second end flood wall and support pile which is the flood wall and support pile adjacent to the first end flood wall and support pile which is the flood wall and support pile connected to the end side of the flood wall and support pile group adjacent to the flood wall and support pile group, each of the water stop joints is provided with a water stop sheet, and each of the water stop sheets is formed by overlapping a light blocking sheet having light blocking properties, a water impermeable sheet having water impermeability, and a pressure resistant sheet having pressure resistance against tsunami wave pressure. . Claim 2 The invention described in Claim 1 The invention described in is characterized in that a protective structure is provided on the outer side of the embankment than the waterstop joint to protect the waterstop joint from expected drifting object loads. Claim 3 The invention described in claim 1 Or claim 2 The invention described in the above is characterized in that the flood barrier / support pile is covered with an impact-resistant or impact-absorbing material. The impact-resistant or impact-absorbing material covering is of a nature that provides the flood barrier / support pile with impact resistance or impact absorption, wear resistance, and rust prevention effects. Claim 4 The invention described in claim 1 Or claim 2 The invention described in the above is characterized in that the flood barrier / support pile is covered with a heavy-duty anticorrosive material or reinforced concrete. The heavy-duty anticorrosive material or the reinforced concrete covering is of a nature that provides the flood barrier / support pile with abrasion resistance and anticorrosion effects. Claim 5 The invention described in claims 1 to Claim 4 In any of the above-described inventions, the present invention is characterized in that the ground on the inside of the embankment of the seawall / support pile is provided with an embankment inside improvement body that strengthens the ground. Claim 6 The invention described in Claim 5 In the invention described above, the initial height of the embankment inner improvement body is set to a height obtained by adding the amount of expected subsidence due to an earthquake before the tsunami hits to the basically required height of the embankment inner improvement body, and the embankment inner improvement body protrudes upward. Claim 7 The invention described in claims 1 to Claim 6In any of the above-described inventions, the present invention is characterized in that the ground on the outside of the embankment of the seawall / support pile is provided with an embankment outer improvement body for strengthening the ground. Claim 8 The invention described in Claim 7 In the invention described above, the initial height of the embankment outer improvement body is set to a height obtained by adding the amount of expected subsidence due to an earthquake before the tsunami hit to the basically required height of the embankment outer improvement body, and the embankment outer improvement body protrudes upward. Effect of the Invention

[0008] In the seawall of the present invention, the increase in stress inside the piles due to the phase difference in the inherent vibration characteristics of the seawall structure and the supporting pile structure is prevented or suppressed, and the load distribution effect of the basic structural body and the local load distribution effect of the supporting ground are maximised, thereby maximising the load capacity that can be borne by the structural body as a whole.This means that even if severe loads such as loads during a massive earthquake, loads during a massive tsunami, and loads caused by the superposition of aftershocks and the wave forces of a massive tsunami are applied, the seawall will have high earthquake resistance and strong tsunami resistance, and will be reusable against repeated tsunamis, ensuring an even higher level of safety. [Brief description of the drawings]

[0009] [Figure 1] This is a front view (longitudinal cross-sectional view) including the seawall / support pile 2, which is the basic structural body of the seawall 1 of the present invention, as well as the ground G and supporting ground B. [Diagram 2] FIG. 2 is a side view (cross-sectional view) of FIG. [Diagram 3] 2 is a central cross-sectional view showing the flood wall / support pile 2 of FIG. 1 and its interior. FIG. [Figure 4] FIG. 3 is a view similar to FIG. 2 showing an embodiment of the wear-resistant and rust-preventive coating material for a seawall 1 according to the present invention, in which the seawall 1 is provided with a coating RP made of a heavy-duty rust-preventive material. [Diagram 5] FIG. 3 is a view similar to FIG. 2, showing a modification of the wear-resistant and rust-preventive covering material for the seawall 1 of the present invention, in which the covering material is made of reinforced concrete. [Figure 6]FIG. 3 is a view similar to FIG. 2 showing another embodiment of the impact-resistant or impact-absorbing, abrasion-resistant and rust-preventive coating material for a seawall 1 of the present invention, in which the seawall is provided with a coating RU made of impact-resistant or impact-absorbing material. [Figure 7] This is a top view of the elevation above ground below the upper end of the seawall / support pile 2 at the connection portion of adjacent seawall / support pile groups of the seawall 1 of the present invention by the watertight joint 20 and its surrounding area. [Figure 8] 8(A) is an enlarged top view of the connection between adjacent flood wall / support pile groups in FIG. 7 by a waterproof joint 20, and (B) is an enlarged schematic cross-sectional view of the waterproof joint member (waterstop sheet 21) in (A). [Figure 9] FIG. 8 is a view similar to FIG. 7 relating to a modified example in which pile bodies having a quadrangular (rectangular) cross-sectional shape are used as the flood barrier / support piles 2 of the flood embankment 1 of the present invention. [Figure 10] 8(A) and 8(B) showing a modified example in which pile bodies having a quadrangular (rectangular) cross-sectional shape are used as the flood barrier / support piles 2 of the flood embankment 1 of the present invention. FIG. [Figure 11] 7 and 8, but of a modified example in which protective work 23 for the watertight joint 20 is added to the connection portion of the watertight joint 20 between adjacent groups of flood barriers and support piles in FIG. [Figure 12] 9 and 10, but of a modified example in which protective work 23 for the watertight joint 20 is added to the connection portion of the watertight joint 20 between adjacent groups of flood barriers and support piles in FIG. [Figure 13] This figure shows various dimensions and joints 10 which are connecting members connecting the flood barrier / support piles 2 to each other, in comparison with FIG. [Figure 14] This figure shows various dimensions in comparison with FIG. 2, and adds a watertight joint 20 which is a connecting member between adjacent groups of flood barriers and supporting piles. [Figure 15] This figure adds arrows indicating the various forces assumed during an earthquake before the tsunami strikes, in comparison to Figure 2. [Figure 16] This figure adds arrows indicating the various forces anticipated during a tsunami to Figure 2. [Figure 17]This figure adds arrows indicating the various forces assumed when aftershocks and tsunami wave forces are superimposed on Figure 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment and modifications of the present invention will be described with reference to the accompanying drawings. Note that the present invention is not limited to the following embodiment and modifications.

[0011] Fig. 1 is a front view (longitudinal cross-sectional view) including a flood wall / support pile 2, which constitutes the basic structural framework of a seawall 1 according to an embodiment of the present invention, as well as ground G and supporting ground B. Fig. 2 is a side view (transverse cross-sectional view) including the flood wall / support pile 2, which constitutes the basic structural framework of a seawall 1, as well as ground G and supporting ground B. The tide embankment 1 has an outer side facing the sea and an inner side facing the land, and prevents seawater and the like from infiltrating into the inner side of the embankment. Note that the outer side of the tide embankment 1 may also face the river, etc. Here, the seaward side of the seawall 1 is referred to as the front, and the landward side as the rear.

[0012] The seawall 1 shown in Figures 1 and 2 has as its basic structural body the seawall / support pile 2, which serves as both a seawall structure and a support pile structure and is a common series of upper and lower structures, from the top end of the aboveground exposed structure SU to the bottom end of the underground buried structure SD that reaches the supporting ground B. The seawall 1 has multiple flood walls and supporting piles 2 as the basic structural body. The flood walls and supporting piles 2 are pile bodies extending from above the ground surface GS to the supporting ground B, and basically have a circular or quadrangular (rectangular) cross-sectional shape in the embodiment of Figures 1 and 2. Incidentally, the ground surface GS is a surface having the ground surface elevation of the original ground (original ground surface). The multiple flood barrier / support piles 2 arranged and joined to each other in the flood embankment 1 are not distinguished between flood barrier and support pile sections, and are a common series of pile bodies that serve both the flood barrier structure and the support pile structure from the top end of the above-ground exposed structure SU to the bottom end of the underground buried structure SD that reaches the supporting ground B, and therefore adjacent flood barrier / support piles 2 arranged and joined to each other in the flood embankment 1 are basic structural bodies that are the same length or approximately the same length. As a result, adjacent flood barrier / support piles 2 arranged and joined to each other in the floodwall 1 have similar natural vibration characteristics and no significant phase difference occurs between their natural vibration characteristics.Therefore, in the floodwall 1, it is possible to prevent or suppress an increase in stress inside the piles due to the phase difference between the natural vibration characteristics of adjacent flood barrier / support piles 2 arranged and joined to each other.

[0013] The seawall 1 has a flood wall / support pile group, which is made up of flood wall / support piles 2 joined together and arranged in a row, as a structural group. Here, in the embodiment shown in Fig. 1, the flood wall / support piles 2 in the flood wall / support pile group, which is made up of flood wall / support piles 2 joined together with joints 10 and arranged in a row, are shown up to the fifth flood wall / support pile 2, but the number of flood wall / support piles 2 constituting the flood wall / support pile group is not limited to five. The number of flood wall / support piles 2 constituting the flood wall / support pile group is appropriately set within the range of the number of piles for which safety has been confirmed against all of the loads during an earthquake, the loads during a tsunami, and the loads when aftershocks and tsunami wave forces are superimposed, as a result of carrying out verification and evaluation by analysis, etc. Thus, the seawall 1 of the embodiment shown in Figure 1 comprises seawall-cum-support pile groups formed by joining and arranging seawall-cum-support piles 2 together. The number of joints of the seawall-cum-support piles 2 constituting each seawall-cum-support pile group is appropriately set within the range of numbers that have been confirmed to be safe for all loads during an earthquake, loads during a tsunami, and loads when aftershocks and tsunami wave forces are superimposed, as a result of carrying out verification and evaluation through analysis, etc., and the number of joints of the seawall-cum-support piles 2 constituting each of the multiple seawall-cum-support pile groups in the seawall 1 may be the same in all of the seawall-cum-support pile groups, or may be different in some or all of the seawall-cum-support pile groups.

[0014] Part or all of the flood barrier / support pile 2 may be a pile body having a cross-sectional shape other than a circular or square (rectangular) cross-sectional shape only if safety is confirmed as a result of verification and evaluation through analysis, experiments, etc., or part or all of the flood barrier / support pile 2 may be a multi-tube pile body in which a pile body of slightly smaller diameter is inserted just inside a pile body of larger diameter, and these pile bodies of multiple diameters are stacked radially in two, three, four, five, etc. layers to be tightly integrated with each other. The pile axis direction of the flood wall / support pile 2 basically faces up and down, and in many cases is the direction of gravitational acceleration, i.e., the vertical direction. However, depending on the installation environment, ground G, and supporting ground B conditions, the pile axis direction of the flood wall / support pile 2 may not necessarily be vertical. The bottom end of flood wall / bearing pile 2 is designed to reach supporting ground B. In other words, flood wall / bearing pile 2 is designed to reach supporting ground B. Supporting ground B is a ground that has sufficient bearing capacity against earthquake loads, tsunami loads, and superimposed loads of aftershocks and tsunami wave forces.

[0015] FIG. 3 is a central cross-sectional view showing the flood wall / support pile 2 and its interior. From the perspective of ensuring bearing performance, the length from the bottom end of the flood wall / support pile 2 shown in Figures 1 to 3 to the top surface of the supporting ground B (bearing layer surface BS), i.e., the embedded length L1 of the flood wall / support pile 2 into the supporting ground B, should basically be about the diameter D of the flood wall / support pile 2. Here, the embedded length L1 into the supporting ground B may be made shorter or longer than the diameter D of the flood wall / support pile 2 only when, as a result of verification and evaluation by analysis, etc., safety is confirmed in accordance with the characteristics of the supporting ground B and ground G on which the flood wall / support pile 2 is to be installed and the load to be supported, etc., and it may also be made different lengths for some or all of the flood wall / support piles 2 arranged in the longitudinal section direction of the flood embankment 1 (direction perpendicular to the pile axis) as shown in Figure 1. The embedded length L1 of the flood wall / support piles 2 that make up the flood wall / support pile group of the flood wall 1 into the supporting ground B is set appropriately within the range of embedded lengths that have been confirmed to be safe for all loads during earthquakes, loads during tsunamis, and loads when aftershocks and tsunami wave forces are superimposed, as a result of verification and evaluation through analysis, etc. In this regard, the vertical lengths of the flood wall / support piles 2 that make up the flood wall 1 are set so that adjacent flood wall / support piles 2 in the flood wall / support pile group do not differ significantly from each other, so that the natural vibration characteristics of adjacent flood wall / support piles 2 in the flood wall / support pile group do not differ significantly, resulting in a significant increase in stress inside the pile due to the phase difference in the natural vibration characteristics of each other during an earthquake or aftershock.

