JP2789407B2 - Soil improvement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for improving soil, and more particularly to a method for improving soft soil having poor drainage.

[0002]

2. Description of the Related Art When a building is built on the ground made of soft and poorly drainable soil, there is a fear that problems such as tilting and cracking of a wall may occur. Also, if there is a lot of rainfall, it may collapse. Further, in a cold region or in winter, a large amount of water contained in the ground freezes or forms a frost column, so that such a ground causes various problems in use.

[0003] The main cause of poor softness and drainage is the high water retention of the soil in the ground. That is, the water in the soil is supplied by the groundwater stored below due to rain rising by capillary action.

When the soil constituting the ground is a fine-grained viscosity or a silt layer having a large capillary attraction, drainage is particularly poor and softening is extremely severe.

[0005] As a method of improving such a soft ground having poor drainage properties, a water-repellent sand is applied to the soil to provide a water-repellent sand layer to suppress the rise of capillary water and reduce the water content in the soil. Attention has been focused on how to lower it.

[0006]

The above method is expected to be an effective method. However, when the soil is very fine powder, the repellent provided in the soil with the passage of time is used. The effect of the water sand layer may be reduced. That is,
If a long period of time has passed since the water-repellent sand layer was provided in the soil, fine soil particles from the soil above and below the water-repellent sand layer may enter the water-repellent sand gap and adhere to it. In such a case, the apparent water repellency of the water-repellent sand decreases, and the efficiency of suppressing the rise of capillary water decreases over a long period of time.

On a road or the like, a dynamic action due to the passage of a vehicle is strong. In such a ground where a dynamic action is particularly strong, the penetration of soil particles into the water-repellent sand layer and the formation of the water-repellent sand layer on the upper and lower sides. Mixing with the soil layer, disintegration, and the like are likely to occur, and the expected effect may not be obtained.

We have made various studies in view of the above points, and as a result, it has been found that the use of a water-repellent membrane can significantly reduce the migration of water to the upper layer due to capillary action in soil. . It has also been found that by combining this water-repellent membrane and water-repellent sand, the effect of the water-repellent layer made of the water-repellent sand can be maintained for a long period of time, and the present invention has been accomplished.

[0009]

That is, the present invention provides a soil improvement method comprising providing a water-repellent water-repellent membrane in soil as described in claim 1 of the present invention. Is provided.

[0010] Further, the present invention relates to claim 2 of the present invention.
As are described in, is to provide a soil improvement method according to claim 1 permeability under no load in the vertical direction of the water-repellent membrane is 10 ^-3 ~10 ³ cm / sec.

[0011] The present invention also relates to claim 3 of the present invention.
The present invention provides the soil improvement method according to claim 1 or 2, wherein the water-repellent membrane is made of synthetic fibers.

Further, the present invention relates to claim 4 of the present invention.
The present invention provides the soil improvement method according to any one of claims 1 to 3, wherein the water-repellent membrane is any one of a nonwoven fabric, a woven fabric, and a knitted fabric.

[0013] The present invention also relates to claim 5 of the present invention.
Above the water-repellent membrane or / and
And a water-repellent layer made of water-repellent sand subjected to a water-repellent treatment in the lower soil, to provide the soil improvement method according to any one of claims 1 to 4.

[0014] The present invention also relates to claim 6 of the present invention.
As described in, the average particle size of the water-repellent sand is 0.02 to
The soil improvement method according to claim 5, which is 2 mm.

[0015] The present invention also relates to claim 7 of the present invention.
Water-repellent membrane or / and water-repellent sand treated with a water-repellent agent containing one or more of silicone-based, fluorosilicone-based, and acrylic emulsion-based water-repellents as described in Claim 1 to Claim 6
The soil improvement method according to any one of the above items is provided.

Further, the present invention provides a method according to claim 8 of the present invention.
As described in the above, the present invention provides a method for preventing salt damage to soil by using the soil improvement method according to any one of claims 1 to 7.

