An ecological and environmental protection type landfill site closing covering structure

Abstract

The application discloses a landfill ecological environment-friendly covering structure, which comprises a supporting layer, a composite drainage net, a water storage layer and a vegetation layer which are sequentially and layerwisely laid on a garbage layer; the water storage layer is fine-grained soil for storing water to supply the vegetation layer; the composite drainage net comprises a first non-woven geotextile layer, a three-dimensional plastic net and a second non-woven geotextile layer which are sequentially and layerwisely arranged, the first non-woven geotextile layer provides a first capillary resistance effect, the second non-woven geotextile layer provides a second capillary resistance effect to prevent seepage, and the three-dimensional plastic net is used for draining water and air; and the supporting layer is coarse-grained soil for supporting the composite drainage net and draining air; the application can effectively prevent seepage, drain air and promote vegetation growth, and can realize the purposes of improving structure service performance, saving raw materials, reusing waste materials and improving ecological environment.

Description

TECHNICAL FIELD

[0001] The present application relates to landfill closure technology field, especially to a kind of ecological environmental protection type closure covering structure of waste landfill. BACKGROUND

[0002] With the improvement of living standards, garbage discharge increases year by year. Except a small amount of recycling and use as fertilizer, most of the garbage is transported to the landfill. In order to prevent the landfill from polluting the environment, the landfill needs to be covered. The structure of the closure covering is the last stage of the landfill operation, and it is also the most critical stage. The closure covering is a man-made structure built on the top of the filled garbage after the landfill stops filling garbage. It provides protection for the filled garbage and is the basis for land use and restoration of the landfill.

[0003] The existing closure covering structure mostly uses geomembrane as the impermeable material. However, long-term engineering practice shows that the contact surface between the geomembrane and the overlying soil is a weak surface, and the overlying soil is prone to sliding instability along this weak surface. When the landfill gas under the geomembrane is not discharged smoothly, it is easy to cause the "whale protrusion" phenomenon of the geomembrane, which threatens the safety and stability of the landfill covering layer. After being affected by wind, sun, rain and other factors for a long time, micro cracks, surface soil landslides and other problems may occur. At the same time, due to the uneven settlement of the garbage body, the width of the cracks may be increased, causing landfill gas leakage and other problems.

[0004] Therefore, in view of the limitations of the existing closure covering structure, a closure covering structure that can effectively prevent seepage, discharge gas and promote vegetation growth is needed. SUMMARY

[0005] The embodiment of the present application provides a kind of ecological environmental protection type closure covering structure of waste landfill, can effectively play the role of preventing seepage, discharging gas and promoting vegetation growth. The present application makes full use of the characteristics of materials and structure itself, realizes the purpose of improving the service performance of structure, saving raw materials, recycling waste materials and improving ecological environment. The technical solution is as follows:

[0006] The present application provides a kind of ecological environmental protection type closure covering structure of waste landfill, which comprises a support layer, a composite drainage net, a water storage layer and a vegetation layer which are sequentially stacked and laid on the garbage layer. The water storage layer is fine-grained soil, which stores water to supply the vegetation layer. The composite drainage net comprises a first non-woven geotextile layer, a three-dimensional plastic net and a second non-woven geotextile layer which are sequentially stacked. The first non-woven geotextile layer provides a first capillary resistance effect, and the second non-woven geotextile layer provides a second capillary resistance effect to prevent seepage. The three-dimensional plastic net is used for drainage and gas discharge. The support layer is coarse-grained soil, which supports the composite drainage net and discharges gas.

[0007] For example, in the ecological landfill site environment-friendly covering structure provided by one embodiment, the laying slope of the support layer, the composite drainage net, the water storage layer and the vegetation layer is not less than 5°, so as to facilitate the drainage and air exhaust of the composite drainage net.

[0008] For example, in the ecological landfill site environment-friendly covering structure provided by one embodiment, the water storage layer is silty soil or silty clay, and the compaction degree is not less than 85% and the thickness is 50-150 cm.

[0009] For example, in the ecological landfill site environment-friendly covering structure provided by one embodiment, the composite drainage net is a three-dimensional geodraining board, and the thickness of the composite drainage net is not less than 5 mm.

[0010] For example, in the ecological landfill site environment-friendly covering structure provided by one embodiment, the support layer is coarse-grained industrial solid waste or construction waste, including waste ore or engineering spoil, and the thickness of the support layer is 10-20 cm.

