JP5168027B2 - Repair method for steel revetment structures - Google Patents

Description

  The present invention relates to a steel revetment such as a steel pipe pile or a steel sheet pile for a revetment, a quay or a breakwater such as a landfill (these revetments, a quay and a breakwater are collectively referred to as “revetment” in the present specification). The present invention relates to a method for repairing a steel revetment structure that can repair a structure in a strong manner and can also restore an ecosystem.

A variety of creatures such as algae, juvenile fish, crustaceans, and shellfish inhabit the sea in a favorable environment like a natural place. These diverse organisms feed on plankton, and when they die, they are broken down into bacteria and deposited on the ocean floor. Those deposited on the sea floor are fed by benthic organisms, and benthic organisms are also fed by large animals and carried out of the system.
In such an environment where diversity is maintained, the circulation of substances is performed without delay, and the water quality is also good. Sea area environmental purification is performed based on the viewpoint of material circulation without delay by various organisms.

However, the conventional revetment has a vertical wall shape where there is no hiding place for seafood and unevenness to which shellfish and algae easily adhere. Therefore, there is no ocean floor that is the epiphysical base in the depth of light where photosynthesis takes place, and it is not an environment where the seaweed and aquatic organisms necessary for the plant chain can live. It was out.
Therefore, in recent years, for the purpose of greening the steel sheet pile revetment, planting of the vertical wall greening porous concrete block on the steel sheet pile wall surface by attaching it closely to the steel sheet pile wall surface that has been driven into the ground A steel sheet pile revetment structure has been proposed (see Patent Document 1).

In addition, steel revetment structures using steel materials such as steel sheet piles and steel pipe piles will not be able to perform their functions sufficiently if they are left in the marine environment for a long time after construction and the corrosion of the steel materials will proceed. ing. In particular, corrosion from the splash zone to the tidal zone progresses remarkably, the steel material cross section decreases, and in extreme cases, there may be holes.
As a repair method for steel sheet pile revetment with reduced cross-sectional performance due to corrosion, a straight steel sheet pile wall as a reinforcing member is constructed by placing a wide sheet steel sheet pile while fitting the joints, The thing which fills the space between this steel sheet pile wall and the existing steel sheet pile is proposed (refer patent document 2).
JP 2001-295242 A JP 2003-74038 A

  First, in the case of Patent Document 2 in which strength reduction due to corrosion of a steel sheet pile revetment is repaired, a new wide panel steel sheet pile is placed on the contact surface of the existing steel sheet pile with water. There is no idea to restore the ecosystem by forming a biosphere suitable for the habitat.

On the other hand, what was shown in said patent document 1 installs the porous concrete block for greening in the contact surface with the water of a steel sheet pile, and the point that it becomes possible to plant on the vertical surface of a steel sheet pile Then we can expect a certain effect on the formation of biota.
However, in Patent Document 1 , a porous concrete block is attached. However, when concrete is placed in water, Ca eluted from the concrete raises the pH of the surrounding water and increases alkalinity. There is a problem of adversely affecting the habitat / growth environment.

In the case of concrete, since the surface is smooth, the fixing power of plants and the like is weak except in the hole portion, and even if organisms (plants, animals) adhere, organisms fall out at once. there is a possibility. When organisms fall to the seabed at this time, there is also a problem that they become sludge on the seabed filled with anoxic water masses.
As described above, Patent Document 1 may adversely affect the habitat and growth environment of aquatic organisms, and it cannot be expected to achieve sufficient results to restore the ecosystem in the degraded coastal waters.
Furthermore, since the thing of patent document 1 is the greening purpose of a steel sheet pile revetment in the first place, what is stuck to a steel sheet pile is porous concrete, and achieves the strength recovery of the steel sheet pile revetment whose strength has been reduced by corrosion. I can't.

