Plateau permafrost region sand dune treatment system

Abstract

A plateau permafrost region sand dune treatment system relates to the technical field of sand dune treatment and comprises a first treatment unit, a second treatment unit and a third treatment unit. The first treatment unit comprises a first treatment bottom layer and a first treatment top layer, and the first treatment bottom layer and the first treatment top layer are arranged in the height direction of the first sand dune; the first treatment top layer comprises a first coal gangue soil layer and a first vegetation layer, and the first vegetation layer is planted in the first coal gangue soil layer; the second treatment unit comprises a second treatment bottom layer and a second treatment top layer, and the second treatment bottom layer and the second treatment top layer are arranged in the height direction of the second sand dune; the second treatment top layer comprises a second coal gangue soil layer and a second vegetation layer, and the second vegetation layer is planted in the second coal gangue soil layer; and the third treatment unit is arranged in an area corresponding to the tuyere. Solid waste recycling and ecological restoration are deeply fused, the problem that a traditional sand stabilization material lacks ecological functions is effectively solved, and the sand stabilization material has the sand stabilization function and the vegetation restoration function.

Description

Technical Field

[0001] The present invention relates to the technical field of sand dune control, and in particular to a sand dune control system in plateau permafrost areas. Background Art

[0002] Plateau permafrost zones are exceptionally sensitive ecological zones globally, facing long-term multiple threats from climate change-driven permafrost degradation, reduced vegetation cover, and human activities. The Qinghai-Tibet Plateau, home to the world's highest and most extensive permafrost zone in the low- to mid-latitudes, boasts a dry, cold climate, strong winds, abundant sand resources, and a fragile ecosystem. This has made it a key area for desertification in China. Desertified land on the Qinghai-Tibet Plateau covers 39 million square kilometers, or 15% of the total plateau area. Of this, the overlap between permafrost and desertification reaches 15 million square kilometers, or 10% of the permafrost area. This plateau permafrost desertification is primarily distributed in the Sanjiangyuan region, the Hoh Xil Mountains, the Qaidam Basin, the northern foothills of the Qilian Mountains, the alpine steppe-desert transition zone surrounding Qinghai Lake, river valleys and basin margins, and degraded alpine meadows. Mobile sand dunes account for approximately 40% of the plateau's total, while semi-fixed and fixed dunes account for approximately 60%.

[0003] The inventors discovered during their research that the existing methods for controlling sand dunes in plateau permafrost areas have at least the following disadvantages:

[0004] With global warming, permafrost regions are experiencing significant temperature increases. This, coupled with the impact of human activities, has further accelerated desertification, with sand damage being a particularly prominent problem. This has severely impacted the ecological balance of the plateau's permafrost regions, severely impacted local agricultural and animal husbandry production, damaged infrastructure, increased the cost of sand control, and posed a challenge to regional sustainable development. Traditional sand fixation technologies, such as grass grids and chemical sand fixation, are difficult to promote due to environmental adaptability and cost issues. While bio-based sand fixation methods are eco-friendly, they are difficult to restore vegetation to the harsh natural conditions of the plateau's permafrost regions, and their slow growth makes it difficult to achieve significant results quickly. Summary of the Invention

[0005] The purpose of the present invention includes, for example, providing a sand dune management system in plateau permafrost areas, which effectively improves the ecological function loss of traditional sand-fixing materials by deeply integrating solid waste resource utilization with ecological restoration, and has both sand fixation and vegetation restoration functions.

[0006] The embodiments of the present invention can be implemented as follows:

[0007] In a first aspect, the present invention provides a plateau permafrost region sand dune control system, which is used to cooperate with adjacent first and second sand dunes, wherein a wind outlet is formed between the first and second sand dunes, and comprises:

[0008] the first governance unit, the second governance unit, and the third governance unit;

[0009] The first treatment unit includes a first treatment bottom layer and a first treatment top layer, and the first treatment bottom layer and the first treatment top layer are arranged in the height direction of the first sand dune; the first treatment top layer includes a first gangue soil layer and a first vegetation layer, and the first vegetation layer is planted on the first gangue soil layer;

[0010] The second treatment unit includes a second treatment bottom layer and a second treatment top layer, and the second treatment bottom layer and the second treatment top layer are arranged in the height direction of the second sand dune; the second treatment top layer includes a second gangue soil layer and a second vegetation layer, and the second vegetation layer is planted on the second gangue soil layer;

[0011] The third treatment unit is arranged in the area corresponding to the tuyere.

