JP2007160174A - Capping sheet and its capping method of construction - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a capping sheet preventing slipping down of covered soil on a slope while reducing a treatment cost of leachate, and a capping method of construction for a waste disposal site using the capping sheet. <P>SOLUTION: The capping sheet has a covered soil slipping down prevention layer comprising a three-dimensional mesh having a thickness of 5 mm or more and a fiber density of 20 kg/m<SP>3</SP>to 200 kg/m<SP>3</SP>on a protection layer side of a moisture-permeable water-proof sheet comprising a moisture-permeable water-proofing layer 3 and a protection layer covering at least one. The moisture-permeable water-proof layer of the sheet is a member selected from a fine porous membrane, a nonporous moisture-permeable sheet, a melt-blown non-woven fabric and a flash-spinning non-woven fabric. The protection layer comprises a long fiber non-woven fabric having a moisture-permeability of 2,000 g/m<SP>2</SP>/24 hour or more and a water-resistance pressure of 50 kPa or more. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a capping sheet for a waste final disposal site in a closed stage and a method for the same.

A large amount of waste is generated in proportion to the concentration of the population in the city and the activation of production / consumption activities. These wastes may be incinerated at the incineration facility, or separated and recovered as resources, but the former is limited in the number of facilities due to problems such as the cost of introducing equipment and the opposition of the surrounding residents. There are limitations. In the latter case, only relatively expensive materials such as plastic, metal, paper, etc. are recovered. In addition, food residues and food waste are discarded as they are, and the problem of bad odor and the problem of dogs, cats and birds hunting food in the garbage have become serious.
In addition, harmful substances mixed in garbage and water-soluble substances from foods flow into nearby rivers and lakes, causing damage to crops and seafood, and factories and water treatment plants that use downstream river water May also be affected.

  In the waste final disposal site, when the landfill of the waste is completed, a surface layer is formed by covering soil so that the waste is not exposed to the surface. Conventionally, as a final earth covering method for forming the surface layer, a common earth covering method using earth and sand or a capping method using a water shielding sheet has been selectively used.

  The soil covering method using earth and sand is breathable and permeable, so that rainwater penetrates into the landfill and promotes air circulation in the waste to create an aerobic environment. , It is possible to expedite the timing of decomposition and stabilization of waste. However, if there is much osmotic water, decomposition does not proceed faster. In general, rainfall in Japan is excessive for decomposing and stabilizing the waste in the final disposal site, and there is a problem that it requires a large amount of money to treat and manage the permeated water contaminated by the decomposition. It was.

    On the other hand, the capping method using a water-impervious sheet is not breathable and permeable, so rainwater during rainfall is drained out of the landfill as surface water. There is no need to do so, and the costs associated with water treatment can be reduced. However, the environment in the landfill becomes anaerobic because the air and water are blocked by the capping by the water shielding sheet. This generates malignant gases such as methane gas and ammonia during the decomposition of organic matter. In addition, there is a problem that the time until the waste in the landfill is decomposed and stabilized is prolonged, and the maintenance and management costs of the final disposal site cannot be reduced.

Therefore, a method of draining surface water that did not enter the interior of the landfill while controlling the amount of water permeability by forming the water-permeable part and the water-impervious part in a belt shape and controlling all the water-impervious parts on the slopes. It is known (see, for example, Patent Document 1).
A waste disposal site is also known in which the entire disposal site is covered with a moisture permeable waterproof sheet (see, for example, Patent Document 2).

Japanese Patent No. 3354920 Japanese Patent Laid-Open No. 11-10104

However, the former is based on the premise that a small amount of water permeates into the waste. However, it is a construction method that requires time and effort, and the amount of waste treated is small relative to the area in order to form a slope. There was a problem of becoming. In the latter case, the sheet is fixed only by fixing pins, and there is a problem that the sheet is peeled off or torn by a strong wind. Furthermore, exposing the capping sheet was not preferable in appearance.
Although it is conceivable to cover the capping sheet with soil, on the slope, there was a problem that the permeated water flowed down the boundary between the cover soil and the sheet due to rain, etc., and the soil covered the slope.

  In view of the problems of the above-described conventional waste disposal site capping method, it is an object of the present invention to provide a capping sheet that reduces the leachate treatment cost and prevents the cover soil from sliding down on the slope. To do. Another object is to provide a capping method for a waste disposal site using the capping sheet.