As described above, in the method for repairing a steel revetment structure disclosed in Patent Document 2, only strength reinforcement is performed with concrete, and it is not possible to restore the ecosystem.
On the other hand, in the steel sheet pile revetment for greening described in Patent Document 1, it is possible to plan greening, but since concrete is used, it is expected that the biocompatibility is low and the ecosystem will be restored. Can not.

  The present invention has been made to solve such a problem, and can reinforce and repair a steel revetment structure using a steel material, and has high biocompatibility for the growth and inhabiting of marine organisms. To provide a method for repairing a steel revetment structure that is suitable, can establish aquatic organisms equivalent to or more than natural coastal reefs, and can restore ecosystems in degraded coastal waters. It is an object.

(1) A method for repairing a steel revetment structure according to the present invention is a method for repairing a steel revetment structure that constitutes a revetment, and a fixing member is installed on the surface of the steel revetment structure that contacts water. And a step of placing the formwork and placing the steelwork slag as an aggregate in the formwork , a binder, an admixture, and water mixed in water, and the formwork is made of steel slag. it forms a CaCO ₃ that the powdery raw material was produced in the carbonation reaction as a raw material in the allowed panel-like carbonated solid consolidation as a binder and is characterized in.

(2) Further, in the above-described (1), the mold is provided with an uneven shape on the surface side that becomes the sea side in the installed state .

According to the method for repairing a steel revetment structure according to the present invention, a hydrated hardened body mainly made of slag generated in a steel manufacturing process is effective as a seaweed settlement base, a fishing reef, a nutrient supply (elution) source, etc. Through these functions, a series of events such as the growth of diatoms and seaweeds, the growth of zooplankton, the emergence of a suitable environment for seafood feeds, hideouts, and spawning grounds, and the growth of seafood are directly performed. Or as a result, it is possible to build an ecosystem that is equal to or better than natural coastal reefs.
Moreover, there exists an effect that strength reinforcement of structural revetment structures, such as a corroded steel sheet pile, can be performed.
Furthermore, because the carbonic acid solidified material that uses steel slag as the main raw material is used as the mold, it is possible to demonstrate the ecological recovery function, and it is not necessary to remove the mold after the hydrated hardened material has solidified. There is also an effect that the construction period can be shortened by omitting the steps.

[Embodiment 1]
FIG. 1 shows an embodiment of the present invention, and is an explanatory diagram of a structure after repair of a steel sheet pile revetment as an example of a steel revetment. First, the repaired structure will be described with reference to FIG. 1, and then the repair method will be described.
The existing steel sheet pile revetment to be repaired in the present embodiment is composed of an existing steel sheet pile 3 standing on the seabed 1 and an upper structure coping 5 provided above the steel sheet pile 3. In addition, although the position of the end surface 5a on the sea side of the coping 5 is the revetment normal, the steel sheet pile 3 is usually installed on the land side of the revetment normal.
In this embodiment, against such an existing steel sheet pile revetment, a hydrated hardened body 7 mainly made of slag generated in the steel manufacturing process is applied to the contact surface of the steel sheet pile 3 with water. It is set. Moreover, the shelf 9 which protrudes in the sea side is provided in the lower end part of the hydration hardening body 7. FIG.
Hereinafter, each configuration will be described in detail.

<Description of configuration>
1. Hydrated cured body
(a) Placing range of hydrated hardened body The hydrated hardened body 7 is a functional member that has both the strength reinforcing function and the ecosystem recovery function of the existing steel sheet pile 3. Therefore, the range in which the hydrated cured body 7 is placed needs to be a range in which these two functions can be exhibited. That is, from the viewpoint of reinforcing the steel sheet pile 3, the existing steel sheet pile 3 is a portion where corrosion has progressed and needs to be repaired, and mainly from the splash zone to the tidal zone.
Further, from the viewpoint of ecosystem recovery, it is preferable that the plant that has settled there needs light in order to carry out photosynthesis, so that it is at least in the range where the sunlight reaches. Therefore, the placement range of the hydrated cured body 7 is at least a range up to the depth of water where the sunlight reaches, and if strength repair is required outside this range, the range is preferably included.

