JP2022041360A - Sea surface landfill method - Google Patents

Abstract

To provide a sea surface landfill method enabling early stage stabilization of a sea surface waste disposal site and a landfill site.SOLUTION: The sea surface landfill method installs an alkaline solidification material in an inside of a shore protection 3, solidifies the alkaline solidification material to form a water shield layer 6 having a certain thickness, and then landfills an inside of the water shield layer 6 with a waste or a landfill material and performs outer drainage of water 8 in a landfill region.SELECTED DRAWING: Figure 1

Description

The present invention relates to a sea surface landfill method for landfilling a sea surface waste treatment plant or a landfill.

Conventionally, alkaline waste such as incinerator ash and coal ash is often disposed of at a marine waste disposal site.

However, this type of alkaline waste contains a large amount of calcium, and the water held at the waste disposal site where this alkaline waste is input often becomes highly alkaline, which accompanies the infiltration of rainwater. Since highly alkaline leachate is generated, it may be necessary to treat the residual water for a long period of time not only during the landfill but also after the landfill is completed.

In particular, from the latter half of the landfill work, the residual water level of the pound decreases, that is, the ratio of water to the disposal material decreases, and the pH and chemical oxygen demand (COD) increase sharply, so that the water is released. There is a problem that the load applied during water treatment of water becomes large.

Conventionally, as a method for early stabilization, it has been proposed to install a water pipe or cover the landfilled waste with thick soil, but there is a problem that the amount of disposal is reduced by the water pipe or soil cover. rice field.

On the other hand, in the landfill disposal site, a so-called solidification type disposal method has been developed as a method for stabilizing the disposal site at an early stage.

In this solidification type disposal method, after mixing a material containing incineration ash and fly ash using a mixer, the material is vibrated to fluidize the powder, which is then buried and compacted to form incineration ash. Since the water permeability of the landfill board is reduced due to the solidification of fly ash and the infiltration of rainwater is suppressed, the water quality of the leachate can meet the abolition criteria of the disposal site at an early stage.

Japanese Unexamined Patent Publication No. 2001-334225

However, with the conventional techniques as described above, it is difficult to vibrate and compact the mixed material after dropping it into water, so that it is difficult to apply the solidification type disposal method to the marine disposal site.

In addition, if a solidified body made of a material containing incinerator ash or fly ash is prepared as it is, or if the solidified body is crushed and put into a disposal site or landfill, the voids between the solidified bodies become large and the disposal capacity decreases. However, when the solidified body is crushed, there is a problem that the pH rises and the like occurs.

Therefore, in view of such conventional problems, the present invention has been made for the purpose of providing a sea surface landfill method capable of early stabilization of a sea surface waste disposal site and a landfill site.

The feature of the invention according to claim 1 for solving the above-mentioned conventional problems is that in a sea surface reclamation method for reclaiming a landfill area surrounded by a revetment, an alkaline solidifying material is placed inside the revetment. After solidifying the alkaline solidifying material to form an impermeable layer having a certain thickness, the inside of the impermeable layer is filled with waste or a landfill material, and water in the landfill area is drained to the outside. There is something in it.

A feature of the invention according to claim 2 is that, in addition to the configuration of claim 1, the alkaline solidifying material is cast on the bottom surface of the revetment to form a bottom surface impermeable layer.

The feature of the invention according to claim 3 is that, in addition to the configuration of claim 1 or 2, a solidified body obtained by mixing cement with incineration ash, coal ash, and fly ash as the waste is embedded inside the impermeable layer. It is in.

The feature of the invention according to claim 4 is that, in addition to the constitution of claim 1 or 2, the surface of the waste put into the inside of the impermeable layer is a solidified body obtained by mixing cement with incineration ash, coal ash, and fly ash. To cover with.

A feature of the invention according to claim 5 is that, in addition to the configuration of claim 1 or 2, cement solidified soil or calcia modified soil is buried inside the impermeable layer as the landfill material.

The feature of the invention according to claim 6 is that, in addition to the constitution of any one of claims 1 to 5, the alkaline solidifying material is cement solidified soil, calcia modified soil, or incinerated ash, coal ash, fly ash. It is to use a solidified body mixed with cement.

A feature of the invention according to claim 7 is that, in addition to the configuration of any one of claims 1 to 6, the fluidity is adjusted by adjusting the amount of water added to the alkaline solidifying material.

The feature of the invention according to claim 8 is that, in addition to the configuration of any one of claims 1 to 7, the external drainage is drained before or after the start of landfill depending on the material for filling the inside of the impermeable layer. It is to change the amount to be done.

The sea surface landfill method according to the present invention can construct an impermeable layer and stably drain water from the landfill area to the outside by providing the configuration of claim 1, so that it is a sea surface waste. Early stabilization of disposal sites and landfills can be achieved.

