JPH08104868A - Capsule-like ground improving material and engineering method for improving ground using the same - Google Patents

Abstract

PURPOSE: To obtain the subject ground improving material capable of readily handling, free from occurrence of dust, etc., by enclosing a water-absorbing expanding material and a solidifying material into a water-permeable capsule. CONSTITUTION: This ground improving material is obtained by enclosing (A) a water-absorbing expanding material 2, preferably a highly water-absorbing resin, (B) a solidifying material 3, preferably a cement-based or lime-based solidifying material into (c) a water-permeable capsule 4, preferably a water-soluble resin. This engineering method for improving ground is to insert a penetrating body for boring holes into ground, charge and pack the ground improving material into a space part obtained by the penetrating body for boring holes together with earth and sand and form earth and sand columns containing the ground improving material at proper intervals. Furthermore, a water- permeable capsule 4 is preferably a granular capsule body having II dimensions of 2-5cm length L, 1-3cm ϕh and 1-3cm ϕb .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground improvement material in the form of a capsule in which a water absorbing expansive material and a solidifying material are enclosed and a ground improvement method using the same.

[0002]

2. Description of the Related Art Ground improvement methods that have been conventionally adopted include a method of eliminating water in soil to promote consolidation and a method of injecting or mixing a solidifying material into soil to stir to solidify the soil. Is mentioned. As a typical example of the former method, a large number of sand piles (sand pillars) are driven into a soft ground such as an alluvial cohesive soil layer, and this is used as a drainage channel to dissipate excess water pressure in the ground. There is a sand drain construction method which is used as a material for the consolidation and solidification of the ground, and a vertical drain construction method which uses a paper drain or the like instead of the sand pile. Further, as a typical example of the latter method, for example, in a region excavated and stirred by a ground improvement machine having a stirring blade, quick-lime, a slurry solidification material such as cement-based solidification material is charged and mixed with soft soil to consolidate the ground. Deep mixing treatment method, powder injection stirring method in which powder such as lime and cement is pneumatically fed as it is in the form of powder, and slurry in water is mixed and solidified by using moisture in the soil. A ground improvement method such as a jet grout method in which cement slurry is introduced into a void formed by cutting the ground with jet energy and replaced with excavated earth and sand to form a solidified body has been developed and put into practical use.

[0003]

However, the ground improvement such as the sand drain method is intended to increase the consolidation speed by shortening the drainage distance, and because of the passive drainage due to the capillary phenomenon between the sand particles, There is a problem that a long period is required as an improvement period. Further, in the case of ground improvement for solidification using a solidifying material, a cement-based material, a water glass-based material, a polymer-based solidifying material or the like is usually used as the solidifying material. Problems such as pollution causing pollution problems and adversely affecting the physical properties of the improved soil are occurring.

Further, in the case of a method in which the powder-type solidifying material is put into the ground and agitated, dust is generated during the processing or pressure feeding of the powder-type solidifying material, which may cause deterioration of the surrounding environment.

Therefore, a main object of the present invention is to provide a ground improvement material which has a small effect on the natural environment or the surrounding environment and which can effectively improve the effect, and a ground improvement method using the same.

[0006]

In order to solve the above-mentioned problems, the present invention is characterized in that a water-absorbent expanding material and a solidifying material are enclosed in a water-permeable capsule. In this case, as the water-absorbent expansion material, from the viewpoint of water absorption capacity and expansion coefficient, it is desirable to use a highly water-absorbent resin, and when the water-permeable capsule is a water-soluble resin, it remains in the ground after improvement. It becomes suitable without doing. As the solidifying material, cement-based or lime-based materials are preferably used from the viewpoint of solidification capacity and cost.

When the ground is improved by using the capsule-like ground improvement material, a hole-drilling penetration body is inserted into the ground, and then the capsule-shaped ground is formed in a space portion formed by the hole-drilling penetration body. The improvement material is charged and filled together with the earth and sand, and a large number of earth and sand columns containing the capsule-like ground improvement material are formed at appropriate intervals. In the case of improving only the shallow layer portion, the capsule-shaped ground improving material is sprayed on the surface layer portion of the ground and is stirred with the surrounding ground.

[0008]

In the present invention, the water absorbing expansive material and the solidifying material are enclosed in a water permeable capsule to provide a ground improvement material. Therefore, it is easy to handle and does not generate dust. Further, the water-absorptive expansive material forcibly absorbs moisture in the soil and expands its own volume to consolidate the surrounding ground and improve soil properties. In addition, the solidifying material fixes and stabilizes the expanded state of the water-absorbing expansive material. Further, since the chemical reaction between the solidifying material and water is basically performed in the capsule, it is possible to prevent the solidifying material from flowing out, and there is no problem in pollution such as contamination of groundwater.

