Design structure of valley refuse landfill
By designing a valley landfill in the gully terrain of the Loess Plateau and adopting a multi-layer anti-seepage system and slope reinforcement structure, the anti-seepage and geological stability problems in traditional designs were solved, and efficient and environmentally friendly waste disposal and resource utilization were achieved.
Patent Information
- Application Number
- CN202422783235.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-14
- Publication Date
- 2025-09-05
- Estimated Expiration
- 2034-11-14
AI Technical Summary
Conventional landfill designs struggle to meet anti-seepage, reinforcement, and environmental protection requirements in the gully terrain of the Loess Plateau, especially due to the high risk of leakage and geological disasters caused by geological erosion and topographic complexity.
A gully landfill structure was designed, including a concave trough in the gully, slope reinforcement structure, retaining dam and a multi-layer anti-seepage system. The retaining dam was formed by filling with loess, and the anti-seepage surface layer was formed by combining GCL waterproof blanket, HDPE geomembrane and filament geotextile. Blind ditches for collecting groundwater and leachate were set up to enhance slope stability and anti-seepage effect.
Effectively prevent leachate infiltration, reduce geological disaster risks, reduce environmental pollution, reduce costs, adapt to landfill expansion needs, and improve system stability and flexibility.
Smart Images
Figure CN223305069U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of environmental protection technology, specifically a garbage landfill structure designed using narrow and steep valleys in loess areas and a construction method thereof, aiming to provide an efficient, stable and environmentally friendly garbage landfill solution. Background Art
[0002] The general design concept of a landfill is to excavate a foundation pit on flat ground at a certain slope and then lay an anti-seepage system to form a composite foundation pit for landfilling garbage.
[0003] Due to the natural conditions of the landfill site, in the loess region, due to geological reasons, there are multiple narrow valleys on site, which can be utilized to construct landfills without the need for additional foundation pit excavation. Loess valley areas often have complex terrain and ravines. These areas are generally underutilized during the urbanization process and therefore have abundant land resources for landfill construction. However, due to the erodibility of loess and the complexity of the valley terrain, traditional landfill design structures cannot meet the requirements of anti-seepage, reinforcement, and environmental protection. Therefore, it is necessary to provide a new comprehensive landfill design structure to address these problems. Utility Model Content
[0004] The utility model aims to provide a gully landfill design structure for the defects of the prior art. The landfill fully utilizes the gully terrain, solves the erodibility of loess and the complexity of the gully terrain, and meets the requirements of anti-seepage, reinforcement and environmental protection.
[0005] In order to achieve the above technical purpose, the utility model provides a gully landfill design structure, including a gully concave trough, slopes on both sides of the gully concave trough, a retaining dam located in the gully concave trough and a bottom anti-seepage structure arranged on the bottom surface of the gully concave trough. The gully concave trough is surrounded by the slopes on both sides and the two retaining dams to form a landfill area. The bottom anti-seepage structure is arranged along the length direction of the gully concave trough, including a main blind ditch for collecting groundwater in the lower layer and a filter ditch on the upper layer. liquid collection main blind ditch; reinforcement structures are constructed on the slope surfaces of the side slopes on both sides of the concave trough in the valley, and the bottom surface of the concave trough in the valley is provided with a foundation treatment layer. Anti-seepage surface layers are respectively provided on the slope surfaces of the side slopes on both sides of the concave trough in the valley, the surface of the foundation treatment layer on the bottom surface of the concave trough in the valley, and the surface of the dam body of the retaining dam. A reinforcement cushion layer and a protective surface layer are laid above the anti-seepage layer on the slope surface of the retaining dam, and the toe lines of the side slopes on both sides of the concave trough in the valley are respectively provided with a slope foot counter-pressure soil layer for counter-pressing the anti-seepage surface layer.
[0006] A further technical solution of the present invention is as follows: the valley is a long and narrow valley in the loess region, which is divided into multiple adjacent landfill areas by multiple retaining dams in the valley. Two adjacent landfill areas share one retaining dam. The retaining dam is an isosceles trapezoidal structure with a flat middle part and sloping surfaces on both sides, and the sloping surfaces on both sides face the two adjacent landfill areas respectively; the retaining dam is a dam structure formed by filling on-site loess.
[0007] The better technical solution of the utility model is as follows: the structure also includes a garbage landfill layer stacked in the garbage landfill area and a covering layer covering the surface of the garbage landfill layer, and the covering layer includes a base layer, an HDPE film layer, a soil barrier layer, an isolation layer, a drainage layer and a nutrient soil layer from bottom to top, and ornamental plants are planted in the nutrient soil layer.
[0008] The preferred technical solution of this utility model is as follows: the reinforcement structure includes a plurality of soil nails driven into the slope surfaces on both sides, steel meshes hung on the slope surfaces on both sides, and a concrete surface layer sprayed on the slope surfaces on both sides. The steel meshes are fixedly welded to the soil nails, and the concrete surface layer covers the steel meshes. The spacing between the soil nails is 1000mm to 1500mm.
[0009] The better technical solution of the utility model is as follows: the anti-seepage surface layer is composed of GCL waterproof blanket, HDPE geomembrane and filament geotextile from the inside to the outside. The GCL waterproof blanket is tightly laid on the slope surface of the side slopes on both sides of the concave trough in the valley and the slope surface of the retaining dam. The HDPE geomembrane is seamlessly connected by heat welding technology.
[0010] The better technical solution of the utility model is as follows: the reinforced cushion layer is composed of a lower gravel cushion layer and an upper crushed stone cushion layer, the protective surface layer is a dry-laid C15 concrete block slope protection layer; the thickness of the foundation treatment layer on the bottom surface of the concave trough in the valley is controlled at 250 to 1000 mm.
