JP6060891B2 - Filling material for sand compaction pile, sand compaction pile method and sand compaction pile - Google Patents

Description

  The present invention relates to a filling material for sand compaction pile, a sand compaction pile method, and a sand compaction pile.

  The Sand Compaction Pile (SCP) method uses vibration, impact load, or static load by press-fitting filling materials such as natural sand, crushed stone, and slag into soft ground such as loose sand layer and soft viscous ground. It is a method of improving the ground by creating one or more compressed sand compaction piles (stakes) with a large diameter and compacting the surrounding ground to increase the density of the ground, and it is also used as a liquefaction countermeasure It is done.

  FIG. 4 is a schematic view showing an example of a construction method of a typical SCP method. In this SCP method, (a) a casing (hollow tube) 102 (generally having a diameter of 400 to 600 mm) into which the filling material 101 is charged is penetrated to (b) a predetermined depth, and (c) the casing 102 is While pulling up or moving up and down, the filling material 101 is discharged into the ground, and the casing 102 is driven again or moved up and down to apply force to the filling material 101 and compact it. The discharge of the filling material 101 and compaction by applying force are repeated, and (d) a sand compaction pile 103 (generally about 700 mm in diameter) having a specified length is formed.

  In the conventional SCP method, natural sand was used as the filling material. However, in recent years, blast furnace slag (blast furnace granulated slag and blast furnace blast furnace slag and blast furnace) generated as a by-product in the steel manufacturing process from the viewpoint of reducing environmental burden and cost. Steel slag such as slow cooling slag and steelmaking slag is used (for example, see Patent Document 1).

表１の数値は、「ＪＩＳ Ａ １１０２：２００６に規定する、公称目開き４．７５ｍｍの金属製網ふるいを通したときに９９％以上１００％以下のものが通過し、かつ、公称目開き２．００ｍｍの金属製網ふるいを通したときに８０％以上１００％以下のものが通過し、かつ、公称目開き０．８５ｍｍの金属製網ふるいを通したときに３０％以上７５％以下のものが通過し、かつ公称目開き０．４２５ｍｍの金属製網ふるいを通したときに７％以上３０％以下のものが通過し、かつ、公称目開き０．２５ｍｍの金属製網ふるいを通したときに３％以上１５％以下のものが通過し、かつ、公称目開き０．１０６ｍｍの金属製網ふるいを通したときに１％以上６％以下のものが通過し、かつ、公称目開き０．０７５ｍｍの金属製網ふるいを通したときに０％以上４％以下のものが通過する」粒度分布を有することを示している。 For example, the above granulated blast furnace slag is lighter than natural sand, has a large shear resistance angle, and has the property of reacting with moisture in the ground after construction (also called self-hardening or latent hydraulic) Therefore, it is suitably used as a filling material for the SCP method.
When blast furnace granulated slag is used as the filling material in the SCP method, the particle size distribution of Table 1 below described in Non-Patent Document 1, which is a technical guide on blast furnace granulated slag (hereinafter simply referred to as “particle size distribution of Table 1”). The particle size of blast furnace granulated slag was adjusted.

The numerical values in Table 1 are “99% to 100% when passing through a metal mesh screen having a nominal opening of 4.75 mm as defined in JIS A 1102: 2006, and a nominal opening of 2 80% or more and 100% or less when passing through a metal mesh screen of .00 mm, and 30% or more and 75% or less when passing through a metal mesh screen with a nominal aperture of 0.85 mm When passing through a metal mesh sieve with a nominal mesh of 0.425 mm and passing through a metal mesh sieve with a nominal mesh of 0.425 mm and passing through a metal mesh sieve with a nominal mesh of 0.25 mm 3% or more and 15% or less pass, and when passing through a metal mesh screen having a nominal opening of 0.106 mm, 1% or more and 6% or less pass, and a nominal opening of 0. It passed through a 075mm metal mesh sieve. Those less than 4% to 0% to come is shown to have to "particle size distribution passage.

