Slope protection and protection method for downstream soft rock enrockment area of stepped concrete faced rockfill dam

Abstract

The invention belongs to the technical field of environmental protection and slope protection reinforcement of water conservancy projects of thermal power plants, and provides a slope protection and protection method for a downstream soft rock enrockment area of a stepped concrete faced rockfill dam, and the slope protection and protection method comprises a first horizontal drainage body arranged from a preset upstream and downstream enrockment area boundary to the surface of a downstream dam slope; the second horizontal drainage body is arranged from the preset upstream and downstream rockfill area boundary to the surface of the downstream dam slope, and the third horizontal drainage body is arranged from the preset upstream and downstream rockfill area boundary to the surface of the downstream dam slope; the boundary of the upstream and downstream rockfill areas is an inclined line from the slope top to the slope bottom; the first horizontal drainage body, the second horizontal drainage body and the third horizontal drainage body are arranged at the preset height positions correspondingly, and the seepage loads in different dam height ranges and the seepage characteristics of downstream soft rock damming materials are fully considered through the design of the three-layer horizontal drainage body structure; a multi-layer smooth drainage channel can be provided for upstream reservoir water leakage and dam face infiltration rainwater at the same time, and the overall stability of a downstream dam slope is effectively guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental protection and slope reinforcement of water conservancy projects in thermal power plants, and in particular relates to a slope protection and protection method for a soft rock rockfill area downstream of a stepped panel dam. Background Art

[0002] In the construction of the face rockfill dam of a pumped storage power station, in order to effectively improve the utilization rate of excavated materials in the reservoir basin, soft rock materials with poor physical and mechanical properties are often used for the dam filling construction in the downstream rockfill area. Compared with the main rockfill area with higher requirements for construction parameters and mechanical strength indicators, the downstream rockfill area filled with soft rock materials usually has a relatively low permeability coefficient. When the dam leaks due to panel damage or joint damage, it may cause water to be difficult to discharge smoothly from the downstream rockfill area, and the infiltration line in the dam will rise, causing landslides on the downstream dam slope; at the same time, under extreme weather conditions, short-term heavy rainfall can not only form strong slope runoff on the surface of the downstream dam slope, causing scouring damage to the dam surface, but may also cause local seepage damage inside the dam body due to rainfall intrusion, thereby posing a threat to the overall stability and safety of the downstream dam slope. In addition, the downstream slope surface of the panel rockfill dam often adopts dry block stone slope protection, concrete grid beam slope protection and other types. These traditional slope protection types with cement, mortar, stone, concrete and other main building materials can only meet the basic protection needs of the dam slope, but are far from achieving satisfactory results in terms of ecological functions and coordination with the surrounding natural landscape.

[0003] At present, setting up horizontal drainage bodies on the dam body can improve the protection capability to a certain extent, but it is limited to extending into the contact surface between the dam body and the dam foundation, and cannot meet the soft rock dam construction situation with high requirements for drainage; specifically, the current slope protection with horizontal drainage bodies does not take into account the infiltration characteristics and destructive characteristics of the upstream reservoir water infiltration flow and the rainwater infiltrating the dam slope, resulting in that when a large number of horizontal drainage bodies are set, the protection capability can be improved, but the construction cost is increased, and the increase in the number of horizontal drainage bodies itself causes certain structural damage to the dam body; and when a small number of horizontal drainage bodies are set, the drainage effect cannot be very good, especially when it is short-term heavy rainfall, and the drainage cannot be very good. Summary of the invention