[0012] In an alternative embodiment, the first treatment bottom layer or / and the second treatment bottom layer includes gramineous plants.

[0013] In an alternative embodiment, the first vegetation layer includes shrubs.

[0014] In an alternative embodiment, the second vegetation layer includes shrubs.

[0015] In an alternative embodiment, the first treatment unit further includes an intermediate treatment layer, and the intermediate treatment layer is located between the first treatment bottom layer and the first treatment top layer; the intermediate treatment layer includes an intermediate gangue soil layer and an intermediate vegetation layer, and the vegetation type of the intermediate vegetation layer is different from that of the first vegetation layer.

[0016] In an alternative embodiment, the intermediate vegetation layer includes gramineous plants and shrubs.

[0017] In an alternative embodiment, the shrubs of the intermediate vegetation layer enclose a planting area, and the gramineous plants of the intermediate vegetation layer are located within the planting area.

[0018] In an alternative embodiment, the third treatment unit includes a third gangue soil layer and a third vegetation layer, and the third vegetation layer is planted on the third gangue soil layer.

[0019] In an alternative embodiment, the top of the third gangue soil layer is higher than the connection position of the first treatment bottom layer and the intermediate treatment layer and the connection position of the second treatment bottom layer and the second treatment top layer at the same time, and lower than the height of the second treatment top layer; the bottom of the third gangue soil layer is lower than the connection position of the first treatment bottom layer and the intermediate treatment layer and the connection position of the second treatment bottom layer and the second treatment top layer at the same time.

[0020] In an optional embodiment, the thickness of the first gangue soil layer is set to (4.5-5.5) cm; the thickness of the second gangue soil layer is set to (4.5-5.5) cm; and the thickness of the middle gangue soil layer is set to (1.8-2.2) cm.

[0021] The beneficial effects of the embodiments of the present invention include, for example:

[0022] In summary, the plateau permafrost zone sand dune control system provided by this embodiment combines coal gangue soil with vegetation. Since coal gangue soil is a solid waste, it is easy to obtain and has low cost. At the same time, coal gangue soil contains a certain amount of organic matter, minerals, and trace elements, and has certain soil improvement potential. Through activation and passivation treatment, it is formed into a composite material with sand fixation, water retention, freeze-thaw resistance, and soil improvement functions, thereby creating favorable conditions for vegetation growth. The restoration of vegetation planted in the coal gangue soil layer can further fix the sand, reduce wind and sand activity, and can fundamentally and effectively improve the sand damage problem. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 This is a schematic diagram of the plateau permafrost area sand dune control system of this embodiment;

[0025] Figure 2 This is the site map before treatment;

[0026] Figure 3 for Figure 2 Schematic diagram of the corresponding area after being treated using the plateau permafrost area sand dune control system of this embodiment.

[0027] icon:

[0028] 100-first treatment unit; 110-first treatment bottom layer; 120-first treatment top layer; 121-first gangue soil layer; 122-first vegetation layer; 130-middle treatment layer; 131-middle gangue soil layer; 132-middle vegetation layer; 200-second treatment unit; 210-second treatment bottom layer; 220-second treatment top layer; 221-second gangue soil layer; 222-second vegetation layer; 300-third treatment unit; 310-third gangue soil layer; 320-third vegetation layer. DETAILED DESCRIPTION

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to 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. Components of the embodiments of the present invention usually described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0031] It should be noted that like reference numerals and letters denote like 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.

[0032] In the description of the present invention, it should be noted that if terms such as "upper", "lower", "inner", "outer", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of this invention is customarily placed during use, it 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.

