A method for fixing the seepage prevention transition section on an irregular rock slope in a mine landfill.

Abstract

This invention discloses a method for fixing a seepage-proof transition section on an irregular rock slope in a mine landfill. A seepage-proof cementitious composite sprayed material is wet-sprayed onto the irregular rock slope (1-2), forming a seepage-proof cementitious composite sprayed material layer (2) on the surface of the seepage-proof transition section. A seepage-proof geomembrane (3) is laid from the regular rock slope (1-1), and then rubber pads (7) and thin steel plates (6) are laid on the geomembrane (3) from the inside out. Hollow grouting anchors (4) are self-drilled through the holes in the thin steel plates (6) and rubber pads (7), and the edges are trimmed with a seepage-proof sealing agent (8). This invention is applied to the reinforcement of seepage-proof transition sections on irregular rock slopes in mine landfills, overcoming the problem of easy damage during the fixing process of seepage-proof transition sections on irregular rock slopes, eliminating potential hazards, and improving the safety and reliability of the seepage-proof system. It not only has good economic benefits but also significant safety and environmental benefits.

Description

Technical Field

[0001] This invention belongs to the field of mine pit slope seepage prevention technology, specifically relating to a reinforcement method for the seepage prevention transition section of an irregular rock slope in a mine pit landfill. It can be widely used in mine pit slope seepage prevention, and is particularly suitable for slope seepage prevention in abandoned mine pits used as solid waste landfills. Background Technology

[0002] The mine pit seepage prevention system consists of two parts: base seepage prevention and slope seepage prevention. The main function of the seepage prevention system is to prevent leachate from seeping in and avoid secondary pollution. Its role in protecting the overall ecological environment of the mine pit and its surroundings cannot be ignored.

[0003] Mine pit seepage prevention systems often use geomembranes as the seepage lining, with protective layers installed above and below according to the slope's undulation. Base seepage prevention can effectively address the issue of base flatness through site preparation, ensuring the safety and reliability of the geomembrane installation. However, due to previous mining activities, slopes often exhibit irregular shapes with significant undulations. Directly laying the geomembrane on these irregular slopes creates stress concentration areas, and the lateral pressure from accumulated solid waste during landfill operation causes seepage damage, which is highly concealed and incurs high repair costs.

[0004] Currently, various new types of seepage-proof materials are being applied to mine pit slope seepage prevention. For example, new cementitious materials, used in conjunction with geomembranes, have solved the problems of high difficulty and low reliability in seepage prevention on irregular rock slopes. Chinese patent application 202411113707.3 discloses a mine pit steep slope seepage prevention system based on polymeric mineral seepage-proof materials, which uses an outer geocell filled with polymeric mineral seepage-proof materials, while the inner geocell is filled with graded pebbles. Chinese patent CN112523264A uses shotcrete with mesh before laying to level and passivate the slope base, which has problems such as high construction costs, high difficulty, and significant hidden dangers in the shotcrete layer. Chinese patent CN217782093U requires slope treatment to improve the anti-slip stability of the protective structure and the geomembrane, which has problems such as complex construction technology, high excavation difficulty, and slope disturbance and instability.

[0005] The method of fixing the seepage prevention transition section is very important to the safety and reliability of the landfill seepage prevention system. To date, there is no unified standard for the method of fixing the transition section, and the single steel bar slope fixing method is often used. This method is prone to damage to the seepage prevention body of the transition section and has significant potential hidden dangers. Summary of the Invention

[0006] The purpose of this invention is to address the technical challenges of fixing the seepage transition section in current methods, such as high construction difficulty, high construction cost, easy damage to the seepage barrier body of the transition section, and potential hidden risks. The invention provides a convenient, economical, effective, safe and reliable method for fixing the seepage transition section on the irregular rock slope of a mine landfill.

[0007] To achieve the above-mentioned objectives of this invention, the present invention provides a method for fixing a seepage-proof transition section on an irregular rock slope in a mine landfill. The seepage-proof transition section is divided by a seepage-proof boundary line, with one side of the boundary line being an irregular rock slope and the other side being a regular rock slope. The method is implemented using the following steps:

[0008] S1 seepage-proof gelled composite spray filler preparation

[0009] A seepage-proof cementitious composite spray filler is prepared by mixing and configuring solidified cementitious material, building sand / tailings sand and water. When the total mass of the seepage-proof cementitious composite spray filler is 100%, the proportion of each component is: solidified cementitious material 19%~26%, building sand / tailings sand 53%~62%, and water 16%~21%.

[0010] S2 seepage-proof gelling composite spray filler wet spraying

[0011] The impermeable cementitious composite sprayed filler prepared in step S1 is wet-sprayed onto the irregular rock slope, and the wet spraying is extended to the regular rock slope on the other side of the impermeable boundary for a length of L1, thereby forming an impermeable cementitious composite sprayed filler layer on the surface of the impermeable transition section; the surface of the impermeable cementitious composite sprayed filler layer sprayed on the irregular rock slope is uniform and straight, and the thickness of the impermeable cementitious composite sprayed filler layer sprayed in the L1 length section transitions smoothly until 0.

[0012] S3 impermeable geomembrane laying

[0013] The impermeable geomembrane is laid on the regular rock slope and extended along the impermeable boundary line to the irregular rock slope for a length of L2. The impermeable cementitious composite sprayed filler layer and the two-way extension section of the impermeable geomembrane form an overlap section.

[0014] S4 rubber pads, thin steel plate laying and fixing

[0015] According to the designed hole diameter and spacing, holes are drilled in the rubber pad and thin steel plate respectively. Then, the rubber pad and thin steel plate are laid on the impermeable geomembrane from the inside out, with the drilled holes on the rubber pad and thin steel plate corresponding to each other. The hollow grouting anchor rod is drilled into the rock in the impermeable cementitious composite sprayed filler layer by self-drilling through the drilled holes in the thin steel plate and rubber pad, with the rock inclination angle being α and the rock penetration depth being La.

[0016] S5 anti-seepage and leak-stopping agent trimming

[0017] After the hollow grouting anchor is fixed, the excess part of the extended section of the impermeable geomembrane is cut off. The gaps between the thin steel plate, rubber pad, impermeable geomembrane and impermeable cementitious composite sprayed filler layer are filled and bonded with an impermeable sealant. The impermeable sealant is then evenly applied around the perimeter of the thin steel plate.

[0018] Generally, the solidified cementitious material used in step S1 is the solidified cementitious material for tailings backfilling. It is prepared according to the "Standard for Pollution Control of Storage and Landfill of General Industrial Solid Waste" (GB 18599-2020) to form a seepage-proof cementitious composite spray filler with the specified seepage-proof effect. The experimental results show that for Class I landfills with specified seepage-proof standards, the best effect is achieved when the mass ratio of solidified cementitious material, construction sand / tailings sand and water is 1:3:1.

[0019] Preferably, the curing cementitious material used in step S1 is a mixture of stabilizer, composite powder, water glass, and cement. The content of each component when the total mass is calculated as 100% is as follows: stabilizer 9%–15%, composite powder 9%–15%, water glass 28%–45%, and cement 28%–47%. The stabilizer is composed of calcium chloride 50%–60% and sodium borate tetrahydrate 40%–50% by mass percentage. The composite powder is a mixture of calcium carbide slag powder, desulfurized gypsum, fly ash, and blast furnace slag, and is composed of calcium carbide slag powder 29%–37%, desulfurized gypsum 15%–20%, fly ash 19%–24%, and blast furnace slag 20%–26% by mass percentage.

[0020] Preferably, the construction sand / tailings sand used in step S1 is medium sand, with particles larger than 0.25 mm accounting for more than 50% of the total weight, and an average particle size of 0.5 mm to 0.25 mm.

[0021] Preferably, in step S2, the thickness of the impermeable cementitious composite spray filler layer formed by wet spraying on the irregular rock slope is δ = 5cm to 15cm, and the wet spraying length on the regular rock slope is L1 = 1.0m to 2.0m.

[0022] Preferably, in step S3, in accordance with the anti-seepage effectiveness requirements of the "Standard for Pollution Control of Storage and Landfill of General Industrial Solid Waste" (GB18599-2020), the laid anti-seepage geomembrane is an HDPE geomembrane with a specification of 1.5mm to 2.0mm and an extended laying length L2 = 0.8m to 1.5m.

[0023] Preferably, in step S4, the hollow grouting anchor rod is a full-length corrugated thread, equipped with a fixing nut and a special quick grouting connector. The specification of the hollow grouting anchor rod is R20~25, the drilling depth into the rock is La = 50cm~1.5m, the plane spacing of the drill holes along the axial direction is M = 30cm~50cm, and the rock inclination angle of the hollow grouting anchor rod is α = 15°~25°. The nut is matched with the specification of the hollow grouting anchor rod, and the nut specification is M16~M20.

[0024] Preferably, in step S4, the thin steel plate is a steel plate with a thickness of less than 3mm, a size of 2mm to 3mm, a width B of 30cm to 50cm, an axial length L3 of 1 to 2m, and pre-drilled holes on the surface. The hole diameter matches the specifications of the hollow grouting anchor rod, the hole spacing M2 of 30cm to 50cm, and a rubber pad is placed inside. The rubber pad is a high-pressure resistant rubber pad with a thickness of 3mm to 5mm.

[0025] Preferably, in step S5, the seepage-proofing and leak-stopping agent is an inorganic waterproof and leak-stopping material with the code FDⅡGB23440-2009.

[0026] The present invention provides a method for fixing a seepage-proof transition section on an irregular rock slope in a mine landfill. After adopting the above technical solution, the method exhibits the following positive effects:

[0027] (1) The present invention improves the stability of the transition section fixing structure by forming an overlapping section through the bidirectional extension of the novel impermeable geomembrane cementitious extension, and has the advantages of strong operability and reliable construction.

[0028] (2) The present invention utilizes the anchoring stability of the hollow grouting anchor rod and the padding effect of the high pressure resistant rubber pad to form a fixed structure with good airtightness, thereby improving the safety and stability of the seepage prevention transition section.

[0029] (3) The impermeable cementitious composite spray filler developed in this invention fully utilizes the chemical properties of fine-grained minerals in tailings sand. Under the action of added compounds, it forms a water-impermeable polymeric gel through physical and chemical reactions. This polymer does not react chemically with acids, alkalis, or other salts, and has good workability and extremely low permeability, only 1 / 3000 that of high-quality clay. The permeability coefficient can reach k = 0.3 × 10⁻⁶. -9 .

[0030] (4) The anti-seepage cementitious composite spray filler developed in this invention has good acid and alkali resistance, strong stability, high consolidation strength, is easy to construct and lay, has high spraying efficiency, and does not require compaction.

[0031] (5) The anti-seepage gelling composite spray filler developed in this invention effectively endows the slurry with good coagulation characteristics and mechanical properties, with a 28-day strength greater than 20MPa.

[0032] (6) The solidified cementitious material developed in this invention and the tailings sand used are both industrial solid wastes. They do not require secondary calcination. The production process is simple, environmentally friendly, and requires less investment, which reduces the carbon emissions and energy consumption of traditional cementitious material clinker calcination.

[0033] (7) This invention is applied to the reinforcement of the seepage prevention transition section of the irregular rock slope in the mine landfill. It overcomes the problem of easy damage during the fixing process of the seepage prevention transition section of the irregular rock slope. It not only has good economic benefits, but also significant safety and environmental protection benefits. Attached Figure Description

[0034] Figure 1 This is a plan view of a method for fixing a seepage-proof transition section on an irregular rock slope in a mine landfill, according to the present invention.

[0035] Figure 2 A cross-sectional view of a method for fixing a seepage-proof transition section on an irregular rock slope in a mine landfill.

[0036] Figure labels: 1-1—Regular rock slope; 1-2—Irregular rock slope; 2—Impering cementitious composite sprayed filler layer; 3—Impering geomembrane; 4—Hollow grouting anchor; 5—Nut; 6—Thin steel plate; 7—Rubber pad; 8—Impering and plugging agent; 9—Impering boundary. Detailed Implementation

[0037] To better describe the present invention, the following describes in further detail, with reference to the accompanying drawings, a method for fixing a seepage-proof transition section on an irregular rock slope in a mine landfill.

[0038] In the embodiment, after the solid waste landfill in an abandoned mine pit was filled to a relative elevation of 15m, the area of ​​the irregular rock slope surface accounted for about 20%. A new type of impermeable cementitious material and HDPE geomembrane were used for combined impermeability. The transition section between the two impermeable materials was fixed by a single steel bar slope. During operation, the impermeable membrane in the transition section was damaged, and effective engineering measures were urgently needed for treatment or remediation.

[0039] Depend on Figure 2 The diagram shown is a cross-sectional view of a method for fixing a seepage-proof transition section on an irregular rock slope in a mine landfill, according to the present invention, and is combined with... Figure 1 It can be seen that the seepage prevention transition section is divided by the seepage prevention boundary line 9. One side of the seepage prevention boundary line 9 is an irregular rock slope 1-2, and the other side of the seepage prevention boundary line 9 is a regular rock slope 1-1. In this embodiment, the method for fixing the seepage prevention transition section of the irregular rock slope in a mine landfill according to the present invention is implemented by the following steps:

[0040] S1 seepage-proof gelled composite spray filler preparation

[0041] According to the "Standard for Pollution Control of Storage and Landfill of General Industrial Solid Waste" (GB 18599-2020), tailings backfilling gelling agent, medium sand, and water are mixed to prepare a seepage-proof gelling composite spraying filler. When the total mass of the seepage-proof gelling composite spraying filler is 100%, the ratio of each component is: tailings backfilling gelling agent 20%, sand 60%, and water 20%, i.e., 1:3:1.

[0042] S2 seepage-proof gelling composite spray filler wet spraying

[0043] The impermeable cementitious composite sprayed filler prepared in step S1 is wet-sprayed onto the irregular rock slope, and then wet-sprayed to a length of L1 = 1.5m on the regular rock slope 1-1 on the other side of the impermeable boundary 9, thereby forming an impermeable cementitious composite sprayed filler layer 2 on the surface of the impermeable transition section; the surface of the impermeable cementitious composite sprayed filler layer 2 sprayed on the irregular rock slope 1-2 is uniformly flat, uniformly covered and has an average thickness δ = 5cm, and the thickness of the impermeable cementitious composite sprayed filler layer 2 sprayed in the L1 length section transitions uniformly from 5cm to 0cm.

[0044] S3 impermeable geomembrane laying

[0045] According to the "Standard for Pollution Control of Storage and Landfill of General Industrial Solid Waste" (GB 18599-2020), a 1.5mm HDPE geomembrane 3 with the specified seepage prevention effect is laid from the regular rock slope 1-1, and a length of L2=1.0m is extended along the seepage prevention boundary line 9 to the irregular rock slope 1-2. The seepage prevention cementitious composite sprayed filler layer 2 and the seepage prevention geomembrane 3 form an overlapping section in both directions.

[0046] S4 rubber pads, thin steel plate laying and fixing

[0047] Pre-drilling holes are made on the surface of the thin steel plate 6 according to the diameter of the hollow grouting anchor rod 4. The thin steel plate 6 is a steel plate with a thickness of 2mm to 3mm and a width B = 30cm. The axial length L3 = 1.5m, and the pre-drilled holes are arranged at equal intervals along the axial direction with a spacing M2 = 30cm. The rubber pad 7 is a high-pressure resistant rubber pad with a thickness of 3mm. Its width, axial length, and hole diameter are arranged in the same manner as the thin steel plate 6. Rubber pads 7 and thin steel plates 6 are laid on the impermeable geomembrane 3 from the inside out, with corresponding drill holes on the rubber pads 7 and thin steel plates 6. The hollow grouting anchor rods 4 are R20 in size. The hollow grouting anchor rods 4 are drilled into the rock inside the impermeable cementitious composite sprayed filler layer 2 by self-drilling through the drill holes in the thin steel plates 6 and rubber pads 7. The rock inclination angle is α = 20°, the rock depth is La = 50cm, and the plane spacing is M = 30cm, which is the same as the hole diameter spacing M. After entering the rock, grout is injected from the bottom, and grout returns from the hole opening. M16 nuts 5 are used for fixing.

[0048] S5 anti-seepage and leak-stopping agent trimming

[0049] After the hollow grouting anchor 4 is fixed, the excess portion of the extended section of the geomembrane 3 is cut off, leaving a 30cm gap. The gaps between the thin steel plate 6, rubber gasket 7, geomembrane 3, and the geotextile composite sprayed filler layer 2 are filled and bonded using a waterproofing and sealing agent 8. The waterproofing and sealing agent 8 is then evenly applied around the perimeter of the thin steel plate 6 to further improve sealing. The waterproofing and sealing agent 8 is a quick-setting type, designated FDⅡGB 23440-2009, selected based on the setting time.

[0050] Example 2

[0051] In Example 2, a seepage-proof cementitious composite spray filler was prepared by mixing solidified cementitious material, tailings sand, and water in a mass ratio of 1:3:1. The tailings sand was medium sand after tailings classification, with particles larger than 0.25 mm accounting for more than 50% of the total weight, and an average particle size of 0.3 mm. The solidified cementitious material was composed of a stabilizer, composite powder, water glass, and cement. The component contents, calculated as 100% of the total mass, were: stabilizer 15%, composite powder 15%, water glass 36%, and cement 34%. The stabilizer, by mass percentage, consisted of 60% calcium chloride and 40% sodium borate tetrahydrate. The composite powder was composed of calcium carbide slag powder, desulfurized gypsum, fly ash, and blast furnace slag, by mass percentage, consisting of 32% calcium carbide slag powder, 18% desulfurized gypsum, 24% fly ash, and 26% blast furnace slag. Other aspects were the same as in Example 1. The test results after implementation showed that the seepage prevention effect was improved by 25% compared with Example 1, and the cost of seepage prevention gel-coated composite spray filler was reduced by 41%.

Claims

1. A method for fixing a seepage-proof transition section on an irregular rock slope in a mine landfill, wherein the seepage-proof transition section is divided by a seepage-proof boundary line (9), with one side of the seepage-proof boundary line (9) being an irregular rock slope (1-2) and the other side of the seepage-proof boundary line (9) being a regular rock slope (1-1), characterized in that... The following steps are to be taken: S1 seepage-proof gelled composite spray filler preparation A seepage-proof cementitious composite spray filler is prepared by mixing and configuring solidified cementitious material, building sand or tailings sand, and water. When the total mass of the seepage-proof cementitious composite spray filler is 100%, the proportion of each component is: solidified cementitious material 19% to 26%, building sand or tailings sand 53% to 62%, and water 16% to 21%. S2 anti-seepage gelling composite spray filler wet spraying The impermeable gel-coagulated composite spray filler prepared in step S1 is wet-sprayed onto the irregular rock slope (1-2), and the wet spraying length L1 is extended to the regular rock slope (1-1) on the other side of the impermeable boundary (9), thereby forming an impermeable gel-coagulated composite spray filler layer (2) on the surface of the impermeable transition section; the surface of the impermeable gel-coagulated composite spray filler layer (2) sprayed on the irregular rock slope (1-2) is uniform and straight, and the thickness of the impermeable gel-coagulated composite spray filler layer (2) sprayed in the L1 length section is uniformly transitioned until 0; S3 impermeable geomembrane laying The impermeable geomembrane (3) is laid from the regular rock slope (1-1) and extended along the impermeable boundary line (9) to the irregular rock slope (1-2) for a length of L2. The impermeable cementitious composite spray filler layer (2) and the two-way extension section of the impermeable geomembrane (3) form an overlap section. S4 rubber pads, thin steel plate laying and fixing According to the designed hole diameter and spacing, holes are drilled in the rubber pad (7) and thin steel plate (6) respectively. Then, the rubber pad (7) and thin steel plate (6) are laid on the impermeable geomembrane (3) from the inside to the outside. The drilling positions on the rubber pad (7) and thin steel plate (6) correspond. The hollow grouting anchor (4) is drilled from the holes in the thin steel plate (6) and rubber pad (7) and penetrates into the rock in the impermeable cementitious composite sprayed filler layer (2). The rock inclination angle of the hollow grouting anchor (4) is α=15°~25° and the rock penetration depth is La=50cm~1.5m. S5 Leak-proofing and sealing agent trimming After the hollow grouting anchor (4) is fixed, the excess part of the extended laying section of the impermeable geomembrane (3) is cut off. The gap between the thin steel plate (6), rubber pad (7), impermeable geomembrane (3) and impermeable cementitious composite spray filling layer (2) is filled and bonded with impermeable sealant (8). The impermeable sealant (8) is evenly applied around the thin steel plate (6).

2. The method for fixing the seepage-proof transition section of an irregular rock slope in a mine landfill as described in claim 1, characterized in that: The curing cementitious material used in step S1 is a mixture of stabilizer, composite powder, water glass, and cement. The content of each component when the total mass is calculated as 100% is as follows: stabilizer 9%~15%, composite powder 9%~15%, water glass 28%~45%, and cement 28%~47%. The stabilizer is composed of calcium chloride 50%~60% and sodium borate tetrahydrate 40%~50% by mass percentage. The composite powder is a mixture of calcium carbide slag powder, desulfurization gypsum, fly ash, and blast furnace slag, and is composed of calcium carbide slag powder 32%~37%, desulfurization gypsum 15%~20%, fly ash 19%~24%, and blast furnace slag 20%~26% by mass percentage.

3. The method for fixing the seepage-proof transition section of an irregular rock slope in a mine landfill as described in claim 2, characterized in that: The construction sand or tailings sand used in step S1 is medium sand, with particles larger than 0.25mm accounting for more than 50% of the total weight, and an average particle size of 0.5mm to 0.25mm.

4. The method for fixing the seepage-proof transition section of an irregular rock slope in a mine landfill as described in claim 3, characterized in that: In step S2, the thickness of the seepage-proof cementitious composite spray filler layer (2) formed by wet spraying on the irregular rock slope (1-2) is δ=5cm~15cm, and the wet spraying length on the regular rock slope (1-1) is L1=1.0m~2.0m.

5. The method for fixing the seepage-proof transition section of an irregular rock slope in a mine landfill as described in claim 4, characterized in that: In step S3, the impermeable geomembrane (3) is an HDPE geomembrane with a specification of 1.5mm~2.0mm and an extended laying length of L2=0.8m~1.5m.

6. The method for fixing the seepage-proof transition section of an irregular rock slope in a mine landfill as described in claim 5, characterized in that: In step S4, the hollow grouting anchor rod (4) is a full-length corrugated thread, equipped with a fixing nut (5) and a special quick grouting connector. The specification of the hollow grouting anchor rod (4) is R20~25, and the plane spacing of the drill holes along the axial direction is M=30cm~50cm.

7. The method for fixing the seepage-proof transition section of an irregular rock slope in a mine landfill as described in claim 6, characterized in that: In step S4, the nut (5) is matched with the hollow grouting anchor rod (4) in terms of specifications and dimensions, and the nut (5) is of model M16~M20.

8. The method for fixing the seepage-proof transition section of an irregular rock slope in a mine landfill as described in claim 7, characterized in that: The thin steel plate (6) has a thickness of 2mm~3mm, a width of B=30cm~50cm, an axial length of L3=1~2m, and pre-drilled holes on its surface. The hole diameter matches the specifications of the hollow grouting anchor rod (4), and the hole spacing M2=30cm~50cm. It is lined with a rubber pad (7). The rubber pad (7) is a high-pressure resistant rubber pad with a thickness of 3mm~5mm.

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