Ecological closed reservoir system for plain dry ash yard of coal-fired power plant and construction method of ecological closed reservoir system

Abstract

The invention belongs to the technical field of ecological restoration engineering, and relates to an ecological closed reservoir system for a plain dry ash yard of a coal-fired power plant and a construction method of the ecological closed reservoir system. The ecological closed reservoir system sequentially comprises an ash residue pile body, a hardening layer, a blocking layer, a water guiding and salt discharging layer, a soil covering layer and a greening layer from bottom to top. An irrigation system is arranged on the greening layer; the system further comprises a monitoring device. The monitoring device comprises a soil salinity sensor and a vegetation growth monitor. The soil salinity sensor is arranged in the greening layer; the vegetation growth monitor is arranged on the upper surface of the greening layer; the monitoring device is connected with the irrigation system; a flood interception and drainage system is arranged on the ash residue pile body; the flood interception and drainage system is connected with the irrigation system; the supporting body of the ash pile is improved, and the long-term stability and safety of the ash yard are ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of ecological restoration engineering, and relates to an ecological closing system for a plain dry ash yard of a coal-fired power plant and a construction method thereof. Background Art

[0002] As an industrial waste, fly ash is generated in large quantities in industries such as power plants and building material factories in many regions, and ash yards are formed by stacking. These ash yards usually occupy a large amount of land. Especially when the ash yards reach the end of their service life or are no longer needed for storing fly ash, how to carry out the closing work of the ash yards and restore the ecological environment has become an increasingly prominent environmental and engineering problem. The closing work is not only to prevent the leakage and diffusion of fly ash and avoid polluting the surrounding environment, but also to carry out ecological restoration on the surface of the ash yard, repair ecological functions, and restore the original environment of the land.

[0003] However, in the existing technologies and engineering practices, relatively few studies have been conducted on the ecological restoration of ash yard closing. Most of the existing ash yard closing constructions draw on the closing technologies of landfills. Specifically, generally after the stack shaping is completed, the closing system is directly laid, and then vegetation soil is covered on the top surface and plants are planted to restore the ecology. However, this approach may not achieve the ideal restoration effect in some special regions, mainly for the following reasons: Poor soil quality and barren nutrients: Fly ash itself has a small particle size and weak binding force between particles, resulting in a loose and unstable surface of the ash pile, which is difficult to provide sufficient nutritional support for plants. In most cases, the covered soil layer is scarce in nutrients and cannot effectively nourish the plant roots, resulting in slow plant growth or even inability to grow. This makes the initial effect of ecological restoration poor, and may even lead to the death of vegetation.

[0004] Harsh climate conditions and scarce precipitation: The climate environment where many ash yards are located may pose great challenges, especially in arid or semi-arid regions with less precipitation. Insufficient precipitation will lead to limited soil moisture supply, and the plant roots cannot obtain enough water support, further affecting the survival rate and growth rate of vegetation.

[0005] Problems of high evaporation and soil salinization: In some arid regions, due to high temperature and high evaporation, the moisture in the covered soil is easily evaporated, resulting in a dry soil surface and unable to maintain sufficient moisture conditions. Moreover, under such climate conditions, salts and minerals in the soil are prone to migrate upward, causing secondary salinization of the surface soil. This salinized soil environment is extremely unfavorable to the growth of plants, restricting the normal growth and development of plants and seriously affecting the effect of ecological restoration.

[0006] The stability of the exposed ash surface is poor: Due to the fine particles and loose structure of fly ash, the exposed ash surface is vulnerable to wind, sun, and rain erosion, resulting in severe dehydration or loss of the ash layer, further weakening the stability of the heap. After rainwater penetrates into the ash heap, it may enhance the fluidity of fly ash, making the instability of the heap more serious, thus affecting the safety and stability of the overall environment.

[0007] In summary, the single method of ecological restoration by covering the soil and planting plants cannot completely solve the challenges faced in the ecological restoration of ash yards. Especially in special environmental conditions such as poor soil quality, scarce precipitation, and large evaporation, traditional restoration techniques often have poor effects. Therefore, there is an urgent need to conduct more in-depth technical research on these issues and develop ecological restoration methods suitable for complex environmental conditions. Summary of the Invention

[0008] The purpose of the present invention is to solve the technical problems in the prior art, and provide an ecological closure system for a plain dry ash yard of a coal-fired power plant and its construction method, which improves the bearing capacity of the ash and slag heap, ensures the long-term stability and safety of the ash yard, and can simultaneously achieve environmental restoration.