(b) Composition of hydrated hardened body Hydrated hardened body 7 is mainly composed of slag generated in the steel manufacturing process, and includes a raw material containing steel slag as a main raw material (aggregate and / or binder). It is obtained by hydration curing. As steel slag, various slags as mentioned above, that is, blast furnace granulated slag generated in blast furnace, dephosphorization slag, desulfurization slag, desiliconization slag, steelmaking slag such as cast slag, ore reduction slag, electric furnace slag, etc. Can be used. The hydrated cured product (block) is produced by kneading the raw material with water, placing it in a mold, and curing it usually for 1 to 4 weeks.
In addition to the fine powder of blast furnace granulated slag as described above, the binder used for the hydrated cured body 7 is a silica-containing substance (for example, clay, fly ash, silica sand, silica gel, silica scum), cement, slaked lime, NaOH or the like can be used in appropriate combination.

  In addition, it is preferable to provide the convex part 11 in the surface of a hydration hardening body, for example, as shown in FIG.

2. As shown in FIGS. 1 and 2, the shelf 9 is installed so as not to protrude from the sea-side end face 5 a of the coping 5 to the sea. By doing in this way, since it becomes the construction inside a seawall normal and it does not change a seawall normal, construction can be performed without going through complicated procedures.
The shelf 9 has a function of catching a living organism, for example, a shellfish, attached to the hydrated cured body 7 when it has died and falling, and preventing the dead body from accumulating on the seabed.
The material for forming the shelf 9 is not limited, and may be concrete, steel, or a hydrated cured body, for example.

In addition, as shown in FIG. 2, it is preferable that the shelf part 9 forms a bottomed frame body and forms a blast furnace granulated slag layer 13 in which blast furnace granulated slag is spread in the frame.
Granulated blast furnace slag is a slag blast furnace slag of water砕化treatment to particulate which solidified which is a kind of steel slag, the particle size is greater than the sea sand (typically, D ₅₀ is, 1.0 The particle size is about 2.0mm), and the true specific gravity is slightly larger than sea sand. Furthermore, granulated blast furnace slag is vitreous with a porous structure for reasons of its production, and has a shape in which slag particles are angular (a shape having a number of sharp portions on the surface).

As granulated blast furnace slag, as-produced, ground iron (iron) removed, crushed such as lightly crushed, crushed such as lightly crushed before or after removal of ground iron, by carbonation treatment Any of those having a carbonic acid film formed on the surface may be used. Since granulated blast furnace slag is generated in large quantities in the steel manufacturing process, it is a material that can be obtained in large quantities at low cost.
The thickness of the granulated blast furnace slag layer 13 is not particularly limited, but is usually 10 cm or more, and more preferably 30 cm or more.

The blast furnace granulated slag layer 13 is a sand granule made of a sand granule containing sand granular slag using steelmaking slag instead of blast furnace granulated slag, or a mixture of fine slag and natural sand. Also good. Sand granulated slag includes sand granulated blast furnace granulated slag, hot metal pretreatment slag, converter slag, electric furnace slag, or a hydrated hardened body of these slags into sand granules, and carbonated solidified bodies are sand granulated. Or those obtained by mixing these sand granular slags with natural sand or clay.
The range of particle size is preferably between 0.01 mm and 80 mm.