  On the other hand, in the blast furnace granulated slag in a general storage state such as yard storage (storage in a piled state), the particles are consolidated due to the self-hardness of the blast furnace granulated slag, and the particle size becomes approximately 5 mm or more. The anti-caking agent was added to the granulated blast furnace slag adjusted to the particle size distribution shown in Table 1 to maintain the particle size distribution.

JP 2007-309091 A

Coastal Development Technology Research Center, Steel Slag Association, “Granulated Slag Use Guide for Port Construction”, August 1989, p. 11-12

  When the SCP method is performed using the filling material containing the granulated blast furnace slag adjusted to the particle size distribution of Table 1 described in Non-Patent Document 1 as a guide, the inside of the slag inlet and the casing of the construction apparatus, There was a risk of clogging the filling material. When the filling material is clogged, there is a problem that the work efficiency is lowered, for example, the operation is interrupted in order to eliminate the clogging, or the processing speed of the filling material is reduced without interrupting the operation.

An object of the present invention is to propose an SCP filling material that can suppress clogging of the filling material in the SCP method.
Another object of the present invention is to propose an SCP method that can suppress clogging of the filling material and suppress a decrease in work efficiency or improve work efficiency.

As a result of the study by the present inventors, the granulated blast furnace slag adjusted to the particle size distribution shown in Table 1 exerts a force for collision with the slag inlet or the inner wall of the casing and compaction using the casing. In addition, the particles of blast furnace granulated slag, or the collision of blast furnace granulated slag with other slag (hereinafter simply referred to as “impact during construction”) were further refined. It was found that granulated blast furnace slag caused clogging.
As a result of further investigation by the present inventors on this problem, it was found that clogging can be suppressed by using a filling material containing granulated blast furnace slag having a particle size (consolidated) of 5 mm or more.
In addition, granulated blast furnace slag having a particle size of 5 mm or more was appropriately crushed by the force applied at the time of construction. As a result, the particle size distribution of granulated blast furnace slag during construction was almost the same as the particle size distribution in Table 1 and was created. It was found that the performance of the sand compaction pile can be sufficiently secured. That is,

(1) The filling material for sand compaction pile according to the present invention is a filling material for sand compaction pile containing blast furnace granulated slag, wherein the particle size of the granulated blast furnace slag is 5 mm or more. To do.
(2) The filling material for sand compaction piles according to (1) above, containing 10% by mass or more of granulated blast furnace slag.
(3) The filling material for sand compaction pile according to (1) above, comprising 100% by mass of granulated blast furnace slag.

(4) Sand compaction pile construction method according to the present invention is a sand compaction pile construction method in which a filling material for sand compaction pile containing granulated blast furnace slag is used, and a force is applied to the medium filling material using a casing for compaction. And the particle size of the said blast furnace granulated slag is 5 mm or more, It is characterized by the above-mentioned.
(5) The sand compaction pile method according to the above (4), which includes 10 mass% or more of granulated blast furnace slag with respect to the total mass of the filling material.
(6) The sand compaction pile construction method according to the above (4), which includes 100% by mass of granulated blast furnace slag with respect to the total mass of the filling material.
(7) A sand compaction pile manufactured by the sand compaction pile method according to any one of (4) to (6) above.

According to the present invention, when the particle size of the granulated blast furnace slag is 5 mm or more, clogging (clogging of the filling material inside the slag inlet of the construction apparatus and inside the casing) is suppressed in the SCP method.
According to the present invention, the cost of the SCP method can be reduced by performing the SCP method using the filling material for SCP including the granulated blast furnace slag having a particle size of 5 mm or more.
Moreover, the sand compaction pile manufactured by the SCP method according to the present invention has the same ground improvement performance as the sand compaction pile manufactured by the conventional SCP method.

