JP2006212568A - Method for applying cover soil on reclaimed waste material and penetrating water capillary barrier layer of reclaimed waste material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for applying cover soil on a reclaimed waste material which is effective for forming a penetrating water capillary barrier layer configuring a cover soil structure on the reclaimed waste material and the penetrating water capillary barrier layer of the reclaimed waste material. <P>SOLUTION: The penetrating water capillary barrier layer 17 is formed by providing a protective layer 16 for covering the reclaimed waste material 10 by soil with an incline, laying a mat 18 having a large space along the inclination of the protective layer 16, and laminating a drainage layer 20 having a smaller space and a larger capillary strength than the mat 18 on the above-described mat 18. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a landfill waste covering method and a landfill waste seepage water capillary barrier layer, and more particularly, a landfill waste suitable for forming a seepage water capillary barrier layer constituting a landfill waste cover structure. The present invention relates to a soil covering construction method and a seepage water capillary barrier layer for landfill waste.

  Under various recycling laws including home appliances, general and industrial waste has been actively reduced, and the amount of waste discharged has been decreasing slightly. However, there are still wastes that need to be landfilled finally. On the other hand, environmental pollution and environmental remediation around the existing landfill waste disposal sites and illegal dumping sites are problematic. This is contaminated when penetrating water such as rainwater penetrates landfill waste, and flows into the surrounding groundwater and pollutes it. Therefore, in order to prevent environmental pollution, it is important to suppress permeated water and avoid contact between pollutants and groundwater.

  One of the preventive measures mentioned above is a waste landfill structure using multi-layered soil. FIG. 3 shows a cross-sectional view thereof. In FIG. 3, the multi-layer covering soil covering the waste surface is formed by applying a water guide gradient to the surface portion of the recessed land 1 and covering it with the locally generated soil 2, and then laying the coarse particle layer 3 and subsequently the fine particle layer 4. A capillary barrier layer configured as described above is formed, and finally the entire structure is covered with locally generated soil and topsoil 5 having low water permeability. Here, the layer boundary between the fine grain layer 4 and the coarse grain layer 3 is given a gradient. This is because the fine-grained layer 4 having a large water-holding capacity composed of small grains is provided on the coarse-grained layer 3 having a large grain constituting the multi-layer covering soil, so that the permeated water due to rain water or the like is stopped by the fine-grained layer 4. At the same time, a capillary barrier effect is used, in which a water guide gradient is applied to the cover soil to cause the soil to flow downward along the boundary surface between the coarse grain layer 3 and the fine grain layer 4.

As a result, the permeated water that has passed through the surface of the multi-layered soil and infiltrated into the fine-grained soil and moved downward changes the direction of flow near the boundary surface with the coarse-grained soil to the side along the gradient, and retains the water in the fine-grained soil The water is then collected by flowing down. By reducing the amount of rainwater infiltrated water in landfill waste, it is possible to downsize the permeate treatment facility installed in landfill waste and reduce maintenance.
JP 2001-17933 A

  However, the capillary barrier layer that constitutes the above-mentioned multi-layered soil uses sand, gravel, crushed rocks, concrete crushed material, and other granular recycled products, etc., in which the particle size is adjusted to a fine particle layer and a coarse particle layer. When such a material is used, it is necessary to increase the thickness of the layer so that the capillary barrier layer has a certain degree of water retention and water permeability at the same time. For this reason, the material which carries in from the outside increases so much, and it becomes the unpreferable situation that material cost increases and the amount of landfill decreases conversely. In addition, if the amount loaded on the landfill waste increases, there is a possibility of causing uneven settlement. Furthermore, there is a problem that the number of days and cost required for construction increase as a whole.

  Moreover, in order to ensure an effective capillary barrier effect, it is necessary to make the upper layer water retention capacity larger than the lower layer water retention capacity. For this purpose, it is necessary to reduce the gap diameter of the upper layer and relatively increase the gap of the lower layer. On the other hand, there is a restriction (piping law) that the material placed on the upper layer does not fall into the lower space. That is, the structure is established by the balance of the size and shape of the gap. Furthermore, it is necessary to make the gap uniform.