[0011] The better technical solution of the utility model is as follows: the bottom anti-seepage structure is constructed on the midline of the bottom surface of the valley concave trough; the bottom anti-seepage structure includes an inverted trapezoidal blind ditch groove opened on the bottom surface of the valley concave trough, the blind ditch groove extends outside the landfill area, and is connected with the bottom anti-seepage structure at the bottom of the next adjacent landfill area, or is connected with the external drainage system; the overall groove depth of the blind ditch groove is 0.8 to 1.2m, the bottom width is 0.8 to 1.2m, the top width is 1.8 to 2.2m, and the slope of the two sides is 1:1; the main blind ditch for collecting groundwater in the lower layer includes a first layer of geotextile filter layer laid in the blind ditch groove, A three-flowered pipe wrapped with geotextile, a gravel layer filled in the lower layer of the blind ditch groove and a final protective filter layer laid on the top of the gravel layer; the upper leachate collection main blind ditch includes an anti-seepage layer laid above the final protective filter layer, an anti-seepage isolation layer arranged above the anti-seepage layer, a pebble leachate diversion layer laid on the anti-seepage isolation layer, a leachate collection and discharge pipe buried in the pebble leachate diversion layer and a geotextile protective layer covering the top surface of the pebble leachate diversion layer; the anti-seepage layer and the anti-seepage surface layer are an integrated structure, the pebble particle size of the pebble leachate diversion layer ranges from 20 to 40 mm; the gravel layer is filled with gravel with a diameter of 3 to 5 cm.
[0012] The better technical solution of the utility model is as follows: anchoring trenches for fixing the anti-seepage surface layer are provided on both sides of the top surface of the landfill area, the width of the anchoring trench is 0.5m-1.0m, and the depth is 0.5m-1.0m. Both sides of the anti-seepage surface layer extend into the corresponding anchoring trenches and are fixed by U-shaped nails. A clay layer is backfilled in the anchoring trench, and a concrete hardening layer is provided on the top surface of the anchoring trench; an intercepting drainage ditch is provided 1-2m outside the anchoring trench, and the cross-sectional width of the intercepting drainage ditch is 0.5-0.8m and the depth is 0.7-1m.
[0013] The better technical solution of the utility model is as follows: the base layer is a clay layer, a sand layer or a gravel layer with a thickness of 300mm to 350mm, the barrier layer is a compacted clay layer of 300mm to 350mm, the isolation layer is a geotextile or a geomembrane, and the drainage layer is a gravel layer or a ceramsite layer.
[0014] The purpose of the slope surface closure reinforcement in this utility model is to enhance the stability of the slope and prevent geological disasters such as soil erosion and landslides. The soil nails serve as the main load-bearing components of the slope reinforcement, forming a composite with the surrounding soil to jointly bear the lateral earth pressure of the slope. In order to further improve the integrity and shear resistance of the slope surface, steel mesh is hung on the slope surface to effectively disperse and transfer the load on the slope surface, preventing soil spalling and crack expansion caused by natural factors such as rain erosion and freeze-thaw cycles. At the same time, the steel mesh also provides a reliable attachment base for the subsequent shotcrete, enhancing the integrity and durability of the slope protection layer. Finally, the slope surface is shotcrete to ensure good bonding between the shotcrete layer, the steel mesh and the soil nails, thereby improving the overall stiffness and stability of the entire protective structure.
[0015] When backfilling a site, prioritize loess generated from slope cutting and leveling, avoiding the use of cleared topsoil that could damage the surrounding environment. When backfilling gully-shaped depressions, compact the soil and stone in layers, ensuring each layer is of moderate thickness to improve foundation density and stability. For foundation treatment, blend uniform, hard, unweathered, and impurity-free natural sand, gravel, and other materials into the loess. Based on the loess's original particle size distribution and project requirements, the appropriate ratio of sand and gravel is determined to improve its physical and mechanical properties, thereby enhancing the foundation's bearing capacity and resistance to deformation. Ensure that each layer of backfill is tightly integrated to avoid stratification or overhangs, thereby ensuring the integrity and stability of the foundation.
[0016] The anti-seepage surface layer in this utility model is composed, from the inside out, of GCL (natural sodium bentonite waterproof blanket), HDPE (high-density polyethylene) geomembrane, and filament geotextile, designed to effectively prevent sidewall leakage. The GCL waterproof blanket adheres tightly to the slope and dam structure, establishing a preliminary and crucial anti-seepage barrier. The HDPE geomembrane further enhances the anti-seepage effect. To further enhance the protective effect of the geomembrane, a layer of filament geotextile is laid. This fabric has excellent mechanical strength and UV resistance, effectively preventing damage to the geomembrane from external factors. To address the stability issues of the cover layer caused by the low shear strength contact surface within the enclosure system on sloped terrain, engineering practice often adopts solutions such as setting anchor trenches at the top of the slope and laying an anti-seepage layer, strictly controlling the compaction quality of the backfill soil, anchoring the anti-seepage layer at the bottom of the slope, and implementing loess backpressure measures to enhance the stability of the enclosure system's slope and the reliability of the anti-seepage layer. These measures ensure that the anti-seepage system can fully perform its anti-seepage, isolation, and reinforcement functions. A layer of gravel cushion and crushed stone cushion is laid outside the anti-seepage surface layer of the retaining dam. The gravel cushion ensures that the cushion has good permeability and bearing capacity, providing a solid foundation for subsequent construction. The addition of the crushed stone cushion further enhances the bearing capacity and stability of the dam body. At the same time, its rough surface provides a good friction foundation for the subsequent laying of slope protection materials; the dry-laid C15 concrete block slope protection provides a solid slope protection layer for the retaining dam, effectively resisting damage from natural factors such as rain scouring and wind erosion.