[0004] In order to solve the above problems, the present invention proposes a slope protection and protection method for the soft rock rockfill area downstream of a stepped panel dam, a first horizontal drainage body is arranged along a preset boundary line of upstream and downstream rockfill areas to the surface of the downstream dam slope, a second horizontal drainage body is arranged at a preset height from the first horizontal drainage body along the preset boundary line of upstream and downstream rockfill areas to the surface of the downstream dam slope, and a third horizontal drainage body is arranged at a preset height from the second horizontal drainage body along the preset boundary line of upstream and downstream rockfill areas to the surface of the downstream dam slope; the infiltration water flow of the upstream reservoir water is drained through the first horizontal drainage body, and the infiltration water flow of the upstream reservoir water is drained through the first horizontal drainage body. The second horizontal drainage body drains the infiltration flow of upstream reservoir water and the rainwater infiltrating into the dam slope, and the third horizontal drainage body drains the rainwater infiltrating into the dam slope, which fully considers the infiltration characteristics and destructive characteristics of the infiltration flow of upstream reservoir water and the rainwater infiltrating into the dam slope, and ensures the protection capability and controls the construction cost on the basis of avoiding too many horizontal drainage bodies. The three horizontal drainage bodies are all arranged along the preset boundary line of the upstream and downstream rockfill areas to the surface of the downstream dam slope, which avoids the problem of too long construction of the horizontal drainage body on the horizontal plane and ensures the protection effect of the downstream dam slope at the same time.

[0005] In order to achieve the above-mentioned object, in a first aspect, the present invention provides a slope protection for a soft rockfill area downstream of a stepped face-filled dam, which adopts the following technical solution:

[0006] A slope protection for a soft rock rockfill area downstream of a stepped face plate dam, comprising a first horizontal drainage body arranged along a preset boundary line of upstream and downstream rockfill areas to a surface of a downstream dam slope, a second horizontal drainage body arranged at a preset height from the first horizontal drainage body along a preset boundary line of upstream and downstream rockfill areas to a surface of a downstream dam slope, and a third horizontal drainage body arranged at a preset height from the second horizontal drainage body along a preset boundary line of upstream and downstream rockfill areas to a surface of a downstream dam slope; the boundary line of upstream and downstream rockfill areas is an inclined line from a slope top to a slope bottom;

[0007] The first horizontal drainage body is used to drain the infiltration flow of the upstream reservoir water; the second horizontal drainage body is used to drain the infiltration flow of the upstream reservoir water and the rainwater infiltrating the dam slope; the third horizontal drainage body is used to drain the rainwater infiltrating the dam slope.

[0008] Furthermore, the first horizontal drainage body is located at the end position outside the dam body and is provided with a dam foot drainage prism; the first horizontal drainage body is connected to the dam foot drainage prism.

[0009] Furthermore, the second horizontal drainage body, located at the end position outside the dam body, and the third horizontal drainage body, located at the end position outside the dam body, are respectively provided with a transverse anti-filtration drainage ditch.

[0010] Furthermore, a first drainage ditch and a downstream second longitudinal drainage ditch are respectively arranged on both sides of the downstream dam slope of the dam body; two transverse anti-filtration drainage ditches connected to the second horizontal drainage body and the third horizontal drainage body are respectively connected to the downstream first longitudinal drainage ditch and the downstream second longitudinal drainage ditch.

[0011] Furthermore, the permeability coefficients of the first horizontal drainage body, the second horizontal drainage body and the third horizontal drainage body are not less than 1.0 cm / s; the filling materials of the first horizontal drainage body, the second horizontal drainage body and the third horizontal drainage body are hard rock rockfill materials with fine particles less than 5 mm screened out.

[0012] Furthermore, the Marsal crushing rate during the construction of the first horizontal drainage body, the second horizontal drainage body and the third horizontal drainage body is not higher than 10%; the Marsal crushing rate is equal to the sum of all positive values ​​of the percentage difference of the particle size groups before and after rolling; the compaction thickness of the first horizontal drainage body, the second horizontal drainage body and the third horizontal drainage body is consistent with the upstream rockfill construction thickness.

[0013] Furthermore, the first horizontal drainage body, the second horizontal drainage body and the third horizontal drainage body all include a gravel drainage body and an inverted filter layer arranged on both sides of the gravel drainage body; the inverted filter layer has an uneven coefficient η<5-8, and the coefficient between two adjacent layers should satisfy:

[0014]

[0015] Among them, D 40-60 The particle size of the filter layer is smaller than this particle size, which accounts for 40-60% of the total soil weight; d 40-60 The particle size of the protected soil, soil smaller than this particle size accounts for 40-60% of the total soil weight.