  The present invention has been achieved as a result of intensive studies to solve the above problems, and will be described in detail below.

The first invention is the following formula (1) on the protective layer 1 side of the moisture-permeable waterproof sheet composed of a moisture-permeable waterproof layer, a protective layer 1 made of a long-fiber nonwoven fabric covering one surface thereof, and a protective layer 2 covering the other. A capping sheet comprising a cover-sliding prevention layer composed of a number of meandering filaments satisfying the relations (4) to (4). 2 ≦ φ ≦ 5 [mm] (1)
10 <M <50 [lines / m width] (2)
15 ≦ L <1000 / M [mm] (3)
L / 4 ≦ P ≦ L [mm] (Formula 4)
Here, φ is the fiber diameter of the filament, M is the number of filaments, L is the meander width, and P is the distance between the meander peaks.

  The second invention is the capping sheet according to the first invention, wherein the moisture-permeable waterproof layer is a member selected from a microporous membrane, a non-porous moisture-permeable sheet, a melt blown nonwoven fabric, and a flash spun nonwoven fabric. .

A third invention is the capping sheet according to the first or second invention, wherein the protective layer 1 is made of a long-fiber nonwoven fabric having a fiber diameter of 1.5 to 10 dtex and a basis weight of 50 to 200 g / m ^2. is there.

According to a fourth aspect of the present invention, any one of the first to third aspects is characterized in that the protective layer 2 is made of a long-fiber nonwoven fabric entangled with a needle punch having a fiber diameter of 1.5 to 10 dtex and a basis weight of 200 to 500 g / m ^2. This is a capping sheet described in the invention.

Fifth invention has moisture permeability 2000g / m ² / 24hr or more, first to capping sheet according to the fourth one of the invention, wherein the water pressure is not less than 50 kPa.

  A sixth invention is the capping sheet according to any one of the first to fifth inventions, which has a tensile strength of 100 N / 5 cm or more and a tear strength of 20 N or more.

  A seventh invention is a capping method for a final disposal site, wherein the capping sheet according to any one of claims 1 to 6 is laid so that a large number of filaments are on the surface, and a soil covering layer is formed thereon. It is a characteristic capping method.

  According to the present invention, in the capping method at the time of closing the final disposal site, it is possible to reduce the cost of water treatment by controlling the intrusion of rainwater into the waste by the water shielding function, and the generated gas by the moisture permeability function can be reduced. In addition to being able to discharge, it is possible to prevent the soil covering from falling on the slope. Therefore, walking after soiling is safe by using the capping sheet of the present invention.

  The present invention is described in detail below.

  The capping sheet of the present invention has a fiber diameter of 3 on the protective layer 1 side of the moisture permeable waterproof sheet composed of a moisture permeable waterproof layer, a protective layer 1 made of a long-fiber nonwoven fabric covering one surface thereof, and a protective layer 2 covering the other. It is preferable to have a structure having a soil covering slip prevention layer composed of a large number of 5 mm filaments.

The moisture permeable waterproof layer is preferably selected from a microporous membrane, a melt blown nonwoven fabric, and a flash spun nonwoven fabric.
Microporous membranes are obtained by dispersing an inorganic filler in a resin composition and making it porous by stretching, forming a membrane by adding a foaming agent to a resin and making it porous by heat foaming, and further assisting extrusion after film formation. It is possible to select from those obtained by evaporating and removing the agent and then stretching it to make it porous.

  The non-porous moisture-permeable sheet can be obtained using a block copolymer polyester composed of a hard segment and a soft segment such as Perprene (manufactured by Toyobo Co., Ltd.) and Hytrel (manufactured by Toray DuPont).

  The melt blown nonwoven fabric is preferably composed of fibers having a fiber diameter of 5 μm or less. Moreover, the melt blown nonwoven fabric preferably has a fiber filling rate increased by calendering and a fiber gap reduced. If the fiber is thick, the fiber gap is large and waterproofness is not exhibited. As the material, thermoplastic resins such as polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, polybutylene terephthalate and polypropylene terephthalate, and polyamides can be used. The product is preferred.

  As the material of the flash spun nonwoven fabric, thermoplastic materials such as polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polypropylene terephthalate, and polyamides can be used. Considering the sheath and price, polyethylene is preferable.