[0011] For example, in the ecological landfill site environment-friendly covering structure provided by one embodiment, the compaction degree of the vegetation layer is 80%-85% and the thickness is not less than 15 cm. 。

[0012] For example, in the ecological landfill site environment-friendly covering structure provided by one embodiment, compost is mixed in the vegetation layer to improve the oxidation efficiency of the methane oxidizing bacteria in the vegetation layer.

[0013] For example, in the ecological landfill site environment-friendly covering structure provided by one embodiment, the first non-woven geotextile layer and the second non-woven geotextile layer are 200 g / m 2 -300 g / m 2 non-woven geotextiles.

[0014] For example, in the ecological landfill site environment-friendly covering structure provided by one embodiment, the first non-woven geotextile layer and the second non-woven geotextile layer are respectively adhered to the upper and lower surfaces of the three-dimensional plastic net.

[0015] The waste landfill ecological environment-friendly covering structure provided by some embodiments of the present application has the beneficial effects that the waste landfill ecological environment-friendly covering structure can reduce rainwater from entering the waste layer, thereby reducing the production of leachate of the waste; reduce the emission of landfill gas generated by waste degradation into the atmosphere, thereby reducing air pollution, greenhouse effect and odor nuisance and other problems; also provides a growth environment for vegetation, which is helpful for ecological greening, the present application makes full use of the advantages of the material itself to improve the service performance of the covering layer, and good impermeability can be achieved in areas with large rainfall; meanwhile, sand and stone resources are effectively saved, and the reuse of industrial solid waste is realized. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0017] Figure 1 is a covering structure schematic diagram in the prior art;

[0018] Figure 2 is a capillary resistance type covering structure schematic diagram in the prior art;

[0019] Figure 3 is a waste landfill ecological environment-friendly covering structure schematic diagram of the present application;

[0020] Figure 4 is a composite drainage net structure schematic diagram of the present application;

[0021] Figure 5 is a working mechanism diagram of the covering structure of the present application when the rainfall is small;

[0022] Figure 6 is a working mechanism diagram of the covering structure of the present application when the rainfall is large.

[0023] Reference signs: 1-waste layer, 2-support layer, 3-composite drainage net, 31-first non-woven geotextile layer, 32-three-dimensional plastic net, 33-second non-woven geotextile layer, 4-water storage layer, 5-vegetation layer. DETAILED DESCRIPTION

[0024] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by those skilled in the art without creative efforts fall within the scope of the present application.

[0025] Unless otherwise defined, technical terms or scientific terms used in the present disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which the present disclosure pertains. The terms "first", "second", and similar terms used in the present disclosure do not denote any order, quantity, or importance, but are used to distinguish different components. The terms "include", "contain", and similar terms mean that the elements or objects before the terms encompass the elements or objects listed after the terms and their equivalents, and do not exclude other elements or objects. The terms "connect" or "connected" and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms "upper", "lower", "left", "right", and the like are used only to represent relative positional relationships, and when the absolute positions of the described objects are changed, the relative positional relationships can also be changed accordingly.

[0026] A prior art closure covering structure is shown in Figure 1 The covering structure of this type includes, from top to bottom, a vegetation layer 1', a drainage layer 2', an impermeable layer 3', and an air exhaust layer 4', and is laid on a waste layer 5'. The impermeable layer 3' generally uses geomembrane as the impermeable material. However, long-term engineering practice shows that the contact surface between the geomembrane and the overlying soil is a weak surface, and the overlying soil is prone to sliding instability along this weak surface. When the gas drainage under the geomembrane is not smooth, the "whale protrusion" phenomenon of the geomembrane is easily caused, which threatens the safety and stability of the landfill covering layer and reduces the service life of the closure covering structure. In addition, due to the poor water permeability and air permeability of the geomembrane, the connection between the root system of the vegetation on the upper part of the geomembrane and the water and gas environment on the lower part of the geomembrane is cut off, which is not conducive to the growth of the vegetation.