[0033] In addition, terms such as "first", "second", etc. are only used for descriptive distinction and cannot be understood as indicating or implying relative importance.

[0034] It should be noted that the features in the embodiments of the present invention can be combined with each other without conflict.

[0035] In the prior art, traditional sand fixation techniques such as straw checkerboards or chemical sand fixation are difficult to promote due to environmental adaptability and cost issues. Although biological sand fixation methods are ecologically friendly, in the harsh natural conditions of the alpine permafrost region, it is difficult to restore vegetation, and the growth is slow, making it difficult to achieve significant results in a short time.

[0036] In view of this, the designer provides a sand dune governance system for the alpine permafrost region, which can improve the survival rate of vegetation, thereby better fixing sand with well-growing vegetation, reducing sand and dust activities, and improving the effect of sand dune governance.

[0037] It should be understood that the sand dune treatment system provided in this embodiment is mainly applied to sand dune treatment, especially in cooperation with adjacent first and second sand dunes. The height of the first sand dune is higher than that of the second sand dune, and a wind gap is formed between the first and second sand dunes.

[0038] Please refer to Figure 1 , this embodiment provides a sand dune treatment system for the plateau permafrost area, including:

[0039] A first treatment unit 100, a second treatment unit 200, and a third treatment unit 300;

[0040] The first treatment unit 100 includes a first treatment bottom layer 110 and a first treatment top layer 120, which are arranged in the height direction of the first sand dune; the first treatment top layer 120 includes a first gangue soil layer 121 and a first vegetation layer 122, and the first vegetation layer 122 is planted on the first gangue soil layer 121;

[0041] The second treatment unit 200 includes a second treatment bottom layer 210 and a second treatment top layer 220, which are arranged in the height direction of the second sand dune; the second treatment top layer 220 includes a second gangue soil layer 221 and a second vegetation layer 222, and the second vegetation layer 222 is planted on the second gangue soil layer 221;

[0042] The third treatment unit 300 is arranged in the area corresponding to the wind gap.

[0043] As described above, the treatment principle of the sand dune treatment system for the plateau permafrost area provided in this embodiment is as follows:

[0044] Combining gangue soil with vegetation, since gangue soil is a solid waste with simple acquisition method and low cost, and at the same time gangue soil contains a certain amount of organic matter, minerals and trace elements, having a certain potential for soil improvement; through activation and passivation treatment, it forms a composite material with functions of sand fixation, water retention, freeze-thaw resistance and soil improvement, thus creating favorable conditions for vegetation growth. The restoration of the vegetation planted on the gangue soil layer can further fix the sand and reduce sandstorm activities, and can effectively improve the sand hazard problem fundamentally.

[0045] The following embodiments will illustrate the details of the sand dune treatment system for the plateau permafrost area of the present application by way of examples.

[0046] Please refer to Figure 1 , in this embodiment, optionally, the sand dune treatment system for the plateau permafrost area includes a first treatment unit 100, a second treatment unit 200, and a third treatment unit 300.

[0047] Among them, the first governance unit 100 includes a first governance bottom layer 110, a first governance top layer 120, and an intermediate governance layer 130. The first governance bottom layer 110, the intermediate governance layer 130, and the first governance top layer 120 are arranged in sequence in the height direction of the first sand dune. The first governance bottom layer 110 is located below the first sand dune. Correspondingly, the first governance top layer 120 is located above the first sand dune.

[0048] At the same time, the first governance bottom layer 110 includes gramineous plants, and the gramineous plants can be planted on the surface of the first sand dune at a set spacing. The spacing of the gramineous plants in the first governance bottom layer 110 can be set relatively dense, which can quickly fix the surface sand.

