JP7633581B2 - Half-precast structure seawall and its construction method - Google Patents

Description

Patent Law Article 30, Paragraph 2 Application Seawall Construction Work Half Precast Consideration Asahi Kasei Corporation Hipore Hyuga Plant Held on February 12, 2020

The present invention relates to a half-precast seawall that is installed along the coastline and serves as a revetment against tsunamis caused by earthquakes and high waves caused by typhoons, and prevents seawater from flooding onto land.

In earthquake-prone countries, including Japan, minimizing damage from tsunamis caused by major earthquakes is an urgent issue. In recent years, typhoons have been getting stronger due to global warming, and damage from high waves caused by typhoons is becoming more serious. Seawalls installed along the coast against these natural disasters are expected to be a means of preventing coastal erosion and seawater flooding inland.

For example, Patent Documents 1 and 2 disclose a technique for constructing a strong embankment using precast members (precast walls) to reduce the amount of cast-in-place concrete used and to reduce the amount of concrete used at the construction site, thereby making it possible to build a strong embankment without requiring skilled workers.

For example, Patent Document 3 discloses a technology for constructing a structure that uses precast members (precast dam body) to reduce the amount of on-site construction work and can be applied to locations with poor ground conditions.

JP 2015-183453 A JP 2015-196983 A JP 2019-35259 A

Japan is surrounded by ocean and has an enormous coastline, and construction is also dependent on the weather, so the installation and maintenance of seawalls requires great costs and time, and there is a demand for more efficient construction. To improve construction efficiency and shorten construction times, it is effective to use components that are manufactured in advance in factories (so-called precast components). However, when using precast components, it is necessary to absorb construction errors that occur in the foundations (such as steel pipe piles and steel pipe sheet piles) constructed on site during construction of the precast components, and to build seawalls with specified dimensions and layout.

In this regard, the embankments described in Patent Documents 1 and 2 above are constructed using a foundation (composite steel/concrete footing) fabricated in a factory and a precast solid wall, and do not take any measures to absorb construction errors in the steel pipe piles installed at the actual construction site, so there is a risk that construction errors at the construction site will not be sufficiently absorbed.

In addition, in the embankment described in Patent Document 3, all of the walls and footings, except for the steel pipe piles, are made of precast members, and there is no mention of construction errors between the steel pipe piles that are directly installed at the construction site and the precast members.

In view of the above circumstances, the object of the present invention is to provide a half-precast seawall that can be constructed with high precision by fully absorbing construction errors that occur when constructing foundation piles at the construction site.

In order to achieve the above object, according to the present invention, there is provided a half-precast seawall comprising a foundation and a plurality of seawall panels arranged on the foundation to form a wall, the foundation comprising foundation piles, parts of which are driven into the ground with their upper ends protruding above the ground surface, levelling concrete for levelling the ground surface within a prescribed range surrounding the foundation piles, and a footing disposed above the levelling concrete, which contains the upper ends of the foundation piles and supports the seawall panels, the foundation piles being The present invention provides a half-precast structure seawall, characterized in that the seawall panels are arranged in two rows parallel to each other, the seawall panels are precast concrete members arranged on the leveled concrete at the midpoint of the two rows of the foundation piles, and their lower ends are supported by being sandwiched between the footing portion and constructed as an integrated unit, and the footing portion is made of cast-in-place concrete containing a reinforcement structure including a group of reinforcement bars fixed to the upper ends of the foundation piles and protruding upwards, and a group of reinforcement bars protruding laterally from the lower part of the seawall panel.

The present invention provides a half-precast seawall that can be constructed with high precision by fully absorbing construction errors that occur when constructing foundation piles at the construction site.