[0009] To achieve the above object, the present invention adopts the following technical solutions: In the first aspect, the present invention provides an ecological closure system for a plain dry ash yard of a coal-fired power plant, which sequentially includes an ash and slag heap, a hardening layer, a barrier layer, a water-conducting and salt-draining layer, a soil covering layer, and a greening layer from bottom to top; an irrigation system is arranged on the greening layer; It further includes a monitoring device, and the monitoring device includes a soil salinity sensor and a vegetation growth monitor; the soil salinity sensor is arranged inside the greening layer; the vegetation growth monitor is arranged on the upper surface of the greening layer; the monitoring device is connected to the irrigation system; a flood interception and drainage system is arranged on the ash and slag heap; the flood interception and drainage system is connected to the irrigation system.

[0010] Preferably, the barrier layer is a geosynthetic non-woven fabric composite geomembrane.

[0011] Preferably, the water-conducting and salt-draining layer is a three-ribbed geocomposite drainage net.

[0012] In the second aspect, the present invention provides a construction method for an ecological closure system for a plain dry ash yard of a coal-fired power plant, including the following steps: Renovate the ash and slag heap; construct a hardening layer on the surface of the ash and slag heap; lay a barrier layer on the surface of the hardening layer; lay a water-conducting and salt-draining layer on the surface of the barrier layer; lay a soil covering layer on the surface of the water-conducting and salt-draining layer; lay a greening layer on the surface of the soil covering layer.

[0013] Preferably, a flood interception and drainage system is arranged on the ash and slag heap during the renovation of the ash and slag heap.

[0014] Preferably, the slope of the side of the ash residue heap after renovation is 1:(3 - 4); a berm is provided every 10 - 15 m on the side.

[0015] Preferably, a dam is provided on the top of the ash residue heap; the side slope ratio of the dam is 1:(3 - 4); the drainage slope of the dam is 0.3% - 0.5%.

[0016] Preferably, the compaction degree of the side of the ash residue heap after renovation is not less than 0.95; the compaction degree of the top surface of the ash residue heap is not less than 0.90.

[0017] Preferably, the specific steps for constructing a hardened layer on the surface of the ash residue heap are: spreading a hardening agent and an auxiliary agent on the surface of the ash residue heap, and performing mixing and rolling to form a hardened layer.

[0018] Preferably, the hardening agent is desulfurized gypsum, and the addition ratio is 20% - 30% of the mass of the ash residue heap to be hardened; the auxiliary agent is quicklime, and the addition ratio is 1% - 3% of the mass of the ash residue heap to be hardened.

[0019] Compared with the prior art, the present invention has the following beneficial effects: The present invention avoids the dehydration and instability of fly ash when the ash surface is exposed by setting a hardened layer on the surface of the ash residue heap, reduces the generation of dust pollution, increases the bearing capacity of the ash residue, and ensures the stability of the ash residue heap; by setting a barrier layer on the surface of the hardened layer, it blocks the intrusion of salts in the ash residue into the surface covering soil layer due to the evaporation of water and other effects, reduces the accumulation of salts in the covering soil layer, and realizes the prevention of salinization; by setting a water - guiding and salt - discharging layer on the barrier layer, it avoids the accumulation of salts at the bottom of the covering soil layer and reduces the salt content of the soil layer; the present invention avoids the occurrence of secondary salinization, ensures the long - term effectiveness of the ecological restoration effect of the ash yard, and also realizes the resource utilization of solid waste.

[0020] In addition, the present invention monitors the soil salt content and the vegetation growth status in real time through the soil salt sensor arranged inside the greening layer and the vegetation growth monitor on the upper surface; customizes the irrigation strategy according to the actual situation through the irrigation system to achieve precise irrigation, optimize the vegetation growth environment, and prevent soil salinization; at the same time, the flood - intercepting and drainage system can collect and transport the rainwater in the rainy season and the excess irrigation water to the irrigation system for recycling, improve the water resource utilization efficiency, and reduce the operation cost. Description of the Drawings

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other relevant drawings can also be obtained based on these drawings.