Further, the present invention is directed to claim 9 of the present invention.
As described in above, the present invention provides a method for preventing freezing of soil by using the soil improvement method according to any one of claims 1 to 7.

[0018] The present invention is also characterized by claim 1 of the appended claims.
The present invention provides a method for greening a desert by using the soil improvement method according to any one of claims 1 to 7, as described in Item 0.

Hereinafter, the present invention will be described in more detail. The present invention, by applying a water-repellent membrane to the soil, significantly reduces the movement of water to the upper layer due to capillary action in the soil, secures drainage of the soil and prevents softening of the soil. is there.

Further, by applying the water-repellent membrane and the water-repellent sand to the soil in combination, the water-repellent membrane serving as the separation material can penetrate the soil particles into the water-repellent sand layer or spread to other soil / sand layers of the water-repellent sand. To prevent intrusion and intrusion.

The water-repellent membrane has an excellent filter performance against earth and sand, and has a structure that is hardly clogged. Therefore, the water-repellent membrane has an excellent drainage property and keeps the drainage of the soil for a long period of time.

Further, the water-repellent membrane has an effect of dispersing and equalizing the stress applied to the soil structure, and thus has an excellent reinforcing effect.

Therefore, due to the effect of the water-repellent membrane,
The performance of the water-repellent sand layer can be maintained for a long time,
It has the effect of suppressing the rise of capillary water, and its excellent drainage performance prevents freezing and the formation of frost pillars in cold regions and low temperatures in winter. For this reason, damage to crops, swelling and peeling of pavement materials can be prevented, and the ground can be stabilized.

In the case of the ground where seawater rises from underground, the occurrence of salt damage can be prevented. Furthermore, since the water-repellent membrane suppresses evaporation of water in the soil, it is also effective for desertification of land or desert greening.

Examples of the water-repellent membrane include non-woven fabrics, woven fabrics and knitted fabrics, and materials having excellent weather resistance are desirable. In particular, those made of synthetic fibers such as vinylon and polyester are desirable, but those made of acrylonitrile, nylon and the like can also be used.

Any water-repellent membrane can be used as long as it has substantially water repellency. However, if the membrane is too coarse, the water-repellent effect is reduced. If the eyes are too fine, clogging tends to occur, which is economically disadvantageous.

Therefore, the degree of water repellency of the water-repellent membrane is 10 ⁻³ to 10 when the vertical water permeability is no load.
^It is preferably in the range of ³ cm / sec, more preferably in the range of 10 ^-2 to 10 cm / sec.

The position where the water-repellent membrane is laid may be determined in consideration of the soil properties of the ground, the groundwater level, the purpose, and the like. Also, especially when using a coarse water-repellent membrane,
It is preferable to apply water-repellent sand to the soil above, below, or both above and below the water-repellent membrane. In particular, it is preferable to provide coarse water-repellent sand below the water-repellent membrane.

Water-repellent sand is obtained by treating the surface of sand particles with a water-repellent, and these can be used alone or in combination. The sand used as the material can be appropriately selected from those generally used as civil engineering and building materials in the fields of mortar, concrete, and the like, such as sea sand, mountain sand, river sand, and silica sand.

It is not necessary to use a special water-repellent sand, but it is advantageous to use relatively coarse sand in consideration of economy and the like. That is, the average particle size of the water-repellent sand is preferably in the range of 0.02 to 2 mm from the viewpoint of the function of completely suppressing the rise of capillary water and the processing cost of the water-repellent agent treatment. When the average particle size is smaller than 0.02 mm, the amount of the water repellent to be treated is increased, and when the average particle size is larger than 2 mm, the effect of suppressing the rise of capillary water becomes small, and the water repellent sand in the soil must be set thick. .

The water-repellent used for obtaining the water-repellent membrane and the water-repellent sand can be used without any particular limitation as long as it is generally used as a water-repellent. It is preferable to use one or two or more of a water repellent of an acrylic type and an acrylic emulsion type. Among them, silicone-based ones are particularly preferred from the viewpoints of water repellency and economics.