[0016] Furthermore, the first horizontal drainage body, the second horizontal drainage body and the third horizontal drainage body are provided with a slope in the horizontal direction.

[0017] Furthermore, a geotextile is laid on the surface of the downstream dam slope, a three-dimensional vegetation net is laid on the geotextile, the three-dimensional vegetation net and the surface of the downstream dam slope are fixed by U-shaped steel nails, the three-dimensional vegetation net is evenly covered with nutrient soil, and herbaceous vegetation is planted on the nutrient soil.

[0018] In order to achieve the above-mentioned purpose, in a second aspect, the present invention also provides a method for protecting the soft rockfill area downstream of a stepped face dam, which adopts the following technical scheme:

[0019] A method for protecting the soft rock rockfill area downstream of a stepped panel dam adopts the slope protection of the soft rock rockfill area downstream of the stepped panel dam as described in the first aspect, including: draining the infiltration flow of upstream reservoir water through the first horizontal drainage body; draining the infiltration flow of upstream reservoir water and rainwater infiltrating into the dam slope through the second horizontal drainage body; and draining the rainwater infiltrating into the dam slope through the third horizontal drainage body.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. In the present invention, the first horizontal drainage body, the second horizontal drainage body and the third horizontal drainage body are respectively arranged at preset height positions. The design of the three-layer horizontal drainage body structure fully considers the seepage load within different dam height ranges and the seepage characteristics of the downstream soft rock dam building materials, and can simultaneously provide multi-level unobstructed drainage channels for upstream reservoir water leakage and rainwater infiltration into the dam surface, effectively ensuring the overall stability of the downstream dam slope. Specifically, a first horizontal drainage body is arranged along the preset boundary line of the upstream and downstream rockfill areas to the surface of the downstream dam slope, a second horizontal drainage body is arranged at a preset height from the first horizontal drainage body along the preset boundary line of the upstream and downstream rockfill areas to the surface of the downstream dam slope, and a third horizontal drainage body is arranged at a preset height from the second horizontal drainage body along the preset boundary line of the upstream and downstream rockfill areas to the surface of the downstream dam slope; the infiltration flow of the upstream reservoir water is drained through the first horizontal drainage body, the infiltration flow of the upstream reservoir water and the rainwater infiltrating the dam slope are drained through the second horizontal drainage body, and the rainwater infiltrating the dam slope is drained through the third horizontal drainage body, which fully considers the infiltration characteristics and destructive characteristics of the infiltration flow of the upstream reservoir water and the rainwater infiltrating the dam slope, ensures the protection capability and controls the construction cost on the basis of avoiding too many horizontal drainage bodies, and the three horizontal drainage bodies are all arranged along the preset boundary line of the upstream and downstream rockfill areas to the surface of the downstream dam slope, which avoids the problem of excessive length of construction of the horizontal drainage body on the horizontal plane and ensures the protection effect on the downstream dam slope at the same time.

[0022] 2. The present invention sets up multi-level unobstructed drainage channels to effectively ensure the overall stability of the downstream dam slope. On this basis, the horizontal drainage body filling materials, Marsal crushing rate, compaction thickness, filter layer parameters and slope are comprehensively selected and designed. For soft rock dam construction materials, it not only greatly improves the drainage performance in the dam, but also proposes an implementable plan with practical engineering guidance significance from multiple angles such as permeability, construction conditions, particle crushing rate and filter soil drainage function, which ensures the overall stability of the downstream dam slope and better meets the soft rock dam construction conditions.