[0022] Figure 1 is a schematic diagram of the overall structure of the present invention; Figure 2 is Figure 1 a partial view of; Wherein: 1. Ash slag heap; 11. Drainage ditch at the foot of the slope; 12. Bench; 13. Dam; 14. Ring road around the site; 15. Intercepting flood ditch; 2. Hardened layer; 3. Barrier layer; 4. Water-conducting and salt-draining layer; 5. Covering soil layer; 51. Ridge platform; 6. Greening layer; 61. Salt-tolerant plants; 62. Pioneer plants; 63. Irrigation system. Specific embodiments

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and shown in the accompanying drawings here can be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0025] It should be noted that similar reference numerals and letters indicate similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0026] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper", "lower", "horizontal", "inner", etc. are used to indicate the orientation or positional relationship, it is based on the orientation or positional relationship shown in the drawings or the orientation or positional relationship in which the product of the invention is usually placed during use. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, terms such as "first", "second", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0027] In addition, when the term "horizontal" appears, it does not mean that the component is required to be absolutely horizontal, but it can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and it does not mean that the structure must be completely horizontal, but it can be slightly inclined.

[0028] In the description of the embodiments of the present invention, it should also be noted that unless otherwise clearly specified and limited, when terms such as "arranged", "installed", "connected", and "coupled" appear, they should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] The following further describes the present invention in detail with reference to the accompanying drawings: The first object of the present invention is to provide an ecological closure system for a plain dry ash yard of a coal-fired power plant, which sequentially includes a slag heap body 1, a hardening layer 2, a barrier layer 3, a water-conducting and salt-discharging layer 4, a soil covering layer 5, and a greening layer 6 from bottom to top; an irrigation system 63 is arranged on the greening layer 6. The present invention realizes multiple protection functions by sequentially arranging the hardening layer 2, the barrier layer 3, the water-conducting and salt-discharging layer 4, the soil covering layer 5, and the greening layer 6 on the surface of the slag heap body 1. The hardening layer 2 prevents the fly ash from dehydrating and becoming unstable and rainwater erosion, and improves the stability of the heap body; the barrier layer 3 blocks the upward movement of the ash slag salt and prevents salinization of the soil covering layer 5; the water-conducting and salt-discharging layer 4 discharges the leached salts to reduce the soil layer salt content; the soil covering layer 5 protects the lower structure from mechanical impact and temperature change effects; the greening layer 6 fixes the soil through plant roots, reduces wind erosion and soil erosion. This structure provides a stable foundation for the land use of the ash yard, and at the same time effectively controls the problems of dust pollution and salt accumulation. Through the irrigation system 63, plants can be irrigated to promote the growth of vegetation.

[0030] The system of the present invention further includes a monitoring device, which includes a soil salinity sensor and a vegetation growth monitor; the soil salinity sensor is disposed inside the greening layer 6; the vegetation growth monitor is disposed on the upper surface of the greening layer 6; the monitoring device is connected to the irrigation system 63; a flood interception and drainage system is disposed on the ash yard heap 1; the flood interception and drainage system is connected to the irrigation system 63. By means of the soil salinity sensor disposed inside the greening layer 6 and the vegetation growth monitor on the upper surface, the present invention can monitor the soil salinity and the vegetation growth status in real time, and feed them back to the irrigation system 63. The irrigation system 63 formulates an irrigation strategy according to the actual situation to achieve precise irrigation, optimize the vegetation growth environment and prevent soil salinization; secondly, the flood interception and drainage system is connected to the irrigation system 63, which can collect and recycle the rainwater in the rainy season and the excess water from irrigation, improve the water resource utilization efficiency and reduce the operation cost.

[0031] The barrier layer 3 is a geosynthetic non-woven fabric composite geomembrane, which is welded by hot melt. The membrane lap width is 100±20mm, and there shall be no horizontal joints within 1.5m in the slope direction from the slope surface and the slope top.

[0032] The water-conducting and salt-draining layer 4 is a three-rib geocomposite drainage net, with a lap width of 75±15mm. The geonet is required to be bundled, the lower geotextile is lapped, and the upper geotextile is stitched with a polymer thread resistant to ultraviolet and chemical corrosion.