<Action>
In the repaired steel sheet pile revetment as described above, the hydrated hardened body 7 has a compressive strength of 18 N / mm ² or more, which is the design standard strength of a general deformed block at the age of 28 days, like concrete. Therefore, it is possible to recover the strength of the steel sheet pile that has become insufficient in strength due to corrosion.
In addition, nutrient salts such as silicic acid and iron are eluted from the hydrated cured body 7 into the sea. For this reason, phytoplankton such as diatoms proliferate in shallow regions, and as a result, growth of zooplankton that prey on phytoplankton → increase of small seafood such as small fish that prey on zooplankton → prey on small seafood An ecosystem based on the food chain of increasing the number of large fish to be produced is completed. In addition, the hydrated and cured body 7 in a light reachable range (5 to 7 m or less shallow water) that can be used for the growth of seaweeds is a suitable seaweed curing base, and the seaweeds are cured and prospered. It becomes a feeding ground and a spawning ground and brings about further growth of marine resources. Moreover, the hydrated cured body in a place where the light that is installed only for the purpose of reinforcement does not reach becomes a nutrient supply source. Moreover, when the convex part 11 and the recessed part 11a are formed, it functions as a fish reef (seafood hiding place).

Moreover, when the blast furnace granulated slag layer 13 is formed in the shelf 9, this provides a suitable habitat for bentos such as sandworms. That is, as described above, the granulated blast furnace slag is vitreous with a porous structure, and the slag particles have an angular shape, so the blast furnace granulated slag layer 13 has a large slag gap and excellent water permeability. ing. For this reason, the water in the slag gap is easily replaced, and the dissolved oxygen concentration in this gap is sufficiently secured.
In addition, a small amount of Ca is slowly eluted from the glassy slag particles over a long period of time, so that the pH in the pore water is maintained at about 8.5, which effectively prevents the generation of hydrogen sulfide by sulfate-reducing bacteria over a long period of time. It is suppressed.
From the above points, the blast furnace granulated slag layer 13 is a suitable habitat for benthos such as sandworms.
Therefore, even if the excrement, carcasses, wastes, etc. of marine organisms that grow and inhabit in the hydrated cured body 7 are set on the shelf 9, bentos that inhabit the blast furnace granulated slag layer 13 prey and decompose it. It is possible to appropriately suppress the accumulation of organic substances on the bottom of the water. In addition, since the granulated blast furnace slag is porous, microorganisms that decompose organic substances are likely to adhere to the blast furnace granulated slag layer. Therefore, the granulated blast furnace slag layer 13 is excellent in the resolution of organic substances by microorganisms.

In addition, 100% of the hydrated hardened body 7 and blast furnace granulated slag of this embodiment is recycled material, and since no cement is used, generation of CO ₂ during raw material production is suppressed, and natural aggregates are collected. There is also an effect that the environmental destruction caused by can be suppressed.

<Repair method>
FIG. 3 is an explanatory view of a method for repairing a steel revetment structure according to the present embodiment. FIG. 3 (a) shows a part of the revetment structure after repair shown in FIG. FIG. 3B is a cross-sectional view taken along the line AA in FIG. Hereinafter, the repair method of the repair revetment comprised as mentioned above is demonstrated based on FIG.
Even if the steel sheet pile 3 needs to be repaired or no strong repair is required, a stud gibber 15 as a fixing material is installed in a range where light can reach from the sea surface. At this time, reinforcing bars 16 may be arranged as shown in FIG.
After the installation of the stat gibel 15 is completed, the mold is installed in the range where the hydrated cured body 7 is to be placed. At this time, it is preferable to provide unevenness for forming the convex part 11 and the concave part 11b as shown in FIG.
After the installation of the formwork, steelmaking slag as aggregate, blast furnace slag fine powder as binder, fly ash / blast furnace granulated slag as admixture, and water kneaded into the above formwork Set up.
When the hydrated cured body 7 cast on the mold is solidified, the mold is removed.

Note that the shelf 9 is installed before or simultaneously with or after the hydrated cured body 7 is constructed. For the installation of the shelf 9, a known construction method suitable for the material to be used may be adopted. For example, when formed with concrete or a hydrated hardened body, the method may be the same as that of the above-mentioned hydrated hardened body 7, and when formed with a steel material, it may be installed by bolting or the like.
After the shelf 9 is formed, the ground granulated blast furnace slag is spread to the necessary thickness described above.

