Collaborative ecological backfilling method for shield dried soil and coal gangue

Abstract

The invention provides a shield dried soil and coal gangue collaborative ecological backfilling method which comprises the following steps: firstly, respectively obtaining initial shield dried soil, initial coal gangue, modified coal gangue and modified shield dried soil to meet backfilling requirements; secondly, a bottom impermeable layer is laid in the area to be backfilled from bottom to top, N + 1 coal gangue backfilling layers and N shield drying soil backfilling layers are alternately laid, each shield drying soil backfilling layer is located between every two adjacent coal gangue backfilling layers, an ecological impermeable layer is laid on the N + 1 coal gangue backfilling layer, and therefore a repairing backfilling area is obtained; and finally, digging pits every 0.8-1.2 m in the repairing and backfilling area, and planting shrubs. The shield dried soil backfill layer is used as interlayer covering soil of the coal gangue backfill layer, and the oxygen isolation and flame retardance effects are achieved; the shield drying soil is modified through the coal gangue, the coal gasification slag and the agriculture, forestry and animal husbandry waste to obtain the regenerated shield drying soil, so that the nutritional ingredients and the water-holding capacity of the repaired and backfilled area are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of ecological restoration backfilling, and in particular relates to a method for coordinated ecological backfilling of shield dried soil and coal gangue. Background Art

[0002] Shield soil refers to the waste soil and rock fragments generated by shield machines when excavating underground space. It is usually disposed of by open-air stacking or landfill. However, the surfactants contained in shield soil are difficult to dry, have high fluidity, and large amounts of accumulation are prone to landslides and other safety hazards. Landfilling will cause surfactants to pollute water bodies. Therefore, there is an urgent need to provide a method for harmlessly treating shield soil.

[0003] my country uses coal as its main energy source, and produces a large amount of gangue. At the same time, the large amount of gangue accumulation will cause a waste of resources to a certain extent. Gangue is usually utilized by ground backfilling. However, the main method of ground backfilling is to fill the ground with a layer of gangue and a layer of loess. After compaction, gangue and loess are alternately filled. After reaching the specified filling capacity, the backfill site is covered with loess, and then ecological restoration is carried out. During the entire backfilling and restoration process, loess is used as the isolation material and for vegetation growth in ecological restoration, and the amount used is huge. However, loess is in short supply in most mining areas, and the method of cutting mountains to obtain soil will cause secondary damage.

[0004] Therefore, how to provide a method for synergistic ecological backfilling of shield-dried soil and coal gangue, replace loess with shield-dried soil, and combine it with coal gangue to construct a repair backfill area through the synergistic effect of shield-dried soil and coal gangue, is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0005] The object of the present invention is to provide a method for shield-turbine dried soil and coal gangue coordinated ecological backfilling, so as to solve at least one of the above-mentioned technical problems.

[0006] To achieve the above-mentioned purpose, the first aspect of the present invention provides a method for the coordinated ecological backfilling of shield drying soil and coal gangue, the method comprising the following steps: obtaining initial shield drying soil, the leaching concentration of the surfactant in the initial shield drying soil is less than 0.3 mg / L; obtaining initial coal gangue, the initial coal gangue is composed of crushed coal gangue with a particle size of 3-5 mm and a mass proportion of 40%, crushed coal gangue with a particle size of 1-3 mm and a mass proportion of 30%, and crushed coal gangue with a particle size of less than 1 mm and a mass proportion of 30%; adding the initial coal gangue to a pelletizing machine, and adding the initial shield drying soil, mixing, and obtaining modified coal gangue; dehydrating the initial shield drying soil with fly ash and carbide slag to obtain modified shield drying; Soil; first lay a bottom anti-seepage layer in the area to be backfilled, the bottom anti-seepage layer is formed by rolling the modified shield dried soil, and the compaction degree is greater than 90%; on the top of the bottom anti-seepage layer, N+1 layers of coal gangue backfill layer and N layers of shield dried soil backfill layer are laid in sequence, each layer of shield dried soil backfill layer is located between two adjacent layers of coal gangue backfill layer, the coal gangue backfill layer is formed by rolling the modified coal gangue, and the compaction degree is 70-80%; the shield dried soil backfill layer is formed by rolling the modified shield dried soil, and the compaction degree is 80-90%; on the N+1th layer of the coal gangue backfill layer, lay an ecological anti-seepage layer to obtain a repaired backfill area; in the repaired backfill area, trenches are excavated every 0.8-1.2m and shrubs are planted; wherein N is a positive integer.

[0007] In the first aspect, the obtaining of initial shield dried soil comprises: adding activated sludge to shield soil, mixing evenly, and obtaining initial shield dried soil; the amount of activated sludge added is 3-5% of the mass of the shield soil.

