JP6196186B2 - How to install a layer to shield high salt concentration leachate from the final disposal site - Google Patents

Description

In the present invention, the infiltrated water for detoxifying the incinerated ash buried in the final disposal site comes into contact with the incinerated ash and is gradually purified and detoxified as leachate. More than twice, since the water shielding performance is remarkably lowered, the present invention relates to a method for installing a layer that blocks high salt concentration leachate in a final disposal site that can prevent the water shielding performance from being lowered.

  Conventionally, the final disposal site has formed a water-impervious layer using bentonite crushed stone and clay, and buried incineration ash inside it.

  However, the buried incinerated ash makes leachate whose salt concentration is more than five times that of seawater, and the water-impervious layer using bentonite crushed stone or clay has its swelling property hindered by salt solution, and the leachate with high salt concentration to the outside Had the disadvantage of being discharged.

Japanese Patent No. 4104775

In view of the above-mentioned conventional drawbacks, the present invention is a high-salt in a final disposal site that can reliably shield water with high salt-concentrated leachate without inhibiting the swelling characteristics of the water-impervious layer by a salt solution. It aims at providing the installation method of the layer which intercepts concentration leachate.

The above and other objects and novel features of the present invention will become more fully apparent when the following description is read in conjunction with the accompanying drawings.
However, the drawings are for explanation only and do not limit the technical scope of the present invention.

In order to achieve the above object, the present invention provides a leveling step of spreading a bentonite crushed stone having a particle size of 9.5 mm or less and a water content of 25% or less to a predetermined thickness, and a predetermined level after the leveling step. A rolling process that rolls bentonite crushed stone spread over the thickness of water, and after this rolling process, water is sprayed so that the moisture content of the bentonite crushed stone layer is 30% or more, pre-swelling, and transpiration prevention measures are taken. The measure process constitutes a method of installing a layer that blocks high salt concentration leachate at the final disposal site .

As is clear from the above description, the present invention has the following effects.
(1) According to claim 1, since a layer having a particle size of bentonite crushed stone of 9.5 mm or less and a moisture content of 30% or more can be installed, it is possible to prevent leachate of high salt concentration. .
(2) According to the above (1), since the leveling step and the rolling step are performed using bentonite crushed stone having a water content of 25% or less, the viscosity of bentonite crushed stone itself is low and the work can be performed efficiently. .
(3) According to the above (1), the leveling step and the rolling step are performed using bentonite crushed stone having a moisture content of 25% or less, and then watering is performed in the transpiration prevention measure step so that the moisture content becomes 30% or more. And since it pre-swells, it can process into the layer crimped more reliably.
(4) In claim 2, the same effects as in the above (1) to (3) can be obtained, and bentonite crushed stone can be efficiently laid.
(5) In claim 3, the same effects as in (1) to (3) can be obtained, and bentonite crushed stone can be efficiently rolled.
(6) According to the fourth aspect, the same effects as in the above (1) to (3) can be obtained, and since water is sprinkled in a rolled state, watering work can be performed easily.

Explanatory drawing of the bentonite crushed stone used for the 1st form for implementing this invention. The process drawing of the 1st form for carrying out the present invention. Explanatory drawing of the leveling process of the 1st form for implementing this invention. Explanatory drawing of the compaction process of the 1st form for implementing this invention. Explanatory drawing of the transpiration prevention measure process of the 1st form for implementing this invention. Explanatory drawing of the experimental result of the relationship between elapsed time and a hydraulic conductivity. Explanatory drawing of the penetration | infiltration state after 54-hour progress.

  Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings.

  In the first embodiment for carrying out the present invention shown in FIG. 1 to FIG. 7, reference numeral 1 denotes a layer that blocks high salt concentration leachate from the final disposal site 2, and a layer that blocks this high salt concentration leachate. 1 is a bentonite crushed stone 3 that is used to block high salt concentration leachate having a particle size of 9.5 mm or less and a water content of 30% or more.

  The layer 1 for blocking high salt concentration leachate has a particle size of 9.5 mm or less and a bentonite crushed stone 3 a having a moisture content of 25% or less, such as a bulldozer or a backhoe having a thickness of 5 to 30 cm, for example. A leveling step 5 for leveling with the leveling machine 4 and a leveling process for rolling the leveled bentonite crushed stone 3b using the pressure roller 7 and the tire roller pressure reduction machine 7 after the leveling step 5. Pressure treatment step 8 and after this rolling step 8, water is sprayed with a watering machine 9 so that the moisture content of the compacted bentonite crushed stone layer 3 c is 30% or more, pre-swelled, and a curing sheet 10 for preventing transpiration. It is formed by the installation method using the transpiration prevention measure step 11 for laying.

