Ecological water retaining dam for canyon area hydroelectric engineering slag field

Abstract

The utility model discloses a kind of ecological water retaining dam for gorge area hydropower engineering slag field and its construction method in the field of water conservancy and hydropower engineering, the dam body of the water retaining dam is in turn from center to upstream and downstream two sides for inverse filtration material heaped layer, stone residue heaped layer and soil-stone mixture heaped layer, the center of inverse filtration material heaped layer is provided with a steel wire mesh along vertical direction, composite geomembrane is laid on steel wire mesh, the slope of inverse filtration material heaped layer, stone residue heaped layer and soil-stone mixture heaped layer decreases in turn.The water retaining dam is stacked in the mode from inside to outside, uses inverse filtration material interlayer composite geomembrane as core wall, and composite geomembrane is supported by vertically erected steel wire mesh in inverse filtration material heaped layer, with good water retaining and sand retaining effect, outside stone residue and soil-stone mixture provide firm outer protective layer and good drainage passage, can significantly improve the seepage safety of core wall and the structural stability and scouring resistance of entire dam body, while giving consideration to construction economy and long-term durability.

Description

Technical Field

[0001] This utility model relates to the field of water conservancy and hydropower engineering, and in particular to an ecological water-retaining dam for slag heaps in hydropower projects in canyon areas. Background Technology

[0002] Currently, in water conservancy and hydropower projects or road transportation projects in high mountain and canyon areas, it is often difficult to find sufficiently open sites for dumping waste. Transporting it outside the canyon involves long distances and high transportation costs. Therefore, the common method is to select relatively flat small ditches near the construction site for dumping waste. To prevent the waste from being washed away by the water flow in the ditches, a dam needs to be built upstream of the waste dump, and the upstream water is guided and treated by excavating drainage tunnels, drainage ditches, or laying drainage pipes. Currently, reinforced concrete dams are commonly used for dams. Although structurally stable, they are expensive and incompatible with the surrounding environment, which is detrimental to ecological maintenance. Some solutions use earth-rock dams, but due to cost factors, the sealing effect is usually not high, and water seepage from the ditches is prone to occur, causing erosion of the downstream waste dump. Therefore, it is necessary to study an ecological dam for waste dumps in hydropower projects in canyon areas that is low-cost, has good sealing effect, and is conducive to ecological maintenance. Utility Model Content

[0003] To overcome the aforementioned shortcomings of existing slag heap dams, the technical problem to be solved by this utility model is to provide an ecological dam for slag heaps in hydropower projects in canyon areas that is low in cost, has good sealing effect, and is conducive to ecological maintenance.

[0004] The technical solution adopted by this utility model to solve its technical problem is: An ecological water-retaining dam for a hydropower project spoil disposal site in a canyon area includes a dam body and a drainage culvert located at the bottom of the dam body. The dam body consists of a filter material layer, a stone slag layer, and a soil-rock mixture layer, arranged sequentially from the center to the upstream and downstream sides. A steel wire mesh is installed vertically at the center of the filter material layer, and a composite geomembrane is laid on the steel wire mesh. The slopes of the filter material layer, the stone slag layer, and the soil-rock mixture layer decrease sequentially. The surface of the soil-rock mixture layer is covered with a nutrient geotextile and nutrient soil from the inside out, and green plants are planted on the nutrient soil.

[0005] Furthermore, the slope of the upstream and downstream sides of the filter material stack layer is 1:1.2~1.5, the slope of the stone slag stack layer is 1:1.5~1.8, and the slope of the soil-rock mixture stack layer is 1:1.8~3.0.

[0006] Furthermore, the top of the dam body is provided with a raised layer, which is constructed of bagged gravel.

[0007] Furthermore, the slope of the upper and lower sides of the heightened building is 1:1.5~1.8.

[0008] Furthermore, the bottom of the dam body is laid with a first cushion layer, a reverse filter geotextile, and a second cushion layer from bottom to top. The drainage culvert is located below the first cushion layer, and the dam body is built on the second cushion layer.

[0009] Furthermore, multiple steel pipes are inserted at intervals along the length of the dam body at its center, and the wire mesh is fixed to the steel pipes.