[0017] In the pebble leachate diversion layer of the present invention, the selection of pebbles should meet the particle size range of 20 to 40 mm to ensure good permeability, pressure resistance and durability. The pebbles should be laid tightly and flatly to avoid gaps or uneven stacking to ensure the diversion effect. A layer of woven geotextile is laid above the pebble diversion layer as a protective layer to prevent garbage from directly pressing on the pebble layer. The design of the diversion layer needs to be combined with the overall anti-seepage system of the landfill to ensure that the leachate can be discharged smoothly. An anti-seepage isolation layer is set below the diversion layer to prevent the leachate from leaking into the groundwater. A collection pipe and a discharge pipe are set above the diversion layer to transport the collected leachate to the treatment facility. The cover layer in this utility model includes a base layer, which provides stable support for the subsequent cover layer. A high-density polyethylene (HDPE) membrane layer is laid atop the base layer. This membrane layer, made of high-density polyethylene (HDPE) with excellent impermeability and aging resistance, is used to prevent the leakage of landfill leachate and the spread of odors. A barrier layer, made of materials such as geotextile or geomembrane, is placed atop the HDPE membrane layer to further block the spread of odors and pollutants. A drainage layer, made of highly permeable materials such as crushed stone and ceramsite, is placed atop the barrier layer to collect and drain accumulated water on the landfill surface, maintaining a dry and stable cover layer. A nutrient layer, made of a mixture of soil and fertilizer, is laid atop the drainage layer to provide nutrients and a growing environment for green plants. Landscaping and landscaping are carried out around the landfill, selecting appropriate plant species based on the climate, soil, and other conditions surrounding the landfill, and planting plants that are adaptable, fast-growing, and have ornamental value.
[0018] This application has the following beneficial effects:
[0019] (1) The utility model builds on the slope surface without further excavation, so there will be no land red line, which solves the land use problem and protects the environment. The slope surface is provided with a backfill anti-seepage structure, which not only has the effect of trimming the slope surface, but also effectively prevents the infiltration of garbage leachate into the slope. When facing an existing steep valley, the slope surface and slope bottom are trimmed using the technical solution of this application, and the existing slope can be reused without digging a new pit. It also overcomes the problem that the existing slope does not meet the requirements of the landfill, which is conducive to reducing costs.
[0020] (2) The utility model divides the retaining dam system into several independent sections according to the phased construction and operation plan of the landfill, and each section is designed and constructed separately; this not only reduces the construction difficulty, but also allows the position and height of the retaining dam to be flexibly adjusted according to the actual operation of the landfill to adapt to the continuous expansion of the landfill; at the same time, the retaining dam system constructed in sections is easier to maintain and overhaul, ensuring the long-term stable operation of the system.
[0021] (3) The utility model uses the narrow valleys in the loess region as landfills, which have the advantages of rich land resources, suitable geological conditions, less environmental impact, low cost, and is conducive to waste treatment and resource utilization. Dams are built at both ends of the loess valley to form storage capacity, which is simple to operate and manage, with low investment and low operating costs, which can reduce the impact on residents' lives and reduce the risk of environmental pollution caused by the waste treatment process;
[0022] Further optimize the specific composition of the anti-seepage layer structure, and build a new anti-seepage system with the cooperation of layers of different materials and specifications, so as to have a better self-defense effect, slow down the infiltration of garbage leachate, and help protect the slope surface.
[0023] (4) The utility model provides an anti-seepage group, which can protect the HDPE geomembrane layer through the bentonite waterproof blanket and the non-woven fabric layer, reduce the damage rate of the HDPE geomembrane layer, and further increase the anti-seepage effect. The slope of the valley reservoir bottom is set to introduce the garbage liquid into the middle concrete infiltration pipe, and the garbage liquid is discharged by being concentrated in the main pipeline, thereby reducing the corrosion of the garbage liquid on the anti-seepage group and reducing the impact of garbage odor on the surrounding environment. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 This is a plan view of the landfill site in the first phase of the gully in the embodiment;
[0025] Figure 2 yes Figure 1 Middle aa section;
[0026] Figure 3 yes Figure 1 Middle bb cross-section;
[0027] Figure 4 is a plan view of the slope reinforcement structure in the embodiment;
[0028] Figure 5 is a cross-sectional view of the slope reinforcement structure in the embodiment;
[0029] Figure 6 This is a structural diagram of the main blind ditch for collecting leachate and groundwater in the embodiment;
[0030] Figure 7 This is a structural diagram of the anti-seepage surface layer in the embodiment;
[0031] Figure 8 This is a diagram of the slope top anchoring trench structure in the embodiment;
[0032] Figure 9 It is a structural diagram of the landfill cover layer and surface greening in the embodiment.
[0033] In the figure: 1-slope, 1-1-slope top line, 1-2-slope foot line, 2-retaining dam, 3-valley concave trough, 4-anti-seepage surface layer, 5-reinforcement structure, 5-1-soil nails, 5-2-steel mesh, 5-3-concrete surface layer, 6-slope foot counterpressure soil layer, 7-cover layer, 7-1-foundation layer, 7-2-HDPE membrane layer, 7-3-compacted clay barrier layer, 7-4-isolation layer, 7-5-drainage layer, 7-6-nutrient soil layer, 8-foundation treatment, 9-bottom anti-seepage structure, 9-1-groundwater collection main blind ditch, 9-2-groundwater collection main blind ditch, 9-3-groundwater collection main blind ditch, 9-4-groundwater collection main blind ditch, 9-5-groundwater collection main blind ditch, 9-1-groundwater collection main blind ditch, 9-4 ... -11—first geotextile filter layer, 9-12—three-flower pipe, 9-13—gravel layer, 9-14—final protective filter layer, 9-2—main blind ditch for leachate collection, 9-21—pebble leachate diversion layer, 9-22—leachate collection and discharge pipe, 9-23—geotextile protective layer, 9-24—anti-seepage isolation layer, 10—landfill area, 11—intercepting drainage ditch, 12—reinforced cushion layer, 13—protective surface layer, 14—anchor trench, 15—U-shaped nails, 16—clay layer, 17—concrete hardening layer, 18—landfill layer. DETAILED DESCRIPTION
[0034] In order to further understand the content, features and effects of the present invention, the present invention will be further described below with reference to the accompanying drawings and embodiments. Figures 1 to 8 The accompanying drawings are simplified examples and are intended solely to clearly and concisely illustrate the embodiments of the present invention. The technical solutions presented in the accompanying drawings are specific examples of the present invention and are not intended to limit the scope of the claimed invention. All other examples derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are also within the scope of protection of the present invention.
[0035] The utility model is further described below with reference to the accompanying drawings. Figure 1 and Figure 2As shown, it includes a landfill area 10 formed by a narrow valley in the loess region, a bottom anti-seepage structure 9 constructed on the bottom surface of the landfill area, a reinforcement structure 5 constructed on the slopes on both sides of the landfill area, and a covering layer 7 laid on the surface of the landfill area 10. The landfill area 10 is a concave area formed by a concave trough 3 in the valley, side slopes 1 on both sides of the concave trough 3 in the valley, and a retaining dam 2 provided in the concave trough 3 in the valley; the narrow valley in the loess region is divided into multiple adjacent landfill areas 10 by multiple retaining dams 2, and two adjacent landfill areas 10 share one retaining dam 2. The retaining dam 2 is an isosceles trapezoidal structure with a flat middle part and sloping surfaces on both sides, and the sloping surfaces on both sides face the two adjacent landfill areas 10 respectively. Reinforcement structures 5 are constructed on the slopes 1 on both sides of the concave trough 3. A foundation treatment layer 8 is provided on the bottom of the concave trough 3. The thickness of this foundation treatment layer 8 is controlled to be 150-250mm. It is backfilled with sand and gravel mixed into loess, with the mixing ratio controlled to be 5%-30%. The compaction coefficient of this foundation treatment layer 8 should be no less than 0.93. An anti-seepage surface layer 4 is provided on the slopes 1 on both sides of the concave trough 3, on the surface of the foundation treatment layer 8 on the bottom of the concave trough 3, and on the surface of the retaining dam 2.
[0036] The embodiment provides a design structure of a ravine landfill, such as Figures 1 to 2 As shown, the bottom anti-seepage structure 9 is arranged on the bottom surface of the concave area of the valley concave trough 3 along the length direction of the valley concave trough 3. The bottom anti-seepage structure 9 is constructed on the midline of the bottom surface of the valley concave trough 3, including the main blind ditch 9-1 for collecting groundwater in the lower layer and the main blind ditch 9-2 for collecting leachate in the upper layer. The bottom anti-seepage structure 9 extends outside the landfill area 10 and is connected to the bottom anti-seepage structure 9 at the bottom of the next adjacent landfill area 10, or is connected to the external drainage system to discharge groundwater and leachate. Figure 6As shown, the bottom anti-seepage structure 9 includes an inverted trapezoidal blind ditch groove opened on the bottom surface of the valley concave trough 3, the blind ditch groove extends outside the landfill area 10, and is connected to the bottom anti-seepage structure 9 at the bottom of the next adjacent landfill area 10, or is connected to the external drainage system; the overall groove depth of the blind ditch groove is 0.8 to 1.2 meters, the bottom width is 0.8 to 1.2 meters, the top width is 1.8 to 2.2 meters, and the slope of both sides is 1:1; the lower groundwater collection main blind ditch 9-1 includes a first layer of geotextile filter layer 9-11 laid in the blind ditch groove, a three-flowered pipe wrapped with geotextile, and a gravel layer 9 filled in the lower layer of the blind ditch groove. -13 and a final protective filter layer 9-14 laid on the top surface of the gravel layer; the upper leachate collection main blind ditch 9-2 includes an anti-seepage layer laid above the final protective filter layer 9-14, an anti-seepage isolation layer 9-24 arranged above the anti-seepage layer, a pebble leachate diversion layer 9-21 laid on the anti-seepage isolation layer 9-24, a leachate collection and discharge pipe 9-22 buried in the pebble leachate diversion layer and a geotextile protective layer 9-23 covering the top surface of the pebble leachate diversion layer; the anti-seepage layer and the anti-seepage surface layer 4 are an integrated structure, the pebble particle size range of the pebble leachate diversion layer is 20 to 40 mm; the gravel layer is filled with gravel with a diameter of 3 to 5 cm.
[0037] In the embodiment, Figure 4 and Figure 5 As shown, the reinforcement structure 5 includes a plurality of soil nails 5-1 driven into the slope surfaces of the two side slopes 1, a steel mesh 5-2 hung on the slope surfaces of the two side slopes 1, and a concrete surface layer 5-3 sprayed on the slope surfaces of the two side slopes 1. The steel mesh 5-2 is fixedly welded to the soil nails 5-1, and the concrete surface layer 5-3 covers the steel mesh 5-2. The spacing between the soil nails 5-1 is 1000mm to 1500mm.
[0038] In the embodiment, the retaining dam 2 is a dam structure formed by filling on-site loess, such as Figure 3 As shown, a reinforcement cushion layer 12 and a protective surface layer 13 are laid above the slope anti-seepage layer 4 of the retaining dam 2. The reinforcement cushion layer 12 is composed of a lower gravel cushion layer and an upper crushed stone cushion layer, and the protective surface layer 13 is a dry-laid C15 concrete block slope protection layer. Figure 7 As shown, the anti-seepage surface layer 4 is composed of GCL waterproof blanket 4-1, HDPE geomembrane 4-2 and filament geotextile 4-3 from the inside to the outside. The GCL waterproof blanket 4-1 is tightly laid on the slope 1 and the slope of the retaining dam 2 on both sides of the valley concave trough 3. The HDPE geomembrane 4-2 is seamlessly connected by heat welding technology. Figure 8As shown, anchor trenches 14 for fixing the anti-seepage surface layer 4 are provided on both sides of the top surface of the landfill area 10. The width of the anchor trench 14 is 0.5m-1.0m and the depth is 0.5m-1.0m. Both sides of the anti-seepage surface layer 4 extend into the corresponding anchor trenches 14 and are fixed by U-shaped nails 15. A clay layer 16 is backfilled in the anchor trench 14, and a concrete hardening layer 17 is provided on the top surface of the anchor trench 14; an intercepting drainage ditch 11 is provided 1 to 2m outside the anchor trench 14, and the cross-sectional width of the intercepting drainage ditch 11 is 0.5 to 0.8m and the depth is 0.7 to 1m.
[0039] The embodiment provides a design structure of a ravine landfill, such as Figure 1 and Figure 9 As shown, the toe lines of the slopes 1 on both sides of the concave trough 3 are respectively provided with toe counter-pressure soil layers 6. After the landfill is completed, the cover layer 7 covers the surface of the landfilled garbage layer in the landfill area 10. The cover layer 7 includes a clay, sand, or gravel base layer 7-1 laid on the surface of the landfill layer 18. The thickness of the base layer 7-1 is 300mm to 350mm. From bottom to top, the HDPE film layer 7-2, the 300mm to 350mm thick compacted clay barrier layer 7-3, the geotextile or geomembrane isolation layer 7-4, the gravel or ceramsite drainage layer 7-5, and the nutrient soil layer 7-6 are laid on the surface of the base layer 7-1 in order. Ornamental plants are planted in the nutrient soil layer.
[0040] In the example, the proposed project site is located in a loess plateau region in Shaanxi Province, with convenient transportation. The site's geomorphic unit is the second-level terrace on the north bank of the Shichuan River, with the overall topography trending from high in the east to low in the west. The ground elevation of the exploration boreholes ranges from 230 to 218 meters, with a maximum elevation difference of 12 meters. The engineering geological characteristics of each rock and soil layer from top to bottom are as follows:
[0041] ①-2 Plain fill Q4 ml : Yellowish brown, uneven soil, loose, mainly clay soil, containing a small amount of plant roots, thickness 0 to 1m.
[0042] ② Loess Q2 eol : Brownish yellow, relatively uniform soil with well-developed macropores, containing calcareous streaks, nodules, snail shells, plant roots, and wormholes. Hard plastic to plastic (some soil samples are hard), with slight collapsibility and self-weight collapsibility, belonging to medium compressibility. Loess layer gravity γ = 17.5kN / m 3 , cohesion c is 30kPa, internal friction angle The temperature is 35 degrees and the thickness is 10 to 20 meters.
[0043] The strata within the gully depth range in this area are mainly loess layers, and the gully depth is about 10m.
[0044] The specific construction steps for the above landfill are as follows:
[0045] S1. Topographic Survey and Site Cover Clearance: Conduct a detailed site topographic survey and create a topographic map to provide basic data for subsequent design and construction. First, perform surface treatment on the original subsoil and slope surface, removing plant roots, rocks, pits, and steep slopes. Clean a 50cm thick layer to create a fresh, flat subsoil surface. Site excavation and clearing should be completed from top to bottom in one go. This can be done in phases, but measures should be implemented to ensure quality and not impact the construction schedule. All removed waste should be transported to a designated dump.
[0046] S2. Slope treatment
[0047] a. Calculate the overall stability of the slope, determine the equivalent internal friction angle of the slope, determine the area and amount of slope cutting required, and perform slope cutting;
[0048] Assume the slope is vertical, take the unit width slope, and the rupture angle is Then the slope height AC=h and the sliding surface length BC=l, so the volume of the unstable block per unit width is
[0049]
[0050] Weight
[0051]
[0052] Normal stress is
[0053]
[0054] The equivalent internal friction angle of soil is widely used in engineering and is also accepted by most engineering technicians. From the definition of the equivalent internal friction angle, we can know that:
[0055]
[0056] but
[0057]
[0058] Where: τ-shear stress;
[0059] θ - soil rupture angle,
[0060] - soil internal friction angle;
[0061] -Equivalent internal friction angle of soil;
[0062] c-cohesion, unit: kPa;
[0063] l-slope sliding surface length, unit: m;
[0064] h-slope height, unit: m;
[0065] The equivalent internal friction angle of soil can be used to determine the overall stability of the slope: when the slope rock mass is in a state of limit equilibrium, that is, the sliding force is equal to the anti-sliding force; assuming the slope safety level is level 1, the safety factor is 1.35, and the angle between the slope excavation angle and the horizontal is β:
[0066]
[0067] but
[0068]
[0069] Where: β-slope repair angle;
[0070] F S -Safety factor.
[0071] Therefore, the slope is repaired according to β = 60° to ensure that the slope is stable in its natural state during the repair process.
[0072] b. Figure 1 As shown, the slopes on both sides of the valley are repaired: during construction, mechanical equipment is first used to shape and repair the slopes around the closed landfill according to the design requirements. For areas that cannot be handled by mechanical equipment, manual repair can be used to make the slopes flat and without bumps. The slope repair equipment uses a long-arm excavator. The repaired slopes are required to be smooth and tidy, without bumps, to facilitate the laying of the anti-seepage system. The corners and edges are required to be rounded, and the radius of the fillet should not be less than 0.3m.
[0073] c. Close and reinforce the slope surface, as follows: Figure 2 、 Figure 4 and Figure 5As shown, the reinforcement structure adopts a slope surface driven system soil nailing + shotcrete; the slope surface sealing is intended to enhance the stability of the slope and prevent the occurrence of geological disasters such as soil erosion and slope landslides; the slope surface driven system soil nails 5-1, as the main load-bearing component of the slope reinforcement, are hammered into the soil nails to form a composite with the slope and the surrounding soil to jointly bear the lateral earth pressure of the slope; the soil nails 5-1 are HRB400 grade Φ16 steel bars with high yield strength and good ductility, the soil nails L = 1m, and the spacing is arranged at 1m×1m; in order to further improve the integrity and shear resistance of the slope surface, a steel mesh 5-2 is hung on the slope surface, which effectively disperses and transmits the load on the slope surface, improves the integrity and shear resistance of the slope surface, and also provides for subsequent The sprayed concrete provides a reliable attachment foundation, enhancing the integrity and durability of the slope protection layer. The steel mesh 5-2 is 6.5mm in diameter @ 200x200mm, and the soil nails 5-1 are welded to the steel mesh to prevent soil spalling and crack expansion caused by natural factors such as rain erosion and freeze-thaw cycles. Finally, the slope sprayed concrete 5-3, model C20 and 100mm thick, ensures good bonding between the sprayed layer and the steel mesh and soil nails. C20 fine stone concrete has high compressive strength and good workability, and forms a good bond with the steel mesh and soil nails, thereby improving the overall stiffness and stability of the entire protective structure, protecting the slope from wind and rain erosion, further strengthening the slope, and improving the safety factor.