As the silicone-based water repellent, for example, a silicone compound represented by the following general formula [Chemical Formula 1] can be mentioned. As it is, it is directly (solvent-free) or diluted with a solvent such as toluene, xylene or trichlene. Alternatively, it is used as an emulsion type. Further, a curing catalyst such as dibutyltin dilaurate, dibutyltin diacetate, dioctyltin laurate, iron octate and the like may be used.

[0033]

Embedded image R ¹ aR ² bSiOx [R ¹ is the same or different unsubstituted or substituted monovalent hydrocarbon group; R ² is the same or different group selected from a hydrolyzable group, —OH or —H A and b are 0 ≦ a <4, 0 ≦ b
≦ 4, 0 <a + b ≦ 4; x = (4-ab) / 2. ]

For example, in the general formula [1], R ¹ is a group having 1 carbon atom such as a methyl group, an ethyl group, a propyl group and a decyl group.
Alkenyl groups such as alkyl groups, vinyl groups and allyl groups, aryl groups such as phenyl groups, part of hydrogen atoms bonded to carbon atoms of the above groups such as CH ₃ CH ₂ CH ₂ − Or a group in which all are substituted with a halogen atom, a cyano group, or the like.

R ² represents a hydrolyzable group such as an alkoxy group, an acyloxy group, a ketoxime group, an amino group, an aminoxy group, an amide group, an enoxy group, an alkenyloxy group, a halogen group such as chlorine, and -OR ³ (R ³ is Na or K), —OH, —H and the like.

As specific silicone compounds, for example, the following compounds represented by [Chemical Formula 2] to [Chemical Formula 5] are used.

HO-Si (ONa) (CH ₃ )-[OSi (ONa) CH
₃ ] n-OH (n: 0, 1, 2)

Embedded image CH _3- [SiO (CH ₃ ) ₂ ] _m- [SiO (H) (C
H ₃ )] _l -Si (CH ₃ ) ₃ (l, m: 0 or an integer)

Embedded image _{^{R 4 - [SiO (CH 3}} ) 2] k-Si (CH 3) 2 R 4 (K:
^{Integer, R 4: -OH, -CH =} CH 2, -OCH 3)

Embedded image CH ₃ SiCl ₃ , C ₁₀ H ₂₁ SiCl ₃ , CF ₃ CH
₂ CH ₂ SiCl ₃ , CH ₃ Si (OCH ₃ ) ₃ or partial hydrolysates thereof

Also,

Embedded image The silazane compound of (CH ₃ ) ₃ SiNH—Si (CH ₃ ) ₃ is also useful as a water repellent used in the present invention.

As a method for treating the surface of the water-repellent sand with a water-repellent agent, a method generally used for the surface treatment of powder may be used. For example, it is possible to produce water-repellent sand by mixing various silicone oils and sand by a mechanochemical method and performing surface treatment. It is also possible to produce water-repellent particles by polymerizing volatile cyclic silicones such as octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane on the surface of sand by gas phase treatment.

The installation position and thickness of the water-repellent membrane are determined in consideration of the position of the groundwater table and the like so that the effects of the present invention can be sufficiently exerted. For example, even if the water-repellent membrane is set to a level lower than the groundwater level, water in the soil will rise due to water pressure. Moreover, even if it is provided in soil that is too close to the surface of the ground, the effect of soil improvement will be diminished.

When a road is laid on soft soil, a water-repellent membrane, water-repellent sand, and gravel are laid in this order on soft ground, and asphalt or concrete pavement is placed thereon. Particles can be effectively prevented from entering the water-repellent sand layer, and are also effective in preventing the road from freezing.

When the soil is used for the purpose of preventing salt damage and the soil is relatively fine, a structure having a water-repellent membrane, a water-repellent sand, a water-repellent membrane, and a surface soil on a basic soil may be used. . Note that the upper water-repellent membrane need not be provided.

The present invention is particularly useful when used in a ground covered with concrete or asphalt, because damage such as cracks and cracks in the concrete or asphalt ground can be effectively prevented.