[0049] Optionally, the intermediate governance layer 130 includes an intermediate gangue soil layer 131 and an intermediate vegetation layer 132. For example, the intermediate vegetation layer 132 includes gramineous plants and shrubs. The intermediate vegetation layer 132 is planted on the intermediate gangue soil layer 131. When planting, several gramineous plants and several shrubs cooperate to form a planting unit. The several shrubs in each planting unit are arranged in a ring to enclose a planting area. Several gramineous plants are located within the planting area, and the several gramineous plants are arranged in a spiral shape. It should be understood that adjacent planting units share some shrubs. Through the cooperation of shrubs and gramineous plants, the shrubs around can effectively reduce the wind speed, reduce the erosion of the soil by the wind, and at the same time can intercept precipitation to provide water for the intermediate gramineous plants, playing a role in soil and water conservation. The gramineous plants planted in a spiral structure in the middle also play a role in wind prevention and wind guidance, reducing the wind speed, reducing soil evaporation, increasing soil humidity, increasing vegetation coverage, and coupled with the developed roots of the gramineous plants, they can penetrate deep into the soil, thereby effectively fixing the surface soil.

[0050] It should be understood that the thickness of the intermediate gangue soil layer 131 can be set to (1.8 - 2.2) cm. For example, the thickness of the intermediate gangue soil layer 131 can be set to 1.8 cm, 2.0 cm, or 2.2 cm, etc.

[0051] Optionally, the first governance top layer 120 includes a first gangue soil layer 121 and a first vegetation layer 122, and the first vegetation layer 122 is planted on the first gangue soil layer 121. The vegetation types of the intermediate vegetation layer 132 and the first vegetation layer 122 are different. For example, the first vegetation layer 122 includes shrubs, and the shrubs can be planted at a set spacing.

[0052] It should be understood that the thickness of the first gangue layer can be set to (4.5 - 5.5) cm. The thickness of the first gangue layer can be set to 4.5 cm, or the thickness of the first gangue layer can be set to 5.0 cm, or the thickness of the first gangue layer can be set to 5.5 cm, etc.

[0053] By designing the thickness of the first gangue soil layer 121 to be greater than that of the middle gangue soil layer 131, while meeting the requirement of withstanding greater wind interference and effectively fixing sand, the consumption of materials can be reduced and the cost can be lowered.

[0054] Optionally, the second treatment unit 200 includes a second treatment bottom layer 210 and a second treatment top layer 220. The second treatment bottom layer 210 and the second treatment top layer 220 are arranged in the height direction of the second sand dune, and the second treatment bottom layer 210 is located below the second treatment top layer 220. Optionally, the second treatment bottom layer 210 includes gramineous plants, and the gramineous plants can be planted on the surface of the second sand dune at a set spacing. The spacing of the gramineous plants in the second treatment bottom layer 210 can be set relatively dense, which can quickly fix the surface sand. Moreover, the gramineous plants in the first treatment bottom layer 110 and the gramineous plants in the second treatment bottom layer 210 can be butted together to form a continuous area.

[0055] Optionally, the second treatment top layer 220 includes a second gangue soil layer 221 and a second vegetation layer 222, and the second vegetation layer 222 is planted on the second gangue soil layer 221. The thickness of the second gangue soil layer 221 can be set to (4.5 - 5.5) cm; for example, the thickness of the second gangue soil layer 221 is set to 4.5 cm, 5.0 cm, or 5.5 cm, etc.

[0056] In addition, the second vegetation layer 222 includes shrubs, and the shrubs can be planted at a set spacing.

[0057] In this embodiment, optionally, the third treatment unit 300 is arranged in the area corresponding to the wind gap. The third treatment unit 300 connects the first treatment unit 100 and the second treatment unit 200. Specifically, the third treatment unit 300 includes a third gangue soil layer 310 and a third vegetation layer 320, and the third vegetation layer 320 is planted on the third gangue soil layer 310. The thickness of the third gangue soil layer 310 is set to (4.5 - 5.5) cm; for example, the thickness of the third gangue soil layer 310 is set to 4.5 cm, 5.0 cm, or 5.5 cm, etc.