FIG. 1 is a graph showing the particle size curves (solid line) of two types of granulated blast furnace slag of the filling material for SCP according to the present invention and the particle size distribution range (dashed line) of Non-Patent Document 1. FIG. 2 is a top view schematically showing an experimental region in which a sand compaction pile was created. FIG. 3 is a graph showing the relationship between the N depth and the depth of the ground before and after the creation of the sand compaction piles of the example and the comparative example. FIG. 4 is a schematic view showing an example of a construction method of a typical SCP method.

  Hereinafter, the sand compaction pile (SCP) filling material, the SCP method, and the sand compaction pile according to an embodiment of the present invention will be described in detail with reference to the drawings. In addition, the following description and drawing are examples for demonstrating the filling material for SCP which concerns on this invention, an SCP construction method, and a sand compaction pile, and this invention is not limited to the form shown and illustrated at all.

In the present invention, “blast furnace granulated slag” refers to a product that is rapidly cooled and granulated (granulated) by injecting pressurized water into molten slag or injecting molten slag into a water tank.
In the present invention, the “particle diameter” is limited to a sieve defined in JIS A 1102: 2006. For example, particles having a particle size of 5 mm or more are assumed to remain in the “5 mm sieve” defined in JIS A 1102: 2006.
In this specification, “sieve” refers to a sieve defined in JIS A 1102. For example, a 5 mm sieve refers to a metal mesh sieve with a nominal aperture of 4.75 mm.
In the present specification, the “blast furnace slow cooling slag” refers to a molten slag that is solidified and cooled in the atmosphere by air cooling or a combination of air cooling and water spraying, or other means known in the field of steelmaking.
In this specification, “steel slag” refers to slag that is produced simultaneously when steel is produced by refining hot metal, scrap, etc. Converter slag, electric furnace slag, hot metal pretreatment slag, secondary refining slag, slag Includes lapping slag, cast slag, and kneading furnace slag.

(Inner packing material for sand compaction pile)
The filling material for sand compaction pile according to the present invention is a filling material for sand compaction pile containing blast furnace granulated slag, wherein the particle size of the granulated blast furnace slag is 5 mm or more.
The SCP filling material according to the present invention includes at least blast furnace granulated slag. That is, part or all of the SCP filling material is granulated blast furnace slag. This is because the granulated blast furnace slag has a weak bonding force between particles, and is easily crushed or crushed by a collision at the time of construction or the like to fit in a desired particle size distribution.

  It is important that the granulated blast furnace slag has a particle size of 5 mm or more. If the particle size is 5 mm or more, clogging of the filling material inside the slag inlet of the construction apparatus and inside the casing is suppressed, and further, pulverized or crushed by a collision at the time of construction and the desired particle size distribution is accommodated. Because. In addition, when the particle size of the granulated blast furnace slag is 5 mm or more, the granulated blast furnace slag is more likely to fall freely inside the inlet or the casing due to its own weight, compared to the case where the particle size is less than 5 mm. This is because clogging is suppressed.

As described above, conventionally, it is necessary to add an anti-caking agent to the blast furnace granulated slag in order to follow the particle size distribution of Table 1 described in Non-Patent Document 1 which is a guide, or the blast furnace granulated slag with rain or moisture. It was necessary to store it so as not to get wet and solidify. Furthermore, even if an anti-caking agent is added, the effect of the anti-caking agent decreases with time, so it is necessary to add an anti-caking agent, and much labor and cost are required to maintain the particle size distribution shown in Table 1. there were. And blast furnace granulated slag that does not conform to the particle size distribution in Table 1, such as granulated blast furnace slag having a particle size of 5 mm or more, has not been used in the SCP method.
On the other hand, the granulated blast furnace slag used in the present invention has a particle size of 5 mm or more, and the granulated blast furnace slag which is stored and consolidated in a general storage state such as yard storage has a particle diameter of approximately 5 mm or more. Therefore, there is no need to add an anti-caking agent, and there are fewer storage restrictions such as storage location and storage method, so it is possible to reduce the labor and cost of producing and storing filling materials. .

