JP6786203B2 - Submarine construction material and submarine structure using this material - Google Patents

Description

The present invention relates to a dike construction material and a dike structure using this material.

An artificial tidal flat is created by putting a filling material such as dredged soil after installing a submarine and covering it with sand (see, for example, Patent Document 4). As the material of the dike, in addition to the gravel material, steelmaking slag (see, for example, Patent Document 1), a solidified body (see, for example, Patent Document 2) and the like are used. Further, a mixed material of dredged soil and steelmaking slag (see, for example, Patent Document 3) is also being used as a submerged material (see, for example, Non-Patent Documents 1 and 2).

FIG. 8 schematically shows an example of a conventional artificial tidal flat structure. In this artificial tidal flat, after the submarine 1 is constructed with a mixed material of dredged soil mixed with steelmaking slag on the original ground G on the bottom of the water, the filling is made of dredged soil on the original ground G on the shore side (land side). It is created by putting the material 2 into the material and covering it with sand 3.

Japanese Patent Application Laid-Open No. 2005-256497 Japanese Unexamined Patent Publication No. 2011-246336 Japanese Unexamined Patent Publication No. 2009-121167 Japanese Unexamined Patent Publication No. 2011-208365

"Calcia Modified Soil Design and Construction Manual" Calcia Modified Soil Study Group (2013) Koichi Yamada, Takumi Tsuji, Yoichi Watanabe, Takaaki Mizutani, Yoshiyuki Morikawa, Ryoyuki Ukai "Experiments and Discussions on Tidal Flat Submersibles Using Calcia Modified Soil on Soft Ground" , Vol.69, No.2, I_1048-1053, 2013 (www.jstage.jst.go.jp/article/jscejoe/69/2/69_I_1048/_article/references/-char/ja/)

According to a report of a model experiment on the embedding of a mixed material of dredged soil and steelmaking slag in soft ground used for a tidal flat submarine (Non-Patent Document 2), the bottom surface 1a of the submarine 1a (Fig. 8) as the mixed material solidifies. Cracks were found in the cracks, and the cracks reached a maximum of several mm. Such cracks are not preferable because they may affect the stability of the dike.

In view of the above-mentioned problems of the prior art, the present invention provides a submarine construction material capable of avoiding the problem of crack generation in the submarine and maintaining the stability of the submarine, and a submarine structure using this material. The purpose is to do.

The submarine construction material for achieving the above objectives is a material for constructing a submarine in which the embankment body is submerged under the water surface, and is a cohesive soil having a water content ratio adjusted to 100 to 300% and a particle size of 37.5 mm. The following steelmaking slags are mixed so that the cohesive soil has an internal division volume ratio of 70 to 90% and the steelmaking slag has an internal division volume ratio of 30 to 10% , and the fibrous material has an external division volume ratio. It is characterized in that it has a property that the compressive stress does not decrease when the compressive strain is 5% or 5% or more in the uniaxial compression test for the material to which 0.1 to 1.0% is added.

According to this submerged levee construction material, the strength can be improved by mixing steelmaking slag with cohesive soil. In addition, the addition of the fibrous substance makes it easier for the fibrous substance to get entangled with the steelmaking slag, which is a granular material, so that it has high deformation followability, and even if strain is applied, the decrease in strength is suppressed and the occurrence of cracks is suppressed. can do. In addition, this submarine construction material has strength recovery property, and even if a crack occurs in the material, the strength can be recovered. In this way, by using this submarine construction material, the problem of crack generation in the submarine can be avoided and the stability of the submarine can be maintained.

When the water content of the cohesive soil is 100% or more, the workability with steelmaking slag and fibrous substances is not deteriorated, and when the water content is 300% or less, the strength is not lowered and it is good. When the mixing amount of the steelmaking slag is 30% or less by volume, the fluidity and workability are not deteriorated, and it is good, and when the volume ratio is 10% or more, the strength can be expected to be improved. Further, when the amount of the fibrous substance added is 0.1% or more by volume, the effects of suppressing the decrease in strength, imparting deformation followability, and recovering the strength can be obtained, and when the amount of the fibrous substance added is 1.0% or less by volume. In addition to ensuring fluidity and workability, the amount of addition does not become too large and the cost does not increase so much.