[0074] S3. Site backfill and foundation treatment: For site backfill, loess produced by slope cutting and site leveling should be used as the preferred backfill, avoiding the use of cleared topsoil that may damage the surrounding environment. For foundation treatment of gully-shaped depressions, natural sand, gravel and other materials with uniform particles, hard texture, no weathering, and no impurities should be mixed into the loess. The layered thickness of the site backfill soil material should be controlled between 150 and 250 mm to ensure the density and stability of the foundation; 5% to 30% of sand, gravel and other materials should be mixed into the loess. According to the original particle grading of the loess and the project requirements, the mixing ratio of sand and gravel should be reasonably determined to improve its physical and mechanical properties and enhance the bearing capacity and deformation resistance of the foundation. Each layer of backfill soil should be tightly combined to avoid stratification or overhead phenomena to ensure the integrity and stability of the foundation. The compaction coefficient of foundation treatment should be no less than 0.93 to ensure that the density and stability of the foundation meet the design requirements; after the trough-shaped depression is leveled, the slope along the axial direction of the valley should be controlled at around 3‰ to ensure the stability and safety of the landfill.
[0075] S4. The end of the valley is blocked by a retaining dam 2; the large amount of loess produced after the slope is cut can be used as the dam body material of the retaining dam 2. The structure of the retaining dam 2 is as follows: Figure 3As shown, loess is layered and filled to the designed height, with a slope ratio of 1:2.5. The thickness of each layer should be controlled within a reasonable range (generally no more than 30 cm) to ensure compaction and overall dam stability. During the construction of retaining dam 2, the loess moisture content must be strictly controlled at 19% to 21% to prevent excessive moisture or dryness from affecting the compaction effect. After each layer is completed, it must be compacted; compaction equipment should be vibratory rollers or tamping machines, and the number of compaction passes should be determined based on the characteristics of the loess and the compaction requirements. During the compaction process, the compaction degree must be monitored in real time to ensure that the compaction degree of each loess layer is no less than 0.94.
[0076] S5. Construct the main blind ditch 9-1 for collecting groundwater as the groundwater drainage system; Figure 2 and Figure 6 As shown, after the site is leveled, the construction of the groundwater drainage system is carried out in accordance with the following steps: ① Excavation of the main blind ditch groove: According to the preset control coordinates and elevation data, the main blind ditch for the groundwater drainage main pipe is excavated in a specific area at the bottom of the site. The main blind ditch has a depth of 1.0 meters, a lower bottom width of 1.0 meters, an upper bottom width of 2.0 meters, and a slope design of 1:1; ② Laying the first layer of protective filter layer 9-11: Covering the inside of the main blind ditch groove with a layer of woven geotextile as the first layer of protective filter layer. The first layer of filter layer material and the final protection and filter layer are all made of woven geotextile with a density of 230 grams / square meter; ③ Placing and wrapping the three-flowered pipe 9-12: Precisely place a high-density polyethylene (HDPE) three-flowered pipe at the center of the bottom of the main blind ditch, and tightly wrap its outer wall with woven geotextile. The diameter of the three-flowered pipe is DN300 high-density polyethylene (HDPE) 4. Seal the pipe end and connect the system: The pipe end is sealed with a special pipe cap, and the end of the groundwater drainage main is reliably connected to the main of the groundwater drainage system in the next stage. The filling gravel has a diameter of 3 to 5 cm, with a fine inner layer and a coarse outer layer, naturally forming an additional filter layer. Before the gravel material is brought into the site, the surface sediment must be cleaned and its calcium carbonate content must not exceed 10% to ensure the quality and applicability of the material. 5. Fill the gravel layer 9-13: Fill the main blind ditch groove with gravel with a diameter of 3 to 5 cm to form an additional filter layer with a filling height of 50 cm. 6. Lay the final protective filter layer 9-14: Lay another layer of woven geotextile on the surface of the gravel layer 9-13 as the final protective filter layer.
[0077] S6. Laying of the anti-seepage surface layer 4. The anti-seepage surface layer 4 covers the valley floor, the slopes on both sides of the valley, and the slope of the retaining dam. The anti-seepage surface layer 4 utilizes a multi-layered structure, composed, from the inside out, of GCL (natural sodium bentonite waterproof blanket), HDPE (high-density polyethylene) geomembrane, and filament geotextile, designed to effectively prevent sidewall leakage. Laying method: The dam body anti-seepage surface layer 4 is laid on flat ground by first splicing and welding the strips into a 20m wide strip. It is then laid from top to bottom on the slope, perpendicular to the dam axis. After the dam body slope is inspected and accepted, the strip is slowly rolled out from the crest of the embankment to the foot, perpendicular to the embankment axis, to the outer top of the trough at the foot of the slope, where it connects with the geomembrane at the reservoir bottom in a T-shaped pattern. The landfill 10 floor is laid after the reservoir bottom excavation is inspected and accepted. The strip is slowly rolled out from the outer top of the trough to the inside of the reservoir, perpendicular to the embankment axis, to a depth of 25m inside the reservoir. GCL natural sodium-based bentonite blanket, HDPE geomembrane and filament geotextile are laid from bottom to top on the slopes on both sides of the landfill area 10 to ensure that the side walls are impermeable. A leakage detection system is set up around the anti-seepage surface layer 4 to regularly check whether the anti-seepage layer is intact and to promptly detect and deal with leakage problems. The slope foot of the dam and the slope of the reservoir area are cleaned and leveled to the clay layer, or filled and rammed to the clay layer, and then a layer of HDPE anti-seepage membrane and a layer of filament geotextile (300g / m 2 ).
[0078] like Figure 8 As shown, an anchoring ditch 14 is set at the top of the slope to fix the composite anti-seepage surface layer; the width and depth of the anchoring ditch 14 should be determined according to the use conditions and stress conditions of the anti-seepage layer, generally the width is 0.5m-1.0m, and the depth is 0.5m-1.0m. The edge of the anti-seepage surface layer 4 is buried in the anchoring ditch 14 and anchored with U-shaped nails 15. The U-shaped nails 15 have a steel bar diameter of 8mm, a length of 0.5m, and a spacing of 0.5m. Then, the soil layer is backfilled in the anchoring ditch 14. When backfilling the soil in the anchoring ditch 14 at the top of the slope, the compaction quality of the backfill soil must be strictly controlled to ensure that the compaction coefficient of the backfill soil layer is not less than 0.93. The increase in the compaction coefficient helps to enhance the density and shear strength of the backfill soil, thereby further improving the overall stability of the anchoring ditch 14 and its internal anti-seepage surface layer. An intercepting drainage ditch 11 is installed 1.5 meters outside the anchor trench 14. The area between the top of the slope and the intercepting drainage ditch 11 is hardened with 100mm thick C30 concrete. The cross-sectional dimensions of the intercepting drainage ditch are 0.5 meters wide and 0.7 meters deep. This intercepts water flowing from outside the slope to the inside, protecting the slope and toe, maintaining slope stability, and reducing soil erosion. At the toe of the slope, loess backpressure measures are implemented, ensuring that the anti-seepage material adheres closely to the inside of the soil pile, ensuring good contact and adhesion with the soil, thereby fully realizing its anti-seepage, isolation, and reinforcement functions. The toe-of-slope backpressure soil layer 6 is trapezoidal, with a top width of 1 meter, a bottom width of 2 meters, and a height of 1 meter. The slope gradient is 1:1.
