Ecological protection structure against runoff erosion of open-pit dump and construction method

Abstract

The application discloses an open-pit mine dump anti-runoff scouring ecological protection structure and a construction method, which comprises a bottom anti-seepage soil consolidation layer, an intermediate anti-scouring layer and a surface ecological vegetation layer which are sequentially laid on a slope surface of the dump from bottom to top; the intermediate anti-scouring layer is provided with a flow interception groove in a transverse direction and a flow guide ditch in a longitudinal direction, the flow interception groove is communicated with the flow guide ditch, and a seepage drainage pipe extending to a slope foot drainage system is laid at the bottom of the flow guide ditch; and a plurality of ecological soil consolidation modules are embedded in the surface ecological vegetation layer, the ecological soil consolidation modules penetrate through the surface ecological vegetation layer and are fixed with the intermediate anti-scouring layer. Through the three-layer cooperative protection, the application realizes runoff interception and dredging combination, and the ecological soil consolidation modules are anchored and cooperated with biological soil consolidation, so that the runoff erosion amount can be reduced by more than 60%, the vegetation can be rapidly recovered, the cost of the application is reduced by 50%-70% compared with a concrete slope protection, and the anti-scouring performance and the ecological recovery effect are considered.

Description

Technical Field

[0001] This invention belongs to the field of mine ecological restoration and soil and water conservation technology, and specifically relates to the ecological protection structure and construction method for open-pit mine spoil heaps to resist runoff erosion. Background Technology

[0002] Open-pit mine spoil heaps are the primary sites for dumping stripped soil and rock during mining operations. Due to geological factors, spoil heap slopes typically have a gradient of 20°-25°, with loose soil layers, high porosity, high gravel content, low organic matter, and extremely low vegetation cover (often less than 5%). In the semi-arid regions of northern my country, the average annual rainfall is 300-500 mm, but rainfall is concentrated, with short-duration, high-intensity heavy rainfall. In the humid regions of southern China, the average annual rainfall exceeds 1000 mm, with prolonged continuous rainfall during the plum rain season. These conditions lead to severe slope erosion from runoff, with soil erosion moduli reaching 5000-20000 t / (km²·a), causing gully erosion and collapse, affecting mine safety, and polluting surrounding water bodies and the ecological environment.

[0003] Existing spoil heap protection technologies are mainly divided into two categories: engineering protection and ecological protection. Engineering protection (such as masonry slope protection and shotcrete) has strong erosion resistance, but it is impermeable to water and air, preventing vegetation growth and resulting in a loss of ecological function. Furthermore, it involves large amounts of concrete, leading to high carbon emissions, and the construction cost is approximately 80-200 yuan / m², making it unsuitable for large-scale implementation. Ecological protection (such as eco-bags and direct seeding) has low cost (approximately 15-40 yuan / m²) and can achieve vegetation coverage, but in the early stages (0-2 years), the root system is not yet developed, and vegetation loss can reach 40%-60% during heavy rainfall exceeding 30mm / h, making the protective effect unsustainable. Currently, there is a lack of a systematic solution that organically combines engineering and ecological protection, balancing erosion resistance and ecological restoration effects, and is economically feasible.

[0004] Therefore, developing an ecological protection structure for open-pit mine spoil heaps that balances runoff erosion resistance and ecological restoration, while being structurally stable, easy to construct, and cost-effective (target comprehensive cost ≤ 60 yuan / m²), has become an urgent technical problem to be solved in the field of mine ecological restoration. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide an ecological protection structure and construction method for open-pit mine spoil heaps to resist runoff erosion, which solves the problems of limited slope protection methods, severe runoff erosion, and difficulty in ecological restoration in existing open-pit mine spoil heaps.