[0016] A filler 4 is filled inside the lower end L2 of the flood wall / support pile 2 shown in Fig. 3. The filler 4 is preferably a solidifying material, such as reinforced concrete, concrete, or cement milk. The filler 4 in the embodiment shown in Fig. 3 is filled over a filling length L2 that exceeds an embedded length L1 into the supporting ground B. The filler 4 closes off the inside of the lower end L2 of the flood wall / support pile 2, improving the supporting performance at the lower end of the flood wall / support pile 2. Furthermore, inside the flood wall and support pile 2, the upper side of the filling material 4 is filled with liquefied treated soil (solidified treated soil) 6 which has been liquefied by adding cement-based solidifying agents and adjusting the amount of water to excavated soil or replacement ground material from the original ground at the location where the flood wall and support pile 2 is to be constructed. The upper end of the liquefied treated soil 6 reaches the ground surface GS or an adjacent area. The liquefied treated soil 6 is used in a liquefied state during construction so that it spreads densely within the structure to be filled, i.e., the section to be filled within the flood wall and support pile 2, but it has the property of solidifying over time after construction. Filling with liquefied treated soil 6 improves the load-bearing performance of the flood wall and support pile 2. Depending on the characteristics of the supporting ground B and the ground G, and the load to be supported, etc., only if safety is confirmed as a result of carrying out verification and evaluation by analysis, etc., the area of ​​the liquefied treated soil 6 above the filling material 4 may be filled with ground material roughly similar to the strata configuration of the original ground at the position where the flood wall / support pile 2 is to be constructed, or both or one of the filling material 4 and the liquefied treated soil 6 may be omitted, or the respective lengths of the filling material 4 and the liquefied treated soil 6 may be made different from those described above. Only if safety is confirmed as a result of carrying out verification and evaluation by analysis, etc., the installation conditions of the filling material 4 and the liquefied treated soil 6 may be made different from those described above for each flood wall / support pile 2, or for each flood wall / support pile group formed by joining and arranging flood wall / support piles 2 together.

[0017] On the other hand, in the embodiment shown in Figure 3, the area above the liquefied treated soil 6 inside the flood wall and support pile 2 up to the upper end (top) of the flood wall and support pile 2 is made a hollow structure to maximize the seismic resistance of the flood wall and support pile 2 by minimizing the inertial force associated with an earthquake or aftershock, based on the purpose of minimizing the mass of the above-ground exposed structure SU, and a high-strength lid that is integrated with the flood wall and support pile 2 is provided at the upper end of the flood wall and support pile 2, creating an airtight structure that prevents air from entering or leaving the flood wall and support pile 2. As mentioned above, the hollow part of the above-ground exposed structure SU is basically made airtight and hollow in order to make it as light as possible from the standpoint of reducing inertial forces. However, as a result of carrying out an inspection and evaluation using analysis etc. that takes into account the mass, rigidity and strength of the filling material in the hollow part of the above-ground exposed structure SU, it is possible to fill the hollow part within the seawall / support piles 2 that make up the above-ground exposed structure SU with a filling material such as lightweight mortar only when it has been confirmed that the hollow part is safe against all loads, including loads during earthquakes, loads during tsunamis, and loads when aftershocks and tsunami wave forces are superimposed.

[0018] The seawall / support piles 2 of the seawall 1 shown in Figures 1 to 3 are arranged along the coastline and the site inside the seawall to protect the safety of the inside of the seawall from the effects of tsunamis. Taking into consideration the conditions of the installation environment, some or all of the arranged seawall / support piles 2 do not have to be parallel to the coastline, and they may be arranged to surround important facilities on the inside of the seawall to protect the safety of the inside of the seawall from the effects of tsunamis.

[0019] The seawall / support pile 2 of the seawall 1 in the embodiment shown in Figures 1 to 3 is basically exposed above ground, and is an integrated structure that is continuously connected in the vertical direction as a common pile body for the upper structure and lower structure from the upper end of the above-ground exposed structure SU that receives tsunamis, etc. to the lower end of the underground buried structure SD that reaches the supporting ground B, which can be used as both a seawall structure and a support pile structure. 1 to 3, the upper end of the flood wall / support pile 2, which is the basic structural frame of the flood embankment 1, is basically positioned above the ground surface GS. The upper end elevation (upper end height) of the flood wall / support pile 2, which is the basic structural frame of the flood embankment 1, is set to be higher than the assumed maximum water level elevation based on the maximum input tsunami water level elevation WL (maximum input tsunami height) in Fig. 2 for the flood embankment 1 due to the maximum tsunami assumed taking into account ground subsidence due to an earthquake and tidal fluctuations, plus the amount of water level rise due to a high tide, etc. Furthermore, the upper end of the flood wall / support pile 2 is basically positioned above the ground surface GS; however, depending on the ground surface elevation of the original ground, original natural ground, developed ground, improved ground, artificial rock base, raised improved ground, raised artificial rock base, etc. surrounding the flood wall / support pile 2, the upper end of the flood wall / support pile 2 that constitutes the seawall 1 does not necessarily have to be exposed above the ground surface, provided that verification and evaluation through analysis, etc. has confirmed safety against all loads during earthquakes, loads during tsunamis, and loads when aftershocks and tsunami wave forces are superimposed.

[0020] In the embodiment shown in Fig. 4, the flood wall / support pile 2 and the joint 10, which are the structural body of the flood wall 1, are provided with a coating made of a heavy-duty rust-preventive material (coating made of a heavy-duty rust-preventive material) RP for the purpose of abrasion resistance and rust prevention (embodiment relating to a coating body). The coating RP made of a heavy-duty rust-preventive material in the embodiment shown in Fig. 4 is of a nature that gives the flood wall / support pile 2 and the joint 10 the effects of abrasion resistance and rust prevention. Here, with regard to the coating RP made of a heavy-duty rust-preventive material, after safety has been confirmed as a result of an evaluation taking into consideration the environmental conditions, importance, required years of service, etc., rust prevention processing using a material other than a heavy-duty rust-preventive material may be applied to the flood wall / support pile 2 and the joint 10. Furthermore, when the flood wall / support piles 2 and joints 10, which form the structural body of the seawall 1, are provided with a covering RP made of a heavy-duty rust-proofing material as shown in Figure 4 for the purposes of wear resistance and rust prevention, since the mass of the covering RP is sufficiently small compared with the mass of the flood wall / support piles 2 and joints 10, which form the structural body of the seawall 1, the covering RP made of a heavy-duty rust-proofing material can provide wear resistance and rust prevention to the structural body of the seawall 1, and also has the advantage of minimizing the impact on the inertial force of the structural body of the seawall 1 due to earthquakes or aftershocks.

[0021] In addition, in the modified example of covering material shown in Figure 5, the flood wall / support piles 2 and joints 10, which form the structural frame of the seawall 1, are provided with covering RC made of reinforced concrete for the purpose of wear resistance and rust prevention only when safety is confirmed as a result of carrying out verification and evaluation through analysis etc. (modified example of covering material). The covering RC made of reinforced concrete is of a nature that gives the flood wall / support piles 2 and joints 10, which form the structural frame of the seawall 1, wear resistance and rust prevention effects. Here, the basic principle of the seawall 1 is that the specifications are such that the structural body, the flood wall / support piles 2 and joints 10, themselves can exhibit the necessary earthquake resistance and tsunami resistance. The portions of the flood wall / support piles 2 and joints 10 of the flood wall 1 that are exposed above the ground surface GS are designed to have sufficient resistance and structural strength in the flood wall / support piles 2 and joints 10 themselves, so that the flood wall / support piles 2 and joints 10 themselves have sufficient earthquake resistance and tsunami resistance that does not cause significant leakage when tsunamis repeatedly strike. In other words, in the seawall 1, the seawall / support piles 2 and joints 10, which are the structural body expected to provide structural strength, are themselves designed to be capable of withstanding the various external forces that occur during earthquakes, tsunamis, and the superposition of aftershocks and tsunami wave forces, and are designed to have specifications that enable them to exhibit sufficient earthquake and tsunami resistance to fully resist various external forces. In this way, the basic specifications for the seawall 1 are to be designed to be able to withstand, with sufficient resistance and a safety margin, all of the loads caused by earthquakes, tsunamis, and the combined loads of aftershocks and tsunami wave forces, thanks to the seawall / support piles 2 and joints 10, which serve as the structural body expected to have sufficient structural strength. However, when considering providing a covering RC made of relatively heavy reinforced concrete, as shown in Figure 5, for the purposes of wear resistance and rust prevention, it is acceptable to provide a covering RC made of reinforced concrete for the seawall / support piles 2 and joints 10 for the purposes of wear resistance and rust prevention of the seawall / support piles 2 and joints 10, which form the structural body of the seawall 1 and have sufficient structural strength and water-stopping capabilities, only if safety is confirmed as a result of inspection and evaluation through analysis, etc. that takes into account the effects of the added weight and added inertial force equivalent to the mass of the covering RC. In addition, the covering RC made of reinforced concrete, which is designed to be wear-resistant and rust-proof, also has an additional shock-absorbing effect that further improves the safety of the flood wall / support piles 2 and joints 10, which form the structural body of the seawall 1, against the expected load of drifting debris.

[0022] Furthermore, in another embodiment of the covering material shown in Fig. 6, the flood wall / support piles 2 and joints 10, which are the structural body of the flood embankment 1, are provided with a covering RU made of an impact-resistant or impact-absorbing material for the purposes of impact resistance or impact absorption, abrasion resistance, and rust prevention (another embodiment of the covering material). The impact-resistant or impact-absorbing material shown as the covering RU in Fig. 6 for the flood embankment 1 is, for example, polyurea. The covering RU made of impact-resistant or impact-absorbing material shown in Figure 6 has properties that give the seawall 1 impact resistance or impact absorption, abrasion resistance, and rust prevention effects, and further improves the safety of the seawall 1 against anticipated drifting object loads. Here, when applying a covering RU made of an impact-resistant or impact-absorbing material as shown in Fig. 6 to the flood wall / support piles 2 and joints 10 that form the structural framework of the flood embankment 1 for the purposes of impact resistance or impact absorption, abrasion resistance, and rust prevention, it is preferable that the mass of the covering RU is sufficiently smaller than the mass of the flood wall / support piles 2 and joints 10 that form the structural framework of the flood embankment 1. For example, a covering RU that uses polyurea as an impact-resistant or impact-absorbing material has a relatively small mass, and therefore can provide the structural framework of the flood embankment 1 with impact resistance or impact absorption, abrasion resistance, and rust prevention effects, and also has the advantage that the effect of the inertial force of the structural framework of the flood embankment 1 due to an earthquake or aftershocks is relatively minor. As shown in FIG. 6, the covering RU made of an impact-resistant or impact-absorbing material may be made of polyurea. However, to further improve safety against anticipated drifting object loads, an appropriate impact-resistant or impact-absorbing material other than polyurea may be used as the covering RU, or an impact-resistant or impact-absorbing material that is a combination of polyurea and another appropriate material may be used.

[0023] On the other hand, only when safety is confirmed as a result of verification and evaluation by analysis, etc., the covering applied to the flood wall / support piles 2 and joints 10, which are the structural body of the seawall 1, may be a covering that follows the surface of the flood wall / support piles 2 and joints 10 (similar to painting), or may be a thick plate or plate that covers the flood wall / support piles 2 and joints 10. If necessary, the buried structure SD may also be covered with a heavy-duty rust-proofing material, reinforced concrete, or an impact-resistant or impact-absorbing material. Cathodic protection may also be used as a method of rust prevention other than those mentioned above.