  The size of the gap affects the ease of flow to the side, that is, the water permeability coefficient. The larger the gap, the greater the water permeability. In order to obtain an effective function, the upper layer needs to increase water permeability while maintaining necessary water retention. However, since the conventional capillary barrier layer achieves the smoothness of the lower layer surface and the uniformity of the voids, the size of the voids in the lower layer is limited. For this reason, it is difficult to increase the water permeability by forming a large gap in the upper layer.

  Accordingly, the present invention has been made to solve the above-described problems in the multi-layer cover soil, and is a landfill waste covering method that is effective for forming a permeated water capillary barrier layer that constitutes the multi-layer cover soil of the landfill waste, and The object was to provide a permeate capillary barrier layer for landfill waste.

  In order to achieve the above object, the landfill waste covering method according to the present invention is provided with a gradient in a protective layer covering the landfill waste, and a mat having a large gap along the gradient of the protective layer. And a drainage layer having a smaller gap than the mat and having a large capillary force is formed on the mat.

  Further, the osmotic water capillary barrier layer for landfill waste according to the present invention is a osmotic water capillary barrier layer in which two layers having different voids are laminated on the upper surface of the landfill waste protective layer to give a water guide gradient. The lower layer of the two layers is a mat having a larger gap than the upper layer.

  According to the landfill waste covering method and the landfill waste permeation capillary barrier layer according to the present invention having the above-described configuration, it is possible to thinly form the lamination width of the lower layer having a large void, and thus the entire capillary barrier layer The lamination width can also be formed thin. As a result, the amount of buried waste and the like can be increased. In addition, the amount of material and material cost used for the capillary barrier layer can be reduced, and the construction period can be greatly shortened.

In forming the multi-layered soil, a high-quality material may not be used due to cost and material availability. In this case, depending on the type of drainage material such as sand, the drainage distance cannot be earned. The drainage distance affects the performance of the capillary barrier layer due to this material. If a mat with a large gap, for example, a lattice, is used, it is an off-the-shelf product that is homogeneous and easily available, and the gap can be set large. In addition, a material having a large particle size can be used for the drain layer of the mat upper layer in accordance with the large gap of the mat, and the material selection increases and the material selection becomes easy. Therefore, it is always easy to ensure a stable drainage distance.
In addition, the lower layer can be formed simply by laying a mat after laying down the protective layer of the waste, and the capillary barrier layer can be easily applied.

DESCRIPTION OF EMBODIMENTS Embodiments of a landfill waste covering method and a landfill wastewater permeation capillary barrier layer according to the present invention will be described below in detail with reference to the drawings.
First, the soil covering structure of landfill waste, which is a construction target of the landfill waste permeated water capillary barrier layer according to the embodiment, will be described. FIG. 2 shows a schematic cross-sectional view of a landfill waste covering structure. The place where the waste 10 is landfilled is set as a landfill area by, for example, creating a recessed land using a gentle slope. Of course, you may build on a flat ground. The water shielding layer 12 is laid on the mountain side slope, the bottom, and the left and right slopes of the depression. This water-impervious layer 12 can prevent water permeation, and if it conforms to the current law, it has a double sheet structure or a structure in which a hardly water-permeable layer is covered with a sheet. For example, a water-impervious soil that has the ability to delay the diffusion of harmful substances produced by mixing soil generated by excavation of a depression and clay mineral bentonite that swells when in contact with water and makes it very difficult for water to penetrate. May be laid in layers and covered with a water shielding sheet. The water shielding layer 12 is laid at the bottom of the recessed area, and is laid so as to rise upward along the mountain side and right and left slopes from the peripheral edge. Thereby, it is possible to prevent groundwater around the recessed area from entering the recessed area.

  The surface of the water-impervious layer 12 is provided with a water guide gradient from the lower end of the slope side on the mountain side toward the valley side. A plurality of drainage culverts 14 are laid in parallel at appropriate intervals along the slope surface. The drainage culvert 14 is formed by opening a large number of holes in the pipe wall, and collects water from the surrounding soil layer and flows it downstream of the gradient. This end-of-drain water culvert 14 communicates with a water treatment facility 15 formed on the valley side. As a result, the leachate flowing through the end-of-end water collecting culvert 14 is stored and purified.