[0010] The beneficial effects of this utility model are as follows: A reverse filter material layer is used as the core wall. On both sides of the core wall, a stone slag layer and a soil-rock mixture layer are sequentially constructed using on-site slag to form the dam body. The stone slag and soil-rock mixture provide a robust outer protective layer and good drainage channels, significantly improving the seepage safety, structural stability, and scour resistance of the core wall, while also considering construction economy and long-term durability. Vertically erected wire mesh supports the composite geomembrane within the reverse filter material layer, effectively blocking sediment and ensuring the water-retaining effect of the core wall. It also serves as the skeleton of the reverse filter material layer, improving the structural strength of the dam's core wall. The slopes of the reverse filter material layer, stone slag layer, and soil-rock mixture layer decrease sequentially, enhancing the overall stability and scour resistance of the dam body. Attached Figure Description

[0011] Figure 1 This is a schematic cross-sectional view of the water-retaining dam of this utility model; Figure 2 This is a schematic diagram of the longitudinal section of the water-retaining dam of this utility model; Figure 3 This is a schematic diagram of the arrangement of the wire mesh of this utility model.

[0012] The markings in the diagram are as follows: 1-Filter material pile layer, 2-Stone slag pile layer, 3-Soil-rock mixture pile layer, 4-Nutrient geotextile, 5-Raising layer, 6-Filter geotextile, 7-Drainage culvert, 11-Wire mesh, 12-Composite geomembrane, 13-Steel pipe, 41-Nutrient soil, 42-Green plants, 51-Raising platform, 61-First cushion layer, 62-Second cushion layer. Detailed Implementation

[0013] The present invention will be further described below with reference to the accompanying drawings.

[0014] It should be noted that if this utility model contains directional indicators such as up, down, left, right, front, and back, these terms are used to describe the relative positional relationships between components and are not specific references to the absolute positions of the components or the relationships between them. They are only used to explain the relative positional relationships and movement of the components in a specific posture. If the specific posture changes, the directional indicator will also change accordingly. If this utility model contains terms related to quantity such as "many," "multiple," or "several," these terms specifically refer to two or more.

[0015] like Figure 1 , Figure 2 As shown, this utility model provides an ecological water-retaining dam for a hydropower project spoil heap in a canyon area, comprising a dam body and a drainage culvert 7 located at the bottom of the dam body. The dam body consists of a filter media layer 1, a stone spoil layer 2, and a soil-rock mixture layer 3, arranged sequentially from the center to the upstream and downstream sides. A wire mesh 11 is vertically arranged at the center of the filter media layer 1, and a composite geomembrane 12 is laid on the wire mesh 11. The slopes of the filter media layer 1, stone spoil layer 2, and soil-rock mixture layer 3 decrease sequentially. The surface of the soil-rock mixture layer 3 is sequentially covered with a nutrient geotextile 4 and nutrient soil 41 from the inside out, and green plants 42 are planted on the nutrient soil 41. The core wall of the dam body adopts a structure of filter media sandwiched with a composite geomembrane 12. The composite geomembrane 12 is used for water retention, and the filter media layer 1 is used for water filtration and sand retention. This reduces the internal water pressure of the core wall and prevents sand and soil loss, ensuring the structural stability of the core wall. The composite geomembrane 12 is supported by wire mesh 11, preferably positioned upstream of the wire mesh 11. This ensures the flat installation of the composite geomembrane 12 and provides support to the wire mesh 11, enhancing its water-retaining effect. The stone slag layer 2 and the soil-rock mixture layer 3 outside the filter media layer 1 are both sourced on-site, significantly reducing costs compared to reinforced concrete dams. The slopes of the filter media layer 1, stone slag layer 2, and soil-rock mixture layer 3 decrease sequentially, improving the overall anti-sliding, anti-overturning stability, and erosion resistance of the dam. Furthermore, it lengthens the seepage path, reduces the water head gradient on the slope, lowers the seepage pressure, and lowers the phreatic line, helping to prevent saturation and softening within the dam body.

[0016] Before constructing the dam, the foundation needs to be leveled and stabilized. This invention preferably uses a structure of two layers of cushion layer sandwiching a layer of geotextile filter. Specifically, the bottom of the dam is laid with a first cushion layer 61, a geotextile filter 6, and a second cushion layer 62, sequentially from bottom to top. The drainage culvert 7 is located below the first cushion layer 61, and the dam is built on the second cushion layer 62. The first cushion layer 61 and the second cushion layer 62 can be made of ordinary soil, primarily serving to protect the geotextile filter 6 from damage caused by hard stones or other objects.

