JPH06101224A - Soil conditioning method - Google Patents

Abstract

PURPOSE:To prevent soil from softening by providing a water repellence treated water repellent membrane into soil, and providing a water repellent layer of water repellence treated water repellent sand to the upper or lower part of the water repellent membrane. CONSTITUTION:A water repellent membrane is constituted of nonwoven fabric of synthetic fiber, and coefficient of water permeability in the case of vertical non-load of the membrane is 10<-3>-10<3>cm/sec. After that, average particle size of water repellent sand is 0.02-2mm, and water repellent treat-ment is made to the membrane and water repellent sand with a water repellent member of silicon, etc. Then, the water repellent nonwoven fabric 31, water repellent sand layer 32, gravel and sand layer 33 are subsequently laid on a poor soil 30 to form a base course, the incursion of soil particles of the poor soil into the sand layer 32 by dynamic action caused by passing of a car is prevented by the nonwoven fabric 31, and the movement of water content to the upper layer by a capillary phenomenon in the soil is lowered by the non-woven fabric 31. According to the constitution, draining efficiency in the soil is ensured by the gravel and sand layer 33 and, at the same time, the softening of the soil can be prevented by the nonwoven fabric 31.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soil improvement method, 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 consisting of soil that is soft and has poor drainage, problems such as tilting and cracking of walls may occur. Also, if there is a large amount of rainfall, it may collapse. Further, in cold regions or in winter, a large amount of water contained in the ground freezes or forms frost columns, which causes various problems in use.

The main cause of weakness and poor drainage is the high water retention of soil in the ground. That is, the water content in the soil is supplied when the groundwater stored below due to rainfall rises due to the capillary phenomenon.

When the soil constituting the ground has a viscosity of a fine particle size having a large capillary attraction and a silt layer, the drainage property is particularly poor and the soil is extremely weakened.

As a method for improving such soft ground having poor drainage property, water-repellent sand is applied to the soil to form a water-repellent sand layer so as to suppress the rise of capillary water and to reduce the water content of the soil. Attention has been paid to a method of lowering it.

[0006]

The above method is expected to be an effective method. However, when the soil is a very fine powder, the repellent agent provided in the soil over time is used. The effect of the sand layer may be reduced. That is,
When a water repellent sand layer is provided in the soil for a long time, fine soil particles may enter the water repellent sand gaps from the soil above and below the water repellent sand layer and adhere thereto. In that case, the apparent water-repellent performance of the water-repellent sand is lowered, and the rise suppression efficiency of the capillary water is lowered for a long time.

[0007] On roads and the like, the dynamic action due to the passage of vehicles is strong, but in the ground where the dynamic action is particularly strong, infiltration of soil particles into the water-repellent sand layer or above and below the water-repellent sand layer. Mixing with the soil layer, disintegration, etc. are likely to occur, and the expected effect may not be obtained in some cases.

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

[0009]

[Means for Solving the Problems] That is, according to the present invention, as described in claim 1 of the present invention, a soil improving method comprising providing a water-repellent water-repellent membrane in soil. Is provided.

The present invention also relates to claim 2 of the claims.
The method for improving soil according to claim 1, wherein the water-repellent membrane has a vertical water permeability of 10 ⁻³ to 10 ³ cm / sec under no load.

Further, the present invention includes claim 3 of the claims.
The method for improving soil according to claim 1 or 2, wherein the water-repellent membrane is made of synthetic fiber.

[0012] The present invention also relates to claim 4 of the claims.
The method for improving soil according to any one of claims 1 to 3, wherein the water-repellent membrane is a non-woven fabric, a woven fabric, or a knitted fabric.

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

The present invention also provides claim 6 in the scope of claims.
, The average particle size of the water-repellent sand is 0.02-
It is 2 mm, and provides the soil improvement method of Claim 5.

The present invention also relates to claim 7 of the claims.
The water-repellent membrane or / and the water-repellent sand treated with a water-repellent agent containing one or more of silicone-based, fluorosilicone-based, and acrylic emulsion-based water-repellent agents as described in 1. Claim 1 thru | or Claim 6 which is
The method for improving soil according to any one of 1.

The present invention also relates to claim 8 of the appended claims.
The present invention provides a method for preventing salt damage to soil using the soil improvement method according to any one of claims 1 to 7.

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

Further, the present invention includes Claim 1 of Claims.
As described in No. 0, there is provided a method for greening a desert by using the soil improvement method according to any one of claims 1 to 7.

The present invention will be described in more detail below. The present invention, by applying a water-repellent membrane in the soil, to significantly reduce the migration of water to the upper layer by capillary action in the soil, to ensure the drainage of the soil and prevent weakening of the soil. is there.