  As the material for the protective layer, thermoplastic resins such as polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polypropylene terephthalate, and polyamides can be used. Further, the fiber form does not have to be a single component, and may be a composite fiber type such as a core-sheath type, a side-by-side type, or a six-leaf type. Furthermore, the fiber cross section is not limited to a solid (round cross section), and may be an irregular cross section fiber such as a triangular cross section or a flat cross section.

  The protective layer 1 is a nonwoven fabric made of long fibers. The fiber diameter of the constituent fibers is preferably 1.5 to 10 dtex, more preferably 2 to 6 dtex, and more preferably 2 to 4 dtex. When the fiber diameter is less than 1.5 dtex, the mechanical properties of the resulting nonwoven fabric are lowered, and the strength as a capping sheet is also lowered. When the fiber diameter exceeds 10 dtex, the productivity is significantly reduced.

The basis weight of the nonwoven fabric is preferably 50 to 200 g / m ² . More preferably, it is 80-200 g / m < ² >, More preferably, it is 100-180 g / m < ² >. When the basis weight is less than 50 g / m ² , the protective effect of the moisture-permeable waterproof layer tends to be insufficient. On the other hand, if it exceeds 200 g / m ² , only the weight increases and no improvement in performance is observed. Therefore, up to 200 g / m ² is sufficient considering the cost.
As the long fiber nonwoven fabric, a conventional tow spread nonwoven fabric or a spunbonded nonwoven fabric is used, but a spunbonded nonwoven fabric is preferable because of its productivity. Furthermore, in the case of a spunbonded nonwoven fabric, a thermocompression bonding type spunbonded nonwoven fabric is preferable in view of mechanical strength and productivity.

  The protective layer 2 is made of a long fiber nonwoven fabric in which fibers are entangled by needle punching. From the viewpoint of productivity and mechanical properties, a spunbonded nonwoven fabric is preferred. As for the fiber diameter, 1.5 to 10 dtex is selected for the same reason as in the protective layer 1, preferably 2 to 6 dtex, and more preferably 2 to 4 dtex.

It is preferable that the fabric weight of a nonwoven fabric is 200-500 g / m < ² >, More preferably, it is 200-400 g / m < ² >, More preferably, it is 250-350 g / m < ² >. When the basis weight is less than 200 g / m ² , the puncture resistance is low, and it is difficult to achieve a sufficient protective function. Moreover, when it exceeds 500 g / m < ² >, the handleability will worsen, it will become bulky, the conveyance cost and storage cost will become high, and it is unpreferable.

  Since the protective layer 2 side is in contact with the waste, a needle punch type spunbonded nonwoven fabric is preferred from the standpoint of the unevenness and productivity.

  As the filament material, thermoplastic resins such as polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polypropylene terephthalate, and polyamides can be used.

  Many meandering filaments are arranged on the surface of the nonwoven fabric arranged on the soil covering side. The fiber diameter of a filament is 2-5 mm, Preferably it is 2-4 mm, More preferably, it is 2-3 mm. Moreover, the number of filaments is 10-50 per 1 m width, Preferably it is 15-45, More preferably, it is 20-40, More preferably, it is 30-40. The meandering width of the filaments is narrower than the interval between the filaments and is 15 mm or more. As for the period of the filament, the distance between the peaks of the period is from 1/4 of the meandering width to the meandering width. The filament is obtained by extruding a thermoplastic resin onto the nonwoven fabric from the orifice. The integration of the filament and the nonwoven fabric is that the filament is grounded before the filament is solidified, so that a part of the fibers constituting the nonwoven fabric is melted by the amount of heat brought in by the filament and the molten filament is introduced into the nonwoven fabric. Integrate by anchor effect.

  When a filament is less than 2 mm, the heat of fusion of a filament is low and adhesion with a nonwoven fabric is weak. Therefore, it becomes impossible to receive the load due to the weight when the cover soil is placed. When the filament exceeds 5 mm, productivity is deteriorated and cost is increased.

  When the number of filaments is less than 10, the covering ability of covering is low, and when the number exceeds 50, the productivity is lowered and the cost is increased.