Further, in the present invention, by providing the configuration of claim 2, it is possible to cope with the case where the bottom is not a water-impervious ground or the case where high water-imperviousness is desired to be ensured at the bottom.

Further, in the present invention, by providing the configuration of claim 3, waste such as incinerator ash can be suitably landfilled, water permeability is lowered, rainwater infiltration is suppressed, and leachate is disposed of at the disposal site. Since the criteria such as these are satisfied at an early stage, it is possible to stabilize the sea surface waste disposal site and the landfill site at an early stage.

Further, in the present invention, by providing the configuration of claim 4, even when landfilling general waste, the water permeability is lowered and the permeation of rainwater is suppressed, and the leachate is set as an early standard for a disposal site or the like. It is possible to stabilize the sea surface waste disposal site and the landfill site at an early stage. In addition, it is possible to reduce the amount of disposal by using a solidified body which is a waste as a soil covering for general waste.

Furthermore, in the present invention, by providing the configuration of claim 5, the ground of the landfill can be strengthened and water can be prevented from infiltrating into the ground.

Further, in the present invention, by providing the configuration of claim 6, the water permeability becomes low after solidification, and a robust impermeable layer can be formed.

Further, in the present invention, by providing the configuration of claim 7, the fluidity can be adjusted according to the charging situation, so that the alkaline solidified body can be easily charged.

Further, in the present invention, by providing the configuration of claim 8, it is possible to reduce the amount of water in the landfill area where it is necessary to control the water quality at the time of drainage, and to reduce the load of water treatment.

It is a schematic cross-sectional view which shows the procedure of the sea surface reclamation method which concerns on this invention, (a) is the revetment and backfill layer construction process, (b) is the impermeable layer construction process, (c) and (d) are. The landfill with the alkaline solidifying material and the external drainage process, (e) is a figure which shows the state of the landfill completion. It is a plan view of FIG. 1 (a) of the same above. It is a plan view of FIG. 1 (b) of the same above. It is a plan view of FIG. 1 (c) of the same above. It is a plan view of FIG. 1 (d) of the same above. It is a plan view of FIG. 1 (e) of the same above. It is schematic cross-sectional view which shows the other aspect of the impermeable layer of the sea surface reclamation method which concerns on this invention.

Next, an embodiment of the sea surface reclamation method according to the present invention will be described based on the examples shown in FIGS. 1 to 6.

In this embodiment, a case where the sea surface waste disposal site 1 is reclaimed will be described as an example. In the figure, reference numeral 1 is a sea surface waste disposal site, and reference numeral 2 is an impermeable ground.

In this sea surface waste disposal site 1, a landfill area 4 partitioned by a revetment 3 is formed, and waste is put into the landfill area 4 to be landfilled.

In the landfill of the sea surface waste disposal site 1, first, as shown in FIGS. 1 (a) and 2, a revetment 3 is formed on the outer edge of the sea surface waste disposal site 1, and a landfill area surrounded by the revetment 3 is formed. 4 is formed, a backfill stone is thrown inside the revetment 3, and a backfill layer 5 is constructed.

The revetment 3 has a sheet pile whose lower end reaches the impermeable ground 2, and a plurality of caissons and revetment structures such as cells having a water-blocking structure at the connecting portion. It is composed of an impermeable revetment 3, and the landfill area 4 and the open sea are separated by the impermeable revetment 3. Multiple caissons, cells, and other shore protection structures with a water-blocking structure are installed on the seabed ground in the direction of the shore protection normal line. Installed on the seabed ground side by side in the normal line direction Multiple caissons, cells, and other shore protection structures with impermeable structures are installed on the seabed ground side by side in the shoreline direction.

The backfill layer 5 is formed in the shape of a bank having a slope 5a inclined inward by throwing backfill stones inside the revetment 3.

Next, as shown in FIGS. 1 (b) and 3, an alkaline solidifying material for the impermeable layer 6 is cast along the backfill layer 5, and the alkaline solidifying material is solidified to obtain a constant thickness. The water-impervious layer 6 to have is formed.

The impermeable layer 6 has a thickness of 50 cm or more, and has a thickness that exhibits impermeable performance equivalent to a water permeability coefficient k of ^10-5 cm / s ( ^10-7 m / s) or less after solidification. An alkaline solidifying material is placed in the water. Here, the equivalent impermeable performance means that the permeation time is the same.

The alkaline solidifying material is a material having an alkaline solidifying property, and is composed of a material having a certain fluidity before solidification and having low water permeability after solidification.