By using a highly water-absorbent resin as the water-absorbent expansive material, the water-absorbing power and the expansiveness are remarkably improved, and the highly water-absorbent resin which has absorbed water and gelated can be applied even if some pressure is applied. Since it has a strong water retention capacity that does not separate water, it is optimal as a consolidation accelerator.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on embodiments.
As shown in FIGS. 1 and 2, a capsule-shaped ground improvement material 1 according to the present invention (hereinafter, also simply referred to as a capsule).
Is a water-permeable expansion material 2 and a solidifying material 3 and a water-permeable capsule 4
It is configured by enclosing it inside. The dimensions of the water-permeable capsule 4 are preferably length L; 2 to 5 cm,
φ _h ; 1 to 3 cm, φ _B ; 1 to 3 cm, and the ground improvement material of the present invention is a granular capsule body in any case. Various materials can be used as the water absorbent expansion material 2. For example, expansive materials such as ettringite or lime, which are used as admixtures for concrete, can also be used, but these have a low expansion coefficient of about 1.3 times, so there is a high demand in the field of sanitary products such as disposable diapers. It is desirable to use a highly water-absorbent resin (water-absorbent polymer). The super absorbent polymer is a structure in which a water-soluble polymer having a large number of hydrophilic groups is slightly cross-linked (three-dimensional network),
It is insoluble in water, and its appearance is a powdery synthetic polymer, but when it comes into contact with water, it absorbs water and expands and changes into a gel, and at the same time, the gel that once absorbed water has a slight pressure. Has a strong water retention capacity that does not separate even when added. In addition, its absorption capacity reaches hundreds to thousands times its own weight. Specific examples of the anionic type include polyacrylic acid type, polysulfone hydrochloric acid type, acrylic acid graft type and acrylic acid copolymer type. In addition, cation-based compounds include quaternary ammonium salt-based compounds, and nonionic-based compounds include polyvinyl alcohol-based compounds, polyacrylamide-based compounds, and polyoxyethylene-based compounds. When the concentration of the electrolyte in the soil water is high, the water absorption capacity of the anionic highly water-absorbent resin decreases as the concentration of the electrolyte increases. On the other hand, the non-ionic type is not affected by the electrolyte concentration but has a characteristic that the water absorption capacity itself is lower than that of the anionic type, so that it has a suitable property depending on the physical properties of the improved ground area. It is desirable to use a super absorbent resin.

On the other hand, examples of the solidifying material 3 include ordinary Portland cement-based, blast furnace cement-based, fly ash-based cement-based solidifying materials, lime-based solidifying materials such as quick lime, slaked lime and granular lime, and lime / pozzolan-based solidifying materials. Etc. can be used. It is desirable that the target ground is properly used depending on the nature of the soil such as organic soil, high water content soil, sandy soil, and volcanic ash soil.

On the other hand, as the water-permeable capsule 4, a plastic material container having an appropriate number of through holes 1a, 1a formed as shown in the figure, or a material such as paper having water permeability in the material itself. Can be used. As the plastic material, low-density polyethylene or polypropylene having high ductility, low-strength soft vinyl chloride, or the like is preferably used. In addition, natural water-soluble resins such as carrageenin, corn starch, guar gum and tragacanth gum, polyvinyl alcohol, polyacrylamide, cationic resin, polyacrylic acid and its derivatives, polyethylene oxide, poly-N-vinyl-2-pyrrolidrin, vinyl ether type It is possible to prevent the capsule container after destruction from disappearing and remaining in the ground by producing it from a water-soluble polymer such as a polymer or a synthetic polymer resin such as a styrene-maleic anhydride copolymer. Furthermore, the water absorbing resin 2 and the solidifying material 3 are made of the water-soluble resin.
It can also be encapsulated by forming a coating surrounding it. In this case, the water-soluble resin coating film has the “water permeability” in the present invention due to the water-soluble property. The water-permeable capsule 4 expands or breaks easily when the superabsorbent resin 2 enclosed therein expands. However, the water-permeable capsule 4 is easy to handle until it is used and penetrates. Since the reaction between the underground water and the solidifying material is basically performed in the capsule 4, the solidifying material is prevented from flowing out and the surrounding environment is prevented from deteriorating.

The water absorbing expansive material 2 and the solidifying material 3 may be enclosed by sandwiching the water absorbing expansive material 2 with the solidifying materials 3 and 3, as shown in FIG. 2, for example. Further, as shown in FIG. 3, the water absorbent expansion material 2 may be enclosed so as to be surrounded by the solidifying material 3.