[0008] In the first aspect, the dehydration treatment of the initial shield drying soil by fly ash and carbide slag includes: selecting fly ash and carbide slag with a particle size of 50-70 μm; adding the fly ash and carbide slag to the initial shield drying soil by tillage, the added amount of fly ash is 3-8% of the dry weight of the initial shield drying soil, and the added amount of carbide slag is 3-8% of the dry weight of the initial shield drying soil; after uniform mixing, dehydration treatment is carried out by tillage and airing until the optimal moisture content is reached to obtain modified shield drying soil.

[0009] In the first aspect, the bottom anti-seepage layer has a thickness of 0.8-1.5 m.

[0010] In the first aspect, the thickness of the gangue backfill layer is 1.5 m, and the thickness of the shield dried soil backfill layer is 1.5 m.

[0011] In the first aspect, laying an ecological impermeable layer on top of the N+1 layer of the gangue backfill layer includes: laying a water-proof and oxygen-blocking layer on top of the N+1 layer of the gangue backfill layer, the water-proof and oxygen-blocking layer being compacted by modified shield-dried soil and having a compaction degree greater than 90%; laying a capillary barrier layer on top of the water-proof and oxygen-blocking layer, the capillary barrier layer being compacted by crushed gangue with a particle size of 1-3mm and having a compaction degree of 60-70%; laying a vegetation layer on top of the capillary barrier layer; and laying shield-dried soil turf on top of the vegetation layer.

[0012] In the first aspect, the thickness of the water-proof and oxygen-blocking layer is 0.5-0.8 m; the thickness of the capillary barrier layer is 0.5-0.8 m.

[0013] In the first aspect, the vegetation layer is formed by rolling regenerated shield-dried soil with a compaction degree of 50-60%; the regenerated shield-dried soil is made by the following method: the initial shield-dried soil, crushed coal gangue with a particle size less than 3 mm, coal gasification slag with a particle size of 0.075-1 mm and agricultural, forestry and animal husbandry waste are mixed evenly in a mass ratio of (5-6): (2-3): (0.5-1): (0.5-1), and decomposed for 7 days to obtain the regenerated shield-dried soil.

[0014] In the first aspect, the agricultural, forestry and animal husbandry waste includes at least one of chicken manure, cow manure, pig manure and straw.

[0015] In the first aspect, the shield dried soil turf is made by the following method: adding pioneer grass seeds to the regenerated shield dried soil, rolling after mixing evenly, and obtaining a compacted soil body with a compaction degree of 50-60%; cutting the compacted soil body into mud cakes with a length of 30 cm, a width of 30 cm, and a thickness of 8-12 cm; watering and cultivating the mud cakes, and forming a shield dried soil turf after 7 days.

[0016] Beneficial effects:

[0017] The present invention provides a method for the coordinated ecological backfilling of shield drying soil and coal gangue. First, initial shield drying soil, initial coal gangue, modified coal gangue and modified shield drying soil are obtained respectively, and the shield soil is purified by activated sludge so that the leaching concentration of the surfactant in the initial shield drying soil is less than 0.3 mg / L; the initial coal gangue is crushed by graded crushing so that the initial coal gangue contains 40% by mass of crushed coal gangue with a particle size of 3-5 mm, 30% by mass of crushed coal gangue with a particle size of 1-3 mm, and 10% by mass of crushed coal gangue with a particle size of 1-3 mm. The invention discloses a method for preparing the modified coal gangue by mixing the crushed coal gangue with a particle size less than 1 mm and the crushed coal gangue with a mass ratio of 30%, thereby reducing the porosity and oxygen content in the initial coal gangue, reducing the risk of spontaneous combustion and stabilizing the structure after compaction; the modified coal gangue obtained by adhering a layer of initial shield drying soil on the surface of the initial coal gangue can reduce the contact between the coal gangue and oxygen, and reduce the leaching rate of heavy metals in the coal gangue; the modified shield drying soil is obtained by dehydrating and drying the initial shield drying soil with fly ash and carbide slag, and controlling the moisture content of the modified shield drying soil can be Improve the compaction degree; then, first lay the bottom anti-seepage layer in the area to be backfilled. The bottom anti-seepage layer is formed by rolling modified shield dried soil, and the compaction degree is greater than 90%. After compaction, the pores are small, the cation exchange capacity is large, and it has good anti-seepage performance; then, N+1 layers of coal gangue backfill layers and N layers of shield dried soil backfill layers are alternately laid on the bottom anti-seepage layer. Each layer of shield dried soil backfill layer is located between two adjacent layers of coal gangue backfill layers. The coal gangue backfill layer is formed by rolling modified coal gangue, and the compaction degree is greater than 90%. The shield drying soil backfill layer is made of modified shield drying soil with a compaction degree of 80-90%. The compacted shield drying soil backfill layer has a low permeability, which can isolate oxygen from entering the gangue backfill layer; finally, an ecological anti-seepage layer is laid on the N+1 layer of gangue backfill layer to provide nutrients for plant growth, thereby obtaining a repaired backfill area; in the repaired backfill area, pits are excavated every 0.8-1.2m to improve the utilization rate of rainfall, so as to plant shrubs. The shield drying soil and coal gangue coordinated ecological backfilling method provided by the present invention obtains modified shield drying soil and modified coal gangue by modifying the shield drying soil and coal gangue, and thus sequentially arranges a bottom anti-seepage layer, an alternating coal gangue backfill layer and a shield drying soil layer, and an ecological anti-seepage layer in the area to be backfilled from bottom to top, and fully utilizes the synergistic effect of the modified shield drying soil and the modified coal gangue, so that shrubs can be normally planted in the repaired backfill area, thereby improving the utilization efficiency of the soil body. At the same time, a large amount of coal gangue and shield soil can be consumed, reducing the hazards of their storage and disposal.