As this alkaline solidifying material, cement solidified treated soil, calcia modified soil, or a solidified body obtained by mixing cement with incinerated ash, coal ash, or fly ash is used.

The solidified body is appropriately mixed with incinerator ash at a ratio of 70 to 80 wt%, fly ash or coal ash at a ratio of 20 to 30 wt%, and cement at a ratio of 5 to 10 wt%. Liquidity is ensured so that no gaps are created. The amount of water added is adjusted so as to ensure fluidity according to the properties of the material.

Further, the solidified body may be mixed with an admixture such as a water reducing agent in addition to the above-mentioned materials, if necessary.

The method for mixing the materials constituting the alkaline solidifying material is not particularly limited, and for example, mixing by a mixer, mixing by a belt conveyor / vibration belt conveyor, drop mixing, or the like can be used.

Further, this alkaline solidifying material has increased fluidity by increasing the amount of water added, facilitated casting in water, and solidified in a state having a desired water permeability coefficient without compaction. There is.

The alkaline solidifying material may be cast by a general waste loading method such as a one-sided push method, a slope flow method, or a direct loading from a dump truck before solidification, or by a tremie pipe. It may be driven by casting, feeding by a grab bucket, or using a pump or the like.

The placement of the alkaline solidifying material is completed, and the alkaline solidifying material is cured for a certain period of time and solidified to form a wall-shaped impermeable layer 6 (impermeable wall) surrounding the inside of the landfill area. To.

After the impermeable layer 6 is formed, as shown in FIGS. 1 (c) to 1 (e) and FIGS. 4 to 6, the water 8 in the landfill area 4 is drained (hereinafter referred to as external drainage), and the impermeable layer 6 is formed. A solidified body is cast inside the layer 6 to form alkaline solidifying material landfill layers 7, 7 ...

It is desirable that the external drainage be drained leaving the minimum necessary internal water 8 according to the waste to be thrown in after the impermeable layer 6 is formed. For example, if the solidified body is to be landfilled as waste, it is not necessary to leave the inland water because there is no scattering or generation of odor. On the other hand, when burying ordinary waste, it is desirable to leave enough internal water to cover the surface of the discarded ordinary waste in order to prevent odor and scattering.

Further, the external drainage may be drained after charging a certain amount of the solidified body, or may be drained to the outside at the same time according to the charged amount of the solidified body, and the entire inside of the landfill area 4 may be drained before the solidified body is charged. You may drain the water. In the figure, reference numeral 9 is a pump for external drainage, and reference numeral 8 is a drainage pipe.

The water-impervious layer 6 made of an alkaline solidifying material has a backup function, that is, a secondary impermeable function, added to the impermeable revetment 3, and even if the water level in the landfill area 4 drops due to external drainage, the water-impervious layer 6 remains external. It has enough thickness and strength to withstand the water pressure outside the landfill disposal site so that the revetment 3 will not be displaced due to the difference in water pressure.

In addition, this external wastewater has only the impermeable layer 6 that can cause alkalinization at the initial stage of landfill, and the high alkalinization of the internal water due to it has not progressed. Alternatively, it can be drained to the outside with a slight residual water treatment.

On the other hand, when the solidified body is discarded or put into the air after external drainage, since there is almost no internal water 8, it is common to use a one-sided push type, a slope flow method, or direct pouring from a dump truck before solidification. It is possible to sequentially inject the waste into the inside of the impermeable layer 6 by the same method as the method of injecting the waste in the landfill disposal site.

When the water depth of the place where the sea surface waste disposal site is installed is deep, the water pressure at the time of external drainage increases. Therefore, in order to drain the entire amount of the inland water 8, the thickness and strength of the impermeable layer 6 are increased. There is a need.

For this reason, in the initial stage of landfill, the entire amount of internal water 8 is not drained in the external drainage, but the impermeable layer 6 is drained within the range that can withstand the water pressure. The solidified body may be put into the air after draining the entire amount of the inland water 8 remaining in the middle or late landfill when the water pressure to 6 is reduced.

In addition, since it is drained to the outside and input into the air, the amount of water added is reduced, and high-frequency vibration is applied to the solidified body before solidification by a vibrator or the like held in a heavy machine after casting to perform vibration and compaction. By doing so, the volume can be reduced.

Then, by repeatedly charging the solidified body inside the impermeable layer 6, a plurality of solidified body landfill layers 7, 7 ... Are sequentially laminated.

At that time, even when the injection of the solidified body on that day is completed, the incinerator ash and the like do not scatter, so that it is not necessary to cover the soil on the same day. In addition, the amount of waste increases because soil covering is not required.

In addition, the landfill ground is strengthened by integrating the solidified landfill layers 7, 7 ...

