JPH0530925B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <<Industrial Application Field>> The present invention relates to a construction method for reclaimed ground, and more particularly to a method for imparting a large bearing capacity to the ground in order to construct a structure on the reclaimed ground.

≪Conventional technology≫ As a construction method for creating reclamation ground in rivers, lakes, marine areas, etc., the common method is to construct a cofferdam using steel sheet piles, steel pipe sheet piles, concrete walls, etc., and fill it by pouring earth and sand into the cofferdam. It is true.

However, with this construction method, the soil particles separate and settle in the water, and are separated into coarse particles and fine particles, so this type of reclaimed ground is heterogeneous and contains a large amount of fine particles. Some parts have a high water content and are very soft.

Therefore, when a large ground bearing capacity is required, such as when constructing an important structure on this reclaimed ground, the conventional method is to lay a sheet on the reclaimed ground after the reclamation is completed and sprinkle earth and sand on the sheet, or to use the method of reclamation. After solidifying the surface layer of the ground with cement, etc. to build a foothold that construction machines can access, drainage from the reclaimed ground is carried out using the drain method, or by stirring and mixing lime, cement, and earth and sand deep into the ground. A method of solidifying and forming a columnar shape has been adopted, but each method has the following problems.

≪Problems to be solved by the invention≫ In other words, the method of spreading earth and sand requires high-strength sheets and girder materials to support them because the reclaimed ground is extremely soft. This may be more effective, but also prolong the construction period.

In addition, with the drain method, when solidifying the surface layer, the target is reclaimed ground that has a high water content and is extremely soft, requiring a large amount of solidifying material and requiring special processing machinery, making it expensive.

Moreover, the more fine particles the reclaimed soil has, the narrower the intervals between drain materials and the need for a large number of drain materials to be placed.
If silty soil is used as reclaimed soil to reduce this, the reclaimed soil itself becomes expensive, and in any case, the construction method becomes expensive.

Furthermore, the method using stirring and mixing is applied to ground with high water content, requires a large amount of solidifying material, and is very expensive because it requires a special stirring and mixing machine.

This invention was made in view of the above-mentioned problems, and its purpose is to select an area that requires sufficient strength, such as an area where a structure is planned to be constructed, and to install a drain method in that area, such as the above-mentioned drain construction method. Eliminates the need for auxiliary construction methods, shortens the construction period, and at the same time
The object of the present invention is to provide a construction method that can create inexpensive, high-yield reclaimed ground by reducing the amount of materials used for reclamation.

<<Means for Solving the Problems>> In order to achieve the above object, the present invention provides a cofferdam in a body of water where the ground is to be formed, and pours earth and sand into the cofferdam to create reclaimed ground. In this construction method, an area that requires high strength, such as the planned area for a structure's foundation, and other areas within the planned ground formation area are separated from other areas using a partition material, and within the area enclosed by the partition material, soil and soil particles are separated. The present invention is characterized in that a mixture of a composition consisting of a binder that binds together, suppresses their separation, and imparts curability as necessary is added.

<<Operation>> According to the above configuration, the area where a structure is planned to be constructed becomes a solid supporting ground made of a mixture of composition consisting of earth and sand and a binder. Furthermore, as the mixture hardens, the partition material that separates this mixture input area from other areas will be subject to virtually no lateral pressure, and the distribution will depend on the placement of the partition material to form a resilient ground. The ground can be separated from other general soil with high precision.

<<Example>> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 to 4 show an embodiment of the reclaimed ground preparation method according to the present invention.

First, in Fig. 1, as in the past, partition plates 2 made of steel sheet piles, steel pipe sheet piles, or concrete plates are driven into the underwater ground 1 to surround the water area where the planned ground formation site A is to be formed. Separate planned site A.

Next, as shown in Fig. 2, the planned structure foundation site B within the planned ground formation site A is selected and the other area C is selected.
A flexible sheet 3 with the boundary line as a partition material
Section by. A float 4 is provided on the upper edge side of the sheet 3, and a sinker 5 is provided on the lower edge of the sheet 3, and the planned structure foundation site B and multiple areas are provided over the entire height from the water bottom ground 1 to the water surface. It is vertically separated from C. In addition, as shown in the figure, by making the lower edge side of the sheet 3 slightly wider and the upper edge side narrower, a trapezoidal load-bearing ground, which will be described later, can be formed.

After the installation work of the sheet 3 is completed, as shown in Fig. 3, the pump P is installed in the planned foundation area B and other areas C.
Landfill work is carried out while draining water.

In this case, without using the pump P, a part of the partition plate 2 may be raised to the same height as the outside water level to drain water by natural overflow.