[0006] The technical solution adopted in the invention is: an ecological protection structure for open-pit mine spoil heaps to resist runoff erosion. Its key technical points are: it includes a bottom impermeable soil stabilization layer, an intermediate erosion-resistant layer and a surface ecological vegetation layer laid sequentially from bottom to top on the slope of the spoil heap, as well as a water interception ditch set along the contour line at the top of the slope and a retaining wall set at the bottom of the slope, wherein a drainage culvert is pre-embedded on the inner side of the retaining wall; Multiple intercepting channels are arranged laterally along the slope within the intermediate erosion-resistant layer, and multiple diversion channels are arranged longitudinally along the slope. The intercepting channels and the diversion channels are interconnected. A drainage pipe is laid at the bottom of the diversion channel, and the drainage pipe extends to the drainage culvert. Multiple prefabricated cylindrical ecological soil stabilization modules are embedded within the surface ecological vegetation layer. Each ecological soil stabilization module includes an outer cylinder and a vegetation substrate filled within the outer cylinder. The outer cylinder has permeable holes on its wall and anchors at its bottom. The ecological soil stabilization module penetrates vertically through the surface ecological vegetation layer and is fixedly connected to the intermediate erosion-resistant layer through the anchors, forming a deep anchoring structure that extends vertically from the slope surface into the erosion-resistant layer.

[0007] In the above scheme, the bottom seepage-proof soil stabilization layer is composed of a self-healing clay composite layer and an HDPE geomembrane; the self-healing clay composite layer is formed by mixing and compacting natural clay and sodium bentonite at a mass ratio of 8:2, with a compaction degree ≥0.93; the HDPE geomembrane is fully laid in the self-healing clay composite layer, together forming a rigid-flexible composite seepage-proof structure; the upper end of the HDPE geomembrane is anchored to the outer wall of the intercepting ditch, and the lower end is anchored to the back side of the toe wall.

[0008] In the above scheme, the intermediate erosion-resistant layer includes a biaxially oriented polyester geogrid and an erosion-resistant matrix filled within the biaxially oriented polyester geogrid; the biaxially oriented polyester geogrid is laid above the bottom impermeable soil stabilization layer, and its mesh size is configured to allow the bottom end of the ecological soil stabilization module to pass through and be anchored, with a tensile strength ≥50kN / m; the erosion-resistant matrix is ​​formed by mixing and layering specific graded mine waste rock powder, humus and 42.5 grade ordinary Portland cement with water in a mass ratio of 6:3:1, with a layer thickness of 30-50cm and a compaction density ≥1500kg / m³.

[0009] In the above scheme, the mine waste rock powder is a powder produced by crushing waste stone from the mining area. and The total content is ≥70%; the humus is filled in the pores of the anti-erosion skeleton formed by the reaction of mine waste rock powder and cement hydration.

[0010] In the above scheme, the intercepting channel is an arc-shaped U-shaped groove, which is excavated laterally along the contour line of the slope. The inner wall of the channel is lined with polyester non-woven fabric, and the bottom of the channel is inclined laterally towards the direction of the diversion channel.

[0011] In the above scheme, the diversion ditch is arranged longitudinally along the slope direction, and the inner wall is filled with ecological concrete. The 28-day compressive strength of the ecological concrete is ≥15MPa, and the end is connected to the drainage culvert.

[0012] In the above scheme, the seepage and drainage pipe is laid at the bottom of the diversion ditch, wrapped with a geotextile filter layer, and extends to the drainage culvert.

[0013] In the above scheme, the outer cylinder of the ecological soil stabilization module is a prefabricated cylinder with a closed bottom made of ABS engineering plastic. The vegetation substrate is a special vegetation substrate, which is composed of 30% vermiculite, 40% peat moss, 20% organic matter, 5% compound slow-release fertilizer and 5% water-retaining agent by mass percentage. The anchor is an expansion anchor. The bottom end of the ecological soil stabilization module passes vertically through the mesh of the biaxially oriented polyester geogrid. The expansion anchor locks the module with the biaxially oriented polyester geogrid at the nodes, so that the module, the geogrid and the erosion-resistant substrate form a three-dimensional interlocking structure.

[0014] In the above scheme, the surface ecological vegetation layer includes a vegetation substrate, which is composed of 50% humus, 20% decomposed straw powder, 25% weathered sand and 5% slow-release compound fertilizer by mass percentage, with an organic matter content of ≥3% and a pH value of 6.5-7.5; the surface ecological vegetation layer forms a stress-resistant vegetation through hydraulic spraying, which is a mixed vegetation of Amorpha fruticosa, Bermuda grass and Kentucky bluegrass.

[0015] A construction method for an ecological protection structure against runoff erosion in an open-pit mine spoil heap, which utilizes such a structure, includes the following steps: On the slope of the spoil heap, a bottom impermeable soil stabilization layer, an intermediate erosion resistant layer, and a top ecological vegetation layer are constructed sequentially from bottom to top. Construct a water interception-drainage network within the intermediate erosion-resistant layer: excavate multiple interception trenches at intervals along the slope horizontally and excavate several diversion ditches along the slope longitudinally, so that the interception trenches and diversion ditches are interconnected; lay drainage pipes at the bottom of the diversion ditches and extend the drainage pipes to the drainage culverts set inside the slope toe wall. After the intermediate scour-resistant layer is laid and before the surface ecological vegetation layer is laid, the prefabricated cylindrical ecological soil stabilization module is vertically implanted, so that its bottom end penetrates the geogrid mesh in the intermediate scour-resistant layer, and is locked to the geogrid node by the anchors set at the bottom of the module, forming a deep anchoring structure that extends vertically from the slope surface into the scour-resistant layer. Then, a surface ecological vegetation layer is laid around the module.

[0016] Compared with the prior art, the beneficial effects of the present invention are: The ecological protection structure and construction method for open-pit mine spoil heaps designed to resist runoff erosion, as described in this invention, offer significant advantages through a three-layer synergistic protection system. The bottom impermeable soil stabilization layer effectively reduces rainwater infiltration and stabilizes the slope; the middle erosion-resistant layer intercepts and diverts runoff; and the surface ecological vegetation layer achieves ecological restoration and soil stabilization. These three layers complement each other, ensuring a long-lasting and stable overall protection effect with a design service life of over 20 years. Regarding runoff control, the intercepting trough laterally intercepts slope runoff, reducing flow velocity by 30%–50%; the diversion ditch longitudinally diverts rainwater to the slope toe; and the drainage pipe promptly removes infiltrated water to prevent water accumulation. The combined effect of these three elements reduces runoff erosion by over 60%. The ecological soil stabilization module design achieves a synergistic effect of mechanical anchoring and biological soil stabilization. The module's anchoring depth penetrates the middle layer, and the internal vegetation substrate retains water and fertilizer. Plant roots achieve a penetration rate of over 85% within 6 months, and vegetation coverage reaches over 70% within two years. In addition, the structure is economical and feasible. The erosion-resistant matrix aggregate uses waste rock powder from the mining area, accounting for 60% of the matrix mass, realizing the resource utilization of solid waste. The construction technology is mature, no large machinery is required, and the comprehensive cost is about 50 to 60 yuan / m², which is 50% to 70% lower than the concrete slope protection scheme. It is suitable for large-scale promotion and application in open-pit mine spoil heaps. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of an ecological protection structure for open-pit mine spoil heaps against runoff erosion, as described in an embodiment of the present invention. The numbers in the diagram are explained as follows: 1. Interception channel, 2. Surface ecological vegetation layer, 3. Intermediate erosion-resistant layer, 4. Bottom seepage-proof soil stabilization layer, 5. Diversion ditch, 6. Foot wall, 7. Drainage pipe, 8. Ecological soil stabilization module. Detailed Implementation

[0019] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the following description is provided in conjunction with the accompanying drawings. Figure 1 The present invention will be further described in detail below with reference to specific embodiments.

[0020] This embodiment employs an ecological protection structure for open-pit mine spoil heaps against runoff erosion, comprising, from bottom to top, a bottom impermeable soil stabilization layer 4, an intermediate erosion-resistant layer 3, and a surface ecological vegetation layer 2 laid on the slope of the spoil heap. The intermediate erosion-resistant layer 3 has several intercepting channels 1 spaced laterally along the slope of the spoil heap, and several diversion ditches 5 arranged longitudinally. The intercepting channels 1 and diversion ditches 5 are interconnected. A drainage pipe 7 is installed through the bottom of the diversion ditches 5, extending to the drainage system at the toe of the spoil heap slope. Multiple ecological soil stabilization modules 8 are embedded within the surface ecological vegetation layer 2, penetrating the surface ecological vegetation layer and fixedly connected to the intermediate erosion-resistant layer 3.

[0021] In this embodiment, the bottom impermeable soil stabilization layer 4 is made by mixing and compacting modified clay (activated sodium bentonite) and sodium bentonite at a mass ratio of 8:2, with a compaction degree ≥0.93 and a thickness of 15-25cm. A 1.5mm thick HDPE geomembrane with a permeability coefficient ≤1×10-12m / s is fully laid within the layer. The geomembrane is laid along the slope, with its upper end anchored to the outer wall of the intercepting ditch at the top of the slope and its lower end anchored to the back side of the toe wall 6 at the bottom of the slope. The function of this layer is to block rainwater infiltration, stabilize the slope, and provide a reliable supporting foundation for the superstructure.

[0022] In this embodiment, the intermediate erosion-resistant layer 3 consists of a biaxially oriented polyester geogrid laid on top of the bottom layer. The geogrid is 4m wide and, after being laid flat, is filled with the erosion-resistant matrix. The erosion-resistant matrix is ​​composed of 60% mine waste rock powder (derived from waste stone materials in the mining area, and tested to be of high quality). and The composition consists of: ≥70% total content, crushed to ≤2mm particle size for solid waste resource utilization; 30% humus (locally sourced, filling the erosion-resistant skeleton pores formed by the hydration reaction of mine waste rock powder and cement); and 10% 42.5 grade ordinary Portland cement. After thorough mixing with water, the mixture is layered and compacted, with each layer being 30–50cm thick and having a compaction density ≥1500kg / m³. The grid mesh size is 50mm × 50mm, with the mesh interlocking with the substrate to form a unified structure. The tensile strength is ≥50kN / m, effectively preventing overall substrate slippage.

[0023] In this embodiment, the intercepting channel 1 is an arc-shaped U-shaped groove, excavated laterally along the contour lines of the slope. The channel is 20-30cm wide, 15-20cm deep, and spaced 2-3m apart (designed according to the slope angle and rainfall intensity). The inner wall of the channel is lined with 200g / m² polyester non-woven fabric. The bottom of the channel is inclined laterally at 3-5° towards the guide ditch 5 to ensure that accumulated water flows into the guide ditch 5 by gravity. The intercepting channel 1 can reduce the slope runoff velocity by 30%-50%, significantly reducing the kinetic energy of runoff erosion.

[0024] In this embodiment, the diversion ditch 5 is arranged longitudinally along the slope direction with a spacing of 3-5m, a ditch width of 30-40cm, and a ditch depth of 25-35cm. The inner wall is made of 5cm thick cast-in-place ecological concrete with a porosity of 20%-30%, and a longitudinal slope of 5-8°. The end is connected to the drainage culvert at the toe of the slope. The ecological concrete has both strong erosion resistance (28-day compressive strength ≥15MPa) and a porous structure that allows for microbial colonization, thus combining engineering protection and ecological functions.

[0025] In this embodiment, the drainage pipe 7 is a DN100-150mm HDPE porous corrugated pipe, laid at the bottom of the diversion ditch 5, and wrapped with a 200g / m² geotextile filter layer (to prevent fine particles from clogging the pipe). The spacing is 1.5-2.5m, the longitudinal slope is ≥1%, and it extends to the drainage culvert at the toe of the slope. The drainage pipe 7 promptly drains the seepage water in the intermediate erosion-resistant layer 3 to prevent water accumulation that could lead to matrix softening and slope instability.