In particular, when used in the ground of a pavement road, the intrusion of soil particles into the water-repellent sand layer due to dynamic action such as traffic of vehicles is suppressed, and the effect of the present invention is maintained for a long period of time. Therefore, the life of paved roads with heavy traffic is dramatically increased.

[0044]

Next, the present invention will be described with reference to examples. The present invention is not limited to this.

First, an experiment was conducted to confirm the effect of preventing soil moistening and softening of the example of the present invention.

Example 1 Materials used Water-repellent sand Silica sand No. 4 (average particle size: 1 mm) was treated with a 0.3% C ₁₀ H ₂₁ Si (0Me) ₃ solution as a water-repellent agent. And water-repellent sand was obtained. Water-repellent nonwoven fabric A polypropylene nonwoven fabric having a thickness of 2 mm and a water permeability of 10 ^-1 cm / sec was used. To this nonwoven fabric, 5 parts of silicone (KP8400, manufactured by Shin-Etsu) was added to the above water repellent and subjected to a water repellent treatment to obtain a water repellent nonwoven fabric.

Production of Soil Structure As shown in FIG. 1, sand (from the bottom) was placed in a container (test device) 1 having a 30 cm × 30 cm × 30 cm drain port 14 made of an acrylic plate so that it could be observed from the outside. Silica sand No.4, no water repellent treatment, saturated water) layer 10, water repellent sand layer 1
1. The water-repellent nonwoven fabric 12 and the silt layer 13 were laid in this order to have a thickness of 10 cm, 4 cm and 15 cm, respectively.

Experimental Method 1.8 liters of water 15 was sprayed once a day from the upper surface of the tester 1 using a jar, and then after one week, four weeks, 12 weeks and 24 hours. After a week, a soil of 5 cm depth from the surface of the silt layer 13 was sampled,
The water content was investigated. The experiment was performed while maintaining the temperature and humidity at 20 ° C. and 70% RH.

[Example 2] In the same container as in Example 1, soil having exactly the same configuration as that of Example 1 was laid except that untreated sand without water-repellent treatment was used instead of water-repellent sand. Example 2 The soil structure of Example 2 was prepared, and the same experiment as in Example 1 was performed.

[Comparative Example 1] Completely the same as in Example 1 except that water-repellent nonwoven fabric was not laid in the same container as in Example 1 and untreated sand which was not subjected to water-repellent treatment was used instead of water-repellent sand. The same structure as in Example 1 was performed on the soil structure of Comparative Example 1 by laying the soil having the same configuration.

[Comparative Example 2] Except for using a non-treated non-woven fabric and a non-water-repellent non-treated non-woven fabric and sand in place of the water-repellent non-woven fabric and the water-repellent sand in the same container as in the first embodiment, the same structure as in the first embodiment Was laid to form the soil structure of Comparative Example 2, and the same experiment as in Example 1 was performed.

Table 1 shows the results of the above experiment.

[0053]

[Table 1] Here, the initial value indicates the value before watering at the start of the experiment.

In the case of Comparative Example 1 in which no nonwoven fabric was used, the moisture content had already increased to about 5 times the initial value one week after the start of the experiment, and there was no significant change thereafter. Further, in the case of Comparative Example 2 using a nonwoven fabric not subjected to the water-repellent treatment, the increase in the water content was slower than in Comparative Example 1, but after 24 weeks, the water content reached the same level as Comparative Example 1.

In contrast, in the case of Example 1 using the water-repellent sand and the water-repellent nonwoven fabric, the water content was less than twice the initial value even after 24 weeks from the start of the experiment. In the case of Example 2 using untreated sand and a water-repellent nonwoven fabric, the water content increased as compared with Example 1, but remained at about three times the initial value even after 24 weeks.

Next, an experiment was conducted to confirm the effect of preventing salt accumulation in the examples of the present invention.