  The layer 1 that shields the high salt concentration leachate formed by the installation method using the spread leveling step 5, the rolling pressure step 8, and the transpiration prevention measure step 11 is inhibited in swelling characteristics by the salt solution. There is nothing, and it can be blocked.

  The experiment was performed in the following procedure.

Experimental procedure Adjust the moisture content of the sample.
(1) Water type All samples are watered to a water content ratio of 30%, cured for 15 hours, and pre-expanded.

(2) Non-hydrous type Use with natural water content (25.5%).
2. Each sample is placed in an acrylic pipe having an outer diameter of 150 mm (inner diameter of 138 mm), a wall thickness of 6 mm, and a height of 250 mm, and adjusted so that the degree of compaction is 90% and the layer thickness is 50 mm.
3. Pebbles are spread on the NB layer, and then the simulated fly ash extract is injected to a water level of 50 mm (dynamic gradient I = 2). After 24 hours, the water level is 100 mm (dynamic gradient I = 3). Change to
4). In order to make the experiment a constant water level method, when the simulated fly ash extract penetrates and the water level drops, the simulated fly ash extract is additionally injected to adjust the water level to be constant.
5. The hydraulic conductivity is calculated from the injection amount of the simulated fly ash extract and the elapsed time.

As a result of the experiments performed as described above, the following results were obtained.

Experimental results Fluid passage time Sample 1 (maximum particle size 19 mm (hydrous)): Confirmed fluid passage after 54 hours Sample 2 (maximum particle shape 9.5 mm (hydrous)): No fluid passage after 7 days Sample 3 ( Maximum particle shape 4.75 mm (hydrous)): No liquid passage after 7 days Sample 4 (maximum particle shape 2 mm (hydrous)): No liquid passage after 7 days Sample 5 (maximum particle shape 9.5 mm) (No water addition)): Confirmation of liquid passage after 48 hours Sample 6 (maximum particle size 4.75 mm (no water addition)): Confirmation of liquid passage after 48 hours Permeability coefficient sample 1 (maximum grain shape 19 mm (hydrous)): 5.5 × 10 −8 (m / s) (value at 66 to 77 hours)
Sample 2 (maximum particle size 9.5 mm (hydrous)): 6.5 × 10 −9 (m / s) (value at 94 to 165 hours)
Sample 3 (maximum particle size 4.75 mm (hydrous)): 5.7 × 10 −9 (m / s) (value at 94 to 165 hours)
Sample 4 (maximum particle size 2 mm (pre-expansion)): 1.3 × 10 −8 (m / s) (value at 45 to 68 hours)
Sample 5 (maximum particle size 9.5 mm (no water addition)): 2.8 × 10 −8 (m / s) (value at 38 to 61 hours)
Sample 6 (maximum particle size 4.75 mm (no water addition)): 3.1 × 10 −8 (m / s) (value at 38 to 61 hours)
In addition, the relationship between elapsed time and a hydraulic conductivity is shown in FIG. 6, and the permeation state after 54 hours is shown in FIG.

  The present invention is used in industries where a layer for shielding high salt concentration leachate is installed at a final disposal site.

1: Layer that shields high salt concentration leachate,
2: Final disposal site, 3: Bentonite crushed stone,
4: spread leveling machine, 5: spread leveling process 7: rolling machine, 8: rolling process,
9: Watering machine, 10: Curing sheet,
11: Transpiration prevention measure process.

Claims (4)

A leveling process in which a bentonite crushed stone having a particle size of 9.5 mm or less and a moisture content of 25% or less is spread to a predetermined thickness, and the bentonite crushed stone that has been leveled to a predetermined thickness after the leveling process is rolled. a compacting step of pressure, final that after this compacting step is the water content of the bentonite crushed stone layer watered such that 30% or more, is pre-swollen, characterized in that it comprises a vaporization prevention measures evaporative emission measures step How to install a layer to shield high salt concentration leachate from the disposal site . 2. The method of installing a layer for shielding high salt concentration leachate in a final disposal site according to claim 1, wherein the leveling step comprises leveling 5 to 30 cm of bentonite with a bulldozer or a backhoe. . 2. The method of installing a layer for shielding high salt concentration leachate in a final disposal site according to claim 1, wherein the rolling step is carried out using a rolling roller or a rolling roller of a tire roller. Evaporative emission measures step by watering bentonite crushed stone layer whose pressure rolling, water content in the 30% or more by pre-swelling the final claim 1, wherein the laying curing sheet for preventing transpiration How to install a layer to shield high salt concentration leachate from the disposal site .