[0023] 3. The present invention arranges three-layer horizontal drainage bodies inside the dam at the dam foundation and at a preset height of times the dam foundation, which are respectively connected to the drainage prism at the dam foot, the transverse anti-filtration drainage ditch on the slope, and the longitudinal drainage ditches on the left and right banks, and constructs a composite green ecological slope protection mainly composed of a three-dimensional vegetation network and herbaceous vegetation on the downstream dam slope surface, which fully considers the seepage load within different dam height ranges and the seepage characteristics of the downstream soft rock dam building materials, and effectively improves the smoothness of the drainage inside the dam body by arranging multi-layer horizontal drainage bodies inside the dam body and proposing corresponding design technical parameters, and ensures the overall stability of the downstream dam slope. By arranging a slope drainage system composed of transverse anti-filtration drainage ditches, longitudinal drainage ditches and dam foot drainage prisms on the dam slope surface, the reduction of slope stability caused by the action of surface water formed by rainfall is prevented, and by constructing a composite green ecological slope protection on the downstream dam slope surface, not only the risk of seepage damage to the dam body and slope erosion caused by rainfall is reduced, but also the problem of organically integrating dam body stability, slope protection, ecology and landscape is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings in the specification that constitute a part of this embodiment are used to provide a further understanding of this embodiment. The schematic embodiments of this embodiment and their descriptions are used to explain this embodiment and do not constitute improper limitations on this embodiment.

[0025] Figure 1 This is a cross-sectional view of the slope protection of Example 1 of the present invention;

[0026] Figure 2 This is a plan view of the slope protection according to Embodiment 1 of the present invention;

[0027] Figure 3 It is a cross-sectional view of a horizontal drainage body in a dam according to Embodiment 1 of the present invention;

[0028] Figure 4 It is a schematic cross-sectional view of a transverse reverse filtration drainage ditch according to Embodiment 1 of the present invention;

[0029] Among them, 1. upstream rockfill area; 2. boundary line between upstream and downstream rockfill areas; 3. downstream rockfill area; 4. downstream dam slope; 5. geotextile; 6. U-shaped steel nails; 7. three-dimensional vegetation net; 8. nutrient soil; 9. herbaceous vegetation; 10. horizontal filtration drainage ditch; 11. drainage body inside the dam; 1101. first horizontal drainage body; 1102. second horizontal drainage body; 1103. third horizontal drainage body; 12. drainage prism at the foot of the dam; 13. first downstream longitudinal drainage ditch; 14. second downstream longitudinal drainage ditch; 15. filtration layer; 16. gravel drainage body; 17. cement mortar masonry stone; 18. cement mortar finishing layer. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0031] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0032] Embodiment 1:

[0033] like Figure 1 As shown, this embodiment provides a slope protection device for the soft rock rockfill area downstream of the stepped panel dam, which is used to solve the slope erosion caused by rainfall and the seepage damage of the dam body in the soft rock rockfill area downstream of the panel dam under the premise of ensuring the overall stability and safety of the dam slope, and at the same time, the ecological protection and landscape coordination functions of the slope protection project can be taken into account. The slope protection device includes an upstream rockfill area 1, an upstream and downstream rockfill area boundary 2, a downstream rockfill area 3, a downstream dam slope 4, a geotextile 5, a U-shaped steel nail 6, a three-dimensional vegetation net 7, nutrient soil 8, herbaceous vegetation 9, a horizontal anti-filtration drainage ditch 10, a dam internal drainage body 11, a dam foot drainage prism 12, a downstream first longitudinal drainage ditch 13 and a downstream second longitudinal drainage ditch 14. The dam internal drainage body 11 includes a first horizontal drainage body 1101, a second horizontal drainage body 1102 and a third horizontal drainage body 1103. The dam foot drainage prism 12 includes cement mortar rough stone 17 and a cement mortar finishing layer 18.