When the width of the meandering of the filament is less than 15 mm, the formed loop is small and the covering capacity is reduced. When the meandering width is increased, there are a method of increasing the discharge amount and a method of reducing the production speed. However, the former has a limit of correspondence and the latter reduces the productivity.
In the present invention, the meandering cycle of the filament is defined by the relationship between the peak-to-peak distance and the meandering width. When the distance is less than ¼ of the meandering width, that is, the meandering width is large, so that productivity is difficult as described above. When the distance is larger than the meandering width, the angle of the covering soil with respect to the sliding direction is small and the covering ability of the covering soil is low.

  As a method for obtaining a moisture permeable waterproof sheet comprising a moisture permeable waterproof layer and a protective layer, a generally known thermal lamination method, a composite method using an adhesive, or the like can be used. In particular, when the moisture-permeable waterproof layer is formed of a microporous film, a composite method using an adhesive is preferable.

Moisture permeability of moisture-permeable waterproof sheet is more than 2000g / m ² / 24hr is preferred. If the moisture permeability is less than 2000g / m ² / 24hr, environment within landfills period until the degradation and stabilize states waste and dry side is prolonged. There is also a problem that methane gas generated during the decomposition of organic matter accumulates between the capping sheet and the waste.

  The water pressure resistance of the moisture permeable waterproof sheet is preferably 50 kPa or more. When the water pressure resistance is less than 50 kPa, there is a risk of water intrusion due to rain, which causes a problem of increasing wastewater treatment costs. Even if the water pressure is high, there is no problem, but if the water pressure is increased, the moisture permeability tends to be impaired or the film tends to become brittle.

  The moisture permeable waterproof sheet preferably has a tensile strength of 100 N / 5 cm or more and a tear strength of 20 N or more. The capping sheet of the present invention is required to have mechanical strength because a load is applied by placing a soil cover or a person walking on it. When the tensile strength is less than 100 N / 5 cm and the tear strength image is less than 20 N, there is a risk that the sheet may be torn against the load. There is no particular upper limit on mechanical strength, but the amount of fibers is increased in order to increase the strength, which is disadvantageous in terms of price. Generally, the upper limit is considered to be about 2000 N / 5 cm and about 500 N.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto.
The evaluation methods used are as follows.

(Thickness)
It measured based on JIS-L-1906 "General long fiber nonwoven fabric test method".
(Nonwoven fabric weight)

It measured based on JIS-L-1906 "General long fiber nonwoven fabric test method".

(Moisture permeability)
According to JIS-L-1099 “Method of testing moisture permeability of textile products” (Method A-1) calcium chloride method, measurement was performed at φ70 mm.

(Water pressure resistance)
Measured according to JIS-L-1902 “Testing method for waterproofness of textile products” water resistance test (hydrostatic pressure method) and high pressure method.

(Tensile strength)
It measured based on JIS-L-1906 "General long fiber nonwoven fabric test method".

(Tear strength)
Measured in accordance with JIS-L-1906 “General Long Fiber Nonwoven Fabric Test Method” single tongue method.

(Soil cover slip prevention function)
Judgment was made by measuring the angle at which landslide slip started using a landslide slip angle evaluation device.
The evaluation device is based on a wooden board (width 30 cm, length 90 cm, thickness 1.4 cm) in which a pair of 5 cm square bars are fixed in parallel to the mask length side, and the width of the upper surface of the base is wide at both ends. A sample consisting of a wooden board (width 25 cm, length 60 cm, thickness 0.5 cm) to which a sample (width 18.5 cm, length 50 cm) is affixed between slid slides, with a 2 cm commercial slidable slide fixed A board is arranged. Then, a rectangular cylindrical sand jar (width of inner space: 19 cm, length: 30 cm, height: 20 cm) is arranged so that its lower end surface comes into contact with the slidable slide.
In the test, a test device was installed in a horizontal place, and the sample plate was fixed. The sand jar was filled with 10 kg of soil for construction (made by Yamatomi Co., Ltd.) with a cocoon content of 6.3%. Then, the earth and sand were flattened with square bars until the height became 11 to 12 cm, and one end on the width side of the foundation was pulled up. The angle (the inclination angle of the foundation) at which the sand jar started moving at the time of this lifting was measured, and this was taken as the earth and sand sliding angle. Grease is applied to the sliding surface of the sill and the bottom surface of the sandbox.
Judgment criteria are as follows.
○: Sliding angle is 40 ° or more ×: Sliding angle is less than 40 °