[0027] In order to overcome the above-mentioned shortcomings of the covering structure shown in Figure 1 , there is a capillary resistance type closure covering structure in the prior art, as shown in Figure 2As shown, the covering structure includes the following parts: vegetation layer 1", water storage layer 2" and capillary resistance layer 3" (also used as air exhaust layer), and is laid on the garbage layer 4". The water storage layer 2" is constructed by using fine-grained soil, and the capillary resistance layer 3" is constructed by using coarse-grained soil. Due to the difference in unsaturated permeability characteristics of fine-grained soil and coarse-grained soil, a capillary resistance effect is formed at the interface of fine-grained soil and coarse-grained soil. During rainfall, when rainwater infiltrates to the interface of fine-grained soil and coarse-grained soil, the capillary resistance effect prevents water from entering the coarse-grained soil, so that more water is stored in the fine-grained soil, thereby realizing the impermeable function of the covering layer. When the water in the fine-grained soil is close to saturation, the capillary resistance effect is invalid, and water can enter the coarse-grained soil. This type of covering structure does not have a weak surface for instability, and avoids the "whale protrusion" phenomenon caused by air pressure accumulation, and provides a continuous water and air environment, which is beneficial to the growth of vegetation. However, the coarse-grained soil in this type of covering structure is usually selected from screened or treated coarse sand or gravel, and the thickness is generally not less than 30 cm, so the material cost and transportation cost are relatively high; in addition, when the rainfall exceeds the water storage capacity of the water storage layer 2", the capillary resistance effect is invalid, and rainwater will enter the coarse-grained soil. Because the water holding capacity of coarse-grained soil is poor, water can penetrate through the coarse-grained soil into the garbage in a very short time. Therefore, when the rainfall is large, the bottom of the covering structure of this type is prone to rainwater leakage. Therefore, this type of covering structure is only suitable for arid or semi-arid regions with less rainfall.

[0028] Therefore, the present application provides a kind of ecological environmental protection type covering structure for landfill, as shown in Figures 3-4 As shown, the present application provides a kind of ecological environmental protection type covering structure for landfill, which is laid on the garbage layer 1, and includes support layer 2, composite drainage net 3, water storage layer 4 and vegetation layer 5 laid in turn on the garbage layer 1;Wherein, the water storage layer 4 is fine-grained soil, to store water and supply the vegetation layer 5;The composite drainage net 3 includes first non-woven geotextile layer 31, three-dimensional plastic net 32 and second non-woven geotextile layer 33 arranged in turn, the first non-woven geotextile layer 31 provides first capillary resistance effect, the second non-woven geotextile layer 33 provides second capillary resistance effect, to prevent seepage, and the three-dimensional plastic net 32 is used for drainage and air exhaust;The support layer 2 is coarse-grained soil, to support the composite drainage net 3 and exhaust air.

[0029] The composite drainage net 3 can play a double capillary resistance effect, and simultaneously serve as a drainage layer and an air exhaust layer. The ecological and environmentally-friendly covering structure of the landfill site can reduce rainwater entering the garbage layer 1, thereby reducing the production of leachate of the garbage; reduce the emission of landfill gas generated by the degradation of the garbage into the atmosphere, thereby reducing air pollution, greenhouse effect, odor nuisance and other problems; and provide a growth environment for vegetation, which is helpful for ecological greening. The ecological and environmentally-friendly covering structure of the landfill site fully utilizes the advantages of the materials to improve the service performance of the covering layer, and can achieve good anti-seepage effect in areas with large rainfall. Meanwhile, the ecological and environmentally-friendly covering structure of the landfill site effectively saves sandstone resources and realizes the reutilization of industrial solid waste.

[0030] For example, in the ecological and environmentally-friendly covering structure of the landfill site provided in an embodiment, the laying slope of the support layer 2, the composite drainage net 3, the water storage layer 4 and the vegetation layer 5 is not less than 5°, and in particular, the laying slope of the composite drainage net 3 is not less than 5°, so as to ensure the drainage and air exhaust capacity of the composite drainage net 3.

[0031] For example, in the ecological and environmentally-friendly covering structure of the landfill site provided in an embodiment, as shown in Figures 3-4 , the composite drainage net 3 is a three-dimensional geodraining plate, and the thickness of the composite drainage net 3 is not less than 5 mm.

[0032] For example, in the ecological and environmentally-friendly covering structure of the landfill site provided in an embodiment, the first non-woven geotextile layer 31 and the second non-woven geotextile layer 33 are 200 g / m 2 -300 g / m 2 non-woven geotextiles.

[0033] For example, in the ecological and environmentally-friendly covering structure of the landfill site provided in an embodiment, as shown in Figures 3-4 , the first non-woven geotextile layer 31 and the second non-woven geotextile layer 33 are respectively adhered to the upper and lower surfaces of the three-dimensional plastic net 32.