[0026] In this embodiment, the ecological soil stabilization module 8 is a prefabricated cylindrical body with an ABS engineering plastic outer cylinder, an outer diameter of 10-15cm, and a height of 50-70cm. The wall surface has Φ5mm permeable holes spaced 30mm apart. It is filled with a special vegetation substrate, which in this embodiment consists of: 30% vermiculite, 40% peat moss, 20% organic matter, 5% compound slow-release fertilizer, and 5% water-retaining agent. The bottom end passes through the geogrid mesh and is fixed with expansion anchors, while the top end is flush with the surface vegetation layer. The modules are arranged in a quincunx pattern with a spacing of 1-1.5m. The anchoring depth of the module extends to the intermediate erosion-resistant layer 3, effectively transferring and resisting slope slippage forces, while providing nutrient reservoirs and water-retaining cores for plant growth, promoting rapid root development, and achieving a root penetration rate of over 85% within 6 months.

[0027] In this embodiment, the surface ecological vegetation layer has a substrate thickness of 15-25 cm, composed of 50% humus, 20% decomposed straw powder, 25% weathered sand, and 5% slow-release compound fertilizer, with an organic matter content ≥3% and a pH value of 6.5-7.5. Resilient vegetation is formed on this substrate through hydraulic hydroseeding at a pressure of 0.3-0.5 MPa. A mixed sowing of native trees, shrubs, and grasses is recommended: Amorpha fruticosa (1200 plants / mu), Bermuda grass (8g / m²), and Kentucky bluegrass (5g / m²), with a total sowing density of 20-30g / m². The native vegetation is highly adaptable, requires no additional irrigation, and can naturally evolve into a stable vegetation community under the barren soil conditions of the spoil heap.

[0028] In this embodiment, a water interception ditch is set up along the contour line at the top of the slope. It is lined with M10 mortar-grouted stone, with a net width of 40-50cm, a net depth of 35-45cm, and a longitudinal slope of ≥0.3%. The inner wall is coated with a 20mm thick M15 mortar waterproof layer, and the end is connected to the slope diversion ditch 5 to introduce the water collected at the top of the slope into the diversion system, so as to avoid the runoff at the top of the slope directly scouring the slope surface.

[0029] In this embodiment, a retaining wall 6 is provided at the toe of the slope. It is made of M7.5 mortar-grouted masonry blocks, with a wall height of 80-100cm, a bottom width of ≥60cm, and a foundation depth of ≥50cm. A Φ300mm HDPE corrugated drainage culvert is pre-embedded on the inner side, with a longitudinal slope of ≥1%. An inspection well is provided every 20m. The end of the culvert is discharged into a natural ditch after passing through a sedimentation tank to prevent the toe of the slope from being eroded by runoff.

[0030] To verify the actual protective effect of the open-pit mine spoil heap anti-runoff erosion ecological protection structure provided in this embodiment, the above-mentioned protection structure was constructed in the spoil heap test area (slope 1:2.5), with an unprotected bare slope as a control. After the test area underwent a simulated rainfall test with a 50-year return period intensity, various indicators were measured, and the results are as follows: The composite seepage-proof structure, consisting of a bottom self-healing clay composite layer and an HDPE geomembrane, effectively prevents rainwater infiltration, with no significant slope deformation observed. The middle erosion-resistant layer rapidly intercepts and directs slope runoff, preventing the formation of penetrating gullies on the surface. The surface vegetation layer exhibits healthy growth. Accelerated aging tests estimate that the structure has a design service life of ≥20 years under normal maintenance conditions, demonstrating a long-lasting and stable three-layer synergistic protective effect.

[0031] The interception channel reduces the runoff velocity on the slope by 30% to 50% compared to an unprotected bare slope; the diversion ditch and drainage pipe promptly discharge the intercepted rainwater to the drainage culvert at the toe of the slope, preventing water accumulation on the slope. Measurements of the sediment content in the runoff at the toe of the slope show that the runoff erosion caused by the protective structure implemented in this method is reduced by more than 60% compared to an unprotected bare slope.