[0034] Optional, such as Figure 1 As shown, the slope of the downstream dam slope 4 is 1:m, the slope of the upstream and downstream rockfill area boundary line 2 is 1:n, and the dam body height is H. Inside the downstream dam body, a first horizontal drainage body 1101 is set at the dam foundation position along the upstream and downstream rockfill area boundary line 2 to the downstream dam slope surface, which is connected to the dam foot drainage prism 12 set at the dam foot, mainly providing a drainage channel for the infiltration flow of the upstream reservoir water. At a height of 0.3H above the first horizontal drainage body 1101, a second horizontal drainage body 1102 is set from the upstream and downstream rockfill area boundary line 2 to the downstream dam slope surface, and its outlet is connected to the transverse filter drainage ditch 10, and at the same time provides a drainage channel for the infiltration flow of the upstream reservoir water and the rainwater infiltrating the dam slope. At a height of 0.3H above the second horizontal drainage body 1102, a third horizontal drainage body 1103 is set from the boundary line 2 of the upstream and downstream rockfill areas to the downstream dam slope surface, and its outlet is also connected to the transverse inverted filtration drainage ditch 10. This layer of drainage body mainly provides a drainage channel for rainwater infiltrating the dam slope, which can cut off the vertical downward infiltration channel of the infiltrating rainwater inside the dam body at the first time, thereby reducing the rainwater seepage volume under the dam body as much as possible.

[0035] like Figure 2 As shown, the two transverse anti-filtration drainage ditches 10 are respectively connected to the downstream first longitudinal drainage ditch 13 and the downstream second longitudinal drainage ditch 14 set on the left and right banks along the dam site.

[0036] According to the existing technical means, the drainage forms of earth-rock dam bodies mainly include prism drainage, vertical drainage, slope drainage, mattress drainage and pipe drainage. The mattress drainage is also set horizontally, but it is limited to the contact surface between the dam body and the dam foundation, and cannot meet the soft rock dam construction situation with high requirements for drainage. Based on this, in this embodiment, the first horizontal drainage body 1101, the second horizontal drainage body 1102 and the third horizontal drainage body 1103 are respectively set at preset height positions. The design of the three-layer horizontal drainage body structure fully considers the seepage load within different dam height ranges and the seepage characteristics of the downstream soft rock dam materials, and can provide multi-level unobstructed drainage channels for upstream reservoir water leakage and rainwater infiltration into the dam surface at the same time, effectively ensuring the overall stability of the downstream dam slope.

[0037] In this embodiment, the following requirements must be met when designing the first horizontal drainage body 1101, the second horizontal drainage body 1102, and the third horizontal drainage body 1103:

[0038] Good drainage performance, the first horizontal drainage body 1101, the second horizontal drainage body 1102 and the third horizontal drainage body 1103 have a permeability coefficient of not less than 1.0 cm / s. The filling material of the horizontal drainage body is made of hard rock rockfill, and fine particles with a particle size of less than 5 mm are screened out.

[0039] The Marsal crushing rate during the construction of the first horizontal drainage body 1101, the second horizontal drainage body 1102 and the third horizontal drainage body 1103 is not higher than 10%. The compressive strength of the parent rock is required to be not less than 50MPa. According to the sieving distribution before and after rolling during the construction process, the percentage difference ΔW of the i-th particle size group before and after rolling is determined. i , take the sum of all positive values ​​and calculate the Marsal breakage rate B g :

[0040] B g =∑ΔW i , ΔW i =W i碾压前 -W i碾压后 ;

[0041] Among them, W i碾压前 , W i碾压后 are the percentage contents of particle size group i in the drainage body before and after rolling, respectively.

[0042] According to the relevant specifications and appropriate construction conditions, the thickness of the dam rockfill is generally 0.8m. Therefore, the compaction thickness of the horizontal drainage body needs to be consistent with the upstream rockfill construction thickness to reduce construction difficulty and improve construction efficiency.