[Embodiment 2]
In the present embodiment, the form for placing the hydrated cured body 7 in the first embodiment is formed of a panel-like carbonate solidified body using steel slag as a main raw material.
Examples of the carbonate solidified body using steel slag as a main raw material include CaCO ₃ (which is proposed in Patent No. 3175694), which is produced by carbonation reaction of a granular raw material mainly made of steel slag. A panel formed by solidifying MgCO ₃ ) as a main binder can be used. Also, as steel slag, blast furnace granulated slag and blast furnace slow cooling slag generated in blast furnace, decarburization slag, dephosphorization slag, desulfurization slag, desiliconization slag, casting generated in the process of pretreatment, converter, casting, etc. Steelmaking slag such as slag, ore reduction slag, electric furnace slag, and the like can be used.

In particular, the carbonic acid solidified body using such steel slag as the main raw material changes most of CaO (or Ca (OH) ₂ generated from CaO) contained in the slag into CaCO ₃ . pH can be prevented, and the entire surface (inside and inside) has a porous property, which makes it easy for seaweeds to adhere to the surface, and ingredients that are effective in promoting the growth of seaweeds (silicic acid, iron, etc.) Since it is easy to elute in seawater, it functions particularly effectively as a seaweed settlement base.
Therefore, as in the present embodiment, when a carbonate solid body using steel slag as a main raw material is used as a formwork, an ecosystem recovery function can be exhibited without providing irregularities on the seaside surface. .
However, it is preferable to provide a concavo-convex shape as shown in FIG. 2 on the surface facing the sea in the installed state when forming a panel. As a result, the ecosystem recovery function can be further exhibited.

  In addition, like this Embodiment, the formwork for placement of the hydrated cured body 7 is formed of a panel-like carbonate solidified body using steel slag as a main raw material. There is no need to remove the mold after solidification, and the construction process can be shortened by shortening the construction period.

[Embodiment 3]
In the present embodiment, as shown in FIG. 4, a massive carbonate solidified body 17 made of steel slag as a main raw material is attached to the surface of the hydrated cured body 7.
The carbonate solidified body 17 can be attached to the hydrated cured body 7 with an adhesive such as an underwater bond after the hydrated cured body 7 placed in the first embodiment is solidified and the mold is removed. Good.
By sticking the lump-shaped carbonate solidified body 17, the seaweed of the above-mentioned carbonate solidified body is easy to adhere, and components (silicic acid, iron, etc.) effective for promoting the growth of seaweed are easily eluted into seawater. Thus, the surface of the hydrated cured body 7 functions more effectively as a seaweed settlement base, and the ecosystem recovery function can be more effectively exhibited.

As an alternative to the bulk carbonate solidified body, a bulk Ca-containing hydrated cured body having a calcium carbonate coating layer on at least the outer surface may be used.
The Ca-containing hydrated cured product is obtained by forming a calcium carbonate coating layer on at least the outer surface of the Ca-containing hydrated cured product serving as a base.
Since the calcium carbonate coating layer is formed on the surface of the Ca-containing hydrated cured body, the dissolution of Ca from the substrate and the accompanying increase in pH of seawater (especially the seawater in the boundary layer on the substrate surface) can be suppressed. The seawater layer on the surface can be made into an environment suitable for the growth and growth of zoospores and eggs, and the same effect as in the case of using a massive carbonate solidified body can be expected.

Hereinafter, the structure of the massive Ca-containing hydrated cured body having a calcium carbonate coating layer on at least the outer surface will be described in detail.
As described above, the Ca-containing hydrated cured product of the present embodiment is obtained by forming a calcium carbonate coating layer on at least the outer surface of the Ca-containing hydrated cured product serving as a base. The Ca hydrated cured body as the base here is a Ca-containing binder (such as cement), aggregate (fine aggregate and / or coarse aggregate), water, and an admixture blended as necessary. Or the like, or a hydrated and hardened Ca-containing material having a wide particle size distribution from the binder level to the aggregate level, water, an admixture blended as necessary, and the like. It is a Japanese-cured product. The most commonly used Ca hydrated hardened body is cement concrete, but is not limited thereto. For example, FS concrete, eco cement concrete, coal ash hydrated hardened body (for example, fly ash cement concrete). ) And hydrated hardened bodies mainly made of slag generated in the steel manufacturing process (for example, hydrated hardened bodies blended with hot metal pretreated slag, blast furnace slag fine powder, slaked lime, etc.) Japanese cured products can be targeted.
The cement concrete includes concrete using any cement such as Portland cement and blast furnace cement.