  The method for setting the particle size of the granulated blast furnace slag to 5 mm or more is not particularly limited. The method of promoting is mentioned.

The particle size of the granulated blast furnace slag may be 5 mm or more, and may be appropriately adjusted according to the size of the slag inlet of the construction apparatus, the diameter of the casing, and the like. Since the diameter of the casing used for a general SCP method is about 400 to 600 mm, the particle size of the granulated blast furnace slag is preferably equal to or less than the diameter from the viewpoint of work efficiency, and is 5 to 200 mm. It is more preferable. If the particle size is 5 to 200 mm, the blast furnace granulated slag can be crushed when a force is applied to the filling material using a casing in a known SCP method. The particle size distribution is almost the same as the particle size distribution in Table 1, and no construction problems occur. Here, compaction using a casing means a) a casing pipe, b) a vibrator or a compacting device built in the casing, c) a casing pipe having a double steel pipe structure, d) excavation attached to the casing, and And / or compaction using a diameter expanding head or the like.
For this reason, the granulated blast furnace slag that has not been used for the reason that it does not conform to the particle size distribution of Table 1 described in Non-Patent Document 1 described in the manual can be used.
As mentioned above, since granulated blast furnace slag is finely divided even when a relatively small force is applied, the filling material for SCP according to the present invention contains particles having a particle size of less than 5 mm which are unavoidable for handling. It may be.

  FIG. 1 shows particle size curves (solid lines 1 and 2) of two types of granulated blast furnace slag as an example of the blast furnace granulated slag of the filling material for SCP according to the present invention, and the range of the particle size distribution in Table 1 (dashed line 3). It is the graph which showed. The particle size of the granulated blast furnace slag of the solid line 1 is in the range of 5 to 100 mm, and the particle size of the granulated blast furnace slag of the solid line 2 is in the range of 20 to 300 mm. On the other hand, the range of the particle size distribution indicated by the broken line 3 is that of the particle size distribution in Table 1.

The filling material for sand compaction pile (SCP) according to the present invention is a conventionally known SCP such as natural sand, crushed stone, blast furnace slow-cooled slag, steelmaking slag, in addition to blast furnace granulated slag, without departing from the spirit of the present invention. One or more types of materials for the construction method may be included, or the material may be composed only of blast furnace granulated slag.
The blast furnace slow cooling slag and steelmaking slag usually have a large particle size of about 10 to 20 mm, and by combining one or more of these with blast furnace granulated slag, the blast furnace slow slag is formed in a sand compaction pile formed. Blast furnace granulated slag, which is appropriately crushed or crushed during construction, is filled between large particles of cold slag and steelmaking slag, and there is an advantage that an increase in shear resistance angle due to long-term consolidation can be expected.
Moreover, the filling material for SCP which concerns on this invention can obtain the consolidation promotion effect of granulated blast furnace slag by including 10 mass% or more of granulated blast furnace slag.

  The filling material for SCP according to the present invention contains 100% by mass of granulated blast furnace slag, and thus a large-scale apparatus for mixing blast furnace granulated slag and a material different from blast furnace granulated slag such as steelmaking slag. The cost can be reduced.

(Sand compaction pile method)
The sand compaction pile method according to the present invention is a sand compaction pile method using a filling material for sand compaction pile containing blast furnace granulated slag, wherein the particle size of the granulated blast furnace slag is 5 mm or more. To do.
By performing the SCP method using an SCP filling material containing granulated blast furnace slag having a particle size of 5 mm or more, clogging of the filling material is suppressed, and a reduction in work efficiency of the SCP method can be suppressed. Blast furnace granulated slag that does not have the particle size distribution shown in Table 1 can be used as a filling material. Compared to the conventional SCP method using a granulated blast furnace granulated slag as a filling material, the ground improvement performance is equivalent. A sand compaction pile can be created.
Further, as described above, since the filling material for SCP with reduced manufacturing and storage costs and labor can be used, the cost of the SCP method can be reduced, and the filling material before construction can be reduced. Since particle size adjustment is not necessary, work efficiency can be improved.