[0018] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 The present invention is a flow chart of a method for shield drying soil and coal gangue coordinated ecological backfilling. DETAILED DESCRIPTION

[0021] The present invention will be described in detail below in conjunction with specific implementations and examples, and the advantages and various effects of the present invention will be more clearly presented. It should be understood by those skilled in the art that these specific implementations and examples are used to illustrate the present invention, rather than to limit the present invention.

[0022] Throughout the specification, unless otherwise specifically stated, the terms used herein should be understood as meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. In the event of a conflict, the present specification takes precedence.

[0023] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or obtained by existing methods.

[0024] See also Figure 1The present invention provides a method for ecological backfilling of shield dried soil and coal gangue, the method comprising the following steps: obtaining initial shield dried soil, wherein the leaching concentration of the surfactant in the initial shield dried soil is less than 0.3 mg / L; obtaining initial coal gangue, wherein the initial coal gangue is composed of crushed coal gangue with a particle size of 3-5 mm and a mass proportion of 40%, crushed coal gangue with a particle size of 1-3 mm and a mass proportion of 30%, and crushed coal gangue with a particle size of less than 1 mm and a mass proportion of 30%; adding the initial coal gangue into a pelletizing machine, and adding the initial shield dried soil, mixing, and obtaining modified coal gangue; dehydrating the initial shield dried soil by fly ash and carbide slag to obtain modified shield dried soil; A bottom anti-seepage layer is first laid in the backfill area, and the bottom anti-seepage layer is formed by rolling the modified shield dried soil, and the compaction degree is greater than 90%; N+1 layers of coal gangue backfill layer and N layers of shield dried soil backfill layer are laid in sequence on the bottom anti-seepage layer, and each layer of shield dried soil backfill layer is located between two adjacent layers of coal gangue backfill layer, and the coal gangue backfill layer is formed by rolling the modified coal gangue, and the compaction degree is 70-80%; the shield dried soil backfill layer is formed by rolling the modified shield dried soil, and the compaction degree is 80-90%; an ecological anti-seepage layer is laid on the N+1th layer of the coal gangue backfill layer to obtain a repair backfill area; in the repair backfill area, pits are excavated every 0.8-1.2m and shrubs are planted; wherein N is a positive integer.

[0025] Specifically, the present invention provides a method for the coordinated ecological backfilling of shield drying soil and coal gangue. First, initial shield drying soil, initial coal gangue, modified coal gangue and modified shield drying soil are obtained respectively, and the shield soil is purified by activated sludge so that the leaching concentration of the surfactant in the initial shield drying soil is less than 0.3 mg / L; the initial coal gangue is crushed by graded crushing so that the initial coal gangue contains 40% by mass of crushed coal gangue with a particle size of 3-5 mm, 30% by mass of crushed coal gangue with a particle size of 1-3 mm, and 10% by mass of crushed coal gangue with a particle size of 1-3 mm. Crushed gangue and crushed gangue with a mass ratio of 30% less than 1mm, thereby reducing the porosity and oxygen content in the initial gangue, reducing the risk of spontaneous combustion and stabilizing the structure after compaction; modified gangue obtained by adhering a layer of initial shield drying soil on the surface of the initial gangue can reduce the contact between gangue and oxygen, and reduce the leaching rate of heavy metals in the gangue; the initial shield drying soil is dehydrated and dried by fly ash and carbide slag to obtain modified shield drying soil, and the water content of the modified shield drying soil is controlled. The rate can improve the compaction degree; then, the bottom anti-seepage layer is first laid in the area to be backfilled. The bottom anti-seepage layer is formed by rolling modified shield dried soil, and the compaction degree is greater than 90%. After compaction, the pores are small, the cation exchange capacity is large, and it has good anti-seepage performance; then, N+1 layers of coal gangue backfill layers and N layers of shield dried soil backfill layers are alternately laid on the bottom anti-seepage layer. Each layer of shield dried soil backfill layer is located between two adjacent layers of coal gangue backfill layers. The coal gangue backfill layer is formed by rolling modified coal gangue. The compaction The degree of compaction is 70-80%, and the shield dried soil backfill layer is made of modified shield dried soil with a compaction degree of 80-90%. The compacted shield dried soil backfill layer has low permeability, which can isolate oxygen from entering the coal gangue backfill layer; finally, an ecological anti-seepage layer is laid on the N+1 layer of coal gangue backfill layer to provide nutrients for plant growth, thereby obtaining a repaired backfill area; in the repaired backfill area, pits are excavated every 0.8-1.2m to improve the utilization rate of rainfall, so as to plant shrubs. The shield drying soil and coal gangue coordinated ecological backfilling method provided by the present invention obtains modified shield drying soil and modified coal gangue by modifying the shield drying soil and coal gangue, and thus sequentially arranges a bottom anti-seepage layer, an alternating coal gangue backfill layer and a shield drying soil layer, and an ecological anti-seepage layer in the area to be backfilled from bottom to top, and fully utilizes the synergistic effect of the modified shield drying soil and the modified coal gangue, so that shrubs can be normally planted in the repaired backfill area, thereby improving the utilization efficiency of the soil body. At the same time, a large amount of coal gangue and shield soil can be consumed, reducing the hazards of their storage and disposal.