Further, by combining the water-repellent membrane and the water-repellent sand in the soil, the water-repellent membrane as a separation material allows the water-repellent membrane as a separation material to penetrate into the water-repellent sand layer and to the soil / sand layer of the water-repellent sand. Prevents intrusion and penetration.

Further, the water-repellent membrane has excellent filter performance against soil and sand and has a structure that is unlikely to be clogged, so that it is excellent in drainage and keeps the drainage of soil good for a long period of time.

Further, the water-repellent membrane is effective in dispersing and equalizing the stress applied to the soil structure, and is therefore also excellent in the 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 the formation of freezing and frost columns at low temperatures in cold regions and winter. Therefore, damage to crops and swelling or peeling of pavement material can be prevented, and the ground can be stabilized.

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

Examples of the water-repellent membrane include non-woven fabric, woven fabric and knitted fabric, and it is desirable that the material thereof has excellent weather resistance. In particular, those made of synthetic fibers such as vinylon and polyester are preferable, but those made of acrylonitrile and nylon are also usable.

Any water-repellent membrane can be used as long as it is substantially water-repellent, but if the mesh is too coarse, the water-repellent effect will be reduced. If the eyes are too fine, clogging is likely to occur, which is economically disadvantageous.

Therefore, the degree of water repellency of the water repellent membrane is such that the coefficient of water permeability in the vertical direction is 10 ⁻³ to 10 when no load is applied.
The range is preferably ³ cm / sec, and more preferably 10 ^-2 to 10 cm / sec.

The position where the water-repellent membrane is laid may be determined in consideration of the soil quality of the ground, the groundwater level, the purpose, and the like. In addition, especially when using a rough water repellent membrane,
It is preferable to apply water-repellent sand in 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.

The water-repellent sand is obtained by treating the surface of sand particles with a water-repellent agent, and these may be used alone or in combination. As the sand used as the material, those generally used as civil engineering and construction materials in the field of mortar, concrete, etc., such as sea sand, mountain sand, river sand, silica sand, etc., can be appropriately used.

Further, it is not necessary to use a special water repellent sand, but it is advantageous to use relatively coarse sand in consideration of economical efficiency and the like. That is, the particle diameter of the water-repellent sand is preferably an average particle diameter 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 treatment cost of the water repellent treatment. If the average particle size is smaller than 0.02 mm, the amount of water repellent to be treated is bulky, and if it 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 agent used to obtain the water-repellent membrane or the water-repellent sand is not particularly limited as long as it is generally used as a water-repellent agent, but silicone-based or fluorosilicone is preferable. It is preferable to use one type or two or more types of water repellents of the system and acrylic emulsion type. Among them, silicone type is particularly preferable from the viewpoint of water repellency and economics.

Examples of the silicone-based water repellent include silicone compounds represented by the following general formula [Chemical formula 1], which are directly (without solvent) or diluted with a solvent such as toluene, xylene, trichlene, Alternatively, it is used as an emulsion type. Further, a curing catalyst such as dibutyltin dilaurate, dibutyltin diacetate, dioctyltin laurate, iron octate 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 and 0 ≦ b
A number represented by ≤4, 0 <a + b≤4; x = (4-a-b) / 2. ]

For example, in the general formula [Chemical formula 1], R ¹ is a methyl group, an ethyl group, a propyl group, a decyl group or the like, and has 1 carbon atom.
~ 15 alkyl groups, alkenyl groups such as vinyl groups and allyl groups, aryl groups such as phenyl groups, cycloalkyl groups, some of the hydrogen atoms bonded to carbon atoms of the above groups such as CH ₃ CH ₂ CH ₂ — Alternatively, it is a group in which all are substituted with a halogen atom or a cyano group.

R ² is a hydrolyzable group such as an alkoxy group, an acyloxy group, a ketoxime group, an amino group, an aminoxy group, an amido group, an enoxy group or an alkenyloxy group, a halogen group such as chlorine, or —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.

Embedded image 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 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 a partial hydrolyzate thereof

Also,

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

As a surface treatment method for water-repellent sand with a water-repellent agent, a method generally used for surface treatment of powder may be used. For example, it is possible to manufacture 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 the volatile cyclic silicone such as octamethylcyclotetrasiloxane or decamethylcyclopentasiloxane on the surface of the sand by gas phase treatment.

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

When laying a road on soft soil, if a water-repellent membrane, water-repellent sand, and gravel are laid in this order on soft ground, and asphalt or concrete pavement is laid on it, the soil on the soft ground below The particles can be effectively suppressed from entering the water repellent sand layer, and also effective in preventing the freezing of the road surface.

Further, when the soil is used for the purpose of preventing salt damage and the soil is relatively fine, it is preferable to have a structure in which a water-repellent membrane, a water-repellent sand, a water-repellent membrane and a surface soil are arranged in this order on the basic soil. . Note that the upper water-repellent membrane may not be provided.