1 is a schematic explanatory diagram of a half-precast structure seawall according to a first embodiment of the present invention. FIG. FIG. 1 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall according to a first embodiment. FIG. 1 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall according to a first embodiment. FIG. 1 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall according to a first embodiment. FIG. 1 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall according to a first embodiment. FIG. 1 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall according to a first embodiment. FIG. 1 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall according to a first embodiment. FIG. 1 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall according to a first embodiment. FIG. 11 is a schematic explanatory diagram of a half-precast structure seawall according to a second embodiment of the present invention. FIG. 11 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall relating to the second embodiment. FIG. 11 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall in accordance with a second embodiment. FIG. 11 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall in accordance with a second embodiment. FIG. 11 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall in accordance with a second embodiment. FIG. 11 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall in accordance with a second embodiment. FIG. 11 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall in accordance with a second embodiment. FIG. 11 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall in accordance with a second embodiment. FIG. 11 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall in accordance with a second embodiment. FIG. 11 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall in accordance with a second embodiment. FIG. 11 is a schematic explanatory diagram of a half-precast structure seawall according to a third embodiment of the present invention. FIG. 11 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall relating to the third embodiment. FIG. 11 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall relating to the third embodiment. FIG. 11 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall relating to the third embodiment. FIG. 11 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall relating to the third embodiment. FIG. 11 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall relating to the third embodiment. FIG. 11 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall relating to the third embodiment. FIG. 11 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall relating to the third embodiment. FIG. 13 is a schematic explanatory diagram of a half-precast structure seawall according to a fourth embodiment of the present invention. FIG. 13 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall in accordance with the fourth embodiment. FIG. 13 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall in accordance with the fourth embodiment. FIG. 13 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall in accordance with the fourth embodiment. FIG. 13 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall in accordance with the fourth embodiment. FIG. 13 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall in accordance with the fourth embodiment. FIG. 13 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall in accordance with the fourth embodiment. FIG. 13 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall in accordance with the fourth embodiment. FIG. 13 is a schematic explanatory diagram showing a method for constructing a half-precast structure seawall in accordance with the fourth embodiment.

The following describes an embodiment of the present invention with reference to the drawings. In this specification and the drawings, components that have substantially the same functional configuration may be given the same reference numerals to avoid repetitive explanation. In other words, in the following specification, components that are common to each embodiment may be illustrated with the same reference numerals, and their explanation may be omitted. For the sake of explanation, the ground and ground surface are not illustrated, and steel pipe piles driven into the ground are illustrated.

First Embodiment
(Configuration of half-precast seawall 1a)
Fig. 1 is a schematic diagram of a half-precast seawall 1a according to a first embodiment of the present invention. As shown in Fig. 1, the half-precast seawall 1a comprises a plurality of steel pipe piles 2 as a foundation installed along the coastline, leveling concrete 3, and a footing 5 provided above the leveling concrete 3. In addition, a plurality of seawall panels 10 are arranged above the footing 5. Note that the "coastline" here also includes the river bank into which seawater enters.

When constructing the foundation 20 of the half-precast seawall 1a, multiple steel pipes as foundation piles are driven into the ground, and are arranged in a substantially straight line (substantially in a row) at a predetermined interval (for example, equal intervals) as multiple steel pipe piles 2. There are no particular limitations on the method of driving the steel pipe piles 2 into the ground. The steel pipe piles 2 are installed with a portion of them driven into the ground and their upper ends protruding above the ground surface. In addition, leveling concrete 3 is provided around the steel pipe piles 2 to level the ground surface in a predetermined area surrounding the multiple steel pipe piles 2. The leveling concrete 3 is applied to level out unevenness in the ground surface at the location where the half-precast seawall 1a is to be constructed.

A footing 5 made of cast-in-place concrete is provided above the leveling concrete 3. The shape and configuration of the footing 5 are arbitrary, but it may be configured as a substantially rectangular parallelepiped with a predetermined height and a rectangular cross section, as shown in the figure. As described below, the interior of the footing 5 contains the upper end of the steel pipe pile 2 and multiple reinforcing bars (reinforcing bar group) as reinforcing bars, and multiple reinforcing bars protrude upward from the upper surface of the footing.

The foundation 20 of the half-precast seawall 1a is constructed by constructing the steel pipe piles 2, the leveling concrete 3, and the footing 5. All of these structures are constructed on-site.

In addition, a plurality of (four in FIG. 1) seawall panels 10, which are precast concrete members (hereinafter also referred to as precast members), are supported and arranged on the upper part of the footing part 5. The seawall panels 10 are preferably arranged directly above the steel pipe piles 2. The seawall panel 10 has a substantially rectangular parallelepiped shape, and the thickness d1 of the lower part is thicker than the thickness d2 of the upper part. The thickness of the seawall panel 10 in the present invention is not particularly limited and may be uniform, for example, but by making the thickness d1 of the lower part thicker than the thickness d2 of the upper part, the rigidity of the lower part of the seawall panel 10 can be increased and the wave resistance can be improved. In addition, as described later, a plurality of reinforcing bars protruding upward from the footing part 5 are contained inside the seawall panel 10 via a connecting means such as a sleeve joint, and the footing part 5 and the seawall panel 10 are connected to each other.