[0017] like Figure 3 As shown, to facilitate the installation of the wire mesh 11, multiple steel pipes 13 are inserted at intervals along the length of the dam body at its center. The wire mesh 11 is fixed to the steel pipes 13 by welding or binding. The steel pipes 13 need to be inserted into the foundation to a certain depth to ensure the stability of the overall structure after the wire mesh is installed. In addition, geotextile fabric needs to be laid between the steel pipes 13 and the foundation surface to prevent soil and water loss along the steel pipes 13.

[0018] Regarding the specific slopes of the filter media layer 1, the stone slag layer 2, and the soil-rock mixture layer 3, the preferred embodiment of this utility model is that the slopes of the upstream and downstream sides of the filter media layer 1 are 1:1.2~1.5, the slope of the stone slag layer 2 is 1:1.5~1.8, and the slope of the soil-rock mixture layer 3 is 1:1.8~3.0. These slopes are primarily determined based on the stress conditions of the dam body and the characteristics of the selected materials. This ensures the stability of each layer during construction, and also ensures uniform stress distribution across all layers of the constructed dam body. This significantly improves the overall stability, seepage resistance, and erosion resistance of the dam body, while reducing maintenance costs during long-term operation.

[0019] Furthermore, the height of the dam is primarily determined by the historical flood season water level in the valley during the design phase. The dam height should ideally be higher than the historical flood season water level. However, considering that the drainage capacity of culverts or drainage tunnels might be insufficient after the dam is built, leading to a rise in upstream water level, a further solution is to install a raised platform 5 at the top of the dam. This raised platform 5 is constructed from bagged gravel. To improve the stability of the raised platform 5, the slope on both the upstream and downstream sides is preferably 1:1.5~1.8. To facilitate the construction of the raised platform 5, a raised platform 51 of a certain width can be reserved at the top of the dam. The raised platform 5 can be constructed before the flood season, depending on the actual situation. Additionally, the wire mesh 11 and composite geomembrane 12 can extend beyond the top of the dam, facilitating their integration with the bagged gravel and improving the water-retaining effect of the raised platform 5.

[0020] When constructing the ecological dams used as spoil heaps for hydropower projects in the canyon area, the following steps can be taken: Step 1: Excavate a trench from upstream to downstream at the location where a water-retaining dam needs to be built, then bury drainage pipe culvert 7 in the trench, and then backfill and compact it. Step 2: Level and compact the foundation surface, then lay the reverse filter geotextile 6, and then cover it with a layer of soil and compact it. Step 3: Insert steel pipes 13 at intervals along the dam axis on the foundation surface, then weld or tie the wire mesh 11 between the steel pipes 13, and then tie the composite geomembrane 12 to the wire mesh 11. Step 4: Based on the slope of the upstream and downstream sides of the filter material stacking layer 1, simultaneously stack the filter material on both sides of the wire mesh 11 and compact it firmly. Step 5: Construct stone slag layer 2 on both sides of the filter material pile layer 1. Stone slag layer 2 is backfilled in layers of 20-30cm. Each backfilled layer is compacted, and the compaction density is not less than 95%, until the slope of stone slag layer 2 meets the requirements. Step 6: Construct the soil-rock mixture layer 3 on the outside of the stone slag layer 2, and compact it in layers in the same way as the stone slag layer 2 until the slope of the soil-rock mixture layer 3 meets the requirements. Step 7: Lay nutrient geotextile 4 and nutrient soil 41 on the surface of the soil-rock mixture layer 3 in sequence, and then plant green plants 42 on the nutrient soil 41 and maintain them.

[0021] In step one, the backfill soil should be compacted in layers, with each layer not exceeding 20cm in thickness and a compaction degree of over 90%. Backfilling on both sides of the culvert should be symmetrical, and the height difference between the backfill layers on both sides should not exceed 30cm during compaction to prevent displacement of the culvert. Mechanical compaction can only be used when the top of the culvert is covered with at least 50cm of soil to prevent damage to the culvert. For valley areas with insufficient foundation bearing capacity, gravel or lime-soil can be used for backfill compaction.