The submarine construction material has a property that the compressive stress does not decrease when the compressive strain is 5% or 5% or more in the uniaxial compression test for the submarine construction material .

The submarine structure for achieving the above object is characterized in that it is constructed from the above-mentioned submarine construction material. According to such a submarine structure, the problem of crack generation in the submarine can be avoided, so that a submarine structure capable of maintaining stability can be realized.

Another submarine structure is characterized by having a submarine lower part constructed from the above-mentioned submarine construction material and a submarine upper part constructed from a material other than the submarine construction material. According to such a submarine structure, the problem of crack generation in the lower part of the submarine can be avoided, so that a submarine structure capable of maintaining stability can be realized and the material cost of the entire submarine can be reduced.

In the other submarine structure, the material other than the submarine construction material is preferably a material in which the addition of the fibrous substance is omitted in the submarine construction material.

According to the present invention, it is possible to provide a levee construction material capable of avoiding the problem of crack generation in the levee and maintaining the stability of the levee, and a levee structure using this material.

It is the schematic which shows the dike for artificial tidal flat by this embodiment. It is a schematic diagram which shows another dike for artificial tidal flat by this embodiment. It is a figure which shows the stress-strain diagram obtained from the uniaxial compression test performed on the material of Table 1 in this Example. (A) to (i) are diagrams showing stress-strain diagrams obtained from the uniaxial compression test performed on the materials shown in Table 2 in this example. It is a figure which shows the relationship between the compressive strain and the compressive stress ratio obtained from the uniaxial compression test performed on the material of Table 3 for confirmation of strength recovery in this Example. It is a figure which shows the result of the flow test performed on the material shown in Table 4 in this Example. It is a figure which shows the result of the flow test performed on the material shown in Table 5 in this Example. It is a schematic diagram which shows an example of the conventional artificial tidal flat structure.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing a submarine for an artificial tidal flat according to the present embodiment.

As shown in FIG. 1, the artificial tidal flat submarine 10 according to the present embodiment uses a submarine construction material in which cohesive soil and steelmaking slag are mixed and a fibrous substance is added on the original ground G of the water bottom. It is constructed to be submerged under the surface of the water. The artificial tidal flat is provided on the submarine 10, the filling material 11 made of the dredged soil and the like thrown onto the original ground G on the shore side (land side) after the construction of the submarine 10, and the filling material 11. It is composed of a sand cover 12.

The submarine construction materials for constructing the submarine 10 in FIG. 1 are cohesive soil (70-90% in terms of internal volume ratio) whose water content is adjusted to 100 to 300% and steelmaking slag with a particle size of 37.5 mm or less (internal division volume ratio). It is a mixture of 10 to 30% by volume of internal division) and 0.1 to 1.0% of fibrous substance added by volume ratio of external division.

As the above-mentioned cohesive soil, in addition to dredged soil, purchased materials such as mountain clay and bentonite can be used. Adjust the water content to 100-300% before use.

The above-mentioned steelmaking slag has a particle size of 37.5 mm or less, and the mixing amount of the steelmaking slag is adjusted in the range of 10 to 30% (volume ratio) according to the target strength and the like. As the steelmaking slag, it is preferable to use a converter-type steelmaking slag which is a granular material produced in the process of refining pig iron produced in a blast furnace in a converter.

Various fibers can be used as the above-mentioned fibrous substance, and for example, polyester, polypropylene, polyethylene, vinylon and the like can be used. The size of the fiber is arbitrary, but since the fiber is caught on the rough surface of the steelmaking slag, it is possible to save the trouble of loosening the short fiber in advance at the time of kneading. Further, by using fine fibers, it is possible to exert the effect with a small amount of fibers. The amount of addition is adjusted in the range of 0.1 to 1.0% in terms of the volume ratio of the outer division.