[0024] Fig. 7 is a top view of the connection part of adjacent groups of flood barriers and supporting piles related to the seawall 1 by the waterproof joint 20 and the surrounding area, below the upper end of the flood barrier and supporting piles 2 and above ground level. Also, Fig. 8(A) shows an enlarged top view of the connection part of adjacent groups of flood barriers and supporting piles in Fig. 7 by the waterproof joint 20, and Fig. 8(B) shows an enlarged schematic cross-sectional view of the waterproof joint member (waterstop sheet 21) in Fig. 7 and Fig. 8(A). The embankment 1 of the embodiment shown in Figures 7, 8(A) and 8(B) comprises a plurality of flood wall / support pile groups each formed by arranging flood wall / support piles 2 side by side and joining them to each other with joints 10. That is, the embankment 1 comprises flood wall / support pile groups GR1, GR2, .... In addition, the flood wall / support pile groups GR1, GR2, ... are provided with water stop joints 20 at the connection parts of adjacent flood wall / support pile groups. That is, the embankment 1 of the embodiment shown in Figures 7, 8(A) and 8(B) comprises a plurality of flood wall / support pile groups each formed by arranging flood wall / support piles 2 side by side and joining them to each other with joints 10 in the longitudinal cross-sectional direction (direction perpendicular to the pile axes), and is provided with water stop joints 20 having water stoppage properties, pressure resistance and relative displacement tracking properties at the connection parts of adjacent flood wall / support pile groups. In this way, in the seawall 1, at the connection between the seawall and support pile group GRi (i is a natural number and is the i-th seawall and support pile group) and the seawall and support pile group GRi+1 (the i+1th seawall and support pile group), a watertight joint 20 is provided which has water-stopping properties, pressure resistance and flexibility and can follow the relative displacement even if the seawall and support pile group GRi is displaced relative to the seawall and support pile group GRi+1. Therefore, in the seawall 1, during an earthquake, tsunami, or when aftershocks and tsunami wave force are superimposed, the waterstop joint 20, which has waterstopping properties, pressure resistance, and relative displacement tracking capabilities, absorbs the relative displacement at the connection between the seawall / support pile groups GRi and GRi+1, making it possible to release earthquake energy, etc. In other words, in the seawall 1, the seawall / support pile groups GRi and GRi+1, which are made up of seawall / support piles 2 joined to each other with joints 10 and arranged side by side in the longitudinal section direction (direction perpendicular to the pile axes), are connected by the waterstop joint 20, which has waterstopping properties, pressure resistance, and relative displacement tracking capabilities, so that the entire structural body can maintain a high level of tsunami resistance and release earthquake energy, etc. As described above, the seawall 1 comprises a plurality of seawall / support pile groups each of which is made up of seawall / support piles 2 joined together with joints 10 and arranged in parallel, and which serve as the basic structural body common to the upper and lower structures and can be used for both the seawall structure and the support pile structure. Adjacent seawall / support pile groups are connected by watertight joints 20 which have watertightness, pressure resistance and the ability to follow relative displacement. As a result, in the seawall 1, it is possible to increase the load distribution effect of the basic structural body and the local load distribution effect of the supporting ground against loads during earthquakes, tsunamis, and the combined loads of aftershocks and tsunami wave forces, and to prevent or suppress concentrated load transfer to some of the piles and supporting ground.Since this makes it possible to reduce the load burden per each pile that makes up the structural body and the local load burden on the supporting ground, it is possible to increase the load capacity that can be borne by the structural body as a whole.

[0025] The flood wall / support pile group GRi (i is a natural number, the i-th flood wall / support pile group) is formed by connecting flood wall / support piles 2 to each other with joints 10 and arranging them in a row so that the extension in the longitudinal section (the length in the direction perpendicular to the pile axis) is an extension that has been confirmed as safe against all loads during an earthquake, loads during a tsunami, and loads when aftershocks and tsunami wave forces are superimposed, as a result of inspection and evaluation through analysis, etc., for each target site. Similarly, the flood wall / support pile group GRi+1 (the i+1th flood wall / support pile group) is formed by connecting flood wall / support piles 2 to each other with joints 10 and arranging them in a row so that the extension in the longitudinal section (the length in the direction perpendicular to the pile axis) is an extension that has been confirmed as safe against all loads during an earthquake, loads during a tsunami, and loads when aftershocks and tsunami wave forces are superimposed, as a result of inspection and evaluation through analysis, etc., for each target site. In addition, the longitudinal section extension (length perpendicular to the pile axis) of each flood wall / support pile group GR1, GR2, etc. may be of a type that has been confirmed to be safe against earthquake loads, tsunami loads, and superimposed loads of aftershocks and tsunami wave forces as a result of verification and evaluation through analysis, etc. for each target site, and is not limited to one type of extension.

[0026] As shown in Fig. 7, flood wall and support pile group GR1 has a plurality of central flood wall and support piles 2A, a first end flood wall and support pile 2B joined to one end side of GR1, and a second end flood wall and support pile 2C joined to the other end side of GR1. Similarly, flood wall and support pile group GR2 has a plurality of central flood wall and support piles 2A, a first end flood wall and support pile 2B joined to one end side of GR2, and a second end flood wall and support pile 2C joined to the other end side of GR2. The following describes flood wall / bearing pile groups GR1 and GR2. This description also applies to flood wall / bearing pile groups GR2 and GR3, GR3 and GR4, ... other than the flood wall / bearing pile groups GR1 and GR2 shown in Fig. 7. In other words, the following description of flood wall / bearing pile groups GR1 and GR2 also applies to the generalized notations GRi and GRi+1 (i is a natural number, and the i-th flood wall / bearing pile group and the i+1-th flood wall / bearing pile group) of adjacent flood wall / bearing pile groups. The central flood wall and support pile 2A in the flood wall and support pile group GR1 has a pair of male joint 10M and female joint 10F as the joint 10. On the other hand, the first end flood wall and support pile 2B in the flood wall and support pile group GR1 has one male joint 10M as the joint 10. One side of a water stop joint 20 is installed in the first end flood wall and support pile 2B. On the other hand, the second end flood wall and support pile 2C in the flood wall and support pile group GR2 has one female joint 10F as the joint 10. One side of a water stop joint 20 is also installed in the second end flood wall and support pile 2C. Here, the male and female joints 10M and 10F are collectively referred to as joints 10. The male joint 10M has a T-shaped cross section perpendicular to the pile axis and is a long body that extends along the pile axis direction (up and down direction) of the flood wall / support pile 2. The female joint 10F has a "C" shaped cross section in the direction perpendicular to the pile axis and is an elongated body that extends along the pile axial direction (vertical direction) of the flood wall / support pile 2, just like the male joint 10M, so that the male joint 10M can be inserted from the upper end or lower end of the flood wall / support pile 2 and slid in the pile axial direction (vertical direction) to accept it. When the female joint 10F accepts the male joint 10M, it prevents the male joint 10M from coming off in the direction perpendicular to the pile axis. In each of the flood wall / support pile groups GR1 and GR2 shown in Figure 7, adjacent central flood wall / support piles 2A are joined by inserting one male joint 10M into the other female joint 10F from the upper end or lower end side of the flood wall / support pile 2A and sliding them in the pile axial direction (up and down direction). By repeating this process as necessary to join the piles, the central side excluding the first end and second end in each of the flood wall / support pile groups GR1 and GR2 is constructed. In addition, the first end flood wall / support pile 2B in each of the flood wall / support pile groups GR1 and GR2 is constructed by inserting the male joint 10M into the female joint 10F of the central flood wall / support pile 2A located at one end and sliding it in the pile axial direction (up and down) to join them, thereby constructing the first end in each of the flood wall / support pile groups GR1 and GR2. Furthermore, the second end flood wall / support pile 2C in each of the flood wall / support pile groups GR1 and GR2 is constructed by inserting the male joint 10M of the central flood wall / support pile 2A arranged at the other end into the female joint 10F and sliding it in the pile axial direction (up and down) to join the second end flood wall / support pile 2C in each of the flood wall / support pile groups GR1 and GR2. The basic principle of the flood wall / support pile groups GR1, GR2, ... is that each flood wall / support pile group is formed by repeatedly performing the inter-pile joints at the first end, central side, and second end within each group as described above, thereby joining the flood wall / support piles 2 together with joints 10 and arranging them in a continuous line. In the seawall 1, adjacent flood wall / support piles 2 in each flood wall / support pile group have joints 10, and are joined to each other by combining these joints 10. Therefore, as described above, joining of flood wall / support piles 2 with sufficient strength and water-stopping properties can be easily realized. Note that, as a method of joining the floodwall-cum-support piles 2 within each floodwall-cum-support pile group, an embodiment of the joint 10 in which the male joint 10M and the female joint 10F are so-called PT joints is shown here; however, as a result of carrying out verification and evaluation through analysis, etc., the shape, structural type and joining method of some or all of the joints 10 within each floodwall-cum-support pile group may use joint structures such as LT joints, PP joints, HH joints or other types of joining methods, as long as safety is confirmed for all loads during earthquakes, loads during tsunamis, and loads when aftershocks and tsunami wave forces are superimposed.

[0027] The joints 10 are fixed by welding or the like to the peripheral surface (outer surface, side surface) of the flood wall / support pile 2 along the pile axial direction (up-down direction) of the flood wall / support pile 2. The joints 10 serve as a joining member between each pile in the flood wall / support pile group and as a water-stopping member that does not cause significant leakage. The upper end of joint 10 is adjacent to the upper end of flood wall / support pile 2. Joint 10 is installed continuously from the elevation of the upper end of the adjacent flood wall / support pile 2 along the pile axis direction to an elevation underground, and the lower end of joint 10 is set at a depth underground sufficient to prevent boiling and piping from the ground in the event of a tsunami, and at a depth underground that does not block the slow seepage of groundwater from the inside of the embankment to the outside of the embankment below the lower end of joint 10 under normal circumstances. In this way, joints 10 are installed continuously from the upper end elevation of the above-ground exposed structure SU of the flood wall and support pile 2 to a depth underground sufficient to prevent boiling and piping, and to a depth underground that does not block the slow-speed infiltration of groundwater from the inside of the embankment to the outside of the embankment deeper than the lower end of joint 10 under normal conditions.Therefore, the basic principle is that the underground installation range of joints 10 of the flood wall and support pile 2 should be appropriately set, taking into consideration both its contribution to preventing boiling and piping due to tsunamis attacking from the outside of the embankment, and its contribution to suppressing a rise in the groundwater level on the inside of the embankment under normal conditions. Here, the prevention of boiling and piping is also contributed to by the embankment inner improvement body 30 and the embankment outer improvement body 33 shown in Figures 2 and 4 to 6 (both of which will be described in detail later), and therefore, at the joints between the seawall / support piles 2, safety against boiling and piping is further improved by using a combination of the joints 10, the embankment inner improvement body 30 and the embankment outer improvement body 33 in combination. Therefore, the length in the pile axial direction (up and down) of the joint 10, which is the connecting member between the flood wall and support piles 2, i.e., the length in the pile axial direction of the joint 10 which is installed continuously from the upper end elevation of the adjacent flood wall and support pile 2 to which the joint 10 is attached along the pile axial direction, has been appropriately set within the range of lengths which have been confirmed to be safe for all loads during earthquakes, loads during tsunamis, and loads when aftershocks and tsunami wave forces are superimposed, taking into account the installation of the inner embankment improvement body 30 and the outer embankment improvement body 33, from the perspectives of both preventing boiling and piping in the event of a tsunami attack, and suppressing the rise in the groundwater level inside the embankment under normal circumstances.

[0028] As shown in Figures 7 and 8(A), in order to ensure watertightness without significant leakage within the cross section of the joint 10 in the direction perpendicular to the pile axis, the joint filler 10L having sufficient strength and a sufficiently small coefficient of permeability (water permeability) is filled from the upper end to the lower end of the joint 10 (female joint 10F receiving male joint 10M). The joint filler 10L is, for example, mortar. In the cross section of the joint 10 perpendicular to the pile axis, unconsolidated joint filler 10L is poured densely from the top to the bottom of the joint 10, and the joint filler 10L hardens and solidifies by itself over time, thereby forming a water-stopping structure that does not cause significant leakage from the joint 10. Mortar can be used as the joint filler 10L, but as a result of evaluation by experiments, analyses, etc., a filler other than mortar may also be used as long as it is confirmed to be safe enough to ensure watertightness without causing significant leakage.

[0029] The seawall 1 may be composed of one seawall / support pile group GR1 only if safety is confirmed against all loads during earthquakes, loads during tsunamis, and loads when aftershocks and tsunami wave forces are superimposed as a result of verification and evaluation by analysis, etc., depending on the purpose, environmental conditions, and loading conditions, etc. Furthermore, in the seawall / support pile groups GR1, GR2, ..., the seawall / support piles 2 that join each other within each group may be arranged in a curved or zigzag shape when viewed from above, unlike the straight line shown in Figure 7, only if safety is confirmed as a result of verification and evaluation by analysis, etc. Furthermore, the arrangement shape of the seawall / support piles 2 that join each other within each group when viewed from above may be different from each other in the seawall / support pile groups GR1, GR2, ... within the range where safety is confirmed as a result of verification and evaluation by analysis, etc.