[0058] At the same time, the top of the third gangue soil layer 310 is higher than the connection position of the first treatment bottom layer 110 and the middle treatment layer 130 and the connection position of the second treatment bottom layer 210 and the second treatment top layer 220, and lower than the height of the second treatment top layer 220; the bottom of the third gangue soil layer 310 is lower than the connection position of the first treatment bottom layer 110 and the middle treatment layer 130 and the connection position of the second treatment bottom layer 210 and the second treatment top layer 220. Through the cooperation of the first treatment unit 100, the second treatment unit 200, and the third treatment unit 300, the wind prevention and sand fixation effect can be improved.

[0059] It should be understood that the first gangue soil layer 121, the middle gangue soil layer 131, the second gangue soil layer 221, and the third gangue soil layer 310 are all subjected to activation and passivation treatments before being laid on the sand dune surface. For example, microbial agents can be used to activate and passivate the gangue soil. Microbial activation agents are used to activate nutrients such as nitrogen, phosphorus, potassium, and calcium required for plant growth from the fixed state into the free state that can be directly absorbed to promote plant growth. Microbial passivation agents are used to convert free heavy metal elements into the fixed state that plants cannot absorb. During the treatment, the microbial agents are directly and evenly sprayed onto the gangue, and plants can be planted after 48 hours. When treating sand dunes, the application rate of the activation and passivation biological agents is 1 kg / t. The gangue soil significantly increases the soil organic carbon content from 40 g / kg to 90 g / kg, and the total soil nitrogen content nearly doubles. In addition, alkaline minerals (such as calcium and magnesium) in the gangue regulate the soil pH value. In practical applications, the vegetation coverage increases by 37% in the first year, and the above-ground biomass of the vegetation significantly increases, reaching 45%.

[0060] The sand dune control system provided in this embodiment for the plateau permafrost area promotes the wind prevention and sand fixation effect by laying gangue soil in the middle and at the top of the sand dune and then planting corresponding types of vegetation on the gangue soil, with a high survival rate of the vegetation. Since the wind and sand fixation effect is good in the middle and at the top, the sand dune is not easily mobile, and the bottom is not easily covered by wind and sand. The gangue soil does not need to be laid at the bottom, and plants can be directly planted at the bottom, which can reduce the wind prevention and sand fixation cost while ensuring a relatively high survival rate of the bottom plants.

[0061] The following is the construction method of the sand dune control system for the plateau permafrost area in the embodiments of this application:

[0062] In the top area: First, lay a 5-cm-thick layer of gangue soil flat and plant shrubs in strips with a strip spacing of 1 m - 2 m, which can be adjusted according to the sand-raising wind speed. The greater the wind speed, the smaller the spacing; in the area with a slope of 15° - 30°, first lay a 2-cm-thick layer of gangue soil, plant shrubs in strips (spacing 3 m), and plant herbaceous plants in a spiral shape between the shrub strips with a diameter of 1 m - 1.5 m, which can be adjusted according to the precipitation gradient. The smaller the precipitation, the larger the diameter is set; in the bottom area: evenly broadcast grass seeds. It should be understood that the construction can be carried out sequentially from bottom to top.

[0063] Mainly use cold-resistant, sand-fixing, deep-rooted native plant species, and appropriately introduce plant species that can withstand root damage caused by repeated freezing and thawing and can safely overwinter as associated species, and mix and sow them in proportion. The sowing depth is 5 times the maximum diameter of the seeds. Selecting cold-resistant, drought-tolerant, and water-saving shrubs and herbaceous plants is the key to wind prevention and sand fixation. In addition, the planting period is selected after the spring snowmelt, generally in mid-May, on a sunny and windless day after the local strong winds end.

[0064] Application Example: In 2023, a test demonstration of planting vegetation by laying coal gangue soil was carried out in the Honglianghe permafrost desert area in the northeastern part of the Qinghai-Tibet Plateau. The precipitation in this area varies greatly seasonally, with most of the precipitation concentrated in summer, and the annual precipitation is about 250 - 300 mm. The comparison effects before and after the test are shown in Figure 2 and Figure 3 . Elymus nutans and Festuca elata, the local dominant and perennial herbaceous plants, were selected, and the associated species was Avena sativa, an annual herb. They were sown in a 1:1:1 mixture. The coal gangue soil was mechanically spread flat to a thickness of 2 cm, and drilling was carried out using a drill seeder with a sowing depth of 5 cm. The annual Avena sativa has a high germination rate and fast early growth, which can improve the seed germination rate of perennial herbs. The sowing time was May 30th, and the sowing rate was 15 g / m2. The height of the herbaceous plants could reach 50 cm in the same year.