[0026] In some possible embodiments, the obtaining of initial shield dried soil includes: adding activated sludge to shield soil, mixing evenly, and obtaining initial shield dried soil; the amount of activated sludge added is 3-5% of the mass of the shield soil.

[0027] Those skilled in the art will understand that activated sludge contains a large number of microorganisms, some of which use surfactants in shield soil as organic carbon sources to degrade surfactants. In addition, activated sludge can also be used as a nutrient activator for coal gangue and agricultural, forestry and animal husbandry waste, providing a basis for subsequent regeneration of shield drying soil.

[0028] In some possible embodiments, the dehydration treatment of the initial shield drying soil by fly ash and carbide slag includes: selecting fly ash and carbide slag with a particle size of 50-70 μm; adding the fly ash and carbide slag to the initial shield drying soil by tillage, the amount of fly ash added is 3-8% of the dry weight of the initial shield drying soil, and the amount of carbide slag added is 3-8% of the dry weight of the initial shield drying soil; after uniform mixing, dehydration treatment is carried out by tillage and airing until an optimal moisture content is reached to obtain modified shield drying soil.

[0029] This is because, by controlling the moisture content of the modified shield drying soil, and combining fly ash and carbide slag, the compaction degree of the modified shield drying soil can be improved, so that it has better impermeability, so that it can be used as the bottom anti-seepage layer in the backfill area and the interlayer covering soil of the gangue backfill layer to isolate oxygen; if fly ash and carbide slag are not used to modify the initial shield drying soil, cracking or volume shrinkage and the like are likely to occur during the subsequent rolling process, thereby destroying the structure of the modified shield drying soil and making it lose its anti-seepage blocking effect. In addition, it is also necessary to control the addition amount of fly ash and carbide slag. When the addition amount of fly ash and carbide slag exceeds 8% of the dry weight of the initial shield drying soil, the prepared modified shield drying soil is difficult to roll and compact because the shield soil and fly ash react with water under the action of carbide slag as an activator, and the cementation blocks are formed. Further, due to the excessive addition amount, the alkalinity is enhanced, which is easy to cause secondary pollution to the surrounding environment.

[0030] In some possible embodiments, the thickness of the bottom anti-seepage layer is 0.8-1.5 m.

[0031] In some possible embodiments, the thickness of the gangue backfill layer is 1.5 m, and the thickness of the shield dried soil backfill layer is 1.5 m.

[0032] In some possible embodiments, laying an ecological anti-seepage layer on top of the N+1 layer of the gangue backfill layer includes: laying a water-proof and oxygen-blocking layer on top of the N+1 layer of the gangue backfill layer, the water-proof and oxygen-blocking layer being compacted by modified shield-dried soil and having a compaction degree greater than 90%; laying a capillary barrier layer on top of the water-proof and oxygen-blocking layer, the capillary barrier layer being compacted by crushed gangue with a particle size of 1-3 mm and having a compaction degree of 60-70%; laying a vegetation layer on top of the capillary barrier layer; and laying shield-dried soil turf on top of the vegetation layer.

[0033] Those skilled in the art will appreciate that laying an ecological impermeable layer on top of the N+1th layer of coal gangue backfill layer is used to repair the ecological environment and provide a living environment for the planted trees. The ecological anti-seepage layer includes a water-proof and oxygen-blocking layer, a capillary barrier layer, a vegetation layer and a shield-dried soil turf from bottom to top; the water-proof and oxygen-blocking layer is formed by modified shield drying and rolling, with a compaction degree of more than 90%, and has excellent impermeability, which can isolate the upper air and moisture from entering, and reduce the pollution leaching of the lower coal gangue backfill layer; the capillary barrier layer is formed by crushed coal gangue with a particle size of 1-3mm and a compaction degree of 60-70%. Its particle size is larger than that of the vegetation layer above. Under the capillary action of unsaturated soil, moisture is concentrated in areas with smaller particle pores. Setting a capillary barrier layer can prevent rainwater from the upper vegetation layer from infiltrating and eroding the backfill area, while increasing the water holding capacity of the vegetation layer; further, setting a shield-dried soil turf on the vegetation layer can improve biodiversity, so that the backfill area can quickly enter a benign ecological succession cycle.