According to such a dike construction material, the strength can be improved by mixing steelmaking slag with cohesive soil. In addition, the addition of the fibrous substance makes it easier for the fibrous substance to get entangled with the steelmaking slag, which is a granular material, so that it has high deformation followability, and even if strain is applied, the decrease in strength is suppressed and the occurrence of cracks is suppressed. can do. Therefore, the occurrence of cracks in the lower portion 10a of the dike 10 in FIG. 1 is suppressed. Furthermore, according to this submerged levee construction material, even if a crack occurs in the material, it can be expected that the strength will be restored thereafter. From the above, by using the above-mentioned submarine construction material, it is possible to avoid the problem of crack generation in the submarine made of a mixed material in which dredged soil and steelmaking slag are mixed, and it is possible to maintain the stability of the submarine 10.

When the water content of the cohesive soil is 100% or more, the workability with steelmaking slag and fibrous substances is not deteriorated, and when the water content is 300% or less, the strength is not lowered and it is good. When the mixing amount of the steelmaking slag is 30% or less by volume, the fluidity and workability are not deteriorated, and it is good, and when the volume ratio is 10% or more, the strength can be expected to be improved. Further, when the amount of the fibrous substance added is 0.1% or more by volume, the effects of suppressing the decrease in strength, imparting deformation followability, and recovering the strength can be obtained, and when the amount of the fibrous substance added is 1.0% or less by volume. In addition to ensuring fluidity and workability, the amount of addition does not become too large and the cost does not increase so much.

FIG. 2 is a schematic view showing another artificial tidal flat dike according to the present embodiment. The artificial tidal flat submarine 20 of FIG. 2 has a submarine lower part 21 constructed from a submarine construction material on the original ground G of the water bottom and a submarine upper part 22 constructed on the submarine construction material, and is underwater. It is built to be submerged in. The submarine lower part 21 is constructed by using the same submarine construction material as the submarine 10 in FIG. 1, but the submarine upper part 22 is constructed from a material other than the submarine construction material. The material for the submarine upper portion 22 is preferably a material in which the addition of the fibrous substance is omitted in the submarine construction material.

According to the submarine 20 of FIG. 2, the occurrence of cracks in the lower portion 21a of the submarine lower portion 21 is suppressed, and even if a crack occurs, the strength can be expected to recover thereafter, so that the stability of the entire submarine 20 is maintained. be able to. Further, not the entire submarine, but only the submarine lower part 21 where cracks are likely to occur is constructed from the submarine construction material capable of suppressing the occurrence of cracks, and the submarine upper part 22 is constructed from a material that does not contain fibrous material. Therefore, it is possible to reduce the material cost of the entire submarine. The thickness of the submarine lower portion 21 constructed from the submarine construction material to which the fibrous substance is added is preferably determined based on the installation water depth and structure of the submarine, the required strength, and the like.

Next, an example of the construction method of the submarine 10 of FIG. 1 and the submarine lower part 21 of FIG. 2 will be described. However, the construction method is not limited to this example, and other methods may be used.

(1) Add a predetermined amount of seawater or fresh water to cohesive soil such as mud-adjusted dredged soil, and adjust the water content ratio for cohesive soil.

(2) Kneading Adjusting mud is sent to a mixer, steelmaking slag and short fibers are added and kneaded at a predetermined volume ratio, and a submarine construction material is manufactured.

(3) Pumping The manufactured submarine construction material is transported to the casting site by a pumping pipe using a pumping pump.

(4) Placement The submerged levee construction material is placed underwater at a predetermined position using a tremie pipe. That is, the submarine 10 and the submarine lower portion 21 are constructed by underwater casting of the submarine construction material at positions corresponding to the submarine 10 in FIG. 1 and the submarine lower portion 21 in FIG. The upper part 22 of the submarine can be constructed in the same manner, but the addition of short fibers is omitted when kneading the submarine construction material. Further, the submerged levee construction material may be put into water by grab.

Further, according to the submarine construction material according to the present embodiment, since the fluidity is reduced by mixing the fibers, it is possible to increase the gradient of the submarine as compared with general calcia modified soil. .. Therefore, the material used for the construction of the submarine can be reduced, and the cost can be reduced.