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

Particularly when used in the ground of a paved road, invasion of soil particles into the water repellent sand layer due to a dynamic action such as passage of a vehicle can be suppressed, and the effect of the present invention can be maintained for a long period of time. Therefore, the life of a paved road with heavy traffic is dramatically extended.

[0044]

EXAMPLES 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 weakening in the examples of the present invention.

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

Preparation of Soil Structure As shown in FIG. 1, in a container (tester) 1 having a drain port 14 of 30 cm × 30 cm × 30 cm, the side surface of which is made of an acrylic plate so that it can be observed from the outside, sand ( Quartz sand No. 4, no water repellent treatment, water saturated state 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 thicknesses of 10 cm, 4 cm, and 15 cm, respectively.

Experimental Method 1.8 liters of water 15 was sprinkled evenly from the top surface of the tester 1 with a Jiro at a frequency of once a day, and then 1 week, 4 weeks, 12 weeks and 24 hours later. After a week, the soil of 5 cm depth was sampled from the surface of the silt layer 13,
The water content was investigated. The experiment was performed by keeping the temperature and humidity at 20 ° C. and 70% RH.

Example 2 In the same container as in Example 1, soil having the same structure as in Example 1 was laid except that untreated sand which was not subjected to water repellent treatment was used instead of water repellent sand. The soil structure of Example 2 was prepared, and the same experiment as that of Example 1 was conducted for this.

[Comparative Example 1] The same as Example 1 except that no water-repellent non-woven fabric was laid in the same container as in Example 1 and untreated sand was used instead of water-repellent sand. The soil having the same structure was laid to prepare the soil structure of Comparative Example 1, and the same experiment as that of Example 1 was performed for this.

Comparative Example 2 The same constitution as in Example 1 except that a water-repellent non-woven fabric and untreated non-woven fabric and sand were used in place of the water-repellent non-woven fabric and water-repellent sand in the same container as in Example 1. The soil structure of Comparative Example 2 was prepared by laying the soil of No. 3, and the same experiment as that of Example 1 was performed for this.

Table 1 shows the results of the above experiments.

[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 water content had already increased to about 5 times the initial value one week after the start of the experiment, and there was not much change thereafter. In the case of Comparative Example 2 using a non-woven fabric that was not subjected to water repellent treatment, the increase in water content was slower than that in Comparative Example 1, but after 24 weeks, the water content reached the same level as in Comparative Example 1.

On the other hand, in the case of Example 1 using the water-repellent sand and the water-repellent nonwoven fabric, the water content remained less than twice the initial value even 24 weeks after the start of the experiment. Further, in the case of Example 2 using untreated sand and a water-repellent nonwoven fabric, the water content increased compared to Example 1, but remained at about 3 times the initial value even after 24 weeks.

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

Example 3 Materials used Water-repellent sand Silica sand No. 4 was subjected to a water-repellent treatment with a 2% C ₁₀ H ₂₁ Si (0CH ₃ ) ₃ emulsion to obtain water-repellent sand. Water-repellent nonwoven fabric A vinylon nonwoven fabric having a water permeability coefficient of 1.5 cm / sec was used. To this non-woven 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 non-woven fabric.

Preparation of Soil Structure As shown in FIG. 2, in a container (tester) 1 having a drain port 14 of 30 cm × 30 cm × 30 cm made of an acrylic plate on the side so that it can be observed from the outside, saline solution is fed from the bottom. The salt-containing sand layer 20, the sand layer 21, the test sand layer 22 using water-repellent sand, the water-repellent nonwoven fabric 23, and the silt layer 24 were laid in this order to have predetermined thicknesses.

Experimental Method Water 25 of 40 gr / m ² was sprayed uniformly from the upper surface of the tester 1 using a Joro at a frequency of once a day, and after keeping it at 37 ° C. for 1 week and 10 weeks. , 20 weeks later 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, the test sand layer 2 was replaced with untreated sand instead of water repellent sand.
The soil having the same configuration as in Example 3 except that used in Example 2 was laid to prepare the soil structure of Example 4, and the same experiment as in Example 3 was performed on this.

[Comparative Example 3] A soil structure of Comparative Example 3 was prepared by laying in the same container as in Example 3 the soil having exactly the same configuration as in Example 3 except that the water-repellent nonwoven fabric 23 was not laid. 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 water-repellent non-woven fabric was laid in the same container as the test sand layer 22 and no water-repellent treatment was used instead of the water-repellent sand. Example 3
The 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 that of Example 3 was performed.