Example 3 Materials used Water-repellent sand Silica sand No. 4 was subjected to a water-repellent treatment with 2% C ₁₀ H ₂₁ Si (0CH ₃ ) ₃ emulsion to obtain water-repellent sand. Water-repellent nonwoven fabric A nonwoven fabric made of vinylon having a water permeability of 1.5 cm / sec was used. To this nonwoven fabric, 4 parts of silicone (X61-429I manufactured by Shin-Etsu) was added to the above water repellent, and water repellent treatment was performed to obtain a water repellent nonwoven fabric.

Preparation of Soil Structure As shown in FIG. 2, a saline solution was placed in a container (test device) 1 having a 30 cm × 30 cm × 30 cm drain port 14 made of an acrylic plate so that it could be observed from the outside. , A sand-containing layer 20, a sand layer 21, a test sand layer 22 using water-repellent sand, a water-repellent nonwoven fabric 23, and a silt layer 24 in this order.

Experimental Method 40 g / m ² of water 25 was sprayed once a day from the upper surface of the tester 1 using a jar, and kept at 37 ° C. for 1 week and 10 weeks. After 20 weeks and 40
After a week, the degree of precipitation of salt on the upper surface of the silt layer 24 was observed.

[Example 4] In the same container as in Example 3, instead of water-repellent sand, untreated sand not subjected to a water-repellent treatment was used as a test sand layer 2.
A soil structure of Example 4 was prepared by laying the soil having exactly the same configuration as that of Example 3 except that it was used in Example 2, and the same experiment as in Example 3 was performed.

[Comparative Example 3] In the same container as in Example 3, except that the water-repellent nonwoven fabric 23 was not laid, the same soil as in Example 3 was laid to prepare the soil structure of Comparative Example 3. The same experiment as in Example 3 was performed.

[Comparative Example 4] The same procedure as in Example 3 was carried out except that no untreated sand was used for the test sand layer 22 without laying the water-repellent non-woven fabric and instead of using the water-repellent sand instead of the water-repellent sand. Example 3
A soil structure of Comparative Example 4 was prepared by laying the soil having the same configuration as that of Example 1, and the same experiment as in Example 3 was performed.

[Comparative Example 5] In the same container as in Example 3, an untreated non-woven fabric not subjected to a water-repellent treatment was used in place of the water-repellent nonwoven fabric 23, and an untreated non-treated non-treated fabric was used instead of the water-repellent sand. A soil structure of Comparative Example 5 was prepared by laying the soil having exactly the same configuration as in Example 3 except that sand was used for the test sand layer 22, and the same experiment as in Example 3 was performed.

Table 2 shows the results of the above experiment.

As can be seen from Table 2, Example 3 using water-repellent sand and water-repellent nonwoven fabric had the greatest effect, and no precipitation of salt was observed even after 40 weeks. Further, in the case of Example 4 in which a water-repellent nonwoven fabric was used and no water-repellent sand was used, the effect was great after Example 3. On the other hand, Comparative Example 3 in which the water-repellent sand was used and the nonwoven fabric was not laid was inferior to the above-mentioned examples. In Comparative Examples 4 and 5 in which no water-repellent sand and non-woven fabric were used, or in which a non-woven fabric not subjected to the water-repellent treatment was used, salt precipitation was observed in a short period of time.

[0066]

[Table 2]

Next, an experiment was conducted to confirm the durability of the embodiment of the present invention against the dynamic action caused by the running of the vehicle and the effect of preventing freezing.

Example 5 Materials Used Water-repellent sand Water-repellent sand was obtained by performing the same water-repellent treatment as in Example 1 using a 5-mm sieve of river sand. Water-repellent nonwoven fabric The same one as in Example 1 was used.

Preparation of Soil Structure As shown in FIG.
1. A ground having a structure in which a water-repellent sand layer 32 and a gravel / sand layer 33 were sequentially laid was produced.

Experimental Method After thoroughly dispersing water from the surface of the ground, it was cured for 24 hours at a temperature of 20 ° C. and a humidity of 85% RH. Thereafter, a vehicle (4-ton vehicle) was driven on the ground, and the surface condition was observed. Thereafter, the atmosphere temperature was set to -10 ° C, and the presence or absence of freezing of the ground was observed.