A mixture 6 having a composition consisting of a binder that binds earth and sand and earth and sand particles, suppresses their separation, and, if necessary, imparts hardening properties, is introduced into the area where the foundation is planned. In addition, general earth and sand 7 is thrown into the other area C. In this embodiment, a pumping method using a tremie tube 8 is used as a feeding method, but a feeding method using a bucket or the like may also be used.

By carrying out the above operations, as shown in FIG. 4, a reclaimed ground is obtained in which the planned foundation area B and other areas C are clearly divided into approximately trapezoidal cross sections.

Here, in the mixture 6 to be introduced into the planned foundation area B, the binder is a binder that imparts caking properties between the earth and sand particles and ensures a predetermined fluidity, or the binder It also contains a hardening agent that hardens between the earth and sand particles and solidifies the earth and sand.

The binder is made of a water-soluble natural, semi-synthetic or synthetic polymer, and acts as a kind of glue-like substance to prevent the separation of particles and the incorporation of water.

To give specific examples of the binder, water-soluble natural polymers include various starches, konjac, funori, agar, sodium alginate, molasses, gum tragonth, gum arabic, dextrin, levan,
Glue, gelatin, casein, collagen, etc. are used.

Examples of water-soluble semi-synthetic polymers include viscose, methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose,
Soluble starch, carboxymethyl starch, dialdehyde starch, etc. are used.

As the water-soluble synthetic polymer, polyvinyl alcohol, sodium polyacrylate, polyacrylamide, polyethylene oxide, etc. are used.

In addition, the hardening agents are cement materials, lime-based materials, slag-based materials such as blast furnace slag, asphalt-based materials, etc. that have been conventionally used for soil stabilization treatment, and these hardening agents are Solidify and stabilize the soil quality and improve its strength.

The preferable mixing ratio of these binders and hardeners is 1 to 5 parts by weight of binder and 50 to 200 parts by weight of hardener to 1000 parts by weight of earth and sand, from the viewpoint of economy and degree of achievement of effects. It is within the range.

In the above-mentioned mixture 6, since the earth and sand are bound together by the binder, they do not separate in the water, but settle almost as one body, and are deposited in a homogeneous state. Since there is little water uptake in the water after aging, it becomes a dense state with little decrease in density, and if a hardening agent is added, solidification progresses until it becomes strong quickly after adding it. It has extremely high durability.

In addition, in the charging process shown in FIG. 3, the mixture 6 solidifies quickly within the sheet 3 and no lateral pressure is applied to the sheet 3, so even if there is an imbalance in the accumulation level with the general soil 7, the sheet 3 There is no lateral pressure applied to the sheet 3, and the reclamation can be completed with the cross-sectional shape of the sheet 3 maintained in its installed state. Therefore, construction D is placed on the planned area B as shown by the imaginary line in FIG.
When constructed, the building will be well supported on the ground due to the large bearing capacity of this part.

Note that the sheet 3 may be removed after the reclamation work, or may be left as is. Alternatively, the mixture 6 may be first introduced to fill up the section B where the construction foundation is planned, and then the area C may be filled with the general earth and sand 7.

Furthermore, although the sheet 3 is shown as an example of a partition material in the above embodiment, the present invention is not limited to this, and the invention can be implemented using a plate-shaped partition material, a relatively dense net-like material, a cloth-like material, or even a cloth-like material. The material may be a combination of these nets and cloth.

<<Effects of the Invention>> As explained above in the embodiments, according to the reclaimed ground preparation method according to the present invention, only the ground surface of the area where the structure is planned to be constructed in the reclaimed ground is bonded between earth and sand particles. Because the ground is made of a mixture of composition consisting of a binder that suppresses separation and provides hardening properties as necessary, it provides strong support for the structure and only needs to be filled with the mixture in a volume sufficient to support the structure. , materials can be saved, and there is no need to improve the ground after the reclamation is completed, so the construction period can be significantly shortened. Further, according to the construction method of the present invention, it is possible to accurately divide areas requiring resistance, such as the planned foundation area, from other areas according to the arrangement of the partitioning materials.

[Brief explanation of drawings]

1 to 4 are cross-sectional explanatory views showing one embodiment of the reclaimed ground construction method according to the present invention. 1... Water bottom surface, 2... Closing plate, 3... Sheet,
6...Mixture, 7...General earth and sand, A...Planned ground formation area, B...Planned structure foundation area, C...Other areas, D...Structures.

Claims (1)

[Claims] 1. Construct a cofferdam in the water area where the ground formation is planned,
In a construction method in which earth and sand are poured into the cofferdam to create reclaimed ground, areas that require high strength, such as the area where the foundation for a structure is planned, within the area where the ground is planned to be formed are separated from other areas using partition materials. Into the area surrounded by the partition material, a mixture of a composition consisting of a binder that binds soil and sand particles, suppresses their separation when they are put into the water, and imparts hardening properties as necessary is introduced. A construction method for reclaimed ground that is characterized by: