Leachate guiding and discharging system and guiding and discharging method for fly ash solidified body landfill

Abstract

The invention discloses a percolate guiding and discharging system and method for a fly ash solidified body landfill. An anti-seepage system is arranged at the bottommost end of the fly ash solidified body landfill, a main guiding and discharging device is arranged on the anti-seepage system and communicated with a percolate adjusting tank, and a plurality of water collecting pits are arranged in the main guiding and discharging device and communicated with the main guiding and discharging device; the fly ash chelated solidified bodies are arranged and stacked on the main drainage device, a loess paving layer and a vertical seepage guide device are arranged at the top of each solidified body after each layer of solidified body is stacked, and the vertical seepage guide device corresponds to the water collecting pit; percolate generated by the working face of the first-layer solidified body is collected and drained through the main drainage device, percolate generated by the working face of the second-layer solidified body is collected and drained through the vertical seepage guide device at the top of the first-layer solidified body and converges to a water collecting pit, and the rest can be done in the same way. And the leachate is finally guided and discharged to the leachate adjusting tank for storage through the main guiding and discharging device. The system has the advantages of being low in construction cost, convenient to operate, maintain, adjust and optimize, low in operation cost and the like.

Description

Technical Field

[0001] The invention relates to the technical field of garbage incineration treatment, and in particular to a leachate drainage system and a drainage method for a fly ash solidification body landfill. Background Art

[0002] The fly ash generated by the incineration of domestic waste is currently treated by chelation and solidification to form a solidified body. After reaching the landfill disposal standard, it is landfilled in a fly ash solidified body landfill or a place in an independent partition of a domestic waste landfill. At present, most of the landfill sites dedicated to fly ash chelation solidified bodies are relatively small. During the landfill operation, they are planned as a multi-layer landfill method. After the landfill operation of each layer and each unit of solidified body is completed, the working surface needs to be leveled, and then the membrane welding and covering are performed to prevent rainwater from entering the solidified body pile. Usually, ton bags are used for bagging in the fly ash chelation stabilization process. During bagging, since the fly ash chelate has not yet solidified, the bagged solidified body will become an irregular solidified body, and there will be a lot of gaps during the landfill operation stacking process. At the same time, when leveling the working surface at the top of each unit, considering the problem of solidified body gaps, loess with a certain viscosity is usually used to pave the front. Before each layer of solidified body landfill operation, leachate drainage facilities need to be laid out at the bottom in advance. At present, fly ash solidification landfill sites generally face difficulties in setting up leachate drainage facilities and related construction technology problems. If horizontal drainage pipes are laid at the bottom of each layer of the pile according to the traditional method of landfills and then connected to the drainage pipes at the bottom, the construction will be extremely difficult, and the construction and operation costs will be high. The main problems are analyzed as follows: (1) The fly ash solidification landfill has limited storage capacity and a small site area. The solidification landfill operation is carried out in units and zones. The surface slope is small. When laying horizontal infiltration pipes, it is difficult to meet the slope ratio requirements for long-distance infiltration pipe drainage.

[0003] (2) When setting up horizontal seepage pipes, due to the slope ratio, it is necessary to mechanically excavate deeper trenches, which will destroy a large amount of solidified bodies that have been completely landfilled, affecting the stability of the solidified body landfill. Due to the destruction of the solidified body bags, the chelation stabilization effect of heavy metals in fly ash will be accelerated, the concentration of various pollutants in the fly ash leachate will increase, and the operating cost will also increase simultaneously.

[0004] (3) After a large number of solidified ton bags are destroyed, the fly ash solidified body itself has a low permeability coefficient and a small particle size. When it accumulates around the infiltration system, it will affect the water-conducting function of the infiltration pipe.

[0005] (4) The content of heavy metals such as calcium and magnesium in the landfill leachate of fly ash solidification is high, and the electrical conductivity is high. If the slope ratio of the drainage facility is not enough or the drainage facility is bent, the leachate will accumulate in the drainage pipeline or prolong its residence time in the drainage pipeline, which may easily lead to pipeline scaling and affect the drainage function. If the drainage of leachate is not smooth, it will also cause the leachate to accumulate in the pile. If the solidification body is immersed for a long time, the concentration of the leachate will increase significantly, and the cost of leachate treatment will rise simultaneously.

[0006] (5) The traditional method of constructing horizontal and vertical seepage pipes in layers and regions requires a large amount of construction materials, complex construction operations, a long construction period, and high construction and operating costs. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a leachate drainage system and drainage method for fly ash solidification landfills with compact structure, high stability, convenient operation and maintenance, easy adjustment and optimization, and low operating cost in view of the above-mentioned shortcomings of the prior art.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is: A leachate drainage system for a fly ash solidified body landfill, comprising: an anti-seepage system, a main drainage device, a sump, a vertical seepage guide device and a leachate regulating tank; the anti-seepage system is arranged at the bottom of the fly ash solidified body landfill, the main drainage device is arranged on the anti-seepage system, and the main drainage device is connected to the leachate regulating tank, a plurality of sump pits are arranged in the main drainage device, fly ash chelated solidified bodies are arranged and stacked on the main drainage device, and after each layer of fly ash chelated solidified bodies is stacked, a loess paving layer is laid on the top of the fly ash chelated solidified bodies for leveling, and a vertical seepage guide device is arranged on the top of the fly ash chelated solidified bodies corresponding to the sump pit; In the fly ash solidification landfill, the leachate generated from the working surface of the first layer of fly ash chelating solidification is collected and drained through the main drainage device, and the leachate generated from the working surface of the second layer of fly ash chelating solidification is collected and drained through the vertical seepage guide device on the top of the first layer of fly ash chelating solidification, and converged into the sump; by analogy, the leachate generated from the working surface of the Nth layer of fly ash chelating solidification is collected and drained through the vertical seepage guide device on the top of the N-1th layer of fly ash chelating solidification, and converged into the sump, and finally drained into the leachate regulating tank for storage through the main drainage device.

[0009] As a further improvement of the present invention, the main drainage device includes a main drainage blind ditch, a main drainage perforated pipe, a branch drainage blind ditch, a branch drainage perforated pipe and a main drainage solid pipe; the main drainage blind ditch and the branch drainage blind ditch are both arranged on the top of the anti-seepage system, and a plurality of branch drainage blind ditches are distributed on both sides of the main drainage blind ditch, the main drainage perforated pipe is laid in the main drainage blind ditch, the branch drainage perforated pipe is laid in the branch drainage blind ditch, and one end of the branch drainage perforated pipe is connected to the main drainage perforated pipe, and the main drainage perforated pipe is connected to the leachate regulating tank through the main drainage solid pipe. As a further improvement of the present invention, two main drain perforated tubes are symmetrically arranged in the main drain blind ditch, and one side of the main drain perforated tube is connected to the branch drain perforated tube; the main drain perforated tube and the branch drain perforated tube are both semicircular perforated tubes, and the main drain perforated tube and the branch drain perforated tube are covered with pebbles and wrapped with geotextile as a geofilter. As a further improvement of the present invention, the width of the main drainage blind ditch is 1.2m~1.5m, the height is 0.6m~0.8m, and the slope ratio is not less than 1%; the spacing between two adjacent branch drainage blind ditches is 30m~40m, the width of the branch drainage blind ditch is 0.6m~0.8m, the height is 0.4m~0.6m, and the slope ratio is not less than 0.5%. As a further improvement of the present invention, the sump is arranged at equal intervals in the main drainage blind ditch and the branch drainage blind ditch, and the main drainage perforated pipe and the branch drainage perforated pipe pass through the center position of the corresponding sump. As a further improvement of the present invention, the depth of the sump is the same as the depth of the main drainage blind ditch, and the sump is filled with pebbles. As a further improvement of the present invention, a sump is provided at intervals of 40 m to 50 m in the main drainage blind ditch, and a sump is provided at intervals of 30 m to 40 m in the branch drainage blind ditch. As a further improvement of the present invention, the vertical drainage device includes a drainage vertical pipe, a horizontal fixed pipe, a plane collecting water pit, a drainage branch ditch and a drainage branch pipe; the plane collecting water pit is arranged on the top of the fly ash chelating solidification body and is anchored by a loess paving layer, the drainage vertical pipe is vertically penetrated in the plane collecting water pit, the horizontal fixed pipe is horizontally placed in the plane collecting water pit and passes through the drainage vertical pipe; a plurality of drainage branch ditches are distributed around the plane collecting water pit, the drainage branch pipes are laid in the drainage branch ditches, the leachate collected by the drainage branch pipes is collected in the plane collecting water pit, and then discharged to the collecting water pit by the drainage vertical pipe. As a further improvement of the present invention, a geotextile is laid flat on the bottom of the planar collection puddle as a cushion layer, and a HDPE geomembrane is laid on the cushion layer. The geotextile and the HDPE geomembrane are folded and flipped to the plane around the planar collection puddle, and the inside of the planar collection puddle is filled with pebbles. The vertical drainage pipe is vertically perforated to the top of the planar collection puddle during installation, and the perforated connection between the vertical drainage pipe and the HDPE geomembrane is welded and sealed, and holes are opened around the pipe above the HDPE geomembrane in the vertical drainage pipe. As a general technical concept, the present invention also provides a drainage method based on the above-mentioned leachate drainage system for fly ash solidification body landfill, comprising the following steps: Step S1, constructing an anti-seepage system, a main drainage device, a sump and a leachate regulating tank before the fly ash solidification body landfill is put into operation; Step S2, stacking the fly ash chelate solidified body on the main drainage device, laying a loess paving layer on the top of the fly ash chelate solidified body for leveling after each layer of the fly ash chelate solidified body is stacked, and a vertical seepage guide device is set, and the vertical seepage guide device corresponds to the sump; Step S3, the leachate generated from the working surface of the first layer of fly ash chelating solidified body is collected and drained through the main drainage device, and the leachate generated from the working surface of the second layer of fly ash chelating solidified body is collected and drained through the vertical seepage guide device on the top of the first layer of fly ash chelating solidified body, and converged into the sump; by analogy, the leachate generated from the working surface of the Nth layer of fly ash chelating solidified body is collected and drained through the vertical seepage guide device on the top of the N-1th layer of fly ash chelating solidified body, and converged into the sump, and finally drained into the leachate regulating tank for storage through the main drainage device. Compared with the prior art, the advantages of the present invention are: 1. The leachate drainage system and drainage method for fly ash solidified body landfill of the present invention realizes the collection of plane leachate by constructing a main drainage device at the bottom of the fly ash solidified body landfill, and flexibly setting a vertical seepage guide device in combination with site conditions during landfill operation, and finally effectively drains the leachate to the leachate regulating tank by directing the leachate to the main drainage device at the bottom of the reservoir through the vertical seepage guide device. In the present invention, the vertical seepage guide devices in different areas are connected to the main drainage device, replacing the method of designing horizontal seepage guide blind ditches and seepage guide pipes to drain the leachate in the traditional pile, and effectively solves the process problems such as slope ratio design, pipe bending, pipe scaling and clogging when horizontal seepage guide blind ditches and seepage guide pipes are set separately for each layer of solidified body.

[0010] 2. The leachate drainage system and drainage method for fly ash solidified body landfill of the present invention, by designing the drainage vertical pipe in the vertical seepage guidance device as a short-distance pipeline, utilizes the gap between the solidified bodies to directly flow the leachate into the leachate collection pit at the bottom of the reservoir through the gap between the solidified bodies for drainage. Compared with the traditional drainage using vertical reinforced concrete shafts or pipeline shafts, the construction cost is greatly reduced. The present invention has the advantages of low investment and operation costs, convenient construction and maintenance, and easy implementation, and is particularly suitable for leachate collection and drainage in fly ash solidified body landfills. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic diagram of the structural principle of the leachate drainage system in a specific embodiment of the present invention; Figure 2 It is a schematic diagram of the structural principle of the main discharge device in a specific embodiment of the present invention; Figure 3 It is a schematic diagram of the planar structural principle of the vertical infiltration guiding device in a specific embodiment of the present invention; Figure 4 It is a schematic diagram of the cross-sectional structure principle of the vertical seepage guiding device in a specific embodiment of the present invention; Legend: 1. Anti-seepage system; 2. Main drainage device; 3. Collection pit; 4. Vertical seepage device; 5. Loess paving layer; 6. Fly ash chelating solidification body; 7. Leachate regulating tank; 21. Main drainage blind ditch; 22. Main drainage perforated pipe; 23. Branch drainage blind ditch; 24. Branch drainage perforated pipe; 25. Main drainage solid pipe; 3. Collection pit; 41. Drainage vertical pipe; 42. Horizontal fixed pipe; 43. Plane collection pit; 44. Drainage branch ditch; 45. Drainage branch pipe. DETAILED DESCRIPTION

[0012] The present invention is further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present invention is not limited thereby.

[0013] In the description of the present invention, it should be understood that the terms "side", "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0014] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or suggesting relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0015] Example like Figure 1 As shown, the leachate drainage system for the fly ash solidified body landfill of the present invention comprises: an anti-seepage system 1, a main drainage device 2, a sump 3, a vertical seepage guide device 4 and a leachate regulating tank 7. The anti-seepage system 1 is arranged at the bottom of the fly ash solidified body landfill, the main drainage device 2 is arranged on the anti-seepage system 1, and the main drainage device 2 is connected to the leachate regulating tank 7, and the leachate regulating tank 7 mainly serves as a leachate collection and storage tank. A plurality of sump 3 are arranged in the main drainage device 2, and the fly ash chelated solidified bodies 6 are arranged and stacked on the main drainage device 2, and after each layer of fly ash chelated solidified bodies 6 is stacked, a loess paving layer 5 is laid on the top of the fly ash chelated solidified bodies 6 for leveling, and a vertical seepage guide device 4 is arranged on the top of the fly ash chelated solidified bodies 6 corresponding to the sump 3. Figure 1 Two layers of fly ash chelate solidified bodies 6 are stacked in the middle, and the height of each layer of fly ash chelate solidified bodies 6 is generally between 6 meters and 10 meters. In the fly ash solidification landfill, the leachate generated from the working surface of the first layer of fly ash chelating solidification body 6 is collected and drained through the main drainage device 2, and the leachate generated from the working surface of the second layer of fly ash chelating solidification body 6 is collected and drained through the vertical seepage guide device 4 on the top of the first layer of fly ash chelating solidification body 6, and converges to the sump 3; and so on, the leachate generated from the working surface of the Nth layer of fly ash chelating solidification body 6 is collected and drained through the vertical seepage guide device 4 on the top of the N-1th layer of fly ash chelating solidification body 6, and converges to the sump 3, and finally drained to the leachate regulating tank 7 for storage through the main drainage device 2.

[0016] In this embodiment, the fly ash chelate solidified body 6 is a solidified body that enters the ash landfill for landfill disposal after the fly ash is stabilized by chelate solidification and reaches the landfill disposal standard. The anti-seepage system 1 is an anti-seepage structure set up in accordance with relevant specifications and requirements. Generally, a double-layer artificial anti-seepage lining structure is adopted to ensure that the leachate does not leak into the ecological environment. The anti-seepage system 1 is completed before the fly ash solidified body landfill is put into operation. When the loess paving layer 5 is completed for each layer and each area of ​​the solidified body, the top of the fly ash chelate solidified body 6 needs to be leveled. In the mechanical leveling operation, loess will be used for plane paving, and the loess paving thickness is generally controlled at 10 cm to 15 cm. After the leveling operation is completed, the membrane is covered, which is conducive to the plane cleaning and diversion work, while maintaining a good image of the on-site working surface.

[0017] In this embodiment, in view of the gap characteristics between the solidified body stacks in the landfill operation, the vertical seepage guide device 4 in the local area is combined with the main guide drainage device 2 to replace the traditional planar setting of the blind drainage ditch for the whole line to drain the leachate, which can effectively avoid the related process difficulties such as unfavorable slope ratio control, pipe bending, pipe scaling, sludge or sediment deposition in the pipe leading to blockage of the seepage guide pipe, and effectively reduce or eliminate the problem of leachate accumulation in the pile. By collecting and draining the leachate in an organized manner, the leachate is effectively prevented from staying in the solidified body pile, ensuring the stability of the pile and the safe landfill of the solidified body.

[0018] like Figure 2 As shown, the main drainage device 2 includes a main drainage blind ditch 21, a main drainage perforated pipe 22, a branch drainage blind ditch 23, a branch drainage perforated pipe 24 and a main drainage solid pipe 25. The main drainage blind ditch 21 and the branch drainage blind ditch 23 are both arranged at the top of the anti-seepage system 1, and a plurality of branch drainage blind ditches 23 are distributed on both sides of the main drainage blind ditch 21, and are synchronously designed as a "fishbone type" structure with the main drainage blind ditch 21 according to the terrain conditions. The main drainage perforated pipe 22 is laid in the main drainage blind ditch 21, the branch drainage perforated pipe 24 is laid in the branch drainage blind ditch 23, and one end of the branch drainage perforated pipe 24 is connected to the main drainage perforated pipe 22, and the main drainage perforated pipe 22 is connected to the leachate regulating tank 7 through the main drainage solid pipe 25.

[0019] In this embodiment, two main drainage perforated tubes 22 are symmetrically arranged in the main drainage blind ditch 21, and the main drainage perforated tubes 22 are HDPE tubes with a diameter of de200 to de300; one side of the main drainage perforated tube 22 is connected to the branch drainage perforated tube 24 by hot-melt welding, and the branch drainage perforated tube 24 is a HDPE tube with a diameter of de125 to de200. Both the main drainage perforated tube 22 and the branch drainage perforated tube 24 are semicircular perforated tubes, and holes are opened at a height of more than 5 cm from the bottom of the inner wall of the pipe, with a hole size of 1 cm and a hole spacing of 5 cm to 8 cm. The surroundings of the main drainage perforated tube 22 and the branch drainage perforated tube 24 are covered with pebbles with a particle size of φ20 to 50 mm, and wrapped with 200g / m 3 The geotextile is used as a geotextile filter. Furthermore, the main drainage solid pipe 25 uses two HDPE pipes with a diameter of de200 to de300, which are consistent with the diameter of the main drainage perforated pipe 22. The starting point of the main drainage solid pipe 25 is set 2 to 5 meters inward from the bottom boundary of the ash landfill, and is connected to the main drainage perforated pipe 22 by hot melt welding.

[0020] In this embodiment, the width of the main drainage blind ditch 21 is 1.2m~1.5m, the height is 0.6m~0.8m, and the slope ratio is not less than 1%; the spacing between two adjacent branch drainage blind ditches 23 is 30m~40m, the width of the branch drainage blind ditch 23 is 0.6m~0.8m, the height is 0.4m~0.6m, and the slope ratio is not less than 0.5%.

[0021] like Figure 2 As shown, the sump 3 is arranged at equal intervals in the main drainage blind ditch 21 and the branch drainage blind ditch 23, and the main drainage perforated pipe 22 and the branch drainage perforated pipe 24 pass through the center position of the corresponding sump 3 to increase the collection area for the leachate.

[0022] Furthermore, the sump 3 is designed to be circular, with a diameter of 2m to 4m. The depth of the sump 3 is the same as the depth of the main drainage blind ditch 21, and the sump 3 is filled with pebbles with a particle size of φ20mm to 50mm.

[0023] In this embodiment, a sump 3 is provided at intervals of 40 m to 50 m in the main drainage blind ditch 21, and a sump 3 is provided at intervals of 30 m to 40 m in the branch drainage blind ditch 23.

[0024] like Figure 3 and Figure 4 As shown, the vertical drainage device 4 is arranged just above the center point of the corresponding water collection pit 3, and the vertical drainage device 4 includes a drainage vertical pipe 41, a horizontal fixed pipe 42, a plane water collection pit 43, a drainage branch ditch 44 and a drainage branch pipe 45. The plane water collection pit 43 is arranged on the top of the fly ash chelating solidification body 6 and anchored by the loess paving layer 5. The drainage vertical pipe 41 is vertically penetrated in the plane water collection pit 43, and the horizontal fixed pipe 42 is horizontally placed in the plane water collection pit 43 and passes through the drainage vertical pipe 41. A plurality of drainage branch ditches 44 are distributed around the plane water collection pit 43, and drainage branch pipes 45 are laid in the drainage branch ditches 44. The leachate collected by the drainage branch pipes 45 is collected in the plane water collection pit 43, and then drained to the water collection pit 3 by the drainage vertical pipe 41.

[0025] Furthermore, the drainage vertical pipe 41 is a HDPE pipe with a diameter of de200 to de250, and the length of the drainage vertical pipe 41 is 3 to 5 meters. The transverse fixing pipe 42 is a HDPE pipe with a diameter of de65 to de90, passes through a central opening about 10 to 20 cm below the top of the drainage vertical pipe 41, and is placed horizontally in the plane collection puddle 43, for transversely fixing the drainage vertical pipe 41 to prevent the drainage vertical pipe 41 from sinking downward.

[0026] In this embodiment, the plane collection puddle 43 is a circular structure with a diameter of 2m to 4m and a height of 0.3cm to 0.4cm. The bottom of the plane collection puddle 43 is paved with 200g / m 3The geotextile is used as a cushion layer, and a 1mm thick HDPE geomembrane is laid on the cushion layer. The geotextile and the HDPE geomembrane are folded and turned to the plane around the plane collection pit 43, waiting to be compacted and anchored with loess later. The inside of the plane collection pit 43 is filled with pebbles with a particle size of φ20mm to 50mm. The drainage vertical pipe 41 is vertically perforated to the top of the plane collection pit 43 during installation. The drainage vertical pipe 41 and the HDPE geomembrane perforated connection are connected by hot melt welding, and the drainage vertical pipe 41 is opened around the pipe above the HDPE geomembrane, with a hole size of 1cm and a hole spacing of 4cm to 6cm.

[0027] In this embodiment, the drainage branch ditch 44 is arranged around the plane sump 43 in a cross-shaped or cross-shaped distribution, and each drainage branch ditch 44 is 5m to 10m long, 0.5m to 0.8m wide, and 0.2m to 0.3m high. The bottom of each drainage branch ditch 44 is paved with a 0.5mm to 1.0mm HDPE geomembrane, and the loess paving layer 5 is anchored around the two sides of the geomembrane, and the drainage branch pipe 45 is laid in the geomembrane. The diameter of the drainage branch pipe 45 is de65 to de90, which is a semicircular pipe with an aperture size of 1cm and an aperture spacing of 5cm to 8cm. After the construction of the drainage branch pipe 45 is completed, the entire drainage branch ditch 44 is filled with pebbles with a particle size of φ20mm to 50mm, which is used to actively collect the drainage leachate. Four to six drainage branch ditches 44 can be set around each plane sump 43 according to the terrain.

[0028] In this embodiment, the vertical seepage guide device 4 is constructed during the landfill operation of the later solidified body. After the first layer of fly ash chelated solidified body 6 is stacked to the area directly above each sump 3, a vertical seepage guide device 4 is constructed synchronously during the landfill operation; during the landfill of the second layer of fly ash chelated solidified body 6, when the operation area advances to each plane sump 43 area on the top of the surface of the first layer of fly ash chelated solidified body 6, a vertical seepage guide device 4 is constructed synchronously. Similarly, during the landfill of the third layer of fly ash chelated solidified body 6, when the operation area advances to each plane sump 43 area on the top of the surface of the second layer of fly ash chelated solidified body 6, a vertical seepage guide device 4 is constructed synchronously, until the last layer of fly ash chelated solidified body 6 is landfilled on the top of the ash storage area, the vertical seepage guide device 4 is no longer needed.

[0029] A seepage main pipe plus branch pipe design is adopted at the bottom layer of the landfill, and sump pits 3 are set at certain intervals; when the second layer of fly ash chelated solidified body 6 is filled, there is no need to set up a drainage system in the same way as the first layer of fly ash chelated solidified body 6. It is only necessary to set up a vertical seepage guide device 4 at the top of the fly ash chelated solidified body 6 corresponding to the sump pit 3, and set up a plane sump pit 43 at the outlet of the drainage branch pipe 45 at the top of the first layer of fly ash chelated solidified body 6. Pebbles and geotextile materials are used to protect the pipeline outlet. The surrounding leachate can enter the drainage vertical pipe 41 through the plane sump pit 43, and enter the bottom layer through the gap outside the solidified body to finally complete the seepage; and by analogy, this method can be used for seepage guidance when each subsequent layer of solidified body is filled, and finally a complete drainage system is formed to ensure the safe and stable drainage of the leachate.

[0030] In this embodiment, a drainage method based on the above-mentioned leachate drainage system for fly ash solidification body landfill is also provided, comprising the following steps: Step S1, constructing an anti-seepage system 1, a main drainage device 2, a sump 3 and a leachate regulating tank 7 before the fly ash solidification body landfill is put into operation.