[0033] The second object of the present invention is to provide a construction method for an ecological closure system of a plain dry ash yard of a coal-fired power plant, including the following steps: The ash residue heap 1 is renovated. After renovation, the surface of the ash residue heap 1 is leveled and repaired to eliminate irregular shapes, settlements or cracks, enhance the stability of the overall structure, and reduce the occurrence of adverse events such as heap subsidence and landslides; it can effectively control the diffusion of ash residue dust and reduce the pollution of air and the surrounding environment. After renovation, the slope of the side of the ash residue heap 1 is 1:(3 - 4), which can effectively prevent safety hazards such as landslides and collapses caused by overly steep slopes of the heap side, is conducive to the natural drainage of external water sources such as rainwater, and reduces the risks of soil erosion and water accumulation; a toe drain 11 is arranged at the bottom of the side of the ash residue heap 1, which can effectively guide rainwater to a designated area, prevent rainwater from directly scouring the side of the ash residue heap 1, helps prevent soil erosion and ash residue erosion, and maintains the stability of the heap; a berm 12 is arranged every 10 - 15 m on the side, and the width of the berm 12 is 2 - 5 m. The setting of the berm 12 enables staff to conveniently enter the heap for inspection and maintenance, timely discover potential safety hazards, and ensure the long-term safety and stability of the heap. Secondly, the compaction degree of the side of the ash residue heap 1 after renovation is not less than 0.95; the compaction degree of the top surface of the ash residue heap 1 is not less than 0.90. Good compaction degree can improve the compressive strength of the heap and prevent landslides or settlements caused by the looseness of the slope. A dike 13 is arranged on the top of the ash residue heap 1, which can effectively prevent the ash residue on the top of the heap from overflowing under the action of external forces such as wind and rain, and reduce environmental pollution; the side slope ratio of the dike 13 is 1:(3 - 4); the drainage slope of the dike 13 is 0.3% - 0.5%. A circular field road 14 is also arranged on the ash residue heap 1, which can provide a convenient passage for the transportation of ash residue, the maintenance of peripheral equipment, and the entry and exit of relevant personnel.

[0034] A hardening layer 2 is constructed on the surface of the ash residue heap 1; specifically, a hardening agent and an auxiliary agent are spread on the surface of the ash residue heap 1, mixed and rolled to form the hardening layer 2, and water is sprayed for moisture preservation. After a 3-day curing period, the bearing capacity requirement is not less than 120 kPa. Among them, the hardening agent is desulfurized gypsum, and the addition ratio is 20% - 30% of the mass of the ash residue heap (1) to be hardened; the auxiliary agent is quicklime, and the addition ratio is 1% - 3% of the mass of the ash residue heap (1) to be hardened. The thickness of the hardening layer 2 is 10 - 30 cm, and the flatness error per square meter does not exceed 20 mm. By setting the hardening layer 2 on the surface of the ash residue heap 1 in the present invention, the dehydration and instability of fly ash when the ash surface is exposed are avoided, the generation of dust pollution is reduced; and the erosion of ash residue by rainwater is also prevented, the bearing capacity of the ash residue is increased, the stability of the ash residue heap 1 is ensured, and a basis for the subsequent land use of the ash yard is provided.

[0035] A barrier layer 3 is laid on the surface of the hardening layer 2; the barrier layer 3 can block the intrusion of salts in the ash residue into the surface covering soil layer 5 along with the evaporation of moisture and reduce the accumulation of salts in the covering soil layer 5 to achieve the prevention of salinization.

[0036] The water-conducting and salt-draining layer 4 is laid on the surface of the barrier layer 3; the water-conducting and salt-draining layer 4 drains the salts leached by irrigation water and rainwater to the outside through the water-conducting and salt-draining layer 4, avoiding salt accumulation at the bottom of the soil covering layer 5 and reducing the salt content of the soil layer.

[0037] The soil covering layer 5 is laid on the surface of the water-conducting and salt-draining layer 4; the thickness of the soil covering layer 5 is 20 - 50 cm, and modifiers and nutrients are added to the soil for improvement. When spreading the soil, ridges 51 are formed. The ridge width is 30 cm - 50 cm, the ridge height is 10 - 30 cm, and the ridge spacing is 50 - 100 cm. Since the soil porosity of the ridge 51 is large and it is not easy to harden, it is beneficial for the growth of plant roots; on the other hand, there is a potential difference between the ridge 51 and the furrow, which is beneficial for drainage and waterlogging prevention. During irrigation and rainfall, as the water moves, salts accumulate from the ridge 51 to the furrow, avoiding soil salinization of the ridge 51. At the same time, salt-tolerant plants 61 are planted in the furrow, and the soil salt content is reduced through plant growth.

[0038] The greening layer 6 is laid on the surface of the soil covering layer 5. Specifically, pioneer plants 62 with strong adaptability and drought and barren tolerance are planted on the ridge 51, and salt-tolerant plants 61 are planted in the furrow to form the greening layer 6. By selecting pioneer plants 62 with strong adaptability, the greening layer 6 can be quickly established in places with poor soil conditions, reducing the area of bare land. Planting salt-tolerant plants 61 in the furrow can effectively improve the ecological utilization value of these areas, form a good ecological cycle, and enhance the comprehensive benefits of the land; all the plants are sown by digging planting holes, the sowing depth is 1 - 5 cm, and the sowing rate is 10 - 20 g / m 2 。

[0039] An irrigation system 63 is arranged on the greening layer 6. The irrigation system 63 is a drip irrigation system, adopting an automatic control system to control the irrigation water volume according to the vegetation growth stage, and the irrigation quota is controlled at 200 - 400 m 3 / hm 2 ², and fertilizers are added according to the growth of the vegetation. The irrigation system 63 can accurately control the irrigation water volume according to the actual needs of the plants, avoiding over-watering or water shortage. Combined with the automatic control system, the irrigation volume is adjusted according to the growth stage of the plants (such as seedling stage, vigorous growth stage, dormancy stage, etc.), ensuring that the vegetation can obtain appropriate water at each growth stage and promoting the healthier growth of the plants. At the same time, a fertilization device can be combined in the irrigation system 63 for "integrated water and fertilizer" management. According to the growth and nutritional needs of the vegetation, the amount of fertilizer added is automatically adjusted to match the irrigation water volume, avoiding waste of fertilizer, reducing the negative impact of over-fertilization on the environment, and at the same time improving the absorption rate of the plants to fertilizers, thereby enhancing the growth effect of the vegetation.

[0040] Exemplarily, when renovating the ash residue heap 1, a flood interception and drainage system is set up on the ash residue heap 1; the flood interception and drainage system includes a flood interception ditch 15, a toe drain ditch 11, a berm drain ditch, an ash yard road drain ditch, and a top surface catchment ditch; the toe drain ditch 11 is arranged at the bottom of the side of the ash residue heap 1; the flood interception ditch 15 is arranged at intervals on the ground beside the toe drain ditch 11; the berm drain ditch is arranged on the berm 12, the ash yard road drain ditch is arranged beside the circumferential road 14; the top surface catchment ditch is arranged on the top surface of the ash residue heap 1.

[0041] Example 1 Renovate the ash residue heap 1; construct a hardening layer 2 on the surface of the ash residue heap 1; lay a barrier layer 3 on the surface of the hardening layer 2; lay a water-conducting and salt-draining layer 4 on the surface of the barrier layer 3; lay a covering soil layer 5 on the surface of the water-conducting and salt-draining layer 4; lay a greening layer 6 on the surface of the covering soil layer 5.

[0042] Among them, after renovation, the slope gradient of the side of the ash residue heap 1 is 1:3, a berm is set every 10 m on the side, the width of the berm 12 is 2 m, and the compaction degree of the side ash residue is 0.95. After renovation, the top surface of the ash residue heap 1 is flat, a dam 13 is set on the top surface, the width of the dam 13 is 10 m, the height is 0.5 m, the slope ratio of the dam slope is 1:3, the drainage slope in the reservoir is 0.3%, and the compaction degree of the top surface of the ash residue heap 1 is 0.90.

