Method for managing and controlling fissure water infiltration of landfill in karst landform area

Abstract

The invention discloses a karst landform area landfill fissure water infiltration management and control method which comprises the following steps: exploring a landfill, and determining the position of a mountain karst fissure; a horizontal flow guide tunnel is built on the periphery, close to the mountain karst fissure side, of the landfill; water collecting holes are formed in the horizontal flow guide tunnel; and a leachate pumping and draining well is built in the landfill close to one side of the horizontal diversion tunnel. According to the karst landform area landfill fissure water infiltration management and control method, underground water on the two sides is effectively controlled to infiltrate into the landfill in a planar mode through the mountain karst fissures, the construction investment is greatly saved, the construction difficulty is low, and the construction period is short.

Description

Technical Field

[0001] The invention relates to a method for controlling fissure water infiltration in a landfill in a karst landform area, and belongs to the technical field of pollution control. Background Art

[0002] Landfills are the main disposal facilities for domestic garbage and industrial solid waste. They are widely used because of their advantages such as less earth excavation, large landfill capacity, and low construction costs. In the early days, my country's landfills were mainly based on clay anti-seepage and simple landfill. In the mid-to-late 1990s, the country began to require HDPE membrane anti-seepage on a large scale. Due to irregular site selection and construction, irregular operation and management, the anti-seepage system and leachate drainage system of many landfills have long been ineffective. Pollutants in the landfills spread to the surrounding areas through surface water and groundwater, causing serious environmental pollution. Especially in karst landform areas, underground karst fissures are developed. For valley-type landfills, in addition to entering the landfill through the upstream, surface infiltration through the karst fissures on both sides of the mountain is also one of the main ways for groundwater to enter and exit the landfill, which greatly increases the difficulty of landfill pollution control.

[0003] Patent CN115652974A discloses a pollution control system and construction method for a valley-type landfill, including: a composite barrier wall in the heavily polluted area at the valley mouth, a self-gravity leachate collection and drainage device, an upstream rigid groundwater barrier and anti-seepage area, and a midstream rigid groundwater barrier and anti-seepage area. Combined with the characteristics of the valley-type landfill, a composite barrier wall is used in the low-lying valley mouth heavily polluted area, and a high-pressure rotary spraying and grouting curtain combined anti-seepage structure is used in the direction of groundwater inflow, which can control the pollution leaked from the valley-type landfill or the existing pollution hazards in an independent area. The barrier wall described in this method needs to be deep enough to reach the medium-weathered and slightly weathered rock layers, which is difficult to produce a good control effect in karst areas.

[0004] Patent CN109056764A discloses a composite anti-seepage wall and its construction method for landfill environmental protection in soft soil areas. The flexible core wall of HDPE film is set around the landfill. The depth of the flexible core wall extends from the surface to the impermeable layer, completely wrapping the landfill. The transition zone between the inner side of the flexible core wall and the landfill is equipped with groundwater pumping wells to control the groundwater level of the landfill. This method also requires the flexible core wall to be deeply embedded in the impermeable layer and surround the landfill. It is difficult to implement in karst areas and the cost is high.

[0005] Patent CN214253279U discloses a three-dimensional risk control system for soil contaminated sites, including a lower aquiclude, a vertical barrier layer, a surface covering anti-seepage layer, and a long-term groundwater monitoring well; Patent CN217443338U discloses an efficient soil and groundwater risk control system, including a bottom aquiclude, a vertical barrier layer, a horizontal covering layer, a groundwater monitoring well and a PRB mechanism. The above method focuses on the discussion of the original facilities when the landfill is newly built, rather than the isolation of the groundwater pollution system of the existing valley-type landfill with pollution and potential pollution hazards.

[0006] Therefore, it is necessary to conduct in-depth research on the existing landfill fissure water infiltration control methods to solve the above problems. Summary of the invention

[0007] In order to overcome the above problems, in-depth research was conducted and a method for controlling the infiltration of fissure water in landfills in karst landform areas was designed, which includes the following steps:

[0008] S1. Exploring the landfill site to determine the location of karst fissures in the mountain;

[0009] S2. Build a horizontal diversion tunnel on the periphery of the landfill near the karst fissure side of the mountain;

[0010] S3. Establish water collection holes on the horizontal diversion tunnel;

[0011] S4. Establish a leachate drainage well in the landfill near the horizontal diversion tunnel.

[0012] In a preferred embodiment, in S2, the horizontal diversion tunnel is located in the mountain, and the horizontal diversion tunnel is established along the boundary of the landfill and is within a certain range of distance from the boundary of the landfill.

[0013] In a preferred embodiment, the horizontal distance between the horizontal diversion tunnel and the landfill boundary is not less than 10 m.

[0014] In a preferred embodiment, the bottom elevation of the highest point of the horizontal diversion tunnel is consistent with the highest point of the bottom elevation of the landfill in the horizontal direction.

[0015] In a preferred embodiment, in S3, the water collection hole is arranged directly above the horizontal diversion tunnel, and the lower end of the water collection hole penetrates the top of the horizontal diversion tunnel.

[0016] In a preferred embodiment, the diameter of the water collection hole is 80-150 mm.

[0017] In a preferred embodiment, the top of the water collection hole is sealed.

[0018] In a preferred embodiment, the interior of the water collection hole is supported by a PVC flower pipe or a sandless concrete pipe.

[0019] In a preferred embodiment, in S4, the leachate drainage well is preferably a radial well.

[0020] In a preferred embodiment, the depth of the leachate drainage well exceeds the burial depth of the landfill waste.

[0021] The beneficial effects of the present invention include:

[0022] (1) Effectively control the infiltration of groundwater on both sides into the landfill through the karst fissures in the mountain, which greatly saves construction investment compared with conventional curtain grouting solutions;

[0023] (2) By setting up a leachate extraction well in the landfill near the side of the horizontal diversion tunnel, the spillover of pollutants in the landfill can be prevented from polluting the clean water in the mountain karst fissure water collection and drainage system. At the same time, the collection rate of leachate in the landfill can be increased, and the amount of pollutants released in the landfill can be reduced;

[0024] (3) Compared with conventional curtain grouting solutions, the construction difficulty is low and the construction period is short. It can save more than 40% of the project cost and reduce the unit pollutant control cost by more than 10%. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of a method for controlling groundwater pollution in a landfill in a karst landform region according to a preferred embodiment of the present invention is shown;

[0026] Figure 2 A schematic diagram of groundwater pollution control in a landfill in a karst landform area in Example 1 is shown. DETAILED DESCRIPTION

[0027] The present invention will be further described in detail below through the accompanying drawings and embodiments. Through these descriptions, the characteristics and advantages of the present invention will become more clear and distinct.

[0028] The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise noted.

[0029] According to the method for controlling the infiltration of fissure water in a landfill in a karst landform area provided by the present invention, Figure 1 As shown, the following steps are included:

[0030] S1. Exploring the landfill site to determine the location of karst fissures in the mountain;

[0031] S2. Build a horizontal diversion tunnel on the periphery of the landfill near the karst fissure side of the mountain;

[0032] S3. Establish water collection holes on the horizontal diversion tunnel;

[0033] S4. Establish a leachate drainage well in the landfill near the horizontal diversion tunnel.

[0034] Karst landform areas have well-developed karst fissures in the mountains. The existing management idea for landfills in karst landform areas is to enclose the pollution inside, generally using a fully enclosed curtain approach, that is, curtains are set up around and at the bottom of the landfill. This method is costly, complex to construct, and has a long construction period, and can only be applied to newly built landfills. There is no good management method for existing landfills in karst landform areas.

[0035] The leachate generated by the landfill is the main pollutant. The inventors found that the leachate generated by the solid waste in the landfill itself is relatively small, but the groundwater will come into contact with the solid waste after entering the landfill, which will produce a large amount of leachate. After the leachate seeps out, it will enter the groundwater and then pollute the groundwater. Due to the fluidity of the groundwater, it will cause large-scale pollution leakage. In the present invention, for the valley-shaped landfill, the traditional enclosure method is abandoned, and a diversion tunnel is established to collect and guide the groundwater out, thereby avoiding the contact between the groundwater and the solid waste in the landfill, thereby reducing the generation of leachate and achieving the effect of preventing pollution.

[0036] Furthermore, since there is no need to build a curtain, the construction investment can be greatly saved, the construction difficulty is low, the construction period is short, the maintenance difficulty is reduced, and the management and control stability is improved.

[0037] In addition, this method is suitable for the transformation of existing landfills in karst areas, solving the problem of high difficulty in handling existing valley-type landfills with pollution and potential pollution risks, and can effectively reduce the pollution of karst landfills to the surrounding environment.

[0038] In S2, the horizontal diversion tunnel is located in the mountain. Preferably, the horizontal diversion tunnel is established along the landfill boundary and is within a certain range of distance from the landfill boundary, so that the landfill horizontal diversion tunnel is roughly parallel to the landfill boundary.

[0039] In a preferred embodiment, the horizontal distance between the horizontal diversion tunnel and the landfill boundary is not less than 10 m, so as to avoid the phenomenon of leachate from the slag field contaminating the tunnel water collection.

[0040] In a preferred embodiment, the bottom elevation of the highest point of the horizontal diversion tunnel is consistent with the highest point of the bottom elevation of the landfill in the horizontal direction, so as to prevent the leachate from the slag field from polluting the tunnel water collection. Specifically, if the bottom elevation of the highest point of the horizontal diversion tunnel is lower than the highest point of the bottom elevation of the landfill in the horizontal direction, the leachate from the slag field will pollute the tunnel water collection; if it is higher than the highest point of the bottom elevation of the landfill in the horizontal direction, groundwater will pass through the bottom of the tunnel into the slag field.

[0041] Furthermore, the horizontal diversion tunnel extends from the highest point to the downstream or both ends, and the bottom elevation of the horizontal diversion tunnel outlet is consistent with the surface elevation, so that the water in the horizontal diversion tunnel can flow out of the tunnel by gravity. More preferably, the water flowing out of the horizontal diversion tunnel is connected to the flood interception ditch or drainage channel of the landfill and discharged using the existing facilities of the landfill.

[0042] In a preferred embodiment, the inner wall of the horizontal diversion tunnel is provided with a waterproof lining to prevent water from penetrating from the horizontal diversion tunnel into the landfill.

[0043] In the present invention, the specific construction method of the waterproof lining is not limited, and those skilled in the art can freely choose according to actual needs.

[0044] In S3, the water collecting hole is arranged directly above the horizontal diversion tunnel, and the lower end of the water collecting hole penetrates the top of the horizontal diversion tunnel. The infiltration water passing through the top of the horizontal diversion tunnel is collected through the water collecting hole and diverted into the horizontal diversion tunnel.

[0045] Preferably, the water collecting holes are arranged vertically to achieve better flow diversion.

[0046] In a preferred embodiment, the diameter of the water collection hole is 80-150 mm.

[0047] According to practical experience, if the diameter of the water collection hole is too small, it will affect the water collection effect. If the diameter is too large, it will place high requirements on the strength of the construction machinery, supporting materials and the top of the horizontal tunnel, which is not conducive to construction.

[0048] In a preferred embodiment, the top of the water collection hole is sealed to prevent debris from entering the horizontal diversion tunnel and causing blockage.

[0049] In a preferred embodiment, the side wall of the water collection hole is supported by a PVC flower pipe or a sandless concrete pipe to improve the strength of the water collection hole.

[0050] Since there are holes on the PVC flower pipe and the sandless concrete pipe is not waterproof, this setting can achieve the effect of improving the supporting strength without affecting the water collection effect.

[0051] In the present invention, the spacing and number of the water collection holes are determined according to the geological conditions. The spacing of the water collection holes is their influence radius, preferably 3 to 5 meters, so that all water in the karst fissures of the mountain can be introduced into the horizontal diversion tunnel.

[0052] In S4, the leachate drainage well is preferably a radial well.

[0053] The radial well is a commonly used well, and its structure is not described in detail in the present invention.

[0054] In a preferred embodiment, the depth of the leachate drainage well exceeds the burial depth of the landfill waste, preferably exceeds the burial depth of the landfill waste by 0-5 meters.

[0055] In a preferred embodiment, the liquid level in the leachate extraction well is controlled to be consistent with the buried depth of the waste, and the extracted leachate is discharged into a leachate treatment station for treatment.

[0056] By setting up a leachate drainage well, the seepage liquid near the horizontal diversion tunnel side can be drained away, which can prevent the reverse infiltration of the seepage liquid into the horizontal diversion tunnel and prevent the spread of pollution.

[0057] In a preferred embodiment, the start and stop of the leachate pumping well is automatically controlled by liquid level, and does not need to be kept open, thus saving energy and increasing the life of the equipment.

[0058] In a preferred embodiment, a soaking zone drainage well is provided in the landfill for extracting the permeate generated by the solid waste itself in the landfill and rainwater and the like.

[0059] In a preferred embodiment, a channel radiation drainage well is provided in the landfill, and the channel radiation drainage well is arranged along the original terrain and water flow direction of the landfill. This area is the manganese slag field seepage liquid collection area, which is easy to collect the seepage liquid and prevent the seepage liquid from flowing downward.

[0060] Example 1

[0061] The groundwater pollution control is carried out on a landfill in a karst landform area. The landfill in the karst landform area is a gully-type landfill. Figure 2 As shown, the control includes the following steps:

[0062] S1. Exploring the landfill site to determine the location of karst fissures in the mountain;

[0063] S2. Build a horizontal diversion tunnel on the periphery of the landfill near the karst fissure side of the mountain;

[0064] S3. Establish water collection holes on the horizontal diversion tunnel;

[0065] S4. Establish a leachate drainage well in the landfill near the horizontal diversion tunnel.

[0066] In S2, the horizontal distance between the horizontal diversion tunnel and the landfill boundary is not less than 10m, the bottom elevation of the highest point of the horizontal diversion tunnel is consistent with the highest point of the bottom elevation of the landfill in the horizontal direction, the horizontal diversion tunnel extends from the highest point downstream or at both ends, the bottom elevation of the horizontal diversion tunnel exit is consistent with the ground elevation, and the inner wall of the horizontal diversion tunnel is provided with a waterproof lining.

[0067] In S3, the water collection hole is arranged directly above the horizontal diversion tunnel, the lower end of the water collection hole penetrates the top of the horizontal diversion tunnel, the aperture of the water collection hole is 80-150 mm, and the interior of the water collection hole is supported by a sandless concrete pipe.

[0068] In S4, the leachate pumping well is a radial well, the controlled liquid level in the leachate pumping well is consistent with the buried depth of the waste, and the start and stop of the leachate pumping well is automatically controlled by the liquid level.

[0069] Through actual construction and accounting, compared with the use of curtain grouting to block water seepage in mountain karst fissures, it can save more than 40% of engineering costs and reduce the unit pollutant control cost by more than 10%;

[0070] By setting up a leachate drainage well in the landfill near the side of the horizontal diversion tunnel, the overflow of pollutants in the landfill can be avoided to pollute the clean water in the mountain karst fissure water collection and drainage system. At the same time, the collection rate of leachate in the landfill can be increased and the release of pollutants in the landfill can be reduced.

[0071] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "front", "rear", etc. indicate positions or positional relationships based on the working state of the present invention, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", and "fourth" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0072] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0073] The present invention has been described above in conjunction with preferred embodiments, but these embodiments are only exemplary and serve only as an illustration. On this basis, the present invention may be subjected to a variety of substitutions and improvements, all of which fall within the scope of protection of the present invention.

Claims

1. A method for controlling the infiltration of fissure water in a landfill in a karst landform region, characterized in that: The following steps are involved: S1. Exploring the landfill site to determine the location of karst fissures in the mountain; S2. Build a horizontal diversion tunnel on the periphery of the landfill near the karst fissure side of the mountain; S3. Establish water collection holes on the horizontal diversion tunnel; S4. Establish a leachate drainage well in the landfill near the horizontal diversion tunnel.

2. The method for controlling the infiltration of fissure water in a landfill in a karst landform area according to claim 1, characterized in that: In S2, the horizontal diversion tunnel is located in the mountain, and the horizontal diversion tunnel is established along the boundary of the landfill and is within a certain range from the boundary of the landfill.

3. The method for controlling the infiltration of fissure water in a landfill in a karst landform area according to claim 1, characterized in that: The horizontal distance between the horizontal diversion tunnel and the landfill boundary is not less than 10m.

4. The method for controlling the infiltration of fissure water in a landfill in a karst landform area according to claim 1, characterized in that: The bottom elevation of the highest point of the horizontal diversion tunnel is consistent with the highest point of the bottom elevation of the landfill in the horizontal direction.

5. The method for controlling the infiltration of fissure water in a landfill in a karst landform area according to claim 1, characterized in that: In S3, the water collection hole is arranged directly above the horizontal diversion tunnel, and the lower end of the water collection hole penetrates the top of the horizontal diversion tunnel.

6. The method for controlling the infiltration of fissure water in a landfill in a karst landform area according to claim 1, characterized in that: The diameter of the water collection hole is 80-150 mm.

7. The method for controlling the infiltration of fissure water in a landfill in a karst landform area according to claim 1, characterized in that: The top of the water collection hole is sealed.

8. The method for controlling the infiltration of fissure water in a landfill in a karst landform area according to claim 1, characterized in that: The water collection hole is supported by a PVC flower pipe or a sand-free concrete pipe.

9. The method for controlling the infiltration of fissure water in a landfill in a karst landform area according to claim 1, characterized in that: In S4, the leachate drainage well is preferably a radial well.

10. The method for controlling the infiltration of fissure water in a landfill in a karst landform area according to claim 1, characterized in that: The depth of the leachate drainage well exceeds the burial depth of the landfill waste.

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