[0022] In step two, before laying the geotextile 6, clean the debris and gravel from the surface of the construction base. Then, lay a layer of soil on the foundation surface, lay the geotextile 6, and cover it with another layer of soil, followed by compaction. When laying the geotextile 6, the edges of adjacent pieces should overlap by at least 30cm, and on-site sewing can be performed if necessary.

[0023] In step three, the steel pipes can be installed by drilling holes first and then inserting the steel pipes 13. The steel pipes 13 and the wire mesh 11 are erected in layers as the dam is built. That is, first fix a section of steel pipe 13, and at the same time hang a section of wire mesh 11 and composite geomembrane 12 of the same height. When the filter material layer 1 is piled up later, when it is piled up to near the upper end of the steel pipe 13, the steel pipe 13 is raised by welding or threaded connection, and another section of wire mesh 11 is hung. Then the filter material layer 1 is piled up again, and so on, until the filter material layer 1 is completed.

[0024] In step four, when constructing the filter material layer 1, the filter material can be moistened with water first, then laid using a backhoe, and compacted using a vibratory roller. The contact area between the filter material layer 1 and the bank can be compacted using a vibratory roller along the bank. In step five, the stone chips are obtained by crushing the on-site slag with a crusher. The particle size of the stone chips can be controlled to 3-5 cm. A road roller is used for layered compaction, and water can be sprayed appropriately during this process to improve the density of the stone chips. In step six, the raw material for the soil-rock mixture layer 3 is also soil mixed with stones produced during on-site tunnel excavation. During the laying process, large stones can be removed and fine sand and gravel can be backfilled. Water can also be sprayed appropriately during compaction to increase the compaction degree. During the construction of the dam, considering the structural stability and erosion resistance of the dam, the slope of the upstream and downstream sides of the filter material layer 1 is preferably controlled at 1:1.2~1.5, the slope of the stone slag layer 2 is controlled at 1:1.5~1.8, and the slope of the soil-rock mixture layer 3 is controlled at 1:1.8~3.0. The height of the dam is not lower than the historical flood season water level of the canyon area. A raised platform 51 is reserved at the top of the dam. If the flood season water level exceeds the height of the dam, bagged sand and gravel are piled on the raised platform 51 to form a raised layer 5. The slope of the raised layer 5 on the upstream and downstream sides is controlled at 1:1.5~1.8.

Claims

1. An ecological dam for a slag heap in a hydropower project in a canyon area, comprising a dam body and a drainage culvert (7) located at the bottom of the dam body, characterized in that: The dam body consists of a filter material layer (1), a stone slag layer (2), and a soil-rock mixture layer (3) arranged sequentially from the center to the upstream and downstream sides. A wire mesh (11) is provided vertically in the center of the filter material layer (1), and a composite geomembrane (12) is laid on the wire mesh (11). The slopes of the filter material layer (1), the stone slag layer (2), and the soil-rock mixture layer (3) decrease sequentially. The surface of the soil-rock mixture layer (3) is covered with a nutrient geotextile (4) and nutrient soil (41) from the inside to the outside. Green plants (42) are planted on the nutrient soil (41).

2. The ecological dam for a hydropower project spoil heap in a canyon area as described in claim 1, characterized in that: The slope of the upstream and downstream sides of the filter material stacking layer (1) is 1:1.2~1.5, the slope of the stone slag stacking layer (2) is 1:1.5~1.8, and the slope of the soil-rock mixture stacking layer (3) is 1:1.8~3.

0.

3. The ecological dam for a hydropower project spoil heap in a canyon area as described in claim 1, characterized in that: The top of the dam body is provided with a raised floor (5), which is constructed of bagged gravel.

4. The ecological dam for a hydropower project spoil heap in a canyon area as described in claim 3, characterized in that: The slope of the upper and lower sides of the heightened building (5) is 1:1.5~1.

8.

5. The ecological dam for a hydropower project spoil heap in a canyon area as described in any one of claims 1-4, characterized in that: The bottom of the dam body is laid with a first cushion layer (61), a reverse filter geotextile (6), and a second cushion layer (62) from bottom to top. The drainage culvert (7) is located below the first cushion layer (61), and the dam body is built on the second cushion layer (62).

6. The ecological dam for a hydropower project spoil heap in a canyon area as described in claim 5, characterized in that: Multiple steel pipes (13) are inserted at intervals along the length of the dam body at its center, and the wire mesh (11) is fixed on the steel pipes (13).

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