[0034] In some possible embodiments, the thickness of the water-proof and oxygen-blocking layer is 0.5-0.8 m; the thickness of the capillary barrier layer is 0.5-0.8 m.

[0035] In some possible embodiments, the vegetation layer is formed by rolling regenerated shield-dried soil with a compaction degree of 50-60%; the regenerated shield-dried soil is made by the following method: the initial shield-dried soil, crushed coal gangue with a particle size less than 3 mm, coal gasification slag with a particle size of 0.075-1 mm and agricultural, forestry and animal husbandry waste are mixed evenly in a mass ratio of (5-6): (2-3): (0.5-1): (0.5-1), and decomposed for 7 days to obtain the regenerated shield-dried soil.

[0036] This is because the use of coal gangue, coal gasification slag and agricultural, forestry and animal husbandry waste to modify the initial shield drying soil to obtain regenerated shield drying soil can improve the nutritional content and water holding capacity of the regenerated shield drying soil, improve the survival rate of shrubs, and repair the soil environment. The addition of coal gangue can improve the water-gas-heat migration pore channel and reduce the risk of drying of shield drying soil. On the other hand, it can provide organic carbon, nitrogen, phosphorus, potassium, silicon and magnesium and other nutrients required for plant growth, and provide nutrients for plant growth under activation; the pore structure of coal gasification slag can play a role in retaining water and fertilizer; after the decomposition of agricultural, forestry and animal husbandry waste, pathogens can be reduced and macromolecular organic matter can be decomposed. The regenerated shield drying soil obtained by this modification, on the one hand, brings organic carbon and non-nutritional elements such as nitrogen, phosphorus and potassium required for plant growth, and on the other hand, it contains a large number of microorganisms that can activate coal gangue, which can promote the release of coal gangue nutrients under long-term reproduction and metabolism.

[0037] In some possible embodiments, the agricultural, forestry and animal husbandry waste includes at least one of chicken manure, cow manure, pig manure and straw.

[0038] In some possible embodiments, the shield dried soil turf is made by the following method: adding pioneer grass seeds to the regenerated shield dried soil, mixing evenly and rolling it, with a compaction degree of 50-60%, to obtain a compacted soil body; cutting the compacted soil body into mud cakes with a length of 30 cm, a width of 30 cm, and a thickness of 8-12 cm; watering and cultivating the mud cakes, and forming a shield dried soil turf after 7 days.

[0039] Those skilled in the art can understand that adding pioneer grass seeds to the regenerated shield desiccation soil can create growth conditions for the shrubs planted subsequently, and play a key starting role in the restoration and reconstruction of the ecosystem. In addition, pioneer grass seeds can survive in adverse environments such as scarce resources and poor soil conditions, have strong reproductive capacity and growth rate, and provide ecological restoration conditions for early shield desiccation soil turf, so that it can quickly enter the ecological benign succession cycle and provide growth conditions for the trees being planted.

[0040] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0041] Example

[0042] This embodiment provides a shield drying soil and coal gangue coordinated ecological backfilling method, which specifically includes the following steps:

[0043] (1) Obtaining initial shield-dried soil: adding activated sludge to the shield soil, the amount of activated sludge added is 3% of the mass of the shield soil, and mixing evenly to obtain initial shield-dried soil, the leaching concentration of the surfactant in the initial shield-dried soil is less than 0.3 mg / L; wherein, the shield soil comes from a landfill disposal site, the moisture content is 40%, the activated sludge comes from a sewage treatment plant, the activated sludge is diluted and sprayed on the crushed shield soil at a mass ratio of 3%, the soil is tilled and mixed evenly, and maintained at room temperature for 1 day, the detected surfactant concentration is less than 0.3 mg / L; the method for detecting the surfactant concentration: after leaching the initial shield-dried soil and water at a solid-liquid ratio of 1:10, the concentration of the surfactant in the leachate is detected;

[0044] (2) Obtaining initial gangue: A jaw crusher is used to grade and crush the gangue to obtain crushed gangue of different particle sizes. Based on the optimal compact packing model, the initial gangue is composed of crushed gangue with a particle size of 3-5 mm and a mass proportion of 40%, crushed gangue with a particle size of 1-3 mm and a mass proportion of 30%, and crushed gangue with a particle size of less than 1 mm and a mass proportion of 30%. After rolling and compaction, the initial gangue has a porosity of 0.08 and an air flow velocity of 0.8×10 -5 m / s;

[0045] (3) Obtaining modified coal gangue: adding initial coal gangue with different particle sizes into a rotary / rolling type pelletizing machine, and adding initial shield drying soil, and after mixing, a layer of initial shield drying soil adheres to the surface of the initial coal gangue, thereby obtaining modified coal gangue;