The submarine construction material according to the present invention will be further described with reference to Examples, but the present invention is not limited to the present Examples.

Deformity followability The submarine construction materials of this example are dredged soil (soil particle density 2.633 g / cm ³ , liquid limit 101.3%) adjusted to a water content of 160% and steelmaking slag (particle size 9.5 for laboratory tests). (Adjusted to mm or less) was mixed, and polyester short fibers (fiber length 20 mm, fiber diameter 14.8 μm) were added at a predetermined volume ratio f and mixed. In Examples 1 to 6, the blending ratio of the short fibers was changed in 6 steps from 0.1 to 1.0 vol% by volume, and in Comparative Example 1, the short fibers were not blended. The formulations for Examples 1-6 and Comparative Example 1 are shown in Table 1 below.

As shown in Table 1, a dike construction material with the amount of fiber added as a parameter was prepared, and a uniaxial compression test was carried out 7 days after curing. The stress-strain diagram obtained from this uniaxial compression test is shown in FIG. The uniaxial compression test was carried out based on JIS A 1216.

From the results of FIG. 3, in Comparative Example 1 in which the short fibers were not mixed, the compressive stress decreased before reaching the compressive strain of 5%, whereas the short fibers were 0.2% vol by volume as in Examples 2 to 6. It can be seen that when the above is added, the material does not reduce the compressive stress even at a large strain level of 5% or more. Further, in Example 1 in which short fibers were added in an amount of 0.1 vol% by volume, it can be seen that the compressive stress does not decrease when the compressive strain is 5%. Further, in Examples 2 to 6 in which the fiber addition amount is 0.2 to 1.0 vol% by volume, it can be seen that the compressive stress holding effect is enhanced at a large strain level of 5% or more depending on the fiber addition amount. That is, as the amount of fiber added increases, the deformation followability improves.

As described above, in Examples 1 to 6 in which the amount of fiber added is 0.1 to 1.0 vol%, the compressive stress at a strain of 5% or more does not decrease depending on the amount of fiber added, and the deformation followability is improved. I understand. In addition, it is considered that the compressive stress does not decrease even when the fiber addition amount exceeds 1.0 vol%, but no significant difference is observed by increasing the addition amount at the strain level of 5%, and the addition amount increases. It can be seen that it is appropriate to set the upper limit of the amount of fiber added to 1.0 vol% because it causes a cost increase.

Compressive strength by volume ratio of steelmaking slag Next, using another dred soil (soil particle density 2.668 g / cm ³ , liquid limit 84.3%), as shown in Table 2 below, the water content ratio of the dred soil was 125,150,175. The volume ratio of steelmaking slag (particle size 37.5 mm or less) was changed to 20 vol% (Examples 7 to 11) and 30 vol% (Examples 12 to 16), and polyester short fibers (fiber length 20 mm) were changed. , Fiber diameter 14.8 μm) was changed from 0.1 to 1.0 vol% to prepare a slag construction material. In addition, the volume ratio of steelmaking slag was 20vol% (Comparative Example 2) and 30vol% (Comparative Example 3) without adding fibers, and the volume ratio of steelmaking slag was 40vol% and the amount of fiber added was 0, 0.1. Materials set to ~ 1.0 vol% (Comparative Examples 4 to 9) were prepared in the same manner. For these materials, a uniaxial compression test was carried out 7 days after curing based on JIS A 1216. The stress-strain curves obtained from this uniaxial compression test are shown in FIGS. 4 (a) to 4 (i).

From the results shown in FIGS. 4A to 4F, when the volume ratio of the steelmaking slag is 20vol%, the amount of fiber added is 0.2vol% or more, and the volume ratio of the steelmaking slag is 30vol%. It can be seen that the compressive stress does not decrease at a strain level of 5% when the amount of fiber added is 0.3 vol% or more. This tendency is the same regardless of the water content of the dredged soil of 125,150,175%. Further, from FIGS. 4 (g) to 4 (i), in the case of the comparative example in which the volume ratio of the steelmaking slag is 40 vol%, the compressive stress is applied at a strain level of less than 5% in the case where the fiber addition amount is 0.5 vol% or less. It can be seen that it is decreasing.