[0043] like Figure 3As shown, the soil filter drainage function, in order to prevent the loss of soil particles in the drainage body and maintain the anti-seepage stability of fine particles, the first horizontal drainage body 1101, the second horizontal drainage body 1102 and the third horizontal drainage body 1103 all include a gravel drainage body 16, and a filter layer 15 arranged on both sides of the gravel drainage body 16; optionally, a 0.2m thick filter layer 15 is set above and below the gravel drainage body 16, and sand and gravel with a particle size range of 5mm to 10mm are selected, and are laid from the inside to the outside of the drainage body in the order from fine to coarse. The uneven coefficient η of the filter layer 15 on the drainage body side is <5~8, and the coefficient between two adjacent layers should meet the following requirements:

[0044]

[0045] Among them, D 40-60 The particle size of the filter layer 15 is smaller than the particle size of the soil, which accounts for 40-60% of the total soil weight; d 40-60 The particle size of the protected soil, soil smaller than this particle size accounts for 40-60% of the total soil weight.

[0046] The first horizontal drainage body 1101, the second horizontal drainage body 1102 and the third horizontal drainage body 1103 form a certain slope in the horizontal direction. To ensure the smooth discharge of water in the dam, the horizontal drainage body needs to be made into a slope of 0.5% to 1% downstream for drainage.

[0047] Aiming at the soft rock dam building materials, the multi-level structural design and various specific technical designs of the first horizontal drainage body 1101, the second horizontal drainage body 1102 and the third horizontal drainage body 1103 not only greatly improved the in-dam drainage performance of the traditional earth-rock dam single-layer mattress drainage, but also proposed feasible specific technical parameters and indicators with practical engineering guidance significance from multiple angles such as permeability, construction conditions, particle crushing rate and soil filtration drainage function, filling the technical gap in the design of in-dam drainage bodies of earth-rock dams.

[0048] A geotextile 5 is pre-laid on the surface of the downstream dam slope 4, and a three-dimensional vegetation net 7 is laid on the geotextile 5 and fixed with U-shaped steel nails 6. After the nutrient soil 8 is evenly covered on the three-dimensional vegetation net 7, grass seeds are hydraulically sprayed to construct a green ecological slope protection consisting of the three-dimensional vegetation net 7 and herbaceous vegetation 9.

[0049] The slope of the downstream dam slope 4 is 1:m, and the value of m must meet the stability requirements of the downstream slope in relevant design specifications. The acceptable range is 1.5-2.0, and it can be appropriately adjusted according to the actual shear strength parameters of the dam material.

[0050] The slope of the boundary line 2 between the upstream and downstream rockfill areas is 1:n, and the value of n must meet the requirements for coordinated deformation of the zoning of the face rockfill dam. Optionally, when the compression modulus of the downstream soft rock rockfill area is not less than 50 MPa, the value of n should not be less than 0.6.

[0051] The dam foot drainage prism 12 is set at the dam foot. It is made of crushed stone and block stones to form a dense prism with a height of not less than 5m. The top elevation should exceed the highest water level downstream. Its main function is to lower the dam body infiltration line, prevent the penetration damage of soft rock materials at the dam slope, protect the downstream dam foot from being washed away by tailwater, and support the downstream dam slope to increase stability.

[0052] The transverse anti-filtration drainage ditch 10 is arranged on the downstream slope along the horizontal direction parallel to the dam axis. Its cross-section is an inverted trapezoidal structure, and the bottom elevation is designed in a gradual manner, that is, the location of the largest cross-section of the dam body is used as the dividing line, and it is inclined to the left bank and the right bank at a slope of 5%, respectively, and is connected to the downstream first longitudinal drainage ditch 13 and the downstream second longitudinal drainage ditch 14 arranged on both sides to maintain smooth drainage of water in the ditch.

[0053] The first downstream longitudinal drainage ditch 13 and the second downstream longitudinal drainage ditch 14 are respectively arranged at the junction of the dam body and the dam foundation on both sides, and are used to receive the slope water flow and seepage in the dam collected by the horizontally arranged transverse anti-filtration drainage ditch 10, and divert the flow to the downstream dam foot.