The half-precast seawall 1a according to the first embodiment of the present invention is constructed as described above. In this half-precast seawall 1a, the steel pipe piles 2, leveling concrete 3, and footing 5 that make up the foundation 20 are all constructed on-site. On the other hand, the seawall panel 10 uses precast members that have been manufactured in advance in a factory or the like, and is constructed so that only assembly is performed on-site. As a result, construction errors that may occur during on-site construction, such as when driving the steel pipe piles 2, can be absorbed when constructing the footing 5, and the half-precast seawall 1a can be constructed and built with high precision.

In addition, the use of precast materials for the seawall panel 10 improves the efficiency of construction and shortens the construction period. In particular, for tall materials such as the seawall panel 10, construction on-site requires the erection of scaffolding, which necessitates various processes such as assembling and dismantling the scaffolding. Therefore, there are great benefits to using precast materials for the seawall panel 10.

(Method of constructing half-precast structure seawall 1a)
The construction method of the half-precast seawall 1a according to this embodiment is as follows: Figures 2 to 8, which will be referred to below, are schematic diagrams showing the construction method of the half-precast seawall 1a according to the first embodiment, and the construction method will be explained below with reference to Figures 2 to 8.

(Foundation work)
First, as shown in Fig. 2, in the foundation work for the coast where a half-precast seawall 1a is to be installed, a plurality of steel pipes are driven into the ground as foundation piles at predetermined positions (for example, positions along the coastline) to form a plurality of steel pipe piles 2 arranged in a substantially line at equal intervals in the ground. There is no particular restriction on the method of driving the steel pipe piles 2 into the ground at this time. Parts of the driven steel pipe piles 2 are left protruding above the ground surface.

(Pouring leveling concrete 3)
Next, as shown in Fig. 3, leveling concrete 3 is poured in a predetermined area around the driven steel pipe piles 2 to smooth out unevenness in the ground surface. Even after the leveling concrete 3 is poured, the steel pipe piles 2 are left protruding upward from the surface of the leveling concrete 3.

(Construction of footing portion 5)
Next, as shown in FIG. 4, a group of reinforcing bars 22 is assembled on the upper surface of the leveling concrete 3 so as to surround the plurality of steel pipe piles 2. The group of reinforcing bars 22 is composed of a first group of reinforcing bars 22a arranged so as to cover the plurality of steel pipe piles 2 arranged in a substantially straight line, and a second group of reinforcing bars 22b arranged so as to protrude above the first group of reinforcing bars 22a. Then, in a state in which the group of reinforcing bars 22 is assembled, as shown in FIG. 5, a formwork 25 is assembled on the upper surface of the leveling concrete 3 so as to surround the four side surfaces of the group of reinforcing bars 22. Then, as shown in FIG. 6, a footing portion 5 is constructed by pouring concrete into the space surrounded by the formwork 25. As shown in the figure, the upper end of the second group of reinforcing bars 22b is kept protruding from the upper surface of the footing portion 5 when the footing portion 5 is constructed.

The foundation 20 of the half-precast seawall 1a is made up of the steel pipe piles 2, the leveling concrete 3, and the footing 5 constructed as described above. All of the steel pipe piles 2, the leveling concrete 3, and the footing 5 are constructed on-site.

(Installation of seawall panel 10)
Next, as shown in Fig. 7, the formwork 25 is removed, and a plurality of seawall panels 10 are arranged on the upper part of the footing part 5 to form a wall. A plurality of reinforcing bar receiving parts (not shown), such as sleeve joints, are provided on the lower part of each seawall panel 10, and the reinforcing bar receiving parts are configured to receive the upper end of the second reinforcing bar group 22b protruding from the upper surface of the footing part 5. With the upper end of the second reinforcing bar group 22b received in the reinforcing bar receiving parts, a time-hardening material such as mortar is filled inside, and the seawall panel 10 is installed and fixed at a predetermined position on the upper surface of the footing part 5. In this way, the wall is finally formed as shown in Fig. 8, and the half-precast seawall 1a is constructed.