  The materials such as the filling material used in the SCP method according to the present invention and the blast furnace granulated slag contained in the filling material are the same as those described in the above-mentioned filling material for SCP, and the preferred ranges are also the same. Therefore, explanation is omitted.

  The type of the SCP method according to the present invention is not particularly limited, and any SCP method may be adopted as long as it has a step of compacting while applying force to the filling material. Any of a conventionally known vibration type, impact type, rotary press-fitting type, hydraulic type, and the like may be used. In particular, the construction method in which the casings (A) to (E) described in paragraph [0004] of Patent Document 1 are compacted by using the casing is desirable from the fact that there are many construction results. Here, compaction using a casing means a) a casing pipe, b) a vibrator or a compacting device built in the casing, c) a casing pipe having a double steel pipe structure, d) excavation attached to the casing, and And / or a diameter expansion head.

The construction apparatus used in the SCP method according to the present invention is not particularly limited, and can be a construction apparatus used in a conventionally known SCP method. For example, the casing of the construction apparatus may be either a single pipe or a double pipe. In the case of a double pipe, the blast furnace granulated slag can be more effectively crushed by increasing the number of times the inner pipe is moved up and down.
Further, the casing may be one in which one or more ribs, protrusions and the like are provided at equal intervals or randomly on the inside thereof to collide with the blast furnace granulated slag so as to easily break the blast furnace granulated slag. The ribs, protrusions, and the like may be appropriately adjusted as long as they are in contact with the blast furnace granulated slag, and may be in the middle of the casing or inside the tip portion.

  In the sand compaction pile (SCP) method according to the present invention, by containing 10 mass% or more of the blast furnace granulated slag with respect to the total mass of the filling material, consolidation of the blast furnace granulated slag is promoted for a long time. The shear resistance angle can be expected to increase due to mechanical consolidation.

  In the sand compaction pile (SCP) method according to the present invention, blast furnace granulated slag such as blast furnace granulated slag and steelmaking slag is contained by including 100 mass% of the blast furnace granulated slag with respect to the total mass of the filling material. Since there is no need to mix a material different from the above, there is an advantage that the work efficiency at the time of construction is increased and the cost can be reduced.

(Sand compaction pile)
The sand compaction pile according to the present invention is a sand compaction pile manufactured by the SCP method according to the present invention, and has a ground improvement performance equivalent to that of the sand compaction pile manufactured by the conventional SCP method.
The sand compaction pile according to the present invention solidifies due to the self-hardness of blast furnace granulated slag, although it depends on ground conditions such as the presence or absence of groundwater. When solidified, the effect of suppressing the deformation and slip of the ground can be exerted, so the effect of suppressing the residual deformation of the structure, pile (including sand compaction pile) or the ground at the time of earthquake is further enhanced.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

  The construction apparatus used for the construction of the sand compaction pile is a double pipe method, and the diameter of the casing is 500 mm. With this construction apparatus, a sand compaction pile having a diameter of 700 mm and a length of 10 m was created.

As the filling material for sand compaction, the following filling materials for SCP of Examples 1 to 3 and Comparative Example 1 were prepared.
1) Example 1: Of granulated blast furnace slag that was left in an environment where it was exposed to outdoor rain for one month without using an anti-caking agent, only granulated blast furnace slag having a particle size in the range of 5 mm to 50 mm. did.
2) Example 2: Example 2 was the same as Example 1 except that only the granulated blast furnace slag having a particle size in the range of 5 mm to 100 mm (solid line 1 in FIG. 1) was used.
3) Example 3: Example 3 was the same as Example 1 except that only the granulated blast furnace slag having a particle size in the range of 20 mm to 300 mm was used (solid line 2 in FIG. 1).
4) Comparative Example 1: Only granulated blast furnace slag according to the particle size distribution shown in Table 1 was used (within the range of broken line 3 in FIG. 1). As the granulated blast furnace slag of Comparative Example 1, a blast furnace slag whose particle size was adjusted so as to follow the particle size distribution shown in Table 1 immediately after production was used.