[0046] (4) Obtaining modified shield drying soil: selecting fly ash and carbide slag with a particle size of 50-70 μm; adding fly ash and carbide slag to the initial shield drying soil by tilling, wherein the amount of fly ash added is 3% of the dry weight of the initial shield drying soil, and the amount of carbide slag added is 3-8% of the dry weight of the initial shield drying soil; after mixing evenly, dehydrating the soil by tilling and drying until the optimum moisture content reaches 29%, thereby obtaining modified shield drying soil;

[0047] (5) Obtaining regenerated shield drying soil: the initial shield drying soil, crushed coal gangue with a particle size of less than 3 mm, coal gasification slag with a particle size of 0.075-1 mm, and agricultural, forestry and animal husbandry waste are mixed evenly in a mass ratio of 5:3:1:1, and decomposed for 7 days to obtain regenerated shield drying soil;

[0048] (6) Obtaining shield-dried soil turf: adding pioneer grass seeds to the regenerated shield-dried soil, mixing evenly and rolling it to a compaction degree of 60% to obtain a compacted soil body; cutting the compacted soil body into a mud cake with a length of 30 cm, a width of 30 cm, and a thickness of 10 cm; watering and cultivating the mud cake, and forming a shield-dried soil turf after 7 days;

[0049] (7) A 1m thick bottom anti-seepage layer is first laid in the area to be backfilled. The bottom anti-seepage layer is made of modified shield dried soil with a compaction degree of 92% and a permeability coefficient of 1.3×10 -8 m / s;

[0050] (8) N+1 layers of gangue backfill and N layers of shield dried soil backfill are laid on the bottom anti-seepage layer in sequence. Each layer of shield dried soil backfill is located between two adjacent layers of gangue backfill. The thickness of the shield dried soil backfill and the gangue backfill are both 1.5 m. The gangue backfill is formed by rolling modified gangue with a compaction degree of 70%; the shield dried soil backfill is formed by rolling modified shield dried soil with a compaction degree of 80%.

[0051] (9) Laying an ecological anti-seepage layer on the N+1 layer of gangue backfill layer, including first laying a 0.8m thick water-proof and oxygen-proof layer, which is made of modified shield-dried soil and has a compaction degree of 92%; then laying a 0.5m thick capillary barrier layer, which is made of crushed gangue with a particle size of 1-3mm and a compaction degree of 70%; then laying a 0.8m thick vegetation layer, which is made of recycled shield-dried soil and has a compaction degree of 50%; finally laying shield-dried soil turf, thereby obtaining a repaired backfill area;

[0052] (10) In the repair and backfill area, dig pits every 1m and plant shrubs.

[0053] Comparative Example 1

[0054] In this comparative example, the activated sludge was diluted and sprayed at a mass ratio of 1% on the crushed shield soil, and the soil was evenly plowed and cured at room temperature for 1 day. The concentration of the surfactant in the leachate was detected to be 6.7 mg / L. After 10 days of curing, the concentration of the surfactant in the leachate was detected to be lower than 0.3 mg / L. This indicates that when the added content of activated sludge in the shield soil is low, it takes a longer time to purify the surfactant in the shield soil. If the added amount of activated sludge in the shield soil is high, the risk of pathogens brought by the activated sludge will increase easily.

[0055] Comparative Example 2

[0056] In this comparative example, fly ash and carbide slag were not used to dehydrate the initial shield-dried soil. The maximum compaction degree of the shield-dried soil after rolling was 67.2%, and the permeability coefficient was 2.4×10 -5 m / s, which cannot meet the requirement of more than 90% compaction degree of modified shield drying soil, and thus cannot be used as the bottom anti-seepage layer (permeability coefficient less than 1.0×10 -7 m / s) and water-proof and oxygen-barrier layer, that is, the target backfill requirements cannot be met.

[0057] Comparative Example 3

[0058] In this comparative example, although the same mass of fly ash and carbide slag as in the example was added to dehydrate the initial shield drying soil, the moisture content of the modified shield drying soil obtained after dehydration was 36%, which exceeded the optimal moisture content of 5%, resulting in a maximum compaction degree of 76% and a permeability coefficient of 1.4×10 -6 m / s, and also cannot meet the requirement of more than 90% compaction degree of modified shield drying soil, and cannot be used as the bottom anti-seepage layer (permeability coefficient less than 1.0×10 -7 m / s) and water-proof and oxygen-barrier layer.

[0059] Comparative Example 4

[0060] In this comparative example, the coal gangue was directly obtained without using a jaw crusher to grade and crush the coal gangue. After rolling and compaction, the porosity was 0.3 and the air flow velocity was 0.08, which easily caused the spontaneous combustion of the coal gangue. When the air flow velocity in the coal gangue mountain is lower than 4.4×10-5m / s, the spontaneous combustion of the coal gangue mountain will not be caused.