Second Embodiment
(Configuration of half-precast structure seawall 1b)
Fig. 9 is a schematic explanatory diagram of a half-precast seawall 1b according to a second embodiment of the present invention. As shown in Fig. 9, the half-precast seawall 1b comprises a plurality of steel pipe piles 2 as a foundation installed along the coastline, leveling concrete 3, and a footing 5 provided above the leveling concrete 3. In addition, a plurality of seawall panels 10 are arranged so as to be integrated with the footing 5.

To construct the foundation 20 of the half-precast seawall 1b, multiple steel pipe piles 2, which serve as foundation piles, are driven parallel to each other in approximately two rows. The steel pipe piles 2 are installed with a portion of them driven into the ground and their upper ends protruding above the ground surface. Additionally, leveling concrete 3 is provided around the steel pipe piles 2 to level the ground surface in a specified area surrounding the multiple steel pipe piles 2.

A footing 5 made of cast-in-place concrete is provided above the leveling concrete 3. The footing 5 may have any shape or configuration, but may, for example, be configured as a substantially rectangular parallelepiped with a predetermined height and a rectangular cross section, and may be configured to be integrated with the lower end of the seawall panel 10 (described below) so as to sandwich it. The upper end of the steel pipe pile 2 and a number of reinforcing bars (reinforcing bar groups) serving as reinforcing bars are contained within the footing 5.

The foundation 20 of the half-precast seawall 1b is constructed by constructing the steel pipe piles 2, the leveling concrete 3, and the footing 5. All of these structures are constructed on-site.

In this embodiment, multiple (five in FIG. 9) seawall panels 10, which are precast members, are arranged in the middle of the two rows of steel pipe piles 2 that are driven in parallel in approximately two rows. These seawall panels 10 are supported by having their lower ends sandwiched between the footing portion 5, and are constructed as an integrated unit. As will be described later, the footing portion 5 contains a group of reinforcing bars (reinforcing bar group 30, described later) fixed to the upper ends of the steel pipe piles 2 and multiple reinforcing bars (reinforcing bar group 35, described later) protruding to the lower side of the seawall panel 10, and the steel pipe piles 2, footing portion 5, and seawall panel 10 are connected together.

The half-precast seawall 1b according to the second embodiment of the present invention is constructed as described above. In this half-precast seawall 1b, the steel pipe piles 2, the leveling concrete 3, and the footing 5 that constitute the foundation 20 are all constructed on-site. On the other hand, the seawall panel 10 uses precast members that have been manufactured in advance in a factory or the like, and is constructed so that only assembly is performed on-site. This allows construction errors that may occur during on-site construction, such as when driving the steel pipe piles 2, to be absorbed when constructing the footing 5, and the half-precast seawall 1b can be constructed and constructed with high precision. Also, as in the first embodiment, the use of precast members as the seawall panel 10 improves the efficiency of construction and shortens the construction period.

(Method of constructing half-precast structure seawall 1b)
The method for constructing the half-precast seawall 1b according to this embodiment is as follows: Figures 10 to 18, which will be referred to below, are schematic diagrams showing the method for constructing the half-precast seawall 1b according to the second embodiment, and the construction method will be explained below with reference to Figures 10 to 18.

(Foundation work)
First, as shown in Fig. 10, in the foundation work for the coast where a half-precast seawall 1b is to be installed, a plurality of steel pipe piles 2 as foundation piles are driven into the ground at predetermined positions (for example, positions along the coastline) so as to be parallel to each other and form approximately two rows. The method of driving the steel pipe piles 2 into the ground at this time is not particularly limited. Parts of the driven steel pipe piles 2 are left protruding above the ground surface.

(Pouring leveling concrete 3)
Next, as shown in Fig. 11, leveling concrete 3 is poured in a predetermined area around the driven steel pipe piles 2 to smooth out unevenness in the ground surface. Even after the leveling concrete 3 is poured, the steel pipe piles 2 are left protruding upward from the surface of the leveling concrete 3.