[0079] S7. Construction of the retaining dam's protective layer and slope protection. First, a 200mm thick sand and gravel cushion layer was laid on top of the filament geotextile fabric of the retaining dam's anti-seepage layer. This step ensured the cushion layer had good permeability and bearing capacity, providing a solid foundation for subsequent construction. Next, a 150mm thick crushed stone cushion layer was laid on top of the sand and gravel cushion layer. The addition of the crushed stone cushion layer further enhanced the bearing capacity and stability of the dam body. At the same time, its rough surface provided a good friction foundation for the subsequent laying of slope protection materials. Finally, a 150mm thick crushed stone cushion layer was laid on top of the gravel cushion layer. A layer of dry-laid C15 concrete block slope protection was laid. The C15 concrete blocks are 150mm thick and have high compressive strength and durability. They are connected by dry-laying, that is, no bonding materials such as mortar are used. Instead, the overall stability is maintained by the fit and friction between the stones. It is not only easy to construct, but also able to adapt to slight deformations of the slope, thereby improving the adaptability and durability of the slope protection. This step provides a solid slope protection layer for the retaining dam, effectively resisting damage from natural factors such as rain erosion and wind erosion, and facilitating vehicle passage and garbage unloading.
[0080] S8. Construction leachate collection main blind ditch 9-2, such as Figure 6 As shown in step S6, after the anti-seepage surface layer of the trough-shaped gully is laid, the pebble leachate diversion layer is laid above the anti-seepage layer. The pebbles should be selected with a particle size range of 20 to 40 mm to ensure good permeability, pressure resistance, and durability. The pebbles should be laid tightly and evenly, avoiding gaps or uneven stacking to ensure effective diversion. A woven geotextile is laid above the pebble diversion layer as a protective layer to prevent direct pressure from the waste on the pebble layer. The diversion layer design must be integrated with the landfill's overall anti-seepage system to ensure smooth leachate drainage. An anti-seepage isolation layer is installed below the diversion layer to prevent leachate from leaking into the groundwater. A DN315 HDPE leachate collection pipe is installed above the diversion layer to transport the collected leachate to the treatment facility.
[0081] S9. Construction of covering layer and surface greening, the specific structure is as follows Figure 9As shown, the construction process is as follows: First, after the landfill 10 is completed, the surface of the landfill layer 18 is leveled. A 300mm thick base layer 7-1 is then laid. Its primary materials typically include clay, sand, and gravel, providing stable support for the subsequent cover layer. A 0.5mm thick HDPE membrane layer 7-2 is laid on top of base layer 7-1. This membrane is made of high-density polyethylene and has excellent impermeability and aging resistance, preventing leachate leakage and odor diffusion. A barrier layer 7-3, composed of 300mm thick compacted clay, is placed on top of the HDPE membrane layer 72 to further block the diffusion of odors and pollutants. A geotextile or geomembrane isolation layer 7-4 is laid on top of barrier layer 7-3. A drainage layer 7-5 is then installed. Made of highly permeable materials such as gravel and ceramsite, it collects and drains surface water, maintaining a dry and stable cover layer. A nutrient layer 7-6 is laid above drainage layer 7-5. This layer, 1000mm thick and made of a mixture of soil, fertilizer, and other materials, provides nutrients and a growth environment for green plants. Landscaping and landscaping are being carried out around the landfill, selecting suitable plant species based on the climate and soil conditions surrounding the landfill. Plants with strong adaptability, rapid growth, and ornamental value are being planted.
[0082] The utility model uses the narrow valleys in the loess region as landfills, which have the advantages of rich land resources, suitable geological conditions, less environmental impact, low cost, and is conducive to waste treatment and resource utilization. By trimming the slope surface and the bottom of the slope, the existing slope can be reused without the need to dig another pit, and the problem of the existing slope not meeting the requirements of the landfill is overcome, which is conducive to reducing costs. According to the phased construction and operation plan of the landfill, the retaining dam system is divided into several independent sections, and each section is designed and constructed separately. This not only reduces the difficulty of construction, but also allows the position and height of the retaining dam to be flexibly adjusted according to the actual operation of the landfill to adapt to the continuous expansion of the landfill.
[0083] In summary, the content of the present invention is not limited to the above-mentioned embodiments. People with insight in the same field can easily propose other embodiments within the technical guiding ideology of the present invention, but such embodiments are all included in the scope of the present invention.
Claims
1. A design structure for a ravine landfill, characterized by: The invention comprises a valley concave trough (3), slopes (1) located on both sides of the valley concave trough (3), a retaining dam (2) provided in the valley concave trough (3), and a bottom anti-seepage structure (9) arranged on the bottom surface of the valley concave trough (3); the valley concave trough (3) is surrounded by the slopes (1) on both sides and the two retaining dams (2) to form a landfill area (10); the bottom anti-seepage structure (9) is arranged along the length direction of the valley concave trough (3), and comprises a main blind ditch (9-1) for collecting groundwater in the lower layer and a main blind ditch (9-2) for collecting leachate in the upper layer; the slopes on both sides of the valley concave trough (3) are provided with a retaining dam (2) and a bottom anti-seepage structure (9) arranged on the bottom surface of the valley concave trough (3); A reinforcement structure (5) is constructed on the slope surface of the slope (1), the bottom surface of the valley concave trough (3) is provided with a foundation treatment layer (8), and an anti-seepage surface layer (4) is provided on the slope surface of the slopes (1) on both sides of the valley concave trough (3), the surface of the foundation treatment layer (8) on the bottom surface of the valley concave trough (3), and the surface of the dam body (2). A reinforcement cushion layer (12) and a protective surface layer (13) are laid above the anti-seepage surface layer (4) on the slope surface of the retaining dam (2), and the foot lines of the slopes (1) on both sides of the valley concave trough (3) are provided with a foot back pressure soil layer (6) for back pressure of the anti-seepage surface layer (4).