A sand compaction pile was formed by the SCP method using the filling materials for SCP of Examples 1 to 3 and Comparative Example 1.
In Examples 1 to 3, the SCP method could be applied without causing clogging of the filling material.

  FIG. 2 is a top view schematically showing an experimental region in which a sand compaction pile was created. As shown in FIG. 2, each of the sand compaction piles has a total of 16 columns in the vertical direction and the horizontal direction at an interval of 1.8 m in the vertical direction and in the vertical direction in four rows in the experimental area. Created. The N value was measured at the □ mark point in FIG. 2, which is approximately the center point of the experimental area.

  FIG. 3 shows the depth of the ground (depth from the ground surface) before the formation of the sand compaction pile (sign of ●), Example 1 (sign of □) and Comparative Example 1 (dotted line), and the depth It is the graph which showed the relationship with N value. As shown schematically on the right side of FIG. 3, the ground where the sand compaction pile creation experiment was performed is a sand layer from a surface layer to a depth of 6.8 m, a silt layer from a depth of 6.8 m to a depth of 8.2 m, and a depth of 8. A layer deeper than 2 m is a sand layer. Before the formation (signs of ●), the ground has a N value of 10 or less in most of the depth from 3 m to 10 m.

  As shown in FIG. 3, in both cases of Example 1 and Comparative Example 1, an increase in N value in the soft ground is seen compared to that before the creation of the sand compaction pile, which is improved from the original ground. Recognize. Furthermore, even in Example 1 using a blast furnace granulated slag having a particle size of 5 mm or more in which the particle size distribution in Table 1 was not adjusted, the N value increased to the same level as in Comparative Example 1. In Examples 2-3, the same effect as in Example 1 was obtained.

From these results, the sand compaction pile according to the present invention has the same ground improvement performance as the sand compaction pile created by the conventional SCP method using the granulated blast furnace granulated slag as the filling material. You can see that
In addition, the SCP method according to the present invention using the filling material for SCP containing the granulated blast furnace slag having a particle size of 5 mm or more is compared with the conventional SCP method using the granulated blast furnace granulated slag as the filling material, Sand compaction piles with the same ground improvement performance could be created, and further, the use of anti-caking agent and particle size adjustment became unnecessary, so the cost could be reduced and the work efficiency could be improved.
In addition, the filling material for SCP according to the present invention including granulated blast furnace slag having a particle size of 5 mm or more could be suitably used for the SCP method.

1 Particle size distribution of granulated blast furnace slag of Example 2 Particle size distribution of granulated blast furnace slag of Example 3 Particle size distribution of granulated blast furnace slag of Table 1 101 Filling material 102 Casing 103 Sand compaction pile 104 Material input port 105 Drilling auger

Claims (6)

Filling material for sand compaction pile containing granulated blast furnace slag,
A filling material for sand compaction pile, wherein the granulated particle size distribution of the granulated blast furnace slag is within a range of 5 mm to 300 mm .   The filling material for sand compaction pile according to claim 1, wherein the blast furnace granulated slag is contained in an amount of 10% by mass or more.   The filling material for sand compaction pile according to claim 1, wherein the granulated blast furnace slag is contained by 100% by mass. Using a sand compaction pile filling material containing granulated blast furnace slag, a sand compaction pile method of applying force to the filling material using a casing and compacting,
A sand compaction pile construction method, wherein a particle size distribution of the granulated blast furnace slag is within a range of 5 mm to 300 mm .   The sand compaction pile method according to claim 4, wherein the blast furnace granulated slag is contained in an amount of 10% by mass or more based on the total mass of the filling material.   The sand compaction pile method according to claim 4, wherein the blast furnace granulated slag is included in an amount of 100 mass% with respect to the total mass of the filling material.

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