[0034] According to the above embodiment, the composite drainage net 3 of the present application adopts a three-dimensional geotechnical drainage plate, the three-dimensional geotechnical drainage plate is a geosynthetic material, the composite drainage net 3 is composed of a three-dimensional plastic net 32 with a double-sided bonding non-woven geotextile, has a very high longitudinal and transverse drainage and air exhaust capacity, and has a very strong water permeability when the non-woven geotextile is in a saturated state. However, when the non-woven geotextile is in a dry or unsaturated state, the water permeability is very poor, because the composition material (such as polyester and polypropylene) of the non-woven geotextile has a very strong hydrophobicity. Since the capping structure is usually in an unsaturated state, when the water enters the first non-woven geotextile layer 31 of the composite drainage net 3 from the water storage layer 4 of fine-grained soil, a first capillary barrier effect is formed. Since the coarse-grained soil generally has a hydrophilic property, the capillary barrier effect provided by the non-woven geotextile is more intense than that provided by the coarse-grained soil. In this way, before the water breaks through the first non-woven geotextile layer 31, the overlying fine-grained soil layer will store more water, and thus the anti-seepage function of the capping structure is more favorable.

[0035] When the rainfall is not large, the capillary barrier effect of the first non-woven geotextile layer 31 can achieve the anti-seepage function; when the rainfall is large, the capillary barrier effect of the first non-woven geotextile layer 31 is invalid, and when the water breaks through the first non-woven geotextile layer 31 and enters the three-dimensional plastic net 32 in the middle of the composite drainage net 3, since the structure has a very strong drainage capacity and the second non-woven geotextile layer 33 under the three-dimensional plastic net 32 will provide a second capillary barrier effect. Under the joint action of the two factors, the water can move and drain rapidly along the three-dimensional plastic net 32 and will not break through the second non-woven geotextile layer 33 at the lower part of the composite drainage net 3, and thus the superior anti-seepage effect can also be achieved when the rainfall is large.

[0036] Compared with the traditional capping structure, the new capping structure adopting the composite drainage net 3 of the present application does not use a geomembrane, solves the problems of sliding instability of the capping layer soil along the soil-geomembrane interface and accumulation of gas pressure at the bottom, improves the service life of the capping structure, and at the same time ensures the effective connection between the vegetation in the capping structure and the groundwater gas, improves the survival rate of the vegetation, and improves the ecological environment of the capping area.

[0037] In addition, compared with the existing capillary barrier type capping structure, the composite drainage net 3 of the present application overcomes the defects of difficult material selection and high cost of coarse-grained soil, avoids the problem of rapid downward infiltration of water into the landfill layer after entering the coarse-grained soil, and can also achieve good anti-seepage, drainage and air exhaust functions in humid areas with large rainfall, and at the same time improves the ability of the vegetation to cope with drought conditions.

[0038] For example, in the ecological landfill site environment-friendly covering structure provided by one embodiment, the water storage layer 4 is silty soil or silty clay, and the compaction degree is not less than 85%, and the thickness is 50-150 cm.

[0039] For example, in the ecological landfill site environment-friendly covering structure provided by one embodiment, the support layer 2 is coarse-grained industrial solid waste or construction waste, including waste ore or engineering spoil, and the thickness of the support layer 2 is 10-20 cm.

[0040] According to the above embodiment, the support layer 2 plays a role in supporting the composite drainage network 3, and the coarse-grained engineering spoil, construction waste, waste ore and other industrial solid waste are selected, so that the industrial solid waste is consumed and reused, which is in line with the green, environmental protection and ecological concept, and has a broad application prospect.

[0041] The thickness of the support layer 2 is 10-20 cm. When the capillary resistance effect provided by the first non-woven geotextile layer 31 of the composite drainage network 3 is not invalid, there is no water flow in the intermediate three-dimensional plastic net 32, and at this time the support layer 2 assists the composite drainage network 3 to play the exhaust function, thereby enhancing the exhaust capacity. When the capillary resistance effect of the first non-woven geotextile layer 31 of the composite drainage network 3 is invalid, there is water flow in the intermediate three-dimensional plastic net 32, and at this time the support layer 2 can replace the composite drainage network 3 to play the exhaust capacity.

[0042] Figure 5 The working mechanism diagram of the covering structure of the present application when the rainfall is small is given, Figure 6 The working mechanism diagram of the covering structure of the present application when the rainfall is large is given.