[0032] Six months after construction was completed, some modules were dissected for testing. The water and fertilizer retention properties of the vegetation substrate inside the modules were found to be good, and the plant roots had penetrated the permeable holes in the outer cylinder sidewall and reached deep into the middle erosion-resistant layer, with a root penetration rate of over 85%. Two years after construction was completed, the vegetation coverage rate was observed to be over 70%, forming a deep anchoring structure with synergistic mechanical anchoring and biological soil stabilization.

[0033] The erosion-resistant matrix aggregate uses waste rock powder from the mining area (accounting for 60% of the mass of the erosion-resistant matrix), realizing the resource utilization of solid waste; the construction technology is mature and does not require large machinery. According to the engineering economic analysis, the comprehensive cost of the protective structure in this implementation method is 50-60 yuan / m², which is 50%-70% lower than the concrete slope protection scheme with the same protection requirements, making it suitable for large-scale promotion and application in open-pit mine spoil heaps.

[0034] The above test results show that the protective structure of this embodiment organically combines seepage prevention, drainage interception, erosion resistance and ecological restoration. Each layer works together to perform its function, which not only significantly reduces engineering costs and realizes the resource utilization of solid waste, but also provides long-term, stable and efficient anti-runoff erosion protection for the slope of open mine spoil heap.

[0035] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An ecological protection structure for open-pit mine spoil heaps against runoff erosion, characterized in that, It includes a bottom impermeable soil stabilization layer, an intermediate erosion resistant layer and a surface ecological vegetation layer laid sequentially from bottom to top on the slope of the spoil heap, as well as a water interception ditch set along the contour line at the top of the slope and a retaining wall set at the bottom of the slope, wherein a drainage culvert is pre-embedded on the inner side of the retaining wall. Multiple intercepting channels are arranged laterally along the slope within the intermediate erosion-resistant layer, and multiple diversion channels are arranged longitudinally along the slope. The intercepting channels and the diversion channels are interconnected. A drainage pipe is laid at the bottom of the diversion channel, and the drainage pipe extends to the drainage culvert. Multiple prefabricated cylindrical ecological soil stabilization modules are embedded within the surface ecological vegetation layer. Each ecological soil stabilization module includes an outer cylinder and a vegetation substrate filled within the outer cylinder. The outer cylinder has permeable holes on its wall and anchors at its bottom. The ecological soil stabilization module penetrates vertically through the surface ecological vegetation layer and is fixedly connected to the intermediate erosion-resistant layer through the anchors, forming a deep anchoring structure that extends vertically from the slope surface into the erosion-resistant layer.

2. The ecological protection structure against runoff erosion in open-pit mine spoil heaps according to claim 1, characterized in that, The bottom impermeable soil stabilization layer is composed of a self-healing clay composite layer and an HDPE geomembrane. The self-healing clay composite layer is formed by mixing and compacting natural clay and sodium bentonite at a mass ratio of 8:2, with a compaction degree ≥0.

93. The HDPE geomembrane is fully laid inside the self-healing clay composite layer, together forming a rigid-flexible composite impermeable structure. The upper end of the HDPE geomembrane is anchored to the outer wall of the intercepting ditch, and the lower end is anchored to the back side of the toe wall.

3. The ecological protection structure against runoff erosion in open-pit mine spoil heaps according to claim 1 or 2, characterized in that, The intermediate erosion-resistant layer comprises a biaxially oriented polyester geogrid and an erosion-resistant matrix filled within the biaxially oriented polyester geogrid. The biaxially oriented polyester geogrid is laid above the bottom impermeable soil stabilization layer, and its mesh size is configured to allow the bottom end of the ecological soil stabilization module to pass through and be anchored, with a tensile strength ≥50kN / m. The erosion-resistant matrix is ​​formed by mixing and layering specific graded mine waste rock powder, humus, and 42.5 grade ordinary Portland cement with water in a mass ratio of 6:3:1, with a layer thickness of 30-50cm and a compaction density ≥1500kg / m³.