Recovery of strength Next, as shown in Table 3 below, steelmaking slag (indoor test) was applied to the dredged soil (soil particle density 2.633 g / cm ³ , liquid limit 101.3%) adjusted to a water content of 160%. Therefore, the particle size was adjusted to 9.5 mm or less) at a predetermined volume ratio, and polyester short fibers (fiber length 20 mm, fiber diameter 14.8 μm) were added at a predetermined volume ratio and mixed to obtain a submarine construction material. The amount of fiber added was set to 0.5 vol% because it was close to the median amount of fiber added (0.1 to 1.0 vol%) in the dike construction material according to the present embodiment. Further, in order to compare the recoverability of the shear strength with and without the addition of fibers, a material having a fiber addition amount of 0 vol% was obtained as Comparative Example 10. Assuming that the specific gravity of the fiber is 1.38 g / cm ³ , the fiber weight per unit volume is 6.9 kg / m ³ when the fiber addition amount is 0.5 vol%.

After curing the specimen prepared from the above submarine construction material for 28 days, uniaxial compression is performed to a strain level of 5%, loading is temporarily stopped, the specimen is taken out, exposed for 85 days, and then the uniaxial compression test is performed again. Carried out. The exposure method is a method of wrapping the specimen in a wrap to prevent drying (air exposure). The reason why the compression strain level given first was set to 5% is that in the specimen with a fiber addition amount of 0 vol% in Comparative Example 10, when a compression strain exceeding 5% was applied, the specimen was then taken out to prepare for exposure. This is because there is a risk that the specimen will collapse when doing so.

FIG. 5A shows the results of each compression test of Comparative Example 10 and FIG. 5B shows the results of each compression test of Example 17. The compressive stress on the vertical axis of FIGS. 5 (a) and 5 (b) is normalized (compressive stress ratio) by the maximum value of the compressive stress when the compressive strain is 5% or less. When no fibers were added as shown in FIG. 5 (a), the amount of added fibers was 0.5 vol as shown in FIG. 5 (b), whereas the reloading was less than the uniaxial compressive strength at the time of initial compression. When% is set, by adding steelmaking slag and fibers to the drowned soil, the uniaxial compressive strength at the time of initial compression is exceeded, and strength recovery can be confirmed. As described above, according to the submerged levee construction material of the present embodiment, even if a crack occurs, it can be expected that the strength will be restored thereafter.

Flow test (1)
Next, as shown in Table 4, steelmaking slag (particle size 37.5 mm or less) was applied to the drenched soil (soil particle density 2.668 g / cm ³ , liquid limit 84.3%) having a water content of 126.5% as Examples 18 to 27. Flow test based on JHS A 313 for mixed materials by mixing at a predetermined volume ratio (20vol%, 30vol%), adding short polyester fibers (fiber length 20 mm, fiber diameter 14.8 μm) at a volume ratio of 0.1 to 1.0 vol%. Was carried out. Further, as Comparative Examples 11 to 14, the same flow test was carried out for the materials in which the fiber addition amounts were 0 vol% and 1.5 vol%.

The results of these tests are shown in FIG. Here, the flow value of 85 mm or more is specified as an index of good workability and fluidity. From FIG. 6, it can be seen that the flow value decreases as the amount of short fibers added increases. In Comparative Examples 12 and 14 in which 1.5 vol% of short fibers were added, the flow value was lower than the flow value of 85 mm, which is an index of good workability, but in Examples 22 and 27 in which the fiber addition amount of 1.0 vol% was added, the flow value was higher. Since it was 85 mm or more, it was confirmed that it is preferable that the upper limit of the amount of fiber added is 1.0 vol% in terms of obtaining good workability and fluidity.