A method of forming a coating layer of calcium carbonate on the outer surface of the Ca hydrated cured body serving as the substrate is arbitrary, but usually, the Ca hydrated cured body serving as the substrate is formed by carbonation treatment in contact with carbon dioxide gas.
In order to efficiently perform the carbonation treatment of the outer surface of the Ca hydrated cured body serving as the substrate, it is practically essential that water (surface adhering water) exists on the surface of the Ca hydrated cured body serving as the substrate. For this reason, it is necessary to attach water to at least the outer surface of the Ca hydrated cured body serving as the substrate, or to impregnate at least the surface with water. That is, the reaction mechanism between uncarbonated Ca and CO ₂ contained in the surface layer of Ca hydrated cured body that becomes the base in carbonation treatment is that CO ₂ is dissolved in water (surface adhering water) present on the surface of the hydrated cured body. At the same time, Ca ions are eluted from the hydrated cured body side, and when CO ₂ dissolved and eluted in water reacts with the Ca ions (carbonation reaction), CaCO ₃ is precipitated on the surface of the hydrated cured body. It is thought to be a thing.
Therefore, in order to cause carbonation by the above mechanism, it is necessary that water (surface-attached water) exists on the surface of the hydrated cured body.
The method of adhering water to or impregnating water with the Ca hydrated cured body serving as the substrate is arbitrary. For example, a method of immersing the hydrated cured body in water, a method of watering the hydrated cured body, or the like. Can be taken.

  The specific method of the carbonation treatment is arbitrary. For example, the Ca hydrated cured body serving as a substrate to which water is attached or impregnated as described above is sealed in a sealed container (airtightness can be maintained. The carbonation process is performed by supplying carbon dioxide gas or carbon dioxide-containing gas (hereinafter collectively referred to as “carbon dioxide gas” for convenience) into the sealed container.

  In addition, in said embodiment, although the case where the existing steel sheet pile revetment was restored was demonstrated, it cannot be overemphasized that this invention is not restricted to this, It can apply also when constructing a steel sheet pile revetment newly. Yes. In this case, anti-corrosion measures such as heavy anti-corrosion coating and electro-corrosion protection can be eliminated or reduced, and a cost effect can be expected.

It is explanatory drawing of the steel sheet pile revetment which concerns on one embodiment of this invention. FIG. 2 is a detailed explanatory diagram illustrating a part of FIG. 1 in detail. It is explanatory drawing of the repair method of the steel sheet pile revetment which concerns on one embodiment of this invention. It is explanatory drawing of other embodiment of this invention.

Explanation of symbols

1 Seabed 3 Steel sheet pile 7 Hydration hardened body 7
9 Shelf 11 Convex

Claims (2)

A method of repairing a steel revetment structure that constitutes a revetment, the step of installing a fixing member on the surface of the steel revetment structure in contact with water, and the installation of a formwork as an aggregate on the formwork steelmaking slag, binder, admixtures, water and a step of water hitting set those kneading, and the CaCO ₃ the formwork that generated by the carbonation reaction of particulate material to the iron and steel slag as raw material A method for repairing a steel revetment structure, characterized in that it is formed of a panel-like carbonated solidified body as a binder . The method for repairing a steel revetment structure according to claim 1, wherein the formwork is provided with a concavo-convex shape on a surface side that becomes the sea side in an installed state.

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