[Comparative Example 5] In the same container as in Example 3, a non-treated non-woven fabric which was not water-repellent was used instead of the water-repellent non-woven fabric 23, and non-treated which was not water-repellent instead of water-repellent sand. A soil having the same configuration as in Example 3 was laid except that sand was used for the test sand layer 22 to prepare a soil structure of Comparative Example 5, and the same experiment as in Example 3 was performed.

Table 2 shows the results of the above experiments.

As can be seen from Table 2, the effect of Example 3 using the water-repellent sand and the water-repellent non-woven fabric was greatest, and no salt precipitation was observed even after 40 weeks. Also, in the case of Example 4 in which the water-repellent nonwoven fabric was used and the water-repellent sand was not used, the effect was second largest after Example 3. On the other hand, Comparative Example 3 in which water repellent sand was used and no non-woven fabric was laid was inferior in effect to the above Examples. Further, in Comparative Example 4 and Comparative Example 5 in which neither the water-repellent sand and the water-repellent non-woven fabric were used, or the non-water-repellent non-woven fabric was used, precipitation of salt was observed in a short period of time.

[0066]

[Table 2]

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

[Example 5] Materials used Water-repellent sand Water-repellent sand was obtained by applying the same water-repellent treatment as in Example 1 using a 5 mm sieved product of river sand. Water repellent nonwoven fabric The same as in Example 1 was used.

Preparation of Soil Structure As shown in FIG. 2, the water repellent nonwoven fabric 3 is placed on the soft soil 30.
1. A ground having a structure in which a water-repellent sand layer 32 and a gravel / sand layer 33 were sequentially laid was prepared.

Experimental Method After ten-dispersed water was dispersed from the surface of the ground, it was aged at a temperature of 20 ° C. and a humidity of 85% RH for 24 hours. Then, a vehicle (4 ton vehicle) was run on this ground and the surface condition was observed. After that, the atmosphere temperature was set to −10 ° C. and the presence or absence of freezing of the ground was observed.

[Comparative Example 6] A soil having the same soil structure as that of Example 5 was prepared except that the water-repellent nonwoven fabric was not laid, and the same experiment as that of Example 5 was performed.

Table 3 shows the results of the above experiments.

In Comparative Example 6, in the portion where the vehicle traveled, 2
At 0 ° C, the soft soil floated up and the water repellent sand layer and the gravel / sand layer were mixed. Moreover, the trace of the rut remained deeply. further,
At −10 ° C., the floating soil portion was frozen. On the other hand, in the part where the vehicle did not run, the gravel / sand layer did not freeze even at -10 ° C.

On the other hand, in Example 5, the soft soil was not lifted up even at 20 ° C. in the portion where the vehicle traveled. In addition, some ruts remained. Furthermore, −
Even at 10 ° C, the gravel / sand layer did not freeze. On the other hand, in the portion where the vehicle did not run, the gravel / sand layer did not freeze at -10 ° C.

[0075]

[Table 3]

[0076]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, by applying the water-repellent membrane to the soil, the migration of water to the upper layer due to the capillary phenomenon in the soil can be significantly reduced, and the soil can be moistened. -It is possible to prevent softening.

Further, it is possible to prevent the freezing and the formation of frost columns in cold regions and low temperatures in the winter, prevent damage to crops, swelling and peeling of pavement materials, and stabilize the soil. further,
It is possible to prevent the occurrence of salt damage even in soil where seawater rises above the ground level. Further, since the present invention suppresses evaporation of water from the soil, it is also effective in preventing desertification of land and greening the desert.

By combining the water-repellent membrane and 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 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]

 1 Container 10 Sand Layer 11 Water Repellent Sand Layer 12 Water Repellent Nonwoven Fabric 13 Silt Layer 14 Drainage Port 15 Water 20 Salt 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

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kinya Ogawa 2-6-1, Otemachi, Chiyoda-ku, Tokyo Shin-Etsu Chemical Co., Ltd.

Claims (10)

[Claims] 1. A soil improvement method comprising providing a water-repellent water-repellent membrane in soil. 2. The soil improvement method according to claim 1, wherein the water-repellent membrane has a vertical water permeability coefficient of 10 ⁻³ to 10 ³ cm / sec when no load is applied. 3. The soil improvement method according to claim 1, wherein the water-repellent membrane is made of synthetic fiber. 4. The water-repellent membrane is a non-woven fabric, a 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 which has been water-repellent is provided in the soil above and / or below the water-repellent membrane. Soil improvement method. 6. The average particle diameter of the water repellent sand is 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 is water-repellent treated with a water-repellent agent containing one or more of silicone-based, fluorosilicone-based, and acrylic emulsion-based water-repellent agents. 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 the freezing of soil by using the soil improvement method according to any one of claims 1 to 7. 10. The method according to any one of claims 1 to 7.
A method for greening a desert using the soil improvement method according to the item.