  Next, the waste 10 is usually put into divided areas in the area where the water shielding layer 12 is laid. When the waste 10 becomes full for each section, the upper surface portion of the waste 10 is now processed. A water guide gradient is attached to the upper surface portion of the thrown-in waste 10, and the surface of the waste 10 is set to a condition in which rainwater permeated water tends to flow naturally. This gradient may be set so as to be inclined in the left-right direction from the ridge line portion along the center line of the recessed area while being set in the inclination direction of the gently inclined area where the recessed area is formed.

  The upper surface of the waste 10 with the water guide gradient is covered with a protective layer 16. The protective layer 16 can control the permeability as needed. Further, a so-called permeated water capillary barrier layer 17 is laid on the upper surface of the landfill waste protection layer 16.

  FIG. 1 shows a schematic configuration diagram of a permeated water capillary barrier layer of landfill waste. FIG. 1A shows a cross-sectional view of the multi-layer cover, and FIG. 2B shows a perspective view of the lattice. The permeated water capillary barrier layer 17 according to the embodiment has a two-layer structure in which a mat 18 having a large gap is first laid in the lower layer, and then a drainage layer 20 having a small gap is laid on the upper layer of the mat 18.

  The mat 18 has a larger gap than the upper drainage layer 20, and in the embodiment, for example, a material is made of resin and a three-dimensional lattice-shaped artificial mat is used. In addition, the material of the mat 18 is a mesh body, which is limited to this as long as it has a relatively long-term durability, is strong in compressive force, and supports the upper drainage layer 20 and can maintain lateral drainage by the upper layer. For example, a secondary product of a cement-based material may be used as the material.

Also, the gap of the mat is used for grating, for example, a comb-like shape in which members (flat bars) are arranged in parallel with evenly spaced gaps, a shape in which members are arranged with arbitrary gaps, and a mesh shape Etc. may be used.
In addition, the mat 18 may be laid directly on the protective layer 16 or may be laid on the protective layer 16 in order to ensure the flatness of the water conveyance gradient surface.

  On the other hand, the drainage layer 20 has a smaller gap than the lower mat 18. The drainage layer 20 according to the embodiment uses, for example, single-grain crushed stone having a particle size of 2.5 mm to 5 mm. Thereby, the water which permeate | transmitted the inside of the drainage layer 20 can maintain a water retention state by the capillary action between voids. Further, since the osmotic water capillary barrier layer 17 has a water guiding gradient, the drainage layer 20 needs to be permeable so that the osmotic water can flow and drain sideward along the gradient. As described above, the drainage layer 20 needs to have a water retention capacity larger than that of the mat 18 and have water permeability. There is no difference in water retention between the mat 18 and the drainage layer 20, that is, when the water retention is equal, the permeated water in the permeated water capillary barrier layer 17 falls downward. By providing a difference in the air gap, that is, by providing a difference in the water retention capacity, a capillary effect is produced, and the lateral movement of the permeated water becomes possible.

  By using the mat 18, the porosity of the lower layer material can be set large. The gap diameter affects the magnitude of the capillary force, and the capillary force decreases as the gap increases. In the capillary barrier, it is a condition that the capillary force of the upper layer is larger than the capillary force of the lower layer. When the porosity of the lower layer material is increased, the porosity of the upper layer material can be relatively increased. If the porosity can be increased, the water permeability can be increased and the flow to the side can be increased. By maintaining a balance between capillary force and water permeability, a large amount of water can be drained sideways using a thin layer.

  In this way, the permeated water capillary barrier layer 17 is provided with a drainage layer 20 having a greater water retention capacity than the mat 18 on the upper layer of the mat 18 having a large porosity, so that the permeated water due to rainwater or the like is discharged into the drainage layer. The water flows down according to the gradient along the boundary surface between the mat 18 and the drainage layer 20 while being retained by the water 20. Since the mat 18 is a uniform thin layer having a large gap, the thickness of the laminated layer can be made much thinner than a coarse particle layer made of coarse stone. Accordingly, the amount of landfill such as waste can be increased by the amount of covering. Further, the lower layer of the osmotic water capillary barrier layer 17 can be applied only by laying the mat 18 on the protective layer 16, and the material is relatively easy to obtain when single-grain crushed stone is used for the upper drainage layer 20. Therefore, it can be formed easily.