[0030] The waterproof joint 20 shown in Figures 7 and 8(A) and (B) is a connecting member that has watertightness, pressure resistance, and relative displacement tracking properties for adjacent groups of flood barrier / support piles, and is intended to absorb the relative displacement between each group of flood barrier / support piles caused by earthquake loads, tsunami loads, and loads caused by the superposition of aftershocks and tsunami wave forces, release the generated stress, and ensure watertightness and pressure resistance between each group of flood barrier / support piles against repeated tsunami attacks. The upper end of waterstop joint 20 is adjacent to the upper end of flood wall / support pile 2 located at the joint of adjacent flood wall / support pile groups. Waterstop joint 20 is installed continuously from the elevation of the upper end of flood wall / support pile 2 located at the joint of adjacent flood wall / support pile groups along the pile axial direction to a sufficient depth underground and to an appropriate depth elevation that does not block the slow-speed seepage of groundwater from the inside of the embankment to the outside of the embankment below the lower end of waterstop joint 20 under normal conditions. In this way, the watertight joints 20 are installed continuously from the upper end elevation of the exposed above-ground structure SU of the floodwall / support pile 2 located at the connection point of adjacent floodwall / support pile groups, to a sufficient depth of the underground buried structure SD common to the upper and lower series, and to a depth that does not block the slow-speed infiltration of groundwater from the inside of the embankment to the outside of the embankment deeper than the lower end of the watertight joints 20 under normal conditions.Therefore, it is basic that the underground installation range of the watertight joints 20 of the floodwall 1 should be set appropriately, taking into consideration both its contribution to preventing boiling and piping and its suppression of a rise in the groundwater level inside the embankment under normal conditions. Here, the prevention of boiling and piping is also contributed to by the embankment inner improvement body 30 and the embankment outer improvement body 33 shown in Figures 2 and 4 to 6 (both of which will be described in detail later), and therefore, by using a combination of the waterstop joint 20, the embankment inner improvement body 30 and the embankment outer improvement body 33 at the connection points of adjacent flood wall / support pile groups, safety against boiling and piping is further improved. Therefore, the length in the pile axial direction (up and down) of the watertight joint 20 provided as a connecting member for adjacent groups of floodwall and support piles, i.e., the length in the pile axial direction of the watertight joint 20 which is installed continuously from the upper end elevation of the adjacent floodwall and support pile 2 along the pile axial direction to the ground, has been appropriately set within the range of lengths that have been confirmed to be safe for all loads during earthquakes, loads during tsunamis, and loads when aftershocks and tsunami wave forces are superimposed, taking into account the installation of the inner embankment improvement body 30 and the outer embankment improvement body 33 from the standpoints of both preventing boiling and piping in the event of a tsunami attack, and suppressing the rise in the groundwater level inside the embankment under normal circumstances, as a result of carrying out verification and evaluation through analysis, etc.

[0031] The waterstop joint 20 has a waterstop sheet 21 and a gripping member 22. The waterstop sheet 21 constituting the waterstop joint 20 has properties of waterstopping, pressure resistance, and relative displacement tracking, and is composed of a shading sheet 21A having a shading property, a waterproof sheet 21B having a water shielding property, and a pressure-resistant sheet 21C having sufficient pressure resistance, as shown in Fig. 8(B). Here, the shading sheet 21A, the watershielding sheet 21B, and the pressure-resistant sheet 21C are all flexible members, so the waterstop sheet 21 composed of the shading sheet 21A, the watershielding sheet 21B, and the pressure-resistant sheet 21C as shown in Fig. 8(B) has flexibility capable of tracking the relative displacement of the connecting parts of the adjacent flood wall / support pile groups, in addition to waterstopping and pressure resistance. The gripping member 22 of the waterproof joint 20, which is a connecting member for adjacent flood wall / support pile groups, is fixed to the flood wall / support pile 2 at the connecting portion in the flood wall / support pile groups GR1, GR2, ... while gripping the water stop sheet 21. The water stop sheet 21 of the water stop joint 20 is installed for the purpose of enabling the seawall 1 to maintain its ability to follow the relative displacement of the joints of the groups of seawall and support piles GR1, GR2, ..., as well as its water stop and pressure resistance, against the loads during earthquakes, tsunamis, and the loads during the superposition of aftershocks and tsunami wave forces. For this purpose, the water stop sheet 21 is installed at the joints of adjacent groups of seawall and support piles with sufficient member length and extra length in the direction perpendicular to the pile axis, as shown in Figures 7 and 8(A). In addition, the water stop sheet 21 shown in Figure 8(B) is made entirely of flexible members, so that it can follow the relative displacement of the joints of the adjacent groups of seawall and support piles, and even if the member length of the water stop sheet 21 installed between each group in the direction perpendicular to the pile axis is long, it can be compactly bent to be wavy when viewed from above.

[0032] As shown in Figures 7 and 8(A), the seawall 1 is characterized in that it is provided with a waterstop joint 20 located on the inside of the embankment from the center line CL in a cross section perpendicular to the pile axis of the seawall / support pile 2 at the connection part of adjacent seawall / support pile groups. Therefore, the seawall 1 is basically provided with the waterstop joint 20 at a position sufficiently further inward than the tangent line TAN of the outer surface of the seawall / support pile 2 on the outside of the embankment. The watertight joint 20 of the seawall 1 is located in such a position that, even if driftwood caused by a tsunami (considered as the anticipated driftwood load) approaches the watertight joint 20, the anticipated driftwood load is received by the outer surface of the outside of the seawall / support pile 2, and is prevented from coming into direct contact with the watertight joint 20. That is, as shown in Figures 7 and 8(A), the seawall 1 is characterized by having a watertight joint 20 located on the inside of the embankment relative to the center line CL in the cross section perpendicular to the pile axis of the first end seawall-cum-support pile 2B and the second end seawall-cum-support pile 2C which are associated with the connection between GRi and GRi+1 in the seawall-cum-support pile groups GR1, GR2, ... and therefore the seawall 1 is provided with a watertight joint 20 located sufficiently further inward than the tangent line TAN of the outer surface on the outside of the embankment. Due to the feature that the watertight joint 20 is located at the connection between adjacent flood wall and support pile groups GRi and GRi+1, the anticipated drifting object load from the sea side is supported by the structural strength of the front first end flood wall and support pile 2B and the second end flood wall and support pile 2C, and care can be taken to ensure that the anticipated drifting object load does not come into direct contact with the watertight joint 20, thereby increasing the reliability of maintaining watertightness without causing significant leakage even in the event of repeated tsunamis. Furthermore, because the seawall 1 has the feature of having the waterstop joint 20 in such a position, when it becomes unnecessary to install a heavy additional external component on the outside of the embankment to prevent the anticipated drifting object load from coming into direct contact with the waterstop joint 20, the above-ground exposed structure SU of the seawall 1 becomes the lightest, which can contribute to reducing the inertial force of the seawall 1 during an earthquake and improving its earthquake resistance, as well as improving its tsunami resistance by reducing the inertial force of the seawall 1 when aftershocks and tsunami wave forces are superimposed.

[0033] 7 and 8(A) and (B) of the embodiment of the waterproof joint 20 includes a double waterproof sheet 21. In this way, the waterproof joint 20 includes a plurality of overlapping waterproof sheets 21 at the connection portion of the adjacent flood wall / support pile groups GR1 and GR2, thereby increasing the reliability of the waterproof function (waterstop performance). The connections between the other adjacent flood wall / support pile groups GR2 and GR3, GR3 and GR4, ..., i.e., the connections between GRi and GRi+1 in the generalized notation, are also similarly connected by watertight joints 20. Furthermore, only if safety is confirmed as a result of verification and evaluation through experiments, analyses, etc., waterstop joints 20 made of a waterstop material of a type different from the waterstop sheet 21 of the embodiment shown in Figures 7 and 8(A) and (B) that has waterstop properties, flexibility and sufficient pressure resistance against repeated tsunamis may be used between some or all of the multiple flood wall / support pile groups GR1, GR2, ..., and waterstop joints 20 in a number different from the case where two waterstop sheets 21 of the embodiment shown in Figures 7 and 8(A) and (B) are used (for example, when three or more waterstop sheets 21 are used) may be used between some or all of the multiple flood wall / support pile groups GR1, GR2, ....

[0034] In the embodiment of the waterproof joint 20 shown in Figures 7 and 8(A), the double waterproof sheets 21 are basically made of the same components. As shown in Figure 8(B), the waterproof sheet 21 has a structure in which a light-shielding sheet 21A having light-shielding properties, a water-shielding sheet 21B having water-shielding properties, and a pressure-resistant sheet 21C having sufficient pressure-resistant strength are layered. Here, the light-shielding sheet 21A has a property of blocking external light, the water-shielding sheet 21B has a property of not allowing water to pass through, and the pressure-resistant sheet 21C has a property of being pressure-resistant against tsunami wave pressure. In the embodiment of the waterproof sheet 21 shown in FIG. 8(B), a waterproof sheet 21B and pressure-resistant sheets 21C, 21C arranged in double layers are sandwiched between light-shielding sheets 21A, 21A on the outer and inner sides of the bank. The water-stopping sheet 21 is designed to be safe based on the usage environment, tsunami wave pressure conditions, etc., and as a result of verification and evaluation through experiments, analysis, etc., the type, thickness, number, etc. of each of the shading sheet 21A, water-shielding sheet 21B, and pressure-resistant sheet 21C that make up the water-stopping sheet 21 are set within the range of specifications whose safety has been confirmed. Here, depending on the conditions such as tsunami wave pressure, as a result of carrying out verification and evaluation through experiments and analyses, etc., and within the range of specifications for which safety has been confirmed, it may be possible to use a pressure-resistant sheet 21C in a multi-layer arrangement different from the case where the pressure-resistant sheet 21C of the embodiment shown in Figure 8(B) in the water-stopping sheet 21 in Figure 8(A) is used in a double-layer arrangement (for example, the pressure-resistant sheet 21C is used in a triple or more layer arrangement), or the water-shielding sheet 21B in the water-stopping sheet 21 may be used in a double or more layer arrangement, or the shading sheets 21A arranged on the outer and inner sides of the embankment in the water-stopping sheet 21 may each be used in a double or more layer arrangement. In addition, the water-stopping sheet 21, which is composed of a shading sheet 21A, a water-shielding sheet 21B, and a pressure-resistant sheet 21C, uses shading sheet 21A, water-shielding sheet 21B, and pressure-resistant sheet 21C whose safety has been confirmed through performance confirmation tests, etc. against anticipated weather conditions and tsunami wave pressure, etc., and therefore has the properties of being water-stopping and pressure-resistant against repeated tsunamis. The water stop sheet 21 is set to have a water stop sheet structure in which the shading sheet 21A and the water shielding sheet 21B have sufficient elongation performance margin to accommodate the elongation of the pressure-resistant sheet 21C when the pressure-resistant sheet 21C exerts its pressure-resistant strength against the tsunami wave pressure. In other words, the shading sheet 21A and the water shielding sheet 21B in the water stop sheet 21 have a property that allows them to follow an elongation rate that is sufficiently larger than the elongation rate when the pressure-resistant sheet 21C exerts its pressure-resistant strength while maintaining their shading and water shielding properties.

[0035] As shown in Figures 7 and 8(A) and (B), the waterstop sheet 21 in the waterstop joint 20 is a waterstop member formed by overlapping a light-blocking sheet 21A having light-blocking properties, a water-proof sheet 21B having water-blocking properties, and a pressure-resistant sheet 21C having sufficient pressure-resistant strength, and is installed on each of the first end flood wall and support piles 2B and each of the second end flood wall and support piles 2C of the flood wall and support pile groups GR1, GR2, ... by means of gripping members 22 (here, bolts, gripping plates, etc.). The water stop sheet 21 is a water stop member having water stop properties, pressure resistance, and ability to follow relative displacement, and when the length of the water stop sheet 21 in the direction perpendicular to the pile axis is set long so that it can follow the relative displacement of the connecting parts in the flood wall / support pile groups GR1, GR2, ... of the flood embankment 1, the water stop sheet 21 is installed by being bent compactly in a zigzag shape when viewed from above. In this case, since the shading sheet 21A, the water shielding sheet 21B, and the pressure resistant sheet 21C are all flexible, the water stop sheet 21 formed by stacking the required number of these sheets also has flexibility. Therefore, even if the connecting parts of the flood wall / support pile groups GR1, GR2, ... are displaced relatively due to earthquake loads, tsunami loads, and superimposed loads of aftershocks and tsunami wave forces, the waterstop sheet 21 in the waterstop joint 20 can reliably follow the relative displacement because a length that is sufficient to accommodate the relative displacement plus some extra length has been set in advance based on the results of verification and evaluation through analysis, etc. As shown in Fig. 8(B), the water stop sheet 21 has a water shielding sheet 21B and a pressure resistant sheet 21C as its constituent members, and therefore can exhibit water stoppage performance without causing significant leakage against repeated tsunamis. Furthermore, as shown in Fig. 8(B), the water stop sheet 21 has a light shielding sheet 21A as its constituent members, and therefore the water shielding sheet 21B and the pressure resistant sheet 21C in the water stop sheet 21 are protected by the light shielding sheet 21A so as not to be exposed to external light.