2. A ravine landfill design structure according to claim 1, characterized in that: The ravine is a long and narrow ravine in a loess region, and is divided into a plurality of adjacent landfill areas (10) by a plurality of retaining dams (2) in the ravine. Two adjacent landfill areas (10) share one retaining dam (2). The retaining dam (2) is an isosceles trapezoidal structure with a plane in the middle and sloped surfaces on both sides, and the sloped surfaces on both sides face the two adjacent landfill areas (10) respectively. The retaining dam (2) is a dam structure formed by filling on-site loess.
3. A ravine landfill design structure according to claim 1 or 2, characterized in that: The structure further comprises a landfill layer (18) filled in a landfill area (10) and a covering layer (7) covering the surface of the landfill layer (18), wherein the covering layer (7) comprises, from bottom to top, a base layer (7-1), a HDPE film layer (7-2), a soil barrier layer (7-3), an isolation layer (7-4), a drainage layer (7-5) and a nutrient soil layer (7-6), and ornamental plants are planted in the nutrient soil layer.
4. A ravine landfill design structure according to claim 1 or 2, characterized in that: The reinforcement structure (5) comprises a plurality of soil nails (5-1) driven into the slope surfaces of the two side slopes (1), steel mesh sheets (5-2) hung on the slope surfaces of the two side slopes (1), and a concrete surface layer (5-3) sprayed on the slope surfaces of the two side slopes (1); the steel mesh sheets (5-2) are fixedly welded to the soil nails (5-1), and the concrete surface layer (5-3) covers the steel mesh sheets (5-2); and the spacing between the soil nails (5-1) is 1000 mm to 1500 mm.
5. A ravine landfill design structure according to claim 1 or 2, characterized in that: The anti-seepage surface layer (4) is composed of a GCL waterproof blanket (4-1), a HDPE geomembrane (4-2) and a filament geotextile (4-3) from the inside to the outside. The GCL waterproof blanket (4-1) is tightly laid on the slope surface of the side slope (1) on both sides of the concave trough (3) in the valley and the slope surface of the retaining dam (2). The HDPE geomembrane (4-2) is seamlessly connected by heat welding technology.
6. A ravine landfill design structure according to claim 1 or 2, characterized in that: The bottom anti-seepage structure (9) is constructed on the midline of the bottom surface of the valley concave trough (3); the bottom anti-seepage structure (9) includes an inverted trapezoidal blind ditch groove opened on the bottom surface of the valley concave trough (3), the blind ditch groove extends outside the landfill area (10), and is connected to the bottom anti-seepage structure (9) at the bottom of the next adjacent landfill area (10), or is connected to the external drainage system; the overall groove depth of the blind ditch groove is 0.8 to 1.2 meters, the bottom width is 0.8 to 1.2 meters, the top width is 1.8 to 2.2 meters, and the slope of the two sides is 1:
1. The main blind ditch (9-1) for collecting groundwater in the lower layer includes a first layer of geotextile filter layer (9-11) laid in the blind ditch groove, a three-flowered pipe (9-12) wrapped with geotextile, and a drainage system filled in the blind ditch. A gravel layer (9-13) in the lower layer of the groove and a final protective filter layer (9-14) laid on the top surface of the gravel layer; the upper layer leachate collection main blind ditch (9-2) includes an anti-seepage surface layer laid above the final protective filter layer (9-14), an anti-seepage isolation layer (9-24) arranged above the anti-seepage surface layer, a pebble leachate diversion layer (9-21) laid on the anti-seepage isolation layer (9-24), a leachate collection and discharge pipe (9-22) buried in the pebble leachate diversion layer, and a geotextile protective layer (9-23) covering the top surface of the pebble leachate diversion layer; the anti-seepage surface layer and the anti-seepage surface layer (4) are an integrated structure, the pebble particle size range of the pebble leachate diversion layer is 20 to 40 mm; the gravel layer is filled with gravel with a diameter of 3 to 5 cm.
7. A ravine landfill design structure according to claim 1 or 2, characterized in that: The reinforcing cushion layer (12) is composed of a lower gravel cushion layer and an upper crushed stone cushion layer, and the protective surface layer (13) is a dry-laid C15 concrete block slope protection layer; the thickness of the foundation treatment layer (8) at the bottom surface of the valley concave trough (3) is controlled to be 250 to 1000 mm.
8. A ravine landfill design structure according to claim 1 or 2, characterized in that: Anchor trenches (14) for fixing an anti-seepage surface layer (4) are provided on both sides of the top surface of the landfill area (10), wherein the width of the anchor trenches (14) is 0.5m-1.0m and the depth is 0.5m-1.0m. Both sides of the anti-seepage surface layer (4) extend into the corresponding anchor trenches (14) and are fixed by U-shaped nails (15). A clay layer (16) is backfilled in the anchor trenches (14), and a concrete hardening layer (17) is provided on the top surface of the anchor trenches (14). An intercepting drainage ditch (11) is provided 1-2m outside the anchor trenches (14), wherein the cross-sectional width of the intercepting drainage ditch (11) is 0.5-0.8m and the depth is 0.7-1m.
9. The design structure of a ravine landfill according to claim 3, characterized in that: The base layer (7-1) is a clay layer, a sand layer, or a crushed stone layer with a thickness of 300mm to 350mm. The barrier layer (7-3) is a compacted clay layer with a thickness of 300mm to 350mm. The isolation layer (7-4) is a geotextile or a geomembrane. The drainage layer (7-5) is a crushed stone layer or a ceramsite layer.