[0043] Exemplarily, after renovating the ash residue heap 1, a flood interception and drainage system is set up, including a flood interception ditch 15, a toe drain ditch 11, a berm drain ditch, an ash yard road drain ditch, and a top surface catchment ditch. The toe drain ditch 11 is arranged at the bottom of the side of the ash residue heap 1; the flood interception ditch 15 is arranged at intervals on the ground beside the toe drain ditch 11; the berm drain ditch is arranged on the berm 12, the ash yard road drain ditch is arranged beside the circumferential road 14; the top surface catchment ditch is arranged on the top surface of the ash residue heap 1.

[0044] Exemplarily, the thickness of the hardening layer 2 is 20 cm. Spread desulfurized gypsum hardening agent on the surface of the ash residue heap 1 at a ratio of 30% and spray quicklime water agent with a ratio of 3% (this ratio is the mass ratio of the ash residue heap 1 to be hardened), and use machinery for mixing and rolling. The flatness error does not exceed 20 mm to form the hardening layer 2. Sprinkle water for moisture preservation, and the bearing capacity reaches 128 kPa after 3 days of curing period.

[0045] Exemplarily, the barrier layer 3 is a non-woven geosynthetic composite geomembrane, which is welded by hot melting. The film lap width is 100 ± 20 mm, and there shall be no horizontal joints on the slope surface and within 1.5 m in the direction of the slope from the top of the slope.

[0046] Exemplarily, the water-conducting and salt-draining layer 4 is a three-ribbed geocomposite drainage net, with a lap width of 75 ± 15 mm. The geonet is required to be bundled, the lower geotextile is overlapped, and the upper geotextile is stitched with a polymer thread resistant to ultraviolet and chemical corrosion.

[0047] Exemplarily, the thickness of the covering soil layer 5 is 30 cm. The covering soil is improved by adding modifiers and nutrients. When spreading the covering soil, ridges 51 are formed. The ridge width is 30 cm, the ridge height is 10 cm, and the ridge spacing is 70 cm. Pioneer plants 62 with strong adaptability and tolerance to drought and barrenness are planted on the ridge 51, and salt-tolerant plants 61 are planted in the ridge grooves to form a greening layer 6. The plants are all sown by digging planting holes, with a sowing depth of 3 cm and a sowing rate of 20 g / m 2 ; An irrigation system 63 is arranged on the greening layer 6. The drip heads are matched with the planting holes, and an automatic control system is adopted to control the irrigation water volume according to the growth stage of the vegetation. The irrigation quota is controlled at 300 m 3 / hm 2 , and fertilizers are added according to the growth of the vegetation.

[0048] Exemplarily, the pioneer plants 62 planted on the ridge 51 are one or more of Stipa breviflora, Artemisia scoparia, Artemisia desertorum, Ajania fruticulosa, Oxytropis aciphylla, and Agropyron cristatum; the salt-tolerant plants 61 planted in the ridge grooves are one or more of Medicago sativa, Achnatherum splendens, Onobrychis viciaefolia, Suaeda glauca, and Iris lactea.

[0049] Example 2 The difference between this example and Example 1 is that in this example, the slope ratio of the side slope of the ash residue heap body 1 after renovation is 1:4; a berm is arranged every 15 m on the side, and the width of the berm 12 is 5 m; the compaction degree of the ash residue on the side of the ash residue heap body 1 is 0.96. The slope ratio of the dam slope of the dam 13 on the top surface of the ash residue heap body 1 is 1:4, the drainage slope in the reservoir is 0.5%, and the compaction degree of the top surface of the ash residue heap body 1 is 0.91.

[0050] The thickness of the hardening layer 2 is 10 cm, the proportion of the desulfurized gypsum hardening agent is 20%, the proportion of the quicklime water agent is 1%, the hardening layer 2 is sprinkled with water for moisture preservation, and the bearing capacity reaches 120 kPa after a 3-day curing period.

[0051] The thickness of the covering soil layer 5 is 20 cm, the ridge width is 50 cm, the ridge height is 30 cm, and the ridge spacing is 50 cm. The sowing depth of the plants is 1 cm, and the sowing rate is 10 g / m 2 ; The irrigation quota is controlled at 200 m 3 / hm 2 , and fertilizers are added according to the growth of the vegetation.

[0052] Example 3 The difference between this example and Example 2 is that in this example, the thickness of the hardening layer 2 is 30 cm, the thickness of the covering soil layer 5 is 50 cm; the ridge spacing is 100 cm; the sowing depth of the plants is 5 cm, and the sowing rate is 20 g / m 2 ; The irrigation quota is controlled at 400 m 3 / hm 2 .