[0031] Step S2, stacking the fly ash chelate solidified body 6 on the main drainage device 2, laying a loess paving layer 5 on the top of the fly ash chelate solidified body 6 for leveling after each layer of the fly ash chelate solidified body 6 is stacked, and setting a vertical seepage guide device 4, which corresponds to the sump 3. When stacking to the top Nth layer, there is no need to set a vertical seepage guide device 4 on the top of the fly ash chelate solidified body 6.

[0032] Step S3, the leachate generated on the working surface of the first layer of fly ash chelating solidified body 6 is collected and drained through the main drainage device 2, and the leachate generated on the working surface of the second layer of fly ash chelating solidified body 6 is collected and drained through the vertical seepage guide device 4 on the top of the first layer of fly ash chelating solidified body 6, and converged to the sump 3; and so on, the leachate generated on the working surface of the Nth layer of fly ash chelating solidified body 6 is collected and drained through the vertical seepage guide device 4 on the top of the N-1th layer of fly ash chelating solidified body 6, and converged to the sump 3, and finally drained to the leachate regulating tank 7 for storage through the main drainage device 2.

[0033] In this embodiment, by setting up a vertical seepage guide device 4 in a local area of ​​the landfill area, the process is flexible, the construction requirements are simple, the construction period is short, and it does not affect the normal landfill operation. It can avoid the need for traditional planar seepage guide blind ditch to prepare a long construction period and vacant areas for independent construction during the construction of each layer of the plane, thereby reducing the impact on the landfill operation production.

[0034] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A leachate drainage system for fly ash solidification landfill, characterized in that: include: An anti-seepage system (1), a main drainage device (2), a sump (3), a vertical seepage guide device (4) and a leachate regulating tank (7); the anti-seepage system (1) is arranged at the bottom of a fly ash solidified body landfill, the main drainage device (2) is arranged on the anti-seepage system (1), and the main drainage device (2) is connected to the leachate regulating tank (7), a plurality of sump pits (3) are arranged in the main drainage device (2), fly ash chelate solidified bodies (6) are arranged and stacked on the main drainage device (2), and after each layer of fly ash chelate solidified bodies (6) is stacked, a loess paving layer (5) is laid on top of the fly ash chelate solidified bodies (6) for leveling, and a vertical seepage guide device (4) is arranged on top of the fly ash chelate solidified bodies (6) corresponding to the sump (3); In the fly ash solidification body landfill, the leachate generated by the working surface of the first layer of fly ash chelating solidification body (6) is collected and drained through the main drainage device (2), and the leachate generated by the working surface of the second layer of fly ash chelating solidification body (6) is collected and drained through the vertical seepage guide device (4) on the top of the first layer of fly ash chelating solidification body (6) and converged into the sump (3); and by analogy, the leachate generated by the working surface of the Nth layer of fly ash chelating solidification body (6) is collected and drained through the vertical seepage guide device (4) on the top of the N-1th layer of fly ash chelating solidification body (6) and converged into the sump (3), and finally drained through the main drainage device (2) to the leachate regulating tank (7) for storage.

2. The leachate drainage system for fly ash solidification landfill according to claim 1, characterized in that: The main drainage device (2) comprises a main drainage blind ditch (21), a main drainage perforated pipe (22), a branch drainage blind ditch (23), a branch drainage perforated pipe (24) and a main drainage solid pipe (25); the main drainage blind ditch (21) and the branch drainage blind ditch (23) are both arranged on the top of the anti-seepage system (1), a plurality of branch drainage blind ditches (23) are distributed on both sides of the main drainage blind ditch (21), the main drainage perforated pipe (22) is laid in the main drainage blind ditch (21), the branch drainage perforated pipe (24) is laid in the branch drainage blind ditch (23), and one end of the branch drainage perforated pipe (24) is connected to the main drainage perforated pipe (22), and the main drainage perforated pipe (22) is connected to the leachate regulating tank (7) via the main drainage solid pipe (25).

3. The leachate drainage system for fly ash solidification landfill according to claim 2, characterized in that: Two main drainage perforated pipes (22) are symmetrically arranged in the main drainage blind ditch (21), and one side of the main drainage perforated pipe (22) is connected to the branch drainage perforated pipe (24); the main drainage perforated pipe (22) and the branch drainage perforated pipe (24) are both semicircular perforated pipes, and the main drainage perforated pipe (22) and the branch drainage perforated pipe (24) are covered with pebbles and wrapped with geotextile as a geotextile filter.