[0061] Comparative Example 5

[0062] In this comparative example, the initial gangue and the initial shield drying soil were not mixed and pelletized, and the initial gangue was directly subjected to the HJ299 toxicity leaching standard test, in which the leaching concentrations of Pb, As, and Hg increased by 43% compared with those in the embodiment, and did not meet the backfill requirements. The results show that adhering a layer of initial shield drying soil on the surface of the initial gangue can reduce the exposure of the gangue to the environment and reduce the leaching of heavy metals.

[0063] Comparative Example 6

[0064] In this comparative example, when laying the ecological anti-seepage layer, the water-proof and oxygen-blocking layer formed by rolling the modified shield dry soil was not laid. According to the test, the oxygen content at 1m below the N+1 layer of coal gangue backfill layer increased by 22% compared with the embodiment, increasing the risk of spontaneous combustion of coal gangue.

[0065] Comparative Example 7

[0066] In this comparative example, when laying the ecological anti-seepage layer, the capillary barrier layer formed by rolling crushed coal gangue with a particle size of 1-3 mm was not laid. Through dye tracing and simulated rainfall tests, it was found that the water-proof and oxygen-blocking layer would compete with the vegetation layer for water. The water output of the upper vegetation layer in this comparative example was 38% lower than the water storage capacity of the vegetation layer in the embodiment. The results show that the water in the embodiment is almost completely stored in the vegetation layer under the blocking effect of the large-particle capillary barrier layer. On the one hand, it provides sufficient water supply for plant growth, and on the other hand, it can reduce the risk of surface water infiltration into the landfill area.

[0067] Comparative Example 8

[0068] In this comparative example, no gangue is added to the regenerated shield drying soil in the vegetation layer, and the regenerated shield drying soil is obtained by mixing the initial shield drying soil, coal gasification slag with a particle size of 0.075-1mm and agricultural, forestry and animal husbandry waste in a mass ratio of 5:1:1 and then decomposing for 7 days. According to the test, the agglomerates in the vegetation layer in this comparative example are larger than 0.25mm, which is 52% less than that in the embodiment; the density of the vegetation layer in this comparative example is 30% higher than that in the embodiment, and the vegetation layer is more viscous and has a tight structure, which hinders the water-gas-heat transfer of the vegetation layer and affects the growth of plants.

[0069] Comparative Example 9

[0070] In this comparative example, no coal gasification slag is added to the regenerated shield drying soil in the vegetation layer, and the regenerated shield drying soil is obtained by mixing the initial shield drying soil, crushed coal gangue with a particle size of less than 3 mm, and agricultural, forestry and animal husbandry waste in a mass ratio of 5:3:1 and then decomposing for 7 days. According to the test, the water holding rate of the vegetation layer in this comparative example is 10% lower than that of the vegetation layer in the embodiment.

[0071] Comparative Example 10

[0072] In this comparative example, no pits were excavated in the repaired backfill area. The simulated rainfall test found that the interception of rainfall in this comparative example was 42% less than that in the example. The results showed that the absence of shrub pits in this comparative example reduced plant diversity, and the poor water permeability of the turf resulted in a low utilization rate of precipitation. However, in the example, shrub pits were excavated every 1m, which allowed rainfall to gather there and diffuse to the vegetation matrix, increasing the water storage utilization rate of rainfall.

[0073] In summary, compared with the prior art, the present invention has the following advantages:

[0074] (1) The present invention dehydrates and dries shield-dried soil by using fly ash and carbide slag to obtain modified shield-dried soil with high compaction and good impermeability, and uses the soil as an insulating layer between two adjacent layers of gangue backfill, thereby isolating water and oxygen, and reducing the risk of spontaneous combustion of the gangue backfill layer;

[0075] (2) The present invention is based on the optimal close packing model, graded crushing of coal gangue, and evenly mixing with the initial shield drying soil with high adhesion to obtain modified coal gangue, thereby reducing the spontaneous combustion risk and heavy metal leaching rate of coal gangue;

[0076] (3) The present invention modifies the initial shield drying soil by using coal gangue, coal gasification slag and agricultural, forestry and animal husbandry waste to obtain regenerated shield drying soil, thereby improving the nutrient content and water holding capacity of the regenerated shield drying soil, improving the survival rate of shrubs and repairing the soil environment;

[0077] (4) The present invention constructs an ecological anti-seepage layer on the last layer of coal gangue backfill, and the ecological anti-seepage layer is composed of a water-proof and oxygen-blocking layer, a capillary barrier layer, a vegetation layer and shield-dried soil turf, which creates living conditions for plant growth and thus repairs the ecological environment.

[0078] Finally, it should be noted that the terms "comprises," "includes," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements that are inherent to such process, method, article, or apparatus.