[0054] Optionally, the geotextile 5 is a non-woven material made of polyester, polypropylene, polyethylene, etc., which has certain strength and softness, as well as certain air permeability and waterproofness. When laid on the surface of the downstream dam slope 4 of the soft rock material, it can block the infiltration channel of the slope water, isolate the fine particles of the soft rock filling material, and prevent the slope from being eroded.

[0055] Optionally, the three-dimensional vegetation net 7 is a three-dimensional network-like geosynthetics used for planting grass and consolidating soil, which has the characteristics of being waterproof, anti-corrosive, anti-aging, and hydrolysis-resistant. The mesh gaps can be filled with soil, gravel, and fine stones, which can be passed through by plant roots and grow evenly. Before the grass grows, the three-dimensional vegetation net can protect the slope from wind and rain erosion. After the grass grows, it forms a strong green composite mechanical interlocking system with the net mat and soil, which plays a role in draining water, consolidating soil, and protecting the slope. There are currently a variety of mass-produced products and models available on the market.

[0056] Optionally, the U-shaped steel nail 6 is an anchoring device made of steel bars with a diameter of 6 to 8 mm bent into a U shape, and its function is to tightly connect the three-dimensional vegetation net and geotextile with the dam slope soil to prevent the surface layer from loosening or sliding.

[0057] Optionally, the nutrient soil 8 is a nutrient-rich soil composed of organic matter, which has a relatively compact structure, good water and fertilizer retention properties, and can provide a continuous and stable nutrient supply for plants.

[0058] In this embodiment, by arranging several layers of horizontal drainage bodies from bottom to top inside the downstream rockfill area, the drainage smoothness inside the dam body is improved, the harm of infiltrating rainwater and reservoir water leakage to the dam body is reduced, and the overall stability of the downstream dam slope is ensured; by laying geotextile 5 and three-dimensional vegetation net 7 on the surface of the downstream dam slope 4, the seepage channel of rainfall infiltrating into the dam body is effectively blocked, and the risk of seepage damage to the dam body caused by rainwater infiltration is reduced; by arranging a transverse anti-filtration drainage ditch 10 on the slope surface at the outlet of each layer of drainage body, the slope surface water formed by rainfall is effectively removed, and the reduction of slope stability caused by the action of surface water is prevented; by planting herbaceous vegetation 9 with significant soil-fixing function and easy maintenance in the covering soil of the three-dimensional vegetation net 7, not only can the slope runoff intensity formed by rainfall be effectively reduced, and erosion and damage of the slope can be prevented, but also the single stone or concrete face protection can be replaced by green vegetation, which has positive significance both in terms of landscape effect and ecological environment, thereby organically integrating dam body stability, slope protection, ecology and landscape, and realizing the harmonious unity of engineering construction and natural environment.

[0059] Embodiment 2:

[0060] The present embodiment provides a method for protecting the soft rock rockfill area downstream of a stepped panel dam, which adopts the slope protection of the soft rock rockfill area downstream of the stepped panel dam as described in Example 1, including: draining the infiltration water flow of the upstream reservoir water through the first horizontal drainage body 1101; draining the infiltration water flow of the upstream reservoir water and the rainwater infiltrating into the dam slope through the second horizontal drainage body 1102; and draining the rainwater infiltrating into the dam slope through the third horizontal drainage body 1103.

[0061] The above description is only a preferred embodiment of the present embodiment and is not intended to limit the present embodiment. For those skilled in the art, the present embodiment may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present embodiment shall be included in the protection scope of the present embodiment.

Claims

1. A slope protection for the soft rockfill area downstream of a stepped face dam, characterized in that: It comprises a first horizontal drainage body arranged along a preset boundary line of upstream and downstream rockfill areas to the surface of the downstream dam slope, a second horizontal drainage body arranged at a preset height from the first horizontal drainage body along the preset boundary line of upstream and downstream rockfill areas to the surface of the downstream dam slope, and a third horizontal drainage body arranged at a preset height from the second horizontal drainage body along the preset boundary line of upstream and downstream rockfill areas to the surface of the downstream dam slope; the boundary line of upstream and downstream rockfill areas is an inclined line from the top of the slope to the bottom of the slope; The first horizontal drainage body is used to drain the infiltration flow of the upstream reservoir water; the second horizontal drainage body is used to drain the infiltration flow of the upstream reservoir water and the rainwater infiltrating the dam slope; the third horizontal drainage body is used to drain the rainwater infiltrating the dam slope.