Next, some examples of ground improvement construction methods using the capsule-shaped ground improvement material will be described. First, the first example shown in FIG. 4 is an example of ground improvement intended for deep soft ground. A hollow auger pile 11 is penetrated into the ground by using a pile loader 10, and earth and sand containing the capsule-like ground improvement material 1 (hereinafter referred to as ground improved soil) is pressure-fed through the hollow auger 11 from the penetration state. , Hollow auger 1
Sequentially filling the space created by the pulling out of No. 1 and creating a large number of piles of ground-improved soil in the ground. The capsule-shaped ground improvement material 1 absorbs surrounding soil water to reduce moisture in the ground, and the expansion of the capsule-shaped ground improvement material 1 consolidates the surrounding ground to stabilize the ground.

The second example shows the procedure of another example of forming ground improvement soil piles, which has an air suction port 14 on the upper side and an air injection port 15 on the lower side. A casing 12 having an opening / closing valve 13 at an upper end thereof is used, and compressed air is sent from the air suction port 14 to inject compressed air from an air injection port 15 at a lower end of the casing 1.
2 is inserted into the ground, and then, as shown in FIG. 5 (C), a hopper 16 is installed at the upper end of the casing 12, the opening / closing valve 13 is opened, and a bucket filled with ground improvement soil by a crane or the like. 17 is suspended and the casing 12 is filled with ground improvement soil through the hopper 16. After that, the casing 12 is gradually pulled out to complete the construction of the pile by the ground improvement soil. The second example is an example of directly following the example of the sand pile forming method in the sand drain method, but other sand pile forming methods, for example, jet type, Frankie pile applied type, double casing type, jet casing type, A method such as a jet casing type with a mud discharge port can be applied as it is.

Next, in the case of improving the soft ground layer which is relatively shallow and has a high water content, as shown in FIG. 6, the capsule ground improving material 1 is sprinkled on the soft ground layer and the backhoe 2 is used.
Stir mechanically at 0 or the like. In this case, although the consolidation effect due to expansion is not expected, the capsule-shaped ground improvement material 1 absorbs moisture in the soil and changes the soil having a high water content into the soil having a low water content. Facilitates handling during transportation or re-excavation.

[0017]

As described above in detail, according to the present invention, since the absorbent expansive material and the solidifying material are enclosed in the capsule, they are easy to handle and no dust is generated. In addition, when the capsule is charged and filled in the soft ground, the moisture in the soil is forcibly absorbed, expanded, and simultaneously solidified, so that the surrounding ground is quickly consolidated and stabilized. Further, when the capsule absorbs moisture in the soil and solidifies, the chemical reaction is retained in the capsule, and thus it is not a secondary source of pollution. On the other hand, when excavating and transporting improved soil using the capsule, or when excavating again, the capsule absorbs moisture in the soil and changes it into soil with a low water content, so that it does not re-mud Various effects are brought about, such as not lowering the strength of.

[Brief description of drawings]

FIG. 1 is a side view of a capsule-shaped ground improvement material according to the present invention.

FIG. 2 is a view taken along the line II-II of FIG.

FIG. 3 is a cross-sectional view showing another sealed state.

FIG. 4 is an explanatory diagram of a ground improvement method.

FIG. 5 is an explanatory diagram of another ground improvement method.

FIG. 6 is an explanatory diagram of another ground improvement method.

[Explanation of symbols]

1 ... Capsule-like ground improvement material, 2 ... Absorbable expansion material, 3 ... Solidification material, 4 ... Water-permeable capsule

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C09K 17/22 P 17/44 P 17/48 P 17/50 P E02D 3/12 // C09K 103 : 00

Claims (6)

[Claims] 1. A capsule-like ground improvement material comprising a water-absorbent expansion material and a solidifying material enclosed in a water-permeable capsule. 2. The capsule-like ground improvement material according to claim 1, wherein the water-absorbent expansion material is a highly water-absorbent resin. 3. The capsule-like ground improvement material according to claim 1, wherein the solidifying material is cement-based or lime-based. 4. The capsule-like ground improvement material according to claim 1, wherein the water-permeable capsule is a water-soluble resin. 5. A drilling penetrating body is inserted into the ground, and then the space portion formed by the drilling penetrating body is filled with the capsule-like ground improvement material according to any one of claims 1 to 4 together with earth and sand. , A soil improvement method characterized in that a large number of sediment columns containing capsule-shaped soil improvement materials are formed at appropriate intervals. 6. A ground improvement method, which comprises spraying the capsule-like ground improvement material according to any one of claims 1 to 4 on a surface layer of the ground and stirring the ground material with surrounding ground.