[0036] Figure 9 shows a view similar to Figure 7 relating to a modified example in which pile bodies having a quadrangular (rectangular) cross-section are used as the flood wall / support piles 2 of the flood embankment 1. Also, Figures 10(A) and (B) show views similar to Figures 8(A) and (B) relating to a modified example in which pile bodies having a quadrangular (rectangular) cross-section are used as the flood wall / support piles 2 of the flood embankment 1. As the flood barrier / support pile 2, it is basic to use pile bodies having a circular cross-sectional shape as shown in Figures 7 and 8(A) or a square (rectangular) cross-sectional shape as shown in Figures 9 and 10(A), but pile bodies having cross-sectional shapes other than a circular or square (rectangular) cross-sectional shape may be used only if safety is confirmed as a result of verification and evaluation through analysis, etc. The detailed explanation of the modified example shown in Figures 9 and 10(A) and (B) is similar to the content of the detailed explanation described above regarding Figures 7 and 8(A) and (B), except that the cross-sectional shape of the pile body used as the seawall and support pile 2 of the seawall 1 is changed from a circular cross-sectional shape to a quadrilateral (rectangular) cross-sectional shape.

[0037] Figure 11 shows a view similar to Figures 7 and 8 relating to a modified example in which protective work 23 for the watertight joint 20 is added to the connection portion of the watertight joint 20 between adjacent groups of flood wall and support piles described in Figures 7 and 8. The protective work 23 of the watertight joint 20 comprises a protective member 24 such as a reinforced concrete cage that has sufficient strength to withstand the expected load of drifting debris, a hinge 25 that is rotatable around the pile axial direction (up and down) and is installed by being integrally connected to both the flood wall / support pile 2 and the protective member 24, enabling the protective member 24 to follow the relative displacement between adjacent flood wall / support pile groups, and a mooring member 26 that enables the protective member 24 to follow the relative displacement between adjacent flood wall / support pile groups and is used to moor the protective member 24 to the adjacent flood wall / support pile 2. The protective member 24 is a high-strength rebar cage or the like, and has a property of protecting the waterstop joint 20 against expected drifting object loads. The protective member 24 is installed at the connection part of the adjacent flood wall / support pile group where the protective work 23 of the waterstop joint 20 is to be installed, in a state in which it can be opened and closed via hinge 25 on the outer surface of the outside of the embankment of the flood wall / support pile 2. Mooring members 26 for mooring the protective member 24 are interposed at a plurality of appropriate elevation positions between the end of the protective member 24 opposite the hinge 25 in the longitudinal cross section direction and the second end flood wall / support pile 2C. The mooring members 26 are installed with appropriate spacing in the pile axial direction (vertical direction). As with the above-mentioned waterproof sheet 21, the mooring members 26 are installed with sufficient length plus extra length so that the protective members 24 can follow the relative displacement of the connecting parts of adjacent flood wall / support pile groups against earthquake loads, tsunami loads, and superimposed loads of aftershocks and tsunami wave forces. In addition, since the protective work 23 for the watertight joint 20 is intended to protect the watertight joint 20 from drifting debris caused by a tsunami (considered as the expected drifting debris load), it is positioned outside the embankment rather than at the position where the watertight joint 20 is located, as shown in Figure 11.

[0038] The seawall 1 is characterized by having a waterstop joint 20 located inside the seawall of the center line CL in a cross section perpendicular to the pile axis of the seawall-cum-support pile 2 at the connection part of adjacent seawall-cum-support pile groups. Therefore, the seawall 1 is basically provided with the waterstop joint 20 at a position sufficiently far inside the seawall of the embankment than the tangent line TAN of the outer surface on the outside of the embankment. Due to the positioning of the waterstop joint 20 in this way, which is a characteristic of the seawall 1, even if driftwood considered as the estimated driftwood load in the event of a tsunami approaches the waterstop joint 20, the estimated driftwood load due to the tsunami is received by the outer surface of the seawall-cum-support pile 2, and consideration can be given to preventing direct contact with the waterstop joint 20. Furthermore, by arranging the waterstop joints 20 in this manner, and taking care to ensure that the anticipated load of drifting debris does not come into direct contact with the waterstop joints 20, if the protective work 23 for the waterstop joints 20 becomes unnecessary, the above-ground exposed structure SU of the seawall 1 will be the lightest, which has the advantage of reducing the inertial force of the seawall 1 during earthquakes and improving its earthquake resistance, as well as reducing the inertial force of the seawall 1 and improving its tsunami resistance when aftershocks and tsunami wave forces are superimposed. In other words, even if the protective work 23 is not used, by arranging the waterstop joint 20 in this manner, it is possible to ensure that the anticipated drifting object load does not come into direct contact with the waterstop joint 20. Furthermore, by installing the waterstop sheet 21 in multiple layers, such as by providing a double (or triple or more) layer, it is possible to improve the reliability of the waterstop function (waterstop performance) based on the waterstop joint 20, and the reduction in mass when the protective work 23 is no longer necessary may be advantageous in terms of improving earthquake resistance and tsunami resistance.

[0039] On the other hand, the protective work 23 of the embodiment of the waterstop joint 20 shown in Fig. 11 is of a nature that further enhances reliability in preventing the expected drift load during a tsunami from directly contacting the waterstop joint 20. However, when the protective work 23 is installed, the mass of the aboveground exposed structure SU of the seawall 1 increases slightly, and therefore the inertial force of the aboveground exposed structure SU during an earthquake and aftershock also increases slightly compared to when the protective work 23 is not installed. Therefore, the protective work 23 may be installed only when safety has been confirmed after evaluating the impact on the inertial force and earthquake resistance of the seawall 1 during an earthquake, and the impact on the inertial force and tsunami resistance when aftershocks and tsunami wave forces are superimposed, based on the results of verification and evaluation by analysis, etc. that takes into account the added mass when the protective work 23 is installed. In other words, based on the results of verification and evaluation through analysis, etc., of the loads during earthquakes, loads during tsunamis, and loads due to the superposition of aftershocks and tsunami wave forces, the effects of adding the mass of the protective work 23 have been evaluated, and only when safety has been confirmed, may a protective work 23 be installed, as shown in Figure 11, to further protect the watertight joint 20 against the expected drifting debris loads during a tsunami, if necessary. In addition, the protective member 24 in the protective work 23 of the watertight joint 20 shown in Figure 11 is basically formed from a high-strength reinforcing bar cage, etc., but only when safety is confirmed as a result of verification and evaluation through analysis, etc., may it be formed from a member other than a reinforcing bar cage that has sufficient strength, etc., or may be formed from a member that combines high-strength reinforcing bar with other appropriate materials.

[0040] Figure 12 shows a view similar to Figures 9 and 10 relating to a modified example in which protective work 23 for the watertight joint 20 is added to the connection portion of the watertight joint 20 between adjacent groups of flood barriers and support piles described in Figures 9 and 10. The detailed explanation of the modified example shown in Figure 12 is similar to the content of the detailed explanation described above regarding Figure 11, except that the cross-sectional shape of the pile body used as the seawall and support pile 2 of the seawall 1 is changed from a circular cross-sectional shape to a quadrilateral (rectangular) cross-sectional shape.

[0041] Figure 13 shows a diagram in which various dimensions have been added to Figure 2, as well as joints 10 which are connecting members between the flood wall / support piles 2. Also, Figure 14 shows a diagram in which various dimensions have been added to Figure 2, as well as water stop joints 20 which are connecting members between adjacent groups of flood wall / support piles. In the seawall 1, based on the results of inspections and evaluations by analysis etc., the ground G on the land side of the seawall and supporting pile 2 has been improved as an inside-bank improvement body 30 in the surface layer in contact with the seawall and supporting pile 2 and in areas up to the required depth, as shown in Figures 2, 4 to 6, 13 and 14. In other words, the surface layer of the ground G on the land side of the seawall 1 and in areas up to the required depth are provided with an inside-bank improvement body 30 that strengthens the ground G on the land side in contact with the seawall and supporting pile 2. The embankment inner improvement body 30 has an embankment inner ground improvement body 31 and an embankment inner heightening improvement body 32 which is continuous with the embankment inner ground improvement body 31 above the embankment inner ground improvement body 31 and protrudes above the ground surface GS. The embankment inner improvement body 30 is an auxiliary improvement body on the inside of the embankment that further improves the earthquake resistance of the seawall 1, which consists of the seawall / support piles 2 as its basic structural body, and its tsunami resistance against tsunami loads from the outside of the embankment.

[0042] The embankment inside ground improvement body 31 shown in Figures 2, 4 to 6, 13 and 14 is formed by providing a cement improvement body in the ground deeper than the ground surface GS on the land side that contacts the seawall / support pile 2. The embankment inside ground improvement body 31 is provided at a location below the extension of the ground surface GS. The vertical position of the bottom surface of the embankment inside ground improvement body 31 is appropriately set within a range where safety has been confirmed for all loads during earthquakes, loads during tsunamis, and loads when aftershocks and tsunami wave forces are superimposed, as a result of verification and evaluation by analysis, etc. The embankment inner side height-raising improvement body 32 is formed by continuously providing a cement improvement body on the upper side of the embankment inner side ground improvement body 31. The embankment inner side improvement body 30 is basically protruded above the ground surface GS by the embankment inner side height-raising improvement body 32. The embankment inner height improvement body 32 is vertically continuous with the embankment inner ground improvement body 31 and bulges upward from the upper surface of the embankment inner ground improvement body 31. The land-side toe of the embankment inner height improvement body 32 has a gentle slope that becomes lower toward the landward side, and is shaped to be stable even during earthquakes, etc. The height of the upper face of the embankment inner side raising improvement body 32 (the elevation of the upper face of the embankment inner side improvement body 30) has been set, based on the results of verification and evaluation through analysis, etc., to be suitable for resisting horizontal loads on the sea side part of the seawall / support pile 2 (above the ground surface GS) due to tsunami wave forces, etc. In addition, when setting the shape and height of the inner embankment improvement body 30, the depth of the lower end positions of the joints 10 and waterstop joints 20 installed continuously along the pile axial direction (up and down), as well as the outer embankment improvement body 33 (described in detail later), are also taken into consideration, and it is also confirmed that the weight of the inner embankment improvement body 30 is capable of withstanding the uplift pressure on the inside of the seawall 1 due to a tsunami with a sufficient safety margin. Furthermore, the fore-and-aft size of the embankment inner improvement body 30 (the cross-sectional length of the embankment inner improvement body 30) is set so that the embankment inner improvement body 30 is safe and will not slide, etc., regardless of whether the seawall 1 is subjected to earthquake loads, tsunami loads, or superimposed loads of aftershocks and tsunami wave forces. Here, the bank-side improvement body 30 may be formed by injecting a solidifying agent (chemical solution) at a depth deeper than the groundwater level of the original ground. That is, the bank-side improvement body 30 may be formed as an improved body by injecting a solidifying agent (chemical solution) at the portion of the bank-side ground improvement body 31 deeper than the groundwater level of the original ground, and the bank-side ground improvement body 31 may be formed as a cement-improved portion at the portion shallower than the groundwater level, and then the bank-side height-up improvement body 32 may be formed as a cement-improved portion. Alternatively, while basically forming the portions of the bank-side improvement body 30 deeper than the groundwater level and the portions shallower than the groundwater level as cement-improved portions, the portions of the bank-side improvement body 30 continuing downward from the bottom of the cement-improved portion to a necessary depth deeper than the groundwater level may be formed as improved bodies by injecting a solidifying agent (chemical solution). As a result of carrying out verification and evaluation by analysis, etc., within the range where safety is confirmed, the height, shape, etc. of at least one of the embankment-side ground improvement body 31 and the embankment-side raised improvement body 32 in the embankment-side improvement body 30 may be changed. Furthermore, only when safety is confirmed as a result of carrying out verification and evaluation by analysis, etc., the embankment-side improvement body 30 may be formed from other shapes, materials, etc.