[0043] For example, in the ecological landfill site environment-friendly covering structure provided by one embodiment, the compaction degree of the vegetation layer 5 is 80%-85%, and the thickness is not less than 15 cm 。

[0044] For example, in the ecological landfill site environment-friendly covering structure provided by one embodiment, compost is mixed in the vegetation layer 5 to improve the oxidation efficiency of the methane-oxidizing bacteria in the vegetation layer 5.

[0045] Specifically, 5%-20% of compost is mixed in the vegetation layer 5, which on the one hand provides nutrients for vegetation growth, and on the other hand improves the oxidation efficiency of the methane-oxidizing bacteria in the vegetation layer 5, and reduces the emission of methane in the landfill gas to the atmosphere. The present application improves the methane oxidation capacity of the vegetation layer 5 by mixing compost in the vegetation layer 5, and provides a bottom-up guarantee capability for the treatment and conversion of methane.

[0046] According to the above-mentioned embodiments, fine-grained soil is used as the water storage layer 4, and the increased water content in the water storage layer 4 effectively fills the release channels of the gas, so that most of the landfill gas can be drained along the composite drainage network 3 with strong air permeability, thereby being collected and utilized. A small amount of methane that breaks through the composite drainage network 3 will be converted into carbon dioxide under the action of the methanotrophs in the vegetation layer 5. Since the potential of methane to cause the greenhouse effect is about 25 times that of carbon dioxide, the greenhouse effect is reduced. The increased water content of the fine-grained soil also provides more water for the growth of vegetation, thereby improving the survival ability of the vegetation during drought periods.

[0047] The ecological and environmentally-friendly landfill site sealing and covering structure of the present application uses materials that are easy to obtain and have low cost, fully utilizes the characteristics of the materials that are easy to obtain on the market, overcomes the shortcomings of the existing sealing and covering structures, meets the functional requirements of the sealing and covering structure, reduces the construction and construction costs, saves high-priced raw materials, effectively utilizes industrial solid waste, can meet the environmental protection goals and ecological requirements, and has the advantages of low cost, high efficiency, and the like.

[0048] Although the embodiments of the present application have been disclosed as above, they are not limited to the use listed in the specification and embodiments, and can be fully applied to various fields suitable for the present application, and additional modifications can be easily made by those skilled in the art, and therefore the present application is not limited to specific details and the figures shown and described herein, without departing from the general concept defined by the claims and the equivalent scope.

Claims

1. An ecological and environmentally friendly landfill covering structure, characterized in that: It includes a garbage layer, a support layer, a composite drainage network, a water storage layer and a vegetation layer stacked in sequence; The water storage layer is fine-grained soil, which stores water to supply the vegetation layer; the composite drainage net includes a first non-woven geotextile layer, a three-dimensional plastic net, and a second non-woven geotextile layer stacked in sequence. The first non-woven geotextile layer provides a first capillary retardation effect in an unsaturated state to prevent water from seeping in; the second non-woven geotextile layer provides a second capillary retardation effect after the water breaks through the first non-woven geotextile layer to prevent seepage, and the water moves and is discharged rapidly along the three-dimensional plastic net. The composite drainage net is a three-dimensional geotextile drainage board, and the thickness of the composite drainage net is not less than 5 mm; the support layer is coarse-grained soil to support the composite drainage net and exhaust air; Adhere the first non-woven geotextile layer and the second non-woven geotextile layer to the upper and lower surfaces of the three-dimensional plastic net respectively; The support layer is coarse-grained industrial solid waste, including engineering slag, construction waste or waste ore, and the thickness of the support layer is 10-20 cm. The water storage layer is silt or silty clay, with a compaction degree of not less than 85% and a thickness of 50-150 cm.

2. The ecological and environmentally friendly landfill covering structure according to claim 1 is characterized in that: The vegetation layer has a compaction degree of 80%-85% and a thickness of not less than 15 cm.

3. The ecological and environmentally friendly landfill covering structure according to claim 2 is characterized in that: Compost is mixed into the vegetation layer to improve the oxidation efficiency of methane oxidizing bacteria in the vegetation layer.

4. The ecological and environmentally friendly landfill covering structure according to claim 1 is characterized in that: The first non-woven geotextile layer and the second non-woven geotextile layer are 200g / m 2 —300g / m 2 Non-woven geotextile.

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