4. The leachate drainage system for fly ash solidification landfill according to claim 3, characterized in that: The main drainage blind ditch (21) has a width of 1.2m to 1.5m, a height of 0.6m to 0.8m, and a slope ratio of not less than 1%; the spacing between two adjacent branch drainage blind ditches (23) is 30m to 40m, and the branch drainage blind ditch (23) has a width of 0.6m to 0.8m, a height of 0.4m to 0.6m, and a slope ratio of not less than 0.5%.

5. The leachate drainage system for fly ash solidification landfill according to claim 4, characterized in that: The water collection pits (3) are arranged at equal intervals in the main drainage blind ditch (21) and the branch drainage blind ditch (23), and the main drainage perforated pipe (22) and the branch drainage perforated pipe (24) pass through the center position of the corresponding water collection pit (3).

6. The leachate drainage system for fly ash solidification landfill according to claim 5, characterized in that: The depth of the water collection pit (3) is the same as the depth of the main drainage blind ditch (21), and the interior of the water collection pit (3) is filled with pebbles.

7. The leachate drainage system for fly ash solidification landfill according to claim 5, characterized in that: A water collection pit (3) is provided at intervals of 40 m to 50 m in the main drainage blind ditch (21), and a water collection pit (3) is provided at intervals of 30 m to 40 m in the branch drainage blind ditch (23).

8. The leachate drainage system for fly ash solidification landfill according to claim 5, characterized in that: The vertical seepage guiding device (4) comprises a drainage vertical pipe (41), a transverse fixed pipe (42), a plane collecting water pit (43), a drainage branch ditch (44) and a drainage branch pipe (45); the plane collecting water pit (43) is arranged on the top of the fly ash chelating solidified body (6) and is anchored by a loess paving layer (5); the drainage vertical pipe (41) is vertically penetrated in the plane collecting water pit (43); the transverse fixed pipe (42) is horizontally placed in the plane collecting water pit (43) and passes through the drainage vertical pipe (41); a plurality of drainage branch ditches (44) are distributed around the plane collecting water pit (43); the drainage branch pipe (45) is laid in the drainage branch ditch (44); the leachate collected by the drainage branch pipe (45) is collected in the plane collecting water pit (43) and then drained into the water collecting pit (3) by the drainage vertical pipe (41).

9. The leachate drainage system for fly ash solidification landfill according to claim 8, characterized in that: The bottom of the planar collection pit (43) is paved with a geotextile as a cushion layer, and a HDPE geomembrane is laid on the cushion layer. The geotextile and the HDPE geomembrane are folded and turned to the plane around the planar collection pit (43). The inside of the planar collection pit (43) is filled with pebbles. When installed, the drainage vertical pipe (41) is vertically perforated to the top of the planar collection pit (43). The perforated connection between the drainage vertical pipe (41) and the HDPE geomembrane is welded and sealed, and holes are opened around the pipe located above the HDPE geomembrane in the drainage vertical pipe (41).

10. A drainage method for leachate drainage system for fly ash solidification landfill based on any one of claims 1 to 9, characterized in that: The following steps are involved: Step S1, constructing an anti-seepage system (1), a main drainage device (2), a sump (3) and a leachate regulating tank (7) before the fly ash solidification body landfill is put into operation; Step S2, stacking the fly ash chelate solidified body (6) on the main drainage device (2), laying a loess paving layer (5) on the top of the fly ash chelate solidified body (6) for leveling after each layer of the fly ash chelate solidified body (6) is stacked, and a vertical seepage guide device (4) is provided, wherein the vertical seepage guide device (4) corresponds to the sump (3); Step S3, the leachate generated on the working surface of the first layer of fly ash chelating solidified body (6) is collected and drained through the main drainage device (2), and the leachate generated on the working surface of the second layer of fly ash chelating solidified body (6) is collected and drained through the vertical seepage guide device (4) on the top of the first layer of fly ash chelating solidified body (6), and then flows into the sump (3); by analogy, the leachate generated on the working surface of the Nth layer of fly ash chelating solidified body (6) is collected and drained through the vertical seepage guide device (4) on the top of the N-1th layer of fly ash chelating solidified body (6), and then flows into the sump (3), and finally drained into the leachate regulating tank (7) for storage through the main drainage device (2).

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