[0043] The inner embankment improvement body 30 shown in Figures 2, 4 to 6, 13 and 14 protrudes upward to an initial height which is the basic required height of the inner embankment improvement body 30 plus an amount of expected subsidence due to an earthquake before the tsunami hits, in order to ensure the height of the inner embankment improvement body 30 required in the event of a tsunami hitting. Here, the additional height for the assumed amount of subsidence due to an earthquake before the tsunami strikes, which is added in advance to the basically required height of the inside embankment improvement body 30, may include a margin additional height of more than the assumed amount of subsidence due to an earthquake before the tsunami strikes, within the range of additional height for which safety has been confirmed against all loads during earthquakes, loads during tsunamis, and loads when aftershocks and tsunami wave forces are superimposed, as a result of carrying out verification and evaluation by analysis, etc., and it does not necessarily have to be exactly the same as the assumed amount of subsidence due to an earthquake before the tsunami strikes. Also, only when safety has been confirmed against all loads during earthquakes, loads during tsunamis, and loads when aftershocks and tsunami wave forces are superimposed, as a result of carrying out verification and evaluation by analysis, etc., the inside embankment improvement body 30 does not have to protrude above the ground surface GS. Due to the feature that the initial height of the inside-bank improvement body 30 is the basically required height for the inside-bank improvement body 30 plus the amount of expected subsidence due to an earthquake before the tsunami hits, even if the inside-bank improvement body 30 sinks due to an earthquake before the tsunami hits, the inside-bank improvement body 30 will be able to maintain the basically required height in the event of a tsunami hit, and displacement of the seawall / support piles 2 during earthquakes, tsunamis, and the superposition of aftershocks and tsunami wave forces of the seawall 1 is suppressed, thereby improving the safety of the seawall 1.

[0044] Meanwhile, for the ground G on the sea side of the seawall and supporting pile 2 of the seawall 1, based on the results of inspection and evaluation through analysis etc., the surface layer in contact with the seawall and supporting pile 2 and areas up to the required depth have been improved as an outer-bank improvement body 33, as shown in Figures 2, 4 to 6, 13 and 14. In other words, the surface layer of the ground G on the sea side of the seawall 1 and areas up to the required depth are provided with an outer-bank improvement body 33 that strengthens the ground G on the sea side that contacts the seawall and supporting pile 2. The outer embankment improvement body 33 has an outer embankment ground improvement body 34 deeper than the ground surface GS, and an outer embankment surface improvement body 35 which is continuous with the outer embankment ground improvement body 34 above the outer embankment ground improvement body 34 and protrudes above the ground surface GS. The outer embankment improvement body 33 is an auxiliary improvement body on the outside of the embankment which further improves the earthquake resistance of the embankment 1, which has the seawall / support piles 2 as its basic structural body, and the resistance of the ground in front of the embankment 1 to buckling caused by a tsunami from outside the embankment.

[0045] The embankment-outside soil improvement body 34 is formed by providing a cement improvement body on the ground deeper than the ground surface GS on the sea side in contact with the seawall-cum-support pile 2. The embankment-outside soil improvement body 34 is provided at a location below the extension of the ground surface GS. As shown in Figures 2, 4 to 6, 13, and 14, the vertical position of the bottom of the embankment-outside soil improvement body 34 is basically set at a position of the same elevation as the bottom position of the embankment-inside soil improvement body 31 in the embankment-inside soil improvement body 30. However, as a result of carrying out verification and evaluation by analysis, etc., the bottom elevation of the embankment-outside soil improvement body 34 in the embankment-outside soil improvement body 33 does not necessarily have to be at the same position as the bottom elevation of the embankment-inside soil improvement body 31 in the embankment-inside soil improvement body 30, within the range where safety is confirmed for all of the loads during earthquakes, loads during tsunamis, and loads when aftershocks and tsunami wave forces are superimposed. The embankment outer surface improvement body 35 is formed by continuously providing a cement improvement body on the upper side of the embankment outer ground improvement body 34. The embankment outer improvement body 33 is basically protruded above the ground surface GS by the embankment outer surface improvement body 35. The embankment outer surface improvement body 35 is vertically continuous with the embankment outer ground improvement body 34 and protrudes upward from the upper surface of the embankment outer ground improvement body 34. The sea-side toe of the embankment outer surface improvement body 35 has a gentle slope that becomes lower toward the sea, and is shaped to be stable even during earthquakes, etc. Here, the bank outside improvement body 33 may be formed by injecting a solidifying agent (chemical solution) at a depth deeper than the groundwater level of the original ground, similarly to the bank inside improvement body 30 described above. That is, the bank outside improvement body 33 may be formed as an improved body by injecting a solidifying agent (chemical solution) at a depth deeper than the groundwater level of the original ground in the bank outside ground improvement body 34, and may be formed as a cement-improved body at a depth shallower than the groundwater level in the bank outside ground improvement body 34, and then the bank outside surface improvement body 35 may be formed as a cement-improved body. Alternatively, while basically forming both the parts deeper than the groundwater level and the parts shallower than the groundwater level of the bank outside improvement body 33 as cement-improved bodies, the parts of the bank outside improvement body 33 that continue downward from the bottom of the cement-improved body to a necessary depth deeper than the groundwater level may be formed as improved bodies by injecting a solidifying agent (chemical solution). As a result of carrying out verification and evaluation by analysis, etc., within the range where safety is confirmed, the height, shape, etc. of at least one of the bank-side ground improvement body 34 and the bank-side surface improvement body 35 in the bank-side improvement body 33 may be changed. Furthermore, only when safety is confirmed as a result of carrying out verification and evaluation by analysis, etc., the bank-side improvement body 33 may be formed in a different shape, material, etc.

[0046] The outer embankment improvement body 33 shown in Figures 2, 4 to 6, 13 and 14 protrudes upward to an initial height which is the basic required height of the outer embankment improvement body 33 plus the estimated amount of subsidence due to an earthquake prior to the tsunami's arrival, in order to ensure the height of the outer embankment improvement body 33 required in the event of a tsunami hitting. Here, the protruding height of the bank outer surface improvement body 35 in the bank outer improvement body 33 above the ground surface GS, i.e., the additional height for the assumed subsidence due to an earthquake before the tsunami attack, which is added in advance to the basically required height of the bank outer improvement body 33, may include an additional margin height of more than the assumed subsidence due to an earthquake before the tsunami attack, within the range of additional height for which safety has been confirmed against all of the loads during earthquakes, loads during tsunamis, and loads when aftershocks and tsunami wave forces are superimposed, as a result of carrying out verification and evaluation by analysis, etc., and it does not necessarily have to be exactly the same as the assumed subsidence due to an earthquake before the tsunami attack. Also, only when safety has been confirmed against all of the loads during earthquakes, loads during tsunamis, and loads when aftershocks and tsunami wave forces are superimposed, as a result of carrying out verification and evaluation by analysis, etc., the bank outer improvement body 33 does not have to protrude above the ground surface GS. Due to the feature that the initial height of the outer embankment improvement body 33 is the basically required height of the outer embankment improvement body 33 plus the amount of expected subsidence due to an earthquake before the tsunami hits, even if the outer embankment improvement body 33 sinks due to an earthquake before the tsunami hits, the outer embankment improvement body 33 will be able to maintain the basically required height in the event of a tsunami hit.This improves the resistance of the sea side of the seawall 1 to buckling due to tsunamis, and suppresses displacement of the seawall / support piles 2 during earthquakes, tsunamis, and the superposition of aftershocks and tsunami wave forces, thereby improving the safety of the seawall 1. In addition, one or both of the inner embankment improvement body 30 and the outer embankment improvement body 33 may be omitted only if, as a result of verification and evaluation through analysis, etc., safety is confirmed against all loads during earthquakes, loads during tsunamis, and loads caused by the superposition of aftershocks and tsunami wave forces.

[0047] From the viewpoint of preventing boiling and piping from the ground due to a tsunami at the points where the flood wall / support piles 2 are joined together with the joints 10 as shown in Figure 13, the joints 10, which have a water-stopping property that does not cause significant leakage, have the function of preventing boiling and piping. Therefore, in order to prevent boiling and piping both during a tsunami and when aftershocks and tsunami wave force are superimposed, the joints 10 are installed continuously from the upper end elevation of the adjacent flood wall / support piles 2 along the pile axis direction to the underground elevation, and the lower end of the joints 10 is set at a depth underground sufficient to prevent boiling and piping from the ground when a tsunami approaches, and at a depth underground that does not block the slow infiltration of groundwater from the inside of the bank to the outside of the bank below the lower end of the joints 10 under normal circumstances. In this way, joints 10 are installed continuously from the upper elevation of the above-ground exposed structure SU of the flood wall and support pile 2 to a depth underground sufficient to prevent boiling and piping, and to a depth underground that does not block the slow-speed infiltration of groundwater from the inside of the embankment to the outside of the embankment deeper than the lower end of joint 10 under normal conditions.Therefore, the basic principle is that the underground installation range of joints 10 of the flood wall and support pile 2 shown in Figure 13 should be set appropriately, taking into consideration both its contribution to preventing boiling and piping due to tsunamis approaching from the outside of the embankment, and its contribution to suppressing a rise in the groundwater level on the inside of the embankment under normal conditions. Here, since the embankment inner improvement body 30 and the embankment outer improvement body 33 shown in Figure 13 also contribute to preventing boiling and piping, the use of a combination of the joints 10, the embankment inner improvement body 30 and the embankment outer improvement body 33 at the joints between the seawall / support piles 2 further improves safety against boiling and piping. Therefore, the length in the pile axial direction (up and down) of the joint 10, which is the connecting member between the flood wall-cum-support piles 2 shown in Figure 13, i.e., the length in the pile axial direction of the joint 10 which is installed continuously from the upper end elevation of the adjacent flood wall-cum-support pile 2 to which the joint 10 is attached along the pile axial direction, has been appropriately set within the range of lengths that have been confirmed to be safe for all loads during earthquakes, loads during tsunamis, and loads when aftershocks and tsunami wave forces are superimposed, taking into account the installation of the inner embankment improvement body 30 and the outer embankment improvement body 33, from the perspectives of both preventing boiling and piping in the event of a tsunami attack, and suppressing the rise in the groundwater level inside the embankment under normal circumstances.

[0048] On the other hand, even in locations where a watertight joint 20 is provided at the connection between adjacent groups of flood wall and support piles as shown in Figure 14 (the connection between each first end flood wall and support pile 2B and each second end flood wall and support pile 2C as shown in Figures 7 to 12), the watertight joint 20 is installed continuously from the elevation of the upper end of the flood wall and support pile 2 located at the connection between adjacent groups of flood wall and support piles along the pile axial direction to a sufficient depth underground, and to an appropriate depth elevation that does not block the slow-speed infiltration of groundwater from the inside of the embankment to the outside of the embankment below the lower end of the watertight joint 20 under normal conditions. In this way, the watertight joints 20 are installed continuously from the upper elevation of the exposed above-ground structure SU of the floodwall / support pile 2 located at the connection point of adjacent floodwall / support pile groups, to a sufficient depth of the underground buried structure SD common to the upper and lower series, and to a depth that does not block the slow-speed infiltration of groundwater from the inside of the embankment to the outside of the embankment deeper than the lower end of the watertight joint 20 under normal conditions.Therefore, the basic principle is that the underground installation range of the watertight joints 20 of the floodwall 1 shown in Figure 14 should be set appropriately, taking into consideration both its contribution to preventing boiling and piping and its suppression of a rise in the groundwater level inside the embankment under normal conditions. Here, since the inner embankment improvement body 30 and the outer embankment improvement body 33 shown in Figure 14 also contribute to preventing boiling and piping, the combination of the watertight joint 20, the inner embankment improvement body 30 and the outer embankment improvement body 33 at the connection points of adjacent flood wall / support pile groups further improves safety against boiling and piping. Therefore, the length in the pile axial direction (up and down) of the watertight joint 20, which is the connecting member of adjacent flood wall / support pile groups shown in Figure 14, i.e., the length in the pile axial direction of the watertight joint 20 which is installed continuously from the upper end elevation of the adjacent flood wall / support pile 2 along the pile axial direction to the ground, has been set appropriately within the range of lengths that have been confirmed to be safe for all loads during earthquakes, loads during tsunamis, and loads when aftershocks and tsunami wave forces are superimposed, taking into account the installation of the inner embankment improvement body 30 and the outer embankment improvement body 33 from the standpoints of both preventing boiling and piping in the event of a tsunami attack, and suppressing the rise in the groundwater level inside the embankment under normal circumstances. Furthermore, in places where waterstop joints 20 are provided at the connection parts of adjacent groups of flood wall and support piles as shown in Figure 14 (the connection parts of each first end flood wall and support pile 2B and each second end flood wall and support pile 2C as shown in Figures 7 to 12), in addition to providing the above-mentioned waterstop joints 20 and the inside and outside improvement bodies 30 and 33, safety against boiling and piping can be further improved by also installing sheet piles made of steel plates or the like with waterstop properties on the outside of the flood wall 1 as necessary. However, even in this case, it is essential to set up the structure in a way that takes into consideration both the prevention of boiling and piping in the event of a tsunami and the suppression of a rise in the groundwater level inside the flood wall under normal circumstances.