2. The slope protection for the soft rockfill area downstream of a stepped face dam according to claim 1, characterized in that: The first horizontal drainage body is located at the end position outside the dam body and is provided with a dam foot drainage prism; the first horizontal drainage body is connected to the dam foot drainage prism.

3. The slope protection of the soft rockfill area downstream of the stepped face dam according to claim 1, characterized in that: The second horizontal drainage body is located at the end position outside the dam body, and the third horizontal drainage body is located at the end position outside the dam body, and is respectively provided with a transverse anti-filtration drainage ditch.

4. The slope protection for the soft rockfill area downstream of a stepped face plate dam according to claim 3, characterized in that: The first drainage ditch and the downstream second longitudinal drainage ditch are respectively arranged on both sides of the downstream dam slope of the dam body; the two transverse anti-filtration drainage ditches connected to the second horizontal drainage body and the third horizontal drainage body are respectively connected to the downstream first longitudinal drainage ditch and the downstream second longitudinal drainage ditch.

5. The slope protection of the soft rockfill area downstream of the stepped face dam according to claim 1, characterized in that: The permeability coefficients of the first horizontal drainage body, the second horizontal drainage body and the third horizontal drainage body are not less than 1.0 cm / s; the filling materials of the first horizontal drainage body, the second horizontal drainage body and the third horizontal drainage body are hard rock rockfill materials with fine particles less than 5 mm screened out.

6. The slope protection of the soft rockfill area downstream of the stepped face dam according to claim 5, characterized in that: The Marsal crushing rate during the construction of the first horizontal drainage body, the second horizontal drainage body and the third horizontal drainage body is not higher than 10%; the Marsal crushing rate is equal to the sum of all positive values ​​of the percentage difference of the particle size groups before and after rolling; the compaction thickness of the first horizontal drainage body, the second horizontal drainage body and the third horizontal drainage body is consistent with the upstream rockfill construction thickness.

7. The slope protection of the soft rockfill area downstream of the stepped face dam according to claim 6, characterized in that: The first horizontal drainage body, the second horizontal drainage body and the third horizontal drainage body all include a gravel drainage body and an inverted filter layer arranged on both sides of the gravel drainage body; the inverted filter layer has an uneven coefficient η<5-8, and the coefficient between two adjacent layers should satisfy: Among them, D 40-60 The particle size of the filter layer is smaller than this particle size, which accounts for 40-60% of the total soil weight; d 40-60 The particle size of the protected soil, soil smaller than this particle size accounts for 40-60% of the total soil weight.

8. The slope protection of the soft rockfill area downstream of the stepped face dam according to claim 7, characterized in that: The first horizontal drainage body, the second horizontal drainage body and the third horizontal drainage body are provided with a slope in the horizontal direction.

9. The slope protection of the soft rockfill area downstream of the stepped face dam according to claim 1, characterized in that: The surface of the downstream dam slope is paved with a geotextile, on which a three-dimensional vegetation net is laid. The three-dimensional vegetation net and the surface of the downstream dam slope are fixed by U-shaped steel nails. The three-dimensional vegetation net is evenly covered with nutrient soil, on which herbaceous vegetation is planted.

10. A method for protecting the soft rockfill area downstream of a stepped face dam, characterized in that: The slope protection of the soft rock rockfill area downstream of the stepped panel dam as described in any one of claims 1 to 9 includes: draining the infiltration flow of upstream reservoir water through the first horizontal drainage body; draining the infiltration flow of upstream reservoir water and rainwater infiltrating into the dam slope through the second horizontal drainage body; and draining the rainwater infiltrating into the dam slope through the third horizontal drainage body.

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