(Installation of seawall panel 10 and construction of footing 5)
Next, as shown in Fig. 12, a group of reinforcing bars 30 protruding upward is fixed to the upper end of the steel pipe pile 2. The group of reinforcing bars 30 is fixed by means of, for example, welding. The group of reinforcing bars 30 may be fixed on-site, or may be fixed to the end of the steel pipe pile 2 in advance. Then, as shown in Fig. 13, a plurality of (five in the figure) seawall panels 10 are arranged to form a wall at the midpoint of the two rows of steel pipe piles 2 arranged in approximately two parallel rows on the upper surface of the leveled concrete 3. Here, the seawall panel 10 is provided in advance with a group of reinforcing bars 35 protruding laterally from its lower portion, and is configured so that the group of reinforcing bars 30 and the group of reinforcing bars 35 do not interfere with each other when the seawall panels 10 are arranged.

Next, as shown in Figures 14 and 15, a reinforcing bar group 40 consisting of main reinforcing bars extending vertically to the surface of the seawall panel 10 and distribution bars extending so as to cross horizontally to the main reinforcing bars is installed at a predetermined position on the upper surface of the leveled concrete 3. This reinforcing bar group 40 may be installed so as to connect to the reinforcing bar group 30. By installing each reinforcing bar group in this way, as shown in Figure 15, reinforcing bar group 30, reinforcing bar group 35, and reinforcing bar group 40 are integrally arranged on the upper surface of the leveled concrete 3, forming a reinforcing bar structure 42.

Next, as shown in Fig. 16, formwork 45 is assembled on top of the leveled concrete 3 so as to surround all four side surfaces of the reinforcing steel structure 42. Then, as shown in Fig. 17, concrete is poured into the space enclosed by the formwork 45 so as to bury the reinforcing steel structure 42, thereby constructing the footing 5. The formwork 45 is then removed, and finally, as shown in Fig. 18, the seawall panel 10 and the footing 5 are integrated to form a wall, and the half-precast seawall 1b is constructed.
In this embodiment, a case has been illustrated and described in which a plurality of steel pipe piles 2 are driven into the ground in approximately two rows parallel to each other as foundation piles. However, instead of these steel pipe piles 2, the foundation piles may also be steel pipe sheet piles consisting of a plurality of steel pipe sheet piles arranged in close contact with each other.

Third Embodiment
(Configuration of half-precast structure seawall 1c)
Fig. 19 is a schematic explanatory diagram of a half-precast seawall 1c according to a third embodiment of the present invention. As shown in Fig. 19, the half-precast seawall 1c comprises steel pipe sheet piles 2a as foundations installed along the coastline, leveling concrete 3, and a footing 5 provided above the leveling concrete 3. In addition, a plurality of seawall panels 10 are arranged above the footing 5.

When constructing the foundation 20 of the half-precast seawall 1c, multiple steel pipe sheet piles as foundation piles are driven into the ground and arranged in a substantially straight line as steel pipe sheet pile piles 2a. There are no particular limitations on the method of driving the steel pipe sheet pile piles 2a into the ground. The steel pipe sheet pile pile 2a is configured with multiple steel pipe piles arranged in close contact with each other, and the shape and number of steel pipe piles are optional. The steel pipe sheet pile pile 2a is installed with a portion driven into the ground and the upper end protruding above the ground surface. In addition, around the steel pipe sheet pile pile 2a, leveling concrete 3 is provided to level the ground surface in a predetermined area surrounding the steel pipe sheet pile pile 2a.

A footing 5 made of cast-in-place concrete is provided above the leveling concrete 3. The footing 5 may have any shape or configuration, but may, for example, be configured as a substantially rectangular parallelepiped with a predetermined height and a rectangular cross section, as shown in the figure. The foundation 20 of the half-precast seawall 1c is constructed by constructing the steel pipe sheet piles 2a, the leveling concrete 3, and the footing 5. All of these structures are constructed on-site.

In addition, multiple (four in FIG. 19) seawall panels 10, which are precast members, are supported and arranged on the top of the footing portion 5. As in the first embodiment, multiple reinforcing bars protruding upward from the footing portion 5 are contained inside the seawall panel 10 via connection means such as sleeve joints, connecting the footing portion 5 and the seawall panel 10.