[0049] Figure 15 is a diagram in which arrows and the like indicating various forces assumed during an earthquake before the onset of a tsunami have been added to Figure 2. During an earthquake before the onset of a tsunami, as shown in Figure 15, the weight of the total structure BW, the weight of snow SW, wind load WW, etc. are assumed to act, and it is also considered that horizontal inertial force IH, vertical inertial force IV, and dynamic earth pressure EL act as loads on the above-ground exposed structure SU and the above-ground exposed structure SU and the underground buried structure SD common to the upper and lower series in the flood wall / support piles 2 due to shaking caused by the earthquake EW, and that ground reaction force CF, etc. are applied as reaction forces from the inside embankment improvement body 30, the outside embankment improvement body 33, the ground G, and the supporting ground B. These external forces, i.e., these loads and ground reaction forces, cause shear force SH, bending moment BM, axial force PF, etc. to act as cross-sectional forces in the flood wall 1. In the conventional seawall of Patent Document 1, the flood wall section made of short steel pipes at the top and the support pile section made of long steel pipes that are extended to the supporting ground and embedded every few pipes that make up the flood wall section have different vertical lengths and therefore different natural frequencies.As a result, during an earthquake as shown in Figure 15, there was a possibility that an increase in stress inside the piles would occur due to a phase difference in the natural vibration characteristics between the flood wall section made of short steel pipes and the support pile section made of long steel pipes. In contrast, the flood wall / support piles 2 of the seawall 1 of the present invention are not distinguished between a flood wall portion and a support pile portion, and are a common pile body for both the flood wall structure and the support pile structure, from the upper end of the above-ground exposed structure SU to the lower end of the underground buried structure SD that reaches the supporting ground B, and therefore adjacent flood wall / support piles 2 in the seawall 1 are basic structural bodies that are the same length or roughly the same length. As a result, adjacent flood barriers and support piles 2 in the flood embankment 1 have similar natural vibration characteristics and no significant phase difference occurs between their natural vibration characteristics. Therefore, in the flood embankment 1, during an earthquake as shown in Figure 15, it is possible to prevent or suppress an increase in stress inside the piles due to the phase difference between the natural vibration characteristics of adjacent flood barriers and support piles 2. Furthermore, the conventional seawall in Patent Document 1 was structured to support external forces such as the total body weight BW, snow load SW, wind load WW, horizontal inertia force IH, vertical inertia force IV, dynamic earth pressure EL, and ground reaction force CF during an earthquake as shown in Fig. 15, by support piles made of long steel pipes that were extended from the upper short steel pipe seawall part to the supporting ground and embedded in the supporting ground at intervals of several pipes, and by the supporting ground. Therefore, while it is expected that the external forces shown in Fig. 15 will be applied to the conventional seawall during an earthquake, these external forces acting on the conventional seawall were transmitted in a concentrated manner to the support piles made of long steel pipes that were extended from the upper short steel pipe seawall part to the supporting ground and embedded in the supporting ground at intervals of several pipes. Then, depending on the scale and vibration characteristics of the mega-earthquake specific to the target site during the earthquake shown in Figure 15, there was a possibility that the load transmitted to the supporting piles, which are made of long steel pipes that are extended from the upper short steel pipe flood wall section of a conventional seawall to the supporting ground and embedded therein, would be concentrated and transmitted to a significant extent. In contrast, the seawall 1 of the present invention can resist the external forces during an earthquake shown in Figure 15, namely the total body weight BW, snow weight SW, wind load WW, horizontal inertial force IH, vertical inertial force IV, dynamic earth pressure EL, and ground reaction force CF, with all of the seawall / support piles 2 that reach the supporting ground B. Furthermore, during an earthquake, the seawall 1 comprises a plurality of seawall / support pile groups that are arranged in parallel and joined with joints 10 and serve as a basic structural body common to both the seawall structure and the support pile structure, from the top end of the aboveground exposed structure SU to the bottom end of the underground buried structure SD that reaches the supporting ground B, and adjacent seawall / support pile groups are connected by watertight joints 20 that have watertightness, pressure resistance, and relative displacement tracking capabilities, resulting in a structure that can distribute the load most rationally. Therefore, the seawall 1 shown in Figure 15 has a structure in which the load burden per pile in the entire seawall / support pile 2 during an earthquake is smaller than that of conventional seawalls. Furthermore, the seawall 1 has a structure in which the local load burden on the supporting ground B when the external force during an earthquake is applied to the seawall / support pile 2 as shown in Figure 15 is smaller than that of conventional seawalls. In this way, the seawall 1 is equipped with a plurality of seawall / support pile groups joined together with joints 10 and arranged in parallel, from the top end of the above-ground exposed structure SU to the bottom end of the underground buried structure SD that reaches the supporting ground B. The seawall / support piles 2 serve as the basic structural body common to both the seawall and support pile structures and are connected to each other with joints 10. Adjacent seawall / support pile groups are connected by watertight joints 20 that have watertightness, pressure resistance and relative displacement tracking capabilities. Based on this structure, it has been possible to reduce both the load burden per pile and the local load burden on the supporting ground B against external forces assumed during an earthquake, as shown in Figure 15, more than before, thereby increasing the safety margin. In other words, with seawall 1, when external forces are applied during an earthquake as shown in Figure 15, the load capacity that can be supported by the entire structural body made up of connected seawall / support pile groups, each made up of seawall / support piles 2 joined together and arranged in parallel, which serve as the basic structural body common to the superstructure and substructure and serve as both the seawall structure and the support pile structure, has been realized that can withstand a larger load than conventional structures (having a stronger resistance force with a larger capacity than conventional structures).As a result, seawall 1 can ensure an even higher level of safety in terms of both the safety of the seawall structure against external forces during an earthquake as shown in Figure 15, and the safety of the support performance of the supporting ground B.

[0050] Moreover, Figure 16 is a diagram in which arrows indicating various forces assumed during a tsunami have been added to Figure 2. During a tsunami, as shown in Figure 16, the loads and other conditions are assumed to be exerted by the total body weight BW, snow weight SW, etc., and by the tsunami load TL (tsunami wave force) and drifting object load FL on the underground buried structure SD and the aboveground exposed structure SU common to the upper and lower series of the seawall and support piles 2, and it is taken into consideration that ground reaction force CF and the like are exerted as reaction forces from the inner embankment improvement body 30, ground G, and supporting ground B. These external forces, i.e., these loads and ground reaction forces, cause shear force SH, bending moment BM, axial force PF, etc. to act as cross-sectional forces in the seawall 1. The conventional seawall in Patent Document 1 was structured to support external forces such as the total body weight BW, snow weight SW, tsunami load TL (tsunami wave force), drift load FL, and ground reaction force CF during a tsunami as shown in Figure 16, by support piles made of long steel pipes that were extended from the upper short steel pipe seawall section to the supporting ground and embedded in the supporting ground at intervals of several pipes. Therefore, while it is expected that the conventional seawall will be subjected to the external forces shown in Figure 16 during a tsunami, these external forces acting on the conventional seawall were transmitted in a concentrated manner to the support piles made of long steel pipes that were extended from the upper short steel pipe seawall section to the supporting ground and embedded in the supporting ground at intervals of several pipes. Then, depending on the scale of the giant tsunami wave force specific to the target site during a tsunami, as shown in Figure 16, and the scale of the drifting debris load that is taken into account when superimposed with the giant tsunami wave force, there was a possibility that the load burden transmitted from the short steel pipe seawall at the top of a conventional seawall to the support piles, which are made of long steel pipes that are extended to the supporting ground and embedded every few pipes, could be concentrated and transmitted significantly. In contrast, the seawall 1 of the present invention can resist the external forces during a tsunami shown in Figure 16, i.e., the total body weight BW, snow weight SW, tsunami load TL (tsunami wave force), drifting object load FL, and ground reaction force CF, using all of the seawall / support piles 2 that reach the supporting ground B and are exposed from the ground surface GS. Furthermore, during a tsunami, the seawall 1 comprises a plurality of seawall / support pile groups that are arranged in parallel and joined with joints 10 and serve as a basic structural body common to both the seawall structure and the support pile structure, from the top end of the aboveground exposed structure SU to the bottom end of the underground buried structure SD that reaches the supporting ground B, and adjacent seawall / support pile groups are connected by watertight joints 20 that have watertightness, pressure resistance, and relative displacement tracking capabilities, resulting in a structure that can distribute the load most rationally. Therefore, the seawall 1 has the characteristic that the load burden per pile in the entire seawall / support pile 2 during a tsunami is smaller than that of conventional seawalls. In this way, the seawall 1 is equipped with a plurality of seawall / support pile groups connected to each other with joints 10 and arranged in parallel, and serves as the basic structural body for both the seawall and support pile structures and is a common series of basic structural bodies for the upper and lower structures, from the top end of the above-ground exposed structure SU to the bottom end of the underground buried structure SD that reaches the supporting ground B. Adjacent seawall / support pile groups are connected by watertight joints 20 that have watertightness, pressure resistance and relative displacement tracking capabilities. Based on this structure, it has been possible to reduce the load burden per pile compared to conventional methods, thereby increasing the safety margin, even against the external forces assumed in the event of a tsunami, as shown in Figure 16. In other words, with seawall 1, when external forces are applied during a tsunami as shown in Figure 16, the load capacity that can be supported by the entire structural body made up of connected seawall / support pile groups, each made up of seawall / support piles joined together and arranged in parallel, serves as the basic structural body common to the superstructure and substructure and can be used for both the seawall structure and the support pile structure, has been realized to be able to withstand a larger load than conventional structures (having a stronger resistance force with a larger capacity than conventional structures).As a result, seawall 1 can ensure an even higher level of safety for seawall structures against external forces during a tsunami as shown in Figure 16.