Example 1
Thermocompression type polyester spunbond nonwoven fabric Ecule 6A31AD (Toyobo Co., Ltd .: 2.2 dtex, 130 g / m ² ) and polyethylene porous film YP4400 (Yamatogawa Polymer Co., Ltd.) Copolymerized polyester resin with a melting point of 120 ° C. Apply on a non-woven fabric and integrate by heating and pressing. Further, the needle punch type polyester spunbond nonwoven fabric Borans 4301NB (manufactured by Toyobo Co., Ltd .: 3.5 dtex, 300 g / m ² ) and the above composite product are integrated in the same manner. A strip having a fiber diameter of 2.2 mm was integrated on the thermocompression bonding type spunbond nonwoven fabric side of the three-layer composite product to obtain a capping sheet of the invention. The physical properties are shown in Table 1.

(Example 2)
A capping sheet was obtained in the same manner as in Example 1 except that a 0.3 mm sheet using Perprene P-50B (manufactured by Toyobo Co., Ltd.) was used as the moisture permeable waterproof layer. The physical properties are shown in Table 1.

(Example 3)
A capping sheet was obtained in the same manner as in Example 1 except that the filament was 3 mm. The physical properties are shown in Table 1.

(Comparative Example 1)
A composite sheet was obtained in the same manner as in Example 1 except that the moisture-permeable waterproof layer was removed. The physical properties are shown in Table 1.

(Comparative Example 2)
A composite sheet was obtained in the same manner as in Example 1 except that the filaments were excluded. The physical properties are shown in Table 1.

(Comparative Example 3)
A composite sheet was obtained in the same manner as in Example 1 except that the filament was 1 mm in fiber diameter. The physical properties are shown in Table 1.

  The capping sheet of the present invention is a sheet that has no leachate and has a function to prevent slippage of the covering soil on the slope, which reduces gas accumulation inside the landfill. When the capping method of the waste disposal site using the capping sheet of the present invention is carried out, the leachate treatment cost can be reduced and a safe environment can be provided.

It is a schematic diagram of the capping sheet of the present invention.

Explanation of symbols

1: Line 2: Protective layer 1
3: Moisture permeable waterproof membrane 4: Protective layer 2
L: meandering width M: number of filaments N: spacing of filaments (1000 / M)
P: Distance between ridges and mountains

Claims (7)

The following formulas (1) to (4) are provided on the protective layer 1 side of the moisture permeable waterproof sheet composed of a moisture permeable waterproof layer, a protective layer 1 made of a long-fiber nonwoven fabric covering one surface thereof, and a protective layer 2 covering the other. A capping sheet comprising a covering soil slip prevention layer comprising a number of meandering lines that satisfy the relationship.
2 ≦ φ ≦ 5 [mm] (1)
10 <M <50 [lines / m width] (2)
15 ≦ L <1000 / M [mm] (3)
L / 4 ≦ P ≦ L [mm] (Formula 4)
Here, φ is the fiber diameter of the filament, M is the number of filaments, L is the meander width, and P is the distance between the meander peaks.   The capping sheet according to claim 1, wherein the moisture-permeable waterproof layer is a member selected from a microporous membrane, a non-porous moisture-permeable sheet, a melt blown nonwoven fabric, and a flash spun nonwoven fabric. Capping sheet according to claim 1 or 2 protective layer 1 fiber diameter 1.5～10Dtex, characterized in that it consists of long-fiber nonwoven fabric is a basis weight 50 to 200 g / m ^2. Protective layer 2 is fiber diameter 1.5～10Dtex, capping sheet according to any one of claims 1 to 3, characterized in that it consists of fibers entangled long fiber nonwoven fabric by needle punching a basis weight of 200-500 g / m ² . Moisture permeability is not less 2000g / m ² / 24hr or more, capping sheet according to any one claims 1 to 4 water pressure is characterized by the use of moisture-permeable waterproof sheet is not less than 50 kPa.   The capping sheet according to any one of claims 1 to 5, wherein a moisture-permeable waterproof sheet having a tensile strength of 100 N / 5 cm or more and a tear strength of 20 N or more is used.   A capping method for a final disposal site, wherein the capping sheet according to any one of claims 1 to 6 is laid such that a large number of filaments are on the surface, and a covering layer is formed thereon.

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