Slope gradient In addition, 30 vol% of steelmaking slag (particle size 37.5 mm or less) is mixed with drenched soil (soil particle density 2.668 g / cm ³ , liquid limit 84.3%) with a water content of 126.5% to shorten the polyester. Using a material in which 0.3 vol% of fibers (fiber length 20 mm, fiber diameter 14.8 μm) was added and mixed, the slope of the slope was 1: 3 when placed in water. On the other hand, since the slope gradient when short fibers were not added was about 1: 4, the effect of reducing the materials used as dikes can be expected by using the materials to which short fibers were added.

Flow test (2)
Next, as shown in Table 5, the drenched soil (soil particle density 2.633 g / cm ³ , liquid limit 101.3%) and steelmaking slag (particle size for laboratory test) adjusted to a water content of 160% as Examples 28 to 30. (Adjusted to 9.5 mm or less) is mixed at a predetermined volume ratio, and short polyester fibers (fiber length 20 mm, fiber diameter 14.8 μm) are added at a volume ratio of 0.5 vol% and mixed to improve fluidity. A flow test was carried out based on JHS A 313 for a material to which 2 kg / m ^{3 of a} dispersant (AMPS type) was added. Further, as Comparative Example 15, a flow test was carried out on the same material except that the volume ratio of the steelmaking slag was set to 40 vol%.

FIG. 7 shows the test results. From FIG. 7, it can be seen that as the mixing amount of the steelmaking slag increases, the flow value decreases and the fluidity of the material decreases. In Comparative Example 15 in which the mixing amount of the steelmaking slag was 40 vol%, it was confirmed that the flow value was less than 85 mm, the fluidity was low, the material was hard, and kneading was difficult. On the other hand, in Examples 28 to 30 in which the amount of steelmaking slag added is 30 vol% or less, the flow value exceeds 85 mm, and it can be seen that fluidity can be ensured. A certain level of fluidity is required for mixed casting of materials, but here the required fluidity should be 85 mm or more, and the mixing amount of steelmaking slag should be 10 to 30 vol% as a formulation that satisfies this. It was confirmed that it was appropriate. When the mixing amount of steelmaking slag was 30 vol%, the uniaxial compressive strength on the 28th of the material age was about 300 kN / m ² .

Although the embodiments for carrying out the present invention have been described above, the present invention is not limited to these, and various modifications can be made within the scope of the technical idea of the present invention. For example, the dike construction material and the dike structure according to the present invention can be applied to a dike of an artificial tidal flat, but of course, it can be applied to a dike other than the artificial tidal flat.

Further, the material composed of the cohesive soil, the steelmaking slag and the fibrous material according to the present invention is not limited to the dike, and can be applied to, for example, a filling material for an artificial leaf of a wave-dissipating structure.

According to the submarine construction material and the submarine structure of the present invention, the problem of crack generation in the submarine can be avoided and the stability of the submarine can be maintained. Therefore, for example, a stable submarine is constructed in an artificial tidal flat. Can be done.

10 Artificial tidal flat submarine, submarine 10a Lower part 11 Filling material 12 Sand covering 20 Artificial tidal flat submarine, submarine 21 Submarine lower part 21a Lower part 22 Submarine upper part G Original ground

Claims (4)

It is a material for constructing a submarine where the embankment body is submerged under the surface of the water.
Cohesive soil with a water content adjusted to 100 to 300% and steelmaking slag with a particle size of 37.5 mm or less are divided into 70 to 90% of the cohesive soil and 30 to 10% of the steelmaking slag. In a uniaxial compression test on a material that has been mixed so as to be% and further added a fibrous substance in an external volume ratio of 0.1 to 1.0%, the latent property has a property that the compressive stress does not decrease when the compressive strain is 5% or 5% or more. Embankment construction material. A submarine structure characterized in that it was constructed from the submarine construction material according to claim 1 . A submarine structure having a lower submarine constructed from the submarine construction material according to claim 1 and an upper submarine constructed from a material other than the submarine construction material. The submarine structure according to claim 3 , wherein the material other than the submarine construction material is a material in which the addition of the fibrous substance is omitted in the submarine construction material.

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