[0051] Furthermore, Figure 17 shows a diagram in which arrows and the like indicating various forces assumed when aftershocks and tsunami wave forces are superimposed are added to Figure 2. When aftershocks and tsunami wave forces are superimposed, as shown in Figure 17, it is assumed that a tsunami strikes during the aftershock, and external forces due to the aftershock and the tsunami are applied simultaneously. In other words, when aftershocks and tsunami wave forces are superimposed, as shown in Figure 17, it is assumed that the total body weight BW, snow load SW, etc. act, and that horizontal inertial force IH, vertical inertial force IV, and dynamic earth pressure EL act as loads on the aboveground exposed structure SU in the flood wall / support pile 2 and the aboveground exposed structure SU and the aboveground exposed structure SD common to the upper and lower series due to the shaking caused by the aftershock QW. In addition, it is assumed that tsunami load TL (tsunami wave force) and dynamic water pressure MW act as loads on the aboveground exposed structure SD in the flood wall / support pile 2 and the aboveground exposed structure SU common to the upper and lower series. Also, when aftershocks and tsunami wave forces are superimposed, it is taken into consideration that ground reactions CF and the like are applied as reaction forces from the inner embankment improvement body 30, the outer embankment improvement body 33, the ground G, and the supporting ground B against these loads. These external forces, i.e., these loads and ground reactions, cause the seawall 1 to generate shear force SH, bending moment BM, axial force PF, and other cross-sectional forces. In the conventional seawall of Patent Document 1, the upper flood wall section made of short steel pipes and the supporting pile section made of long steel pipes that are extended to the supporting ground and embedded every few pipes that make up the flood wall section have different vertical lengths, and therefore their natural frequencies are different. Therefore, when aftershocks and tsunami wave forces are superimposed as shown in Figure 17, there is a possibility that an increase in stress inside the piles will occur due to a phase difference in the natural vibration characteristics between the flood wall section made of short steel pipes and the supporting pile section made of long steel pipes. In contrast, the flood wall / support piles 2 of the seawall 1 of the present invention are not distinguished between a flood wall portion and a support pile portion, and are a common pile body for both the flood wall structure and the support pile structure, from the upper end of the above-ground exposed structure SU to the lower end of the underground buried structure SD that reaches the supporting ground B, and therefore adjacent flood wall / support piles 2 in the seawall 1 are basic structural bodies that are the same length or roughly the same length. As a result, the adjacent flood barriers and support piles 2 of the flood wall 1 have similar natural vibration characteristics and no significant phase difference occurs between their natural vibration characteristics. Therefore, in the flood barrier 1, when aftershocks and tsunami wave forces are superimposed as shown in Figure 17, it is possible to prevent or suppress an increase in stress inside the piles due to the phase difference between the natural vibration characteristics of adjacent flood barriers and support piles 2. Furthermore, the conventional seawall in Patent Document 1 was structured to support external forces such as the total body weight BW, snow weight SW, horizontal inertial force IH, vertical inertial force IV, dynamic water pressure MW, dynamic earth pressure EL, tsunami load TL (tsunami wave force), and ground reaction force CF, when aftershocks and tsunami wave force are superimposed as shown in Fig. 17, by support piles made of long steel pipes that were extended and embedded in the supporting ground every few pipes from the upper short steel pipe seawall part, and by the supporting ground. Therefore, while it is expected that the conventional seawall will be subjected to the external forces when aftershocks and tsunami wave force are superimposed as shown in Fig. 17, these external forces acting on the conventional seawall were transmitted in a concentrated manner to the support piles made of long steel pipes that were extended and embedded in the supporting ground every few pipes from the upper short steel pipe seawall part. Then, depending on the scale of the huge tsunami wave force specific to the target site when the aftershock and tsunami wave force are superimposed as shown in Figure 17, and the scale and vibration characteristics of the aftershock taking into account the superposition with the huge tsunami wave force, it is possible that the load transmitted to the supporting piles, which are made of long steel pipes that are extended and embedded in the supporting ground every few pipes from the short steel pipe flood wall section at the top of a conventional seawall, and to the supporting ground, may become significant. In contrast, the seawall 1 of the present invention can resist the external forces occurring when aftershocks and tsunami wave forces are superimposed as shown in Figure 17, namely the total structure weight BW, snow weight SW, horizontal inertia force IH, vertical inertia force IV, dynamic water pressure MW, dynamic earth pressure EL, tsunami load TL (tsunami wave force), and ground reaction force CF, using the entire seawall / support piles 2 that reach the supporting ground B and are exposed from the ground surface GS. In addition, when aftershocks and tsunami wave forces overlap, the seawall 1 comprises a plurality of seawall / support pile groups connected together with joints 10 and arranged in parallel, from the top of the above-ground exposed structure SU to the bottom of the underground buried structure SD that reaches the supporting ground B. The seawall / support piles 2 serve as the basic structural body common to both the seawall and support pile structures and form a series of common upper and lower structures, and are configured to distribute the load most rationally by connecting adjacent seawall / support pile groups with watertight joints 20 that have watertightness, pressure resistance and relative displacement tracking capabilities. Therefore, when aftershocks and tsunami wave force are superimposed, seawall 1 has the characteristic that the load burden per pile in the entire seawall / support pile 2 is smaller than that of conventional seawalls. Furthermore, seawall 1 has the characteristic that the local load burden on supporting ground B in the state in which the external force when aftershocks and tsunami wave force are superimposed, as shown in Figure 17, is applied to seawall / support pile 2 is smaller than that of conventional seawalls. In this way, the seawall 1 is equipped with a plurality of seawall / support pile groups joined together with joints 10 and arranged in parallel, from the top end of the above-ground exposed structure SU to the bottom end of the underground buried structure SD that reaches the supporting ground B. The seawall / support piles 2 serve as the basic structural body common to both the upper structure and the lower structure and can be used for both the seawall structure and the support pile structure. Adjacent seawall / support pile groups are connected by watertight joints 20 that have watertightness, pressure resistance and relative displacement tracking capabilities. Based on this structure, it has been possible to reduce both the load burden per pile and the local load burden on the supporting ground B compared to conventional methods, thereby increasing the safety margin, even against the external forces assumed when aftershocks and tsunami wave forces are superimposed, as shown in Figure 17. In other words, in the case of seawall 1, when external forces are applied when aftershocks and tsunami wave forces are superimposed as shown in Figure 17, the load capacity that can be supported by the entire structural body made up of connected seawall / support pile groups, which are made up of seawall / support piles 2 joined together and arranged in parallel and serve as the basic structural body common to the superstructure and substructure, and which can be used for both the seawall structure and the support pile structure, has been realized to be able to withstand loads of a larger capacity than conventional ones (having a stronger resistance force of a larger capacity than conventional ones) than conventional ones. As a result, seawall 1 can ensure an even higher level of safety in terms of both the safety of the seawall structure against external forces when aftershocks and tsunami wave forces are superimposed as shown in Figure 17, and the safety of the support performance of supporting ground B.

[0052] In the case of a tsunami as shown in Fig. 16 and when aftershocks and tsunami wave forces are superimposed as shown in Fig. 17, the upper elevation of the embankment outer improvement body 33' at the time of the tsunami attack after the expected amount of settlement due to the earthquake before the tsunami has settled is such that the upper surface of the embankment outer improvement body 33' after the earthquake is roughly aligned with the ground surface GS, because the embankment outer surface improvement body 35 before settlement, which is prepared for the earthquake before the tsunami, is protruded above the ground surface GS with a margin in advance to take into account the expected amount of settlement due to the earthquake. Therefore, the embankment outer improvement body 33' shown in Fig. 16 and Fig. 17 can continue to contribute to improving safety in terms of resistance to buckling of the sea-side base of the above-ground exposed structure SU of the seawall 1 even when a tsunami strikes after an earthquake. In addition, since the outer embankment improvement body 33 shown in Figure 15 is based on the principle of protruding above the ground surface GS in advance to accommodate the expected amount of subsidence due to an earthquake, even if it subsides slightly during the earthquake shown in Figure 15, it can continue to make an auxiliary contribution to improving the tsunami resistance of the seawall 1 consisting of the seawall and support piles 2 during a tsunami or when aftershocks and tsunami wave forces are superimposed, and to suppressing displacement of the seawall and support piles 2 that make up the seawall 1, as the outer embankment improvement body 33' after the earthquake shown in Figure 16 and Figure 17. More specifically, in the seawall 1, the inner embankment improvement body 30 and the outer embankment improvement body 33 or 33' (the outer embankment improvement body 33 during an earthquake as shown in Figure 15, and the outer embankment improvement body 33' during a tsunami and when aftershocks and tsunami wave forces are superimposed as shown in Figures 16 and 17) have the effect of auxiliary support for the seawall / support piles 2, which are the basic structural body of the seawall 1, against earthquake loads in both directions, from the land side to the sea side during an earthquake, tsunami loads and drifting object loads that flow from the sea side to the land side during a tsunami, and aftershock loads in both directions, from the land side to the sea side and tsunami loads that flow from the sea side to the land side when aftershocks and tsunami wave forces are superimposed. Therefore, the inner embankment improvement body 30 and outer embankment improvement body 33 shown in Figure 15 further improve the seismic resistance of the embankment 1, which has the flood wall and support piles 2 as its basic structural body, against seismic loads in both directions, from the sea side to the land side, during an earthquake. Also, the inner embankment improvement body 30 and outer embankment improvement body 33' shown in Figures 16 and 17 further improve the tsunami resistance of the embankment 1, which has the flood wall and support piles 2 as its basic structural body, against tsunami loads and drifting object loads that flow from the sea side to the land side during a tsunami, and aftershock loads that flow in both directions, from the land side to the sea side and tsunami loads that flow from the sea side to the land side when aftershocks and tsunami wave forces are superimposed.

[0053] As explained in detail above, the flood wall / support piles 2 of the flood embankment 1 are pile bodies that serve both the flood wall structure and the support pile structure and form a common series of upper and lower structures from the top end of the aboveground exposed structure SU to the bottom end of the underground buried structure SD that reaches the supporting ground B, so that adjacent flood wall / support piles 2 in the flood embankment 1 are basic structural bodies that have the same or roughly similar lengths. As a result, the adjacent flood wall / support piles 2 in the flood embankment 1 have similar natural vibration characteristics and no significant phase difference occurs between their natural vibration characteristics, so that in the flood embankment 1, it is possible to prevent or suppress an increase in stress inside the piles due to the phase difference between the natural vibration characteristics of adjacent flood wall / support piles 2 during both the earthquake and the superposition of aftershocks and tsunami wave forces as shown in Figures 15 and 17, respectively. In addition, for any of the loads during an earthquake, tsunami, and superimposed loads of aftershocks and tsunami wave forces shown in Figures 15, 16, and 17, respectively, the structure is provided with a plurality of groups of flood protection wall / support piles each of which is connected together with joints 10 and continuously arranged in parallel and serves as a basic structural body common to the upper and lower structures and can be used for both the flood protection wall structure and the support pile structure, and adjacent groups of flood protection wall / support piles are connected by watertight joints 20 which have watertightness, pressure resistance, and relative displacement tracking ability. The seawall 1, which is based on this principle, is able to minimize the load burden per single pile and the local load burden on the supporting ground B, and by maximizing the load capacity that the entire structural body can bear, it is possible to firmly resist external forces in order to protect the safety of the inside of the embankment. The seawall 1 of the present invention combines the highest level of earthquake resistance with the strongest level of tsunami resistance, and can be reused against repeated tsunamis, ensuring an even higher level of safety. Therefore, if components with appropriate rigidity and strength, etc., are selected and used to form the structure of the seawall 1, the stress generated in the seawall-cum-support piles 2, which form the basic structural body of the seawall 1, will be below the allowable limit for all of the following loads: earthquake loads caused by a huge earthquake before the huge tsunami strikes, tsunami loads caused by the huge tsunami strikes, and loads caused by the superposition of aftershocks and the wave forces of the huge tsunami. Consideration can be given to ensuring reusability, so that the seawall 1 will be able to continue to ensure an even higher level of safety against repeated tsunamis, etc., and, assuming appropriate regular and extraordinary maintenance, will satisfy the required service life. In addition, taking into consideration the structural characteristics of the seawall 1 described in detail above, the seawall 1 of the present invention will be referred to as a "diaphragm steel pipe wall." [Explanation of symbols]

[0054] 1··Tide embankment, 2··Tide wall / bearing pile (pile body), B··Supporting ground, BS··Top surface of supporting ground, G··Ground, GS··Ground surface, 10··Joint, RP··Coating with heavy anti-corrosive material, RC··Coating with reinforced concrete, RU··Coating with impact-resistant or impact-absorbing material, 20··Waterstop joint, 30··Inner embankment improvement body, 33,33'··Outer embankment improvement body, CL··Center line of the cross section of the watershed wall / bearing pile in the direction perpendicular to the pile axis, TAN··Tangential line to the outer surface of the watershed wall / bearing pile on the outer side of the embankment, 23··Protective work for waterstop joint, GR1,GR2··1st watershed wall / bearing pile group and second watershed wall / bearing pile group, GRi,GRi+1··(generalized where i is a natural number)The i-th watershed wall / bearing pile group and the i+1th watershed wall / bearing pile group.

Claims

1. The flood wall / support pile group is made up of flood wall / support piles that are used for both the flood wall structure and the support pile structure and have a basic structural frame common to the upper structure and the lower structure, and are connected together with joints and continuously arranged in parallel. A connecting portion of adjacent flood wall / support pile groups, the connecting portion being provided with a plurality of water stop joints on the inner side of the embankment from a center line in a cross section perpendicular to the pile axis of the flood wall / support pile related to the connecting portion, one side of each of the waterstop joints is installed on a first end flood wall / support pile, which is the flood wall / support pile connected to the end side of the flood wall / support pile group, and the other side of each of the waterstop joints is installed on a second end flood wall / support pile, which is the flood wall / support pile connected to the end side of the flood wall / support pile group adjacent to the flood wall / support pile group and adjacent to the first end flood wall / support pile; This seawall is characterized in that each of the waterstop joints is equipped with a waterstop sheet, and each of the waterstop sheets is formed by layering a light-blocking sheet that has light-blocking properties, a water-resistant sheet that has water-blocking properties, and a pressure-resistant sheet that has pressure resistance against tsunami wave pressure.

2. A seawall as described in claim 1, characterized in that a protective structure is provided on the outer side of the waterstop joint to protect the waterstop joint from expected drifting object loads.

3. A seawall as claimed in claim 1 or 2, characterized in that the seawall / support pile is covered with an impact-resistant or impact-absorbing material.

4. A seawall as claimed in claim 1 or 2, characterized in that the seawall / support pile is covered with a heavy-duty anti-corrosive material or reinforced concrete.

5. A seawall as claimed in any one of claims 1 to 4, characterized in that the ground on the inside of the seawall / support pile is provided with an inner-side improvement body for strengthening the ground.

6. A seawall as described in claim 5, characterized in that the initial height of the inside embankment improvement body is the basic required height of the inside embankment improvement body plus the amount of expected subsidence due to an earthquake before the tsunami hits, and the inside embankment improvement body protrudes upward.

7. A seawall as claimed in any one of claims 1 to 6, characterized in that an outer improvement body for strengthening the ground is provided on the ground outside the seawall / support pile.

8. A seawall as described in claim 7, characterized in that the initial height of the outer embankment improvement body is the basic required height of the outer embankment improvement body plus the amount of expected subsidence due to an earthquake before the tsunami hits, and the outer embankment improvement body protrudes upward.

Images