The half-precast seawall 1c according to the third embodiment of the present invention is constructed as described above. In this half-precast seawall 1c, the steel pipe sheet piles 2a, the leveling concrete 3, and the footing 5 that constitute the foundation 20 are all constructed on-site. On the other hand, the seawall panel 10 uses precast members that have been manufactured in advance in a factory or the like, and is constructed so that only assembly is performed on-site. This allows the construction errors that may occur during on-site construction, such as when driving the steel pipe sheet piles 2a, to be absorbed when constructing the footing 5, and the half-precast seawall 1c can be constructed and constructed with high precision. Also, as in the first and second embodiments, the use of precast members as the seawall panel 10 improves the efficiency of construction and shortens the construction period.

(Method of constructing half-precast structure seawall 1c)
The construction method of the half-precast seawall 1c according to this embodiment is generally the same as that of the first embodiment. Figures 20 to 26 are schematic explanatory diagrams showing the construction method of the half-precast seawall 1c according to the third embodiment. As shown in Figures 20 to 26, the construction method of the half-precast seawall 1c according to this embodiment is the same as that of the first embodiment, except that steel pipe sheet piles 2a are used instead of the steel pipe piles 2, so detailed explanations will be omitted.

<Fourth embodiment>
(Configuration of half-precast structure seawall 1d)
Fig. 27 is a schematic explanatory diagram of a half-precast seawall 1d according to a fourth embodiment of the present invention. As shown in Fig. 27, the half-precast seawall 1d comprises steel pipe piles 2 as a foundation installed along the coastline, leveling concrete 3, and a footing 5 provided above the leveling concrete 3. In addition, a plurality of seawall panels 10 are arranged above the footing 5.

To construct the foundation 20 of the half-precast seawall 1d, multiple steel pipe piles 2, which serve as foundation piles, are driven parallel to one another in approximately two rows. The steel pipe piles 2 are installed with a portion of them driven into the ground and their upper ends protruding above the ground surface. Additionally, leveling concrete 3 is provided around the steel pipe piles 2 to level the ground surface in a specified area surrounding the multiple steel pipe piles 2.

A footing 5 made of cast-in-place concrete is provided above the leveling concrete 3. The footing 5 may have any shape or configuration, but may, for example, be configured as a substantially rectangular parallelepiped with a predetermined height and a rectangular cross section, as shown in the figure. The foundation 20 of the half-precast seawall 1c is constructed by constructing the steel pipe sheet piles 2a, the leveling concrete 3, and the footing 5. All of these structures are constructed on-site.

In addition, a number of precast seawall panels 10 (five in FIG. 27) are supported and arranged on the top of the footing 5. As in the first and third embodiments, the interior of the seawall panel 10 contains a number of reinforcing bars protruding upward from the footing 5 via connecting means such as sleeve joints, connecting the footing 5 and the seawall panel 10.

The half-precast seawall 1d according to the fourth embodiment of the present invention is constructed as described above. In this half-precast seawall 1d, the steel pipe piles 2, the leveling concrete 3, and the footing 5 that constitute the foundation 20 are all constructed on-site. On the other hand, the seawall panel 10 uses precast members that have been manufactured in advance in a factory or the like, and is constructed so that only assembly is performed on-site. This allows construction errors that may occur during on-site construction, such as when driving the steel pipe piles 2, to be absorbed when constructing the footing 5, and the half-precast seawall 1d can be constructed and constructed with high precision. Also, as in the first to third embodiments, the use of precast members as the seawall panel 10 improves the efficiency of construction and shortens the construction period.

(Method of constructing half-precast structure seawall 1d)
The construction method of the half-precast seawall 1d according to this embodiment is generally the same as that of the first embodiment. Figures 28 to 35 are schematic explanatory diagrams showing the construction method of the half-precast seawall 1d according to the fourth embodiment. As shown in Figures 28 to 35, the construction method of the half-precast seawall 1d according to this embodiment is the same as that of the first embodiment, except that the steel pipe piles 2 are arranged in approximately two rows parallel to each other, and therefore detailed explanations will be omitted.
In this embodiment, a case has been illustrated and described in which a plurality of steel pipe piles 2 are driven parallel to each other in approximately two rows as foundation piles, but instead of these steel pipe piles 2, steel pipe sheet piles in which steel pipe sheet piles are driven into the ground may also be used as foundation piles.

(Action and Effect)
According to the half-precast seawalls 1a to 1d configured as described above, when constructing a seawall with a half-precast structure, construction errors in the foundation piles (steel pipe piles 2 and steel pipe sheet piles 2a) at the construction site can be fully absorbed when constructing the footing 5 and when arranging the seawall panels 10. This enables high-precision construction when constructing the half-precast seawalls 1a to 1d.