[0053] The present invention can improve the bearing capacity and stability of the ash residue heap 1, and promote the subsequent development and utilization of the ash field land; at the same time, measures such as salt resistance, salt drainage, soil improvement, ridging, biological treatment, and efficient water-saving irrigation are taken to effectively avoid the occurrence of secondary salinization, ensure a good growth environment for vegetation, ensure the long-term effect of ecological restoration, and better restore the ecological environment of the ash field. Secondly, in terms of the selection of hardeners and soil conditioners, the present invention effectively and resourcefully utilizes solid wastes such as fly ash, desulfurized gypsum, and cow dung, saves a large amount of land resources, and has good environmental, economic, and social benefits.

[0054] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An ecological closed storage system for a plain dry ash field in a coal-fired power plant, characterized in that: The system comprises, from bottom to top, an ash pile (1), a hardened layer (2), a barrier layer (3), a water-conducting and salt-draining layer (4), a covering layer (5), and a greening layer (6); an irrigation system (63) is provided on the greening layer (6); It also includes a monitoring device, the monitoring device including a soil salinity sensor and a vegetation growth monitor; the soil salinity sensor is arranged inside the greening layer (6); the vegetation growth monitor is arranged on the upper surface of the greening layer (6); the monitoring device is connected to an irrigation system (63); a flood interception and drainage system is arranged on the ash pile (1); and the flood interception and drainage system is connected to the irrigation system (63).

2. The ecological closed storage system for the plain dry ash field of a coal-fired power plant according to claim 1 is characterized in that: The barrier layer (3) is a geosynthetics nonwoven fabric composite geomembrane.

3. The ecological closed storage system for the plain dry ash field of a coal-fired power plant according to claim 1 is characterized in that: The water-conducting and salt-draining layer (4) is a three-rib geocomposite drainage net.

4. A construction method for an ecological closed storage system for a plain dry ash field in a coal-fired power plant, characterized in that: The following steps are involved: The ash pile (1) is repaired; a hardened layer (2) is constructed on the surface of the ash pile (1); a barrier layer (3) is laid on the surface of the hardened layer (2); a water-conducting and salt-draining layer (4) is laid on the surface of the barrier layer (3); a covering soil layer (5) is laid on the surface of the water-conducting and salt-draining layer (4); and a greening layer (6) is laid on the surface of the covering soil layer (5).

5. The construction method of an ecological closed storage system for a plain dry ash field of a coal-fired power plant according to claim 4 is characterized in that: When the ash pile (1) is repaired, a flood interception and drainage system is arranged on the ash pile (1).

6. The construction method of an ecological closed storage system for a plain dry ash field of a coal-fired power plant according to claim 4 is characterized in that: The slope of the side of the ash pile (1) after repair is 1:(3-4); a horse path (12) is arranged every 10-15 m on the side.

7. The construction method of an ecological closed storage system for a plain dry ash field of a coal-fired power plant according to claim 4 is characterized in that: A dam (13) is arranged on the top of the ash pile (1); the side slope ratio of the dam (13) is 1:(3-4); and the drainage slope of the dam (13) is 0.3%-0.5%.

8. The construction method of an ecological closed storage system for a plain dry ash field of a coal-fired power plant according to claim 4 is characterized in that: The compaction degree of the side of the ash pile (1) after repair is not less than 0.95; the compaction degree of the top surface of the ash pile (1) is not less than 0.

90.

9. The construction method of an ecological closed storage system for a plain dry ash field of a coal-fired power plant according to claim 4 is characterized in that: The specific steps of constructing the hardened layer (2) on the surface of the ash pile (1) are: spreading a hardener and an auxiliary agent on the surface of the ash pile (1), mixing and rolling to form the hardened layer (2).

10. The construction method of an ecological closed storage system for a plain dry ash field of a coal-fired power plant according to claim 9, characterized in that: The hardener is desulfurized gypsum, and the addition ratio is 20% to 30% of the mass of the ash pile (1) to be hardened; the auxiliary agent is quicklime, and the addition ratio is 1% to 3% of the mass of the ash pile (1) to be hardened.

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