[0065] As mentioned above, the above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A dune control system in alpine permafrost regions, which is used in cooperation with adjacent first and second dunes, and a wind gap is formed between the first dune and the second dune. It is characterized in that, Including: A first treatment unit (100), a second treatment unit (200), and a third treatment unit (300); The first treatment unit (100) includes a first treatment bottom layer (110) and a first treatment top layer (120), and the first treatment bottom layer (110) and the first treatment top layer (120) are arranged in the height direction of the first sand dune; the first treatment top layer (120) includes a first coal gangue soil layer (121) and a first vegetation layer (122), and the first vegetation layer (122) is planted on the first coal gangue soil layer (121); The second treatment unit (200) includes a second treatment bottom layer (210) and a second treatment top layer (220), and the second treatment bottom layer (210) and the second treatment top layer (220) are arranged in the height direction of the second sand dune; the second treatment top layer (220) includes a second coal gangue soil layer (221) and a second vegetation layer (222), and the second vegetation layer (222) is planted on the second coal gangue soil layer (221); The third treatment unit (300) is arranged in the area corresponding to the air inlet.

2. The sand dune treatment system in the alpine permafrost area according to claim 1, characterized in that: The first treatment bottom layer (110) or / and the second treatment bottom layer (210) includes gramineous plants.

3. The sand dune treatment system in the alpine permafrost area according to claim 1, characterized in that: The first vegetation layer (122) includes shrubs.

4. The sand dune treatment system in the alpine permafrost area according to claim 1, characterized in that: The second vegetation layer (222) includes shrubs.

5. The sand dune treatment system in the alpine permafrost area according to any one of claims 1-4, characterized in that: The first treatment unit (100) further includes an intermediate treatment layer (130), and the intermediate treatment layer (130) is located between the first treatment bottom layer (110) and the first treatment top layer (120); the intermediate treatment layer (130) includes an intermediate coal gangue soil layer (131) and an intermediate vegetation layer (132), and the vegetation type of the intermediate vegetation layer (132) is different from that of the first vegetation layer (122).

6. The sand dune treatment system in the alpine permafrost area according to claim 5, characterized in that: The intermediate vegetation layer (132) includes gramineous plants and shrubs.

7. The sand dune treatment system in the alpine permafrost area according to claim 6, characterized in that: The shrubs of the intermediate vegetation layer (132) enclose a planting area, and the gramineous plants of the intermediate vegetation layer (132) are located within the planting area.

8. The sand dune treatment system in the alpine permafrost area according to claim 5, characterized in that: The third treatment unit (300) includes a third coal gangue soil layer (310) and a third vegetation layer (320), and the third vegetation layer (320) is planted on the third coal gangue soil layer (310).

9. The sand dune treatment system in the alpine permafrost area according to claim 8, characterized in that: The top of the third coal gangue soil layer (310) is simultaneously higher than the connection positions of the first treatment bottom layer (110) and the intermediate treatment layer (130), as well as the connection positions of the second treatment bottom layer (210) and the second treatment top layer (220), and is lower than the height of the second treatment top layer (220); the bottom of the third coal gangue soil layer (310) is simultaneously lower than the connection positions of the first treatment bottom layer (110) and the intermediate treatment layer (130), as well as the connection positions of the second treatment bottom layer (210) and the second treatment top layer (220).

10. The dune treatment system in the plateau permafrost area according to claim 5, characterized in that: The thickness of the first coal gangue soil layer (121) is set to (4.5 - 5.5) cm; the thickness of the second coal gangue soil layer (221) is set to (4.5 - 5.5) cm; the thickness of the intermediate coal gangue soil layer (131) is set to (1.8 - 2.2) cm.

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