In addition, in constructing the half-precast seawalls 1a-1d, the foundation piles (steel pipe piles 2, steel pipe sheet piles 2a), leveling concrete 3, and footing 5 that make up the foundation 20 are constructed on-site. On the other hand, the seawall panel 10 uses precast members that have been manufactured in advance in a factory or the like, and is constructed so that only assembly is performed on-site. In other words, by combining on-site construction such as cast-in-place concrete with precast members, construction efficiency can be improved and the construction period can be shortened.

Although one embodiment of the present invention has been described above, the present invention is not limited to the illustrated embodiment. It is clear that a person skilled in the art can come up with various modified or revised examples within the scope of the ideas described in the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

In the above embodiment, the foundation portion 20 is constructed using steel pipe piles 2 or steel pipe sheet piles 2a as foundation piles, but the present invention is not limited to this. For example, steel sheet piles or hat-shaped steel sheet piles may be used as foundation piles.

The present invention can be applied to half-precast seawalls that are installed along coastlines and serve as revetments against tsunamis caused by earthquakes and high waves caused by typhoons, and to prevent seawater from flooding onto land.

Reference Signs List 1 (1a to 1d)...Half-precast structure seawall 2...Steel pipe pile 2a...Steel pipe sheet pile 3...Leveling concrete 5...Footing 10...Seawall panel 20...Foundation 22...Reinforcing bars 25...Formwork 30...Reinforcing bars (at the top end of the steel pipe pile) 35...Reinforcing bars (on the lower side of the seawall panel) 40...Reinforcing bars (consisting of main reinforcing bars and distribution bars) 42...Reinforcing bar structure 45...Formwork

Claims (4)

A half-precast seawall structure comprising a foundation and a plurality of seawall panels arranged on the foundation to form a wall,
The foundation portion is a foundation pile that is installed with a part of the foundation pile driven into the ground and an upper end of the foundation pile protruding above the ground surface;
A leveling concrete for leveling the ground surface of a predetermined range surrounding the foundation pile;
a footing portion provided above the leveling concrete to contain the upper end of the foundation pile and to support the seawall panel;
The foundation piles are arranged in two rows parallel to each other,
The seawall panel is a precast concrete member, and is arranged at the center of the two rows of the foundation piles on the leveled concrete , and its lower end is supported so as to be sandwiched between the footing portion and is integrally formed,
This is a half-precast seawall structure, characterized in that the footing portion is made of cast-in-place concrete containing a reinforced concrete structure including a group of reinforcement bars fixed to the upper ends of the foundation piles and protruding upward, and a group of reinforcement bars protruding laterally from the lower part of the seawall panel. The half-precast seawall structure described in claim 1, characterized in that the foundation piles are steel pipe piles consisting of two rows parallel to each other and in which a plurality of steel pipes are driven into the ground, or steel pipe sheet piles consisting of a plurality of steel pipe sheet piles driven into the ground in continuous, close contact with each other. 3. A half-precast seawall structure as described in claim 1 or 2, characterized in that a group of reinforcing bars consisting of main reinforcing bars extending perpendicular to the surface of the seawall panel and distribution bars extending so as to intersect with the main reinforcing bars is embedded in the footing portion so as to connect to the group of reinforcing bars fixed to the upper ends of the foundation piles and protruding upward. A method for constructing a half-precast structure seawall consisting of a foundation and a plurality of seawall panels arranged on the foundation to form a wall, comprising the steps of:
A plurality of foundation piles are provided in two rows parallel to each other in the extension direction of the half-precast seawall, with a portion of each pile driven into the ground and an upper end portion protruding above the ground surface.
Pour leveling concrete over a predetermined area of the ground surface surrounding the two rows of foundation piles;
Above the leveling concrete, the plurality of seawall panels are arranged at the center of the two rows of the foundation piles with reinforcing bars protruding laterally from the lower part of the panels;
A method for constructing a half-precast structure seawall as described in claim 3, characterized in that after arranging the main reinforcing bars, the distribution bars, and the reinforcing bars fixed to the upper ends of the foundation piles, all of the reinforcing bars are buried inside, and in-situ concrete is poured to sandwich and support the lower ends of the seawall panels and integrate them, thereby completing the footing.

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