Then, when a certain amount is reclaimed by the solidified landfill layers 7, 7, ..., the remaining portion may be reclaimed by the solidified body, or other waste may be reclaimed.

If a certain amount of inland water is retained, as the landfill work progresses, the residual water level of the pound 12 decreases, that is, the ratio of water to the disposal material decreases, but the solidified body is solidified. As a result, the water permeability is lowered, so that the permeation of rainwater or the like into the solidified landfill layers 7, 7 ... The load on the water treatment of wastewater is reduced.

In the sea surface landfill method configured in this way, solidified landfill layers 7, 7 ... Can satisfy the abolition standard of the landfill site, thereby achieving early stabilization.

In the above-mentioned embodiment, an example in which a solidified body obtained by mixing incineration ash, incineration ash, coal ash, and fly ash with cement as waste is described as an example of a sea surface disposal site, but the inside of the impermeable layer 6 is described. May be landfilled with ordinary waste.

At that time, when the internal water 8 is drained to the outside, the internal water 8 is retained to such an extent that the surface of the ordinary waste thrown into the inside of the impermeable layer 6 can be covered with a predetermined depth, and the internal water 8 is generated from the waste. Prevents odors and waste from scattering.

When ordinary waste is thrown inside the impermeable layer 6, cement is applied to the upper surface of the ordinary waste for incinerator ash, incinerator ash, coal ash, and fly ash instead of the soil covering the surface. It may be covered with a mixed solidified body. In that case, the amount of waste disposed of increases by using a solidified body that is waste instead of covering the soil.

Further, in the above-mentioned embodiment, the case where the revetment 3 is used as the impermeable revetment 3 has been described, but after forming the non-impermeable revetment 3, the impermeable layer 6 is formed by the alkaline solidifying material to landfill. It may be possible to cope with.

Further, in addition to the above-described embodiment, in the construction of a landfill, cement solidified soil or calcia modified soil may be buried inside the impermeable layer 6 as a landfill material.

In that case, the cement-solidified soil and the calcia-modified soil are sequentially reclaimed in the same manner as the landfill layers 7, 7 ... Will be done. As for water permeability, it is difficult for rainwater or the like to penetrate into the landfill because the water permeability is low as in the case of the landfill layer made of solidified material.

Cement solidified soil and Calcia modified soil can be drained after adding a certain amount of cement solidified soil and Calcia modified soil, and at the same time according to the amount of cement solidified treated soil and Calcia modified soil. When draining externally, as in the case of forming the impermeable layer 6, the fluidity is increased by increasing the amount of water added, the pouring in water is facilitated, and the desired permeability coefficient is obtained without compaction. It is designed to solidify in the state of having.

Further, when the bottom is not impermeable ground or when it is desired to secure high impermeable at the bottom, as shown in FIG. 7, a bottom impermeable layer 20 continuous with the impermeable layer 6 is provided at the bottom of the landfill area 4. It may be formed.

1 Sea surface waste disposal site 2 Impermeable ground 3 Seawall 4 Landfill area 5 Backfill layer 6 Impermeable layer 7 Solidified landfill layer 8 Water (internal water)
9 Pump 10 Drainage pipe 12 lbs

Claims (8)

In the sea surface reclamation method to reclaim the landfill area surrounded by the seawall
An alkaline solidifying material is placed inside the revetment, and the alkaline solidifying material is solidified to form a water-impervious layer having a certain thickness, and then the inside of the water-impervious layer is filled with waste or landfill. A sea surface landfill method comprising draining water from the landfill area to the outside. The sea surface reclamation method according to claim 1, wherein the alkaline solidifying material is cast on the bottom surface of the revetment to form a bottom surface impermeable layer. The sea surface landfill method according to claim 1 or 2, wherein a solidified body obtained by mixing cement with incinerator ash, coal ash, and fly ash is buried inside the impermeable layer as the waste. The sea surface landfill method according to claim 1 or 2, wherein the surface of the waste put into the impermeable layer is covered with a solidified body obtained by mixing cement with incinerator ash, coal ash, and fly ash. The sea surface landfill method according to claim 1 or 2, wherein cement solidified soil or calcia modified soil is landfilled inside the impermeable layer as the landfill material. The sea surface landfill method according to any one of claims 1 to 5, wherein the alkaline solidifying material uses a cement solidified treated soil, a calcia modified soil, or a solidified body obtained by mixing cement with incinerated ash, coal ash, or fly ash. .. The sea surface landfill method according to any one of claims 1 to 6, wherein the fluidity is adjusted by adjusting the amount of water added to the alkaline solidifying material. The sea surface landfill method according to any one of claims 1 to 7, wherein the amount of the external drainage is changed before or after the start of landfill depending on the material for landfilling the inside of the impermeable layer.

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