Comparative Example 6 The ground having the same soil structure as in Example 5 was prepared except that the water-repellent nonwoven fabric was not laid, and the same experiment as in Example 5 was performed.

Table 3 shows the results of the above experiment.

In Comparative Example 6, the portion where the vehicle traveled was 2
At 0 ° C., the soft soil rose, and the water-repellent sand layer and the gravel / sand layer were mixed. Also, traces of ruts remained deep. further,
At −10 ° C., the raised soil portion was frozen. On the other hand, in the part where the vehicle did not travel, the gravel / sand layer did not freeze even at −10 ° C.

On the other hand, in Example 5, no lift of the soft soil was observed in the portion where the vehicle traveled even at 20 ° C. Also, some traces of ruts remained. Furthermore,-
Even at 10 ° C., the gravel / sand layer did not freeze. On the other hand, in the part where the vehicle did not travel, the gravel / sand layer did not freeze at -10 ° C.

[0075]

[Table 3]

[0076]

As described above, according to the present invention, by applying a water-repellent membrane to soil, the movement of water to the upper layer due to capillary action in the soil can be significantly reduced, and the soil is moistened. -Softening can be prevented.

In addition, it is possible to prevent freezing and frost columns from occurring in cold regions and low temperatures in the winter period, prevent damage to crops, swelling and peeling of pavement materials, and stabilize the soil. further,
The occurrence of salt damage can be prevented even in soil where seawater rises from underground. Further, the present invention suppresses evaporation of water from soil, so that it is effective in preventing desertification of land and greening deserts.

By combining the water-repellent membrane with the water-repellent sand, the effect of the water-repellent layer made of the water-repellent sand can be maintained for a long period of time.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a soil structure according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a soil structure according to another embodiment of the present invention.

FIG. 3 is a sectional view showing a soil structure according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Container 10 Sand layer 11 Water repellent sand layer 12 Water repellent nonwoven fabric 13 Silt layer 14 Drain port 15 Water 20 Salt-containing sand layer 21 Sand layer 22 Test sand layer 23 Water repellent nonwoven fabric 24 Silt layer 25 Water 30 Soft soil 31 Water repellent nonwoven fabric 32 Water repellent sand layer 33 Gravel / sand layer

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Kinya Ogawa 2-6-1 Otemachi, Chiyoda-ku, Tokyo Shin-Etsu Chemical Co., Ltd. (56) References JP 2-54013 (JP, A) JP Hei 2-279852 (JP, A) Japanese Utility Model 63-95736 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) E02D 3/00 102

Claims (10)

(57) [Claims] 1. A soil improvement method comprising providing a water-repellent membrane having been subjected to a water-repellent treatment in soil. 2. The soil improvement method according to claim 1, wherein the water-repellent membrane has a water permeability of 10 ⁻³ to 10 ³ cm / sec when no load is applied in the vertical direction. 3. The soil improvement method according to claim 1, wherein the water-repellent membrane is made of synthetic fiber. 4. The non-woven fabric, woven fabric,
The soil improvement method according to any one of claims 1 to 3, which is a knitted fabric. 5. The water-repellent layer made of water-repellent sand subjected to a water-repellent treatment is provided in the soil above and / or below the water-repellent membrane. Soil improvement method. 6. The water-repellent sand has an average particle size of 0.02 to 2 m.
The soil improvement method according to claim 5, wherein m is m. 7. The water-repellent membrane and / or the water-repellent sand has been subjected to a water-repellent treatment with a water-repellent agent containing one or more of silicone-based, fluorosilicone-based, and acrylic emulsion-based water-repellents. The soil improvement method according to any one of claims 1 to 6. 8. A method for preventing salt damage to soil by using the soil improvement method according to any one of claims 1 to 7. 9. A method for preventing freezing of soil by using the soil improvement method according to any one of claims 1 to 7. 10. The method according to claim 1, wherein
A method for greening a desert using the soil improvement method described in the above section.