[0079] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0080] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for shield-dried soil and coal gangue coordinated ecological backfilling, characterized in that: The method comprises the following steps: Obtaining initial shield-dried soil, wherein the leaching concentration of the surfactant in the initial shield-dried soil is less than 0.3 mg / L; Obtaining initial coal gangue, wherein the initial coal gangue consists of crushed coal gangue with a particle size of 3-5 mm and a mass proportion of 40%, crushed coal gangue with a particle size of 1-3 mm and a mass proportion of 30%, and crushed coal gangue with a particle size of less than 1 mm and a mass proportion of 30%; Adding the initial coal gangue into a pelletizing machine, and adding the initial shield dried soil, and mixing them to obtain modified coal gangue; Dehydrating the initial shield drying soil by using fly ash and carbide slag to obtain modified shield drying soil; Firstly, a bottom anti-seepage layer is laid in the area to be backfilled, wherein the bottom anti-seepage layer is formed by rolling the modified shield dried soil, and the compaction degree is greater than 90%; N+1 layers of gangue backfill layers and N layers of shield dried soil backfill layers are laid in sequence on the bottom anti-seepage layer, each layer of shield dried soil backfill layer is located between two adjacent layers of gangue backfill layers, the gangue backfill layer is formed by rolling the modified gangue, and the compaction degree is 70-80%; the shield dried soil backfill layer is formed by rolling the modified shield dried soil, and the compaction degree is 80-90%; An ecological anti-seepage layer is laid on the N+1th layer of coal gangue backfill layer to obtain a repaired backfill area; In the repaired backfill area, trenches are dug every 0.8-1.2 m and shrubs are planted; Wherein, N is a positive integer.

2. The method for shield-dried soil and coal gangue coordinated ecological backfilling according to claim 1 is characterized in that: The method of obtaining the initial shield drying soil comprises: adding activated sludge to the shield soil, mixing evenly, and obtaining the initial shield drying soil; the amount of the activated sludge added is 3-5% of the mass of the shield soil.

3. The method for shield-dried soil and coal gangue coordinated ecological backfilling according to claim 1 is characterized in that: The dehydration treatment of the initial shield drying soil by using fly ash and carbide slag comprises: Select fly ash and carbide slag with particle sizes of 50-70 μm; Adding the fly ash and the carbide slag to the initial shield drying soil by tilling, wherein the amount of the fly ash added is 3-8% of the dry weight of the initial shield drying soil, and the amount of the carbide slag added is 3-8% of the dry weight of the initial shield drying soil; After being mixed evenly, the soil is dehydrated by ploughing and drying until the optimum moisture content is reached to obtain modified shield-dried soil.

4. The method for shield-dried soil and coal gangue coordinated ecological backfilling according to claim 1, characterized in that: The thickness of the bottom anti-seepage layer is 0.8-1.5m.

5. The method for shield-dried soil and coal gangue coordinated ecological backfilling according to claim 1, characterized in that: The thickness of the gangue backfill layer is 1.5m, and the thickness of the shield dried soil backfill layer is 1.5m.

6. The method for shield-dried soil and coal gangue coordinated ecological backfilling according to claim 1, characterized in that: The laying of the ecological anti-seepage layer on the N+1 layer of the coal gangue backfill layer comprises: A water-proof and oxygen-blocking layer is laid on the N+1th layer of the gangue backfill layer, wherein the water-proof and oxygen-blocking layer is formed by rolling modified shield-dried soil, and the compaction degree is greater than 90%; A capillary barrier layer is laid on the water-proof and oxygen-blocking layer, wherein the capillary barrier layer is formed by rolling crushed coal gangue with a particle size of 1-3 mm and a compaction degree of 60-70%; Laying a vegetation layer on the capillary barrier layer; Shield-dried soil turf is laid on the vegetation layer.

7. The method for shield-dried soil and coal gangue coordinated ecological backfilling according to claim 6, characterized in that: The thickness of the water-proof and oxygen-blocking layer is 0.5-0.8 m; the thickness of the capillary barrier layer is 0.5-0.8 m.

8. The method for shield-dried soil and coal gangue coordinated ecological backfilling according to claim 6, characterized in that: The vegetation layer is formed by rolling regenerated shield-dried soil with a compaction degree of 50-60%. The regenerated shield-dried soil is made by the following method: the initial shield-dried soil, crushed coal gangue with a particle size of less than 3 mm, coal gasification slag with a particle size of 0.075-1 mm and agricultural, forestry and animal husbandry waste are mixed evenly in a mass ratio of (5-6): (2-3): (0.5-1): (0.5-1), and decomposed for 7 days to obtain the regenerated shield-dried soil.

9. The method for shield-dried soil and coal gangue coordinated ecological backfilling according to claim 7, characterized in that: The agricultural, forestry and animal husbandry waste includes at least one of chicken manure, cow manure, pig manure and straw.

10. The method for shield-dried soil and coal gangue coordinated ecological backfilling according to claim 8, characterized in that: The shield dried soil turf is made by the following method: adding pioneer grass seeds to the regenerated shield dried soil, rolling after mixing evenly, and obtaining a compacted soil body with a compaction degree of 50-60%; cutting the compacted soil body into mud cakes with a length of 30 cm, a width of 30 cm, and a thickness of 8-12 cm; watering and cultivating the mud cakes, and forming a shield dried soil turf after 7 days.

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