  The soil covering structure for landfill waste is configured such that a protective layer 16, a mat 18, and a drainage layer 20 are sequentially laminated on the upper surface of the waste 10 and then covered with a soil covering layer 22. The protective layer 16 and the soil covering layer 22 are configured to be capable of controlling permeability as needed, and control permeability by appropriately combining bentonite mixed soil and sheets. More specifically, by mixing bentonite into the soil covering layer 22 or using good-quality viscous soil, the water permeability is improved and the amount of permeated water into the capillary barrier layer is controlled, and the lateral drainage capacity is balanced. Thus, the penetration into the waste layer can be controlled.

  In order to drain running water such as rainwater that flows from around the landfill, a surface drainage groove 24 is provided in the soil covering layer 22 on the surface of the landfill. Here, it is predicted that the portion of the landfill where the waterfall deformation is greatest due to the groundwater fall in the landfill is a concave land with the largest landfill depth. Are arranged to gather in the center. Further, the drainage groove at the center may be a polyethylene pipe or a lightweight material drainage groove so that it can follow the deformation. Depending on the installation location of the landfill, the surface drainage can be efficiently performed by branching a plurality of drainage grooves around the surface drainage grooves 24.

  If the permeated water capillary barrier layer 17 composed of the drainage layer 20 and the mat 18 is used, the permeated water can be drained sideways. In the lateral drainage water collection, a drainage groove 36 is installed based on the drainage distance of the permeated water obtained from the water shielding performance evaluation test of the multi-layer covered soil. In other words, a simulated structure of the osmotic water capillary barrier layer 17 is created to determine the water retention limit distance (drainage distance) by the drainage layer 20, and if water is collected within a position corresponding to the drainage distance, it is buried by water retention destruction. Control rainwater infiltration into waste.

  The gas generated from the waste 10 protrudes and penetrates from the waste 10 to the surface of the soil covering layer 22 and is released to the outside by installing a gas vent pipe 26 connected to the lower layer void layer. In addition, a part of the permeation hole 46 of rainwater is provided in the permeation water capillary barrier layer 17. Further, the above-mentioned drainage water culvert 14 has a relatively large cross section and is formed by opening a large number of holes (not shown) in the tube wall. Thereby, the contaminated water which permeate | transmitted from the soil covering surface and permeate | transmitted the waste 10 can be collected, and air supply and exhaust_gas | exhaustion to a waste layer can be performed.

  By the way, when the construction object of the osmotic water capillary barrier layer 17 is a steep slope, there is a problem that it is easy to collapse and it is difficult to level the floor if gravel or sand is used. However, by using the mat 18 according to the embodiment and forming the drainage layer 20 as an upper layer, the thickness of the permeated water capillary barrier layer 17 can be reduced. Therefore, even in a relatively steep landfill, it is possible to form a capillary barrier layer that is less likely to collapse than using gravel or sand, and to perform side drainage.

The structure schematic of the capillary barrier layer of a landfill waste is shown. A schematic sectional view of a soil covering structure for landfill waste is shown. It is a cross-sectional view of the waste landfill structure using a multilayer covering soil.

Explanation of symbols

1 ......... Recessed ground, 2 ......... Locally generated soil, 3 ......... Coarse-grained layer, 4 ......... Fine-grained layer, 5 ......... Top soil, 10 ......... Waste, 12 ......... Water shielding , 14 ......... Flushing drainage culvert, 15 ......... Water treatment facility, 16 ......... Protective layer, 17 ......... Osmotic water capillary barrier layer, 18 ......... Mat, 20 ......... Drainage layer, 22 ......... Soil cover layer, 24 ......... surface drainage groove, 26 ......... gas vent pipe, 36 ......... drainage groove.

Claims (2)

  A gradient is applied to the protective layer covering the landfill waste, and a mat having a large gap is laid along the gradient of the protective layer, and the drainage layer having a small capillary and a large capillary force is provided. Covering construction method for landfill waste characterized by forming on mat.   An osmotic water capillary barrier layer in which two layers with different voids are laminated on the upper surface of a landfill waste protection layer to give a water guiding gradient, and the lower layer of the two layers is a mat having a larger void than the upper layer An infiltration water capillary barrier layer for landfill waste.

Images