4. The ecological protection structure against runoff erosion in open-pit mine spoil heaps according to claim 3, characterized in that, The mine waste rock powder is a powder obtained by crushing waste stone from the mining area, and its total SiO2 and Al2O3 content is ≥70%; the humus soil fills the erosion-resistant skeleton pores formed by the reaction of mine waste rock powder and cement hydration.

5. The ecological protection structure against runoff erosion in open-pit mine spoil heaps according to claim 1, characterized in that, The intercepting channel is an arc-shaped U-shaped groove, which is excavated laterally along the contour line of the slope. The inner wall of the channel is lined with polyester non-woven fabric, and the bottom of the channel is inclined laterally towards the direction of the diversion channel.

6. The ecological protection structure against runoff erosion in open-pit mine spoil heaps according to claim 1, characterized in that, The diversion ditch is laid longitudinally along the slope direction, and the inner wall is filled with ecological concrete. The 28-day compressive strength of the ecological concrete is ≥15MPa. The end is connected to the drainage culvert.

7. The ecological protection structure against runoff erosion in open-pit mine spoil heaps according to claim 1, characterized in that, The drainage pipe is laid at the bottom of the diversion ditch, wrapped with a geotextile filter layer, and extends to the drainage culvert.

8. The ecological protection structure against runoff erosion in open-pit mine spoil heaps according to claim 3, characterized in that, The outer cylinder of the ecological soil stabilization module is a prefabricated cylinder with a closed bottom made of ABS engineering plastic. The vegetation substrate is a special vegetation substrate, which is composed of 30% vermiculite, 40% peat moss, 20% organic matter, 5% compound slow-release fertilizer and 5% water-retaining agent by mass percentage. The anchor is an expansion anchor. The bottom end of the ecological soil stabilization module passes vertically through the mesh of the biaxially oriented polyester geogrid. The expansion anchor locks with the nodes of the biaxially oriented polyester geogrid, so that the module, the geogrid and the erosion-resistant substrate form a three-dimensional interlocking structure.

9. The ecological protection structure against runoff erosion in open-pit mine spoil heaps according to claim 1, characterized in that, The surface ecological vegetation layer includes a vegetation substrate, which is composed of 50% humus, 20% decomposed straw powder, 25% weathered sand and 5% slow-release compound fertilizer by weight percentage, with an organic matter content of ≥3% and a pH value of 6.5-7.5; the surface ecological vegetation layer forms a stress-resistant vegetation through hydraulic spraying, which is a mixed planting of Amorpha fruticosa, Bermuda grass and Kentucky bluegrass.

10. A construction method for an ecological protection structure against runoff erosion in an open-pit mine spoil heap, comprising the ecological protection structure against runoff erosion in an open-pit mine spoil heap as described in claims 1-9, characterized in that, Includes the following steps: On the slope of the spoil heap, a bottom impermeable soil stabilization layer, an intermediate erosion resistant layer, and a top ecological vegetation layer are constructed sequentially from bottom to top. Construct a water interception-drainage network within the intermediate erosion-resistant layer: excavate multiple interception trenches at intervals along the slope horizontally and excavate several diversion ditches along the slope longitudinally, so that the interception trenches and diversion ditches are interconnected; lay drainage pipes at the bottom of the diversion ditches and extend the drainage pipes to the drainage culverts set inside the slope toe wall. After the intermediate scour-resistant layer is laid and before the surface ecological vegetation layer is laid, the prefabricated cylindrical ecological soil stabilization module is vertically implanted, so that its bottom end penetrates the geogrid mesh in the intermediate scour-resistant layer, and is locked to the geogrid node by the anchors set at the bottom of the module, forming a deep anchoring structure that extends vertically from the slope surface into the scour-resistant layer. Then, a surface ecological vegetation layer is laid around the module.

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