Design method of drainage structure for debris slope and drainage structure

Abstract

The invention provides a drainage structure design method for a debris side slope and a drainage structure, and relates to the technical field of geological disaster prevention and control, the method comprises the following steps: investigating a target side slope, and obtaining and determining gradient information of the target side slope, form information of side slope furrowing, and grain composition information and mechanical property information of slope debris; based on the gradient information, the form information, the grain composition information and the mechanical property information, calling a ladder pool structure design model pre-constructed through a debris flow interception test, and determining design parameters of a ladder pool; checking the stability of the ladder pool structure under the action of the high-sand-content runoff according to the design parameters and the root reinforcement parameters of the preselected slope protection plants; when the checking calculation result meets a preset safety threshold value, the design parameters are used for implementing drainage structure engineering of the target slope. By means of the technical scheme, the sustainability, the long-term effect and the ecological friendliness of debris slope treatment engineering can be enhanced.

Description

Technical Field

[0001] This application relates to the field of geological disaster prevention and control technology, specifically to a drainage structure design method and drainage structure for debris slopes. Background Technology

[0002] Debris slopes (such as strongly weathered slopes in arid and cold regions, landslide deposits, and collapse deposits) are generally characterized by loose structure, high porosity, and high permeability. Under the influence of heavy rainfall or snowmelt, they are prone to forming surface runoff with high sediment content and high flow velocity. This type of flow often exhibits non-Newtonian fluid characteristics and also has precursory properties of debris flows. It not only has strong scouring force but also easily causes siltation of drainage channels, thereby inducing secondary soil erosion, shallow landslides, and even debris flow disasters. Therefore, scientifically designing drainage structures with efficient drainage, sediment regulation, and energy dissipation functions for such slopes is of great significance for improving slope stability and disaster prevention capabilities.

[0003] Currently, tiered drainage structures are commonly used in engineering to intercept and guide slope runoff in stages. Typical forms include stepped intercepting drainage ditches, drop wells / drop pipes, gravel blind ditches (permeable reverse filter drainage strips), stepped slope protection, vegetated grass swales, and collection wells and underground drainage pipe systems.

[0004] In the process of developing this invention, the inventors discovered that while the aforementioned structure has certain effectiveness in conventional slope management, it still has significant limitations when dealing with debris slopes. Specifically, existing cascade drainage structures are mostly designed based on clear water flow or low-sediment flow, focusing on energy dissipation and resistance enhancement, failing to fully consider the impact of high-concentration sediment on rheological characteristics, deposition behavior, and flow capacity. This leads to easy siltation and blockage, a sharp drop in drainage efficiency, and even structural failure during actual operation. Furthermore, there is a lack of mechanisms for the coordinated utilization of rainwater resources. Especially in cold and arid regions with highly weathered slopes, water resources are extremely scarce, and ecological restoration is difficult. Traditional drainage structures only aim to drain water away, making it difficult to effectively achieve rainwater retention, purification, or guidance for local ecological replenishment, thus missing the opportunity to transform hazardous runoff into ecological resources.

[0005] Therefore, in actual geological disaster prevention and control projects, it is urgent to construct a drainage structure design that can adapt to the characteristics of debris slopes, so as to scientifically guide the implementation of the corresponding projects and synergistically achieve geological disaster prevention and control and ecological function enhancement. Summary of the Invention

[0006] To at least partially overcome the problems existing in the related technologies, this application proposes a drainage structure design method and drainage structure for debris slopes. Based on the characteristics of the target slope, a terraced pool structure is adopted to specifically realize the drainage structure design of the target debris slope, so as to scientifically guide the implementation of related projects.

[0007] First aspect This application provides a drainage structure design method for debris slopes, the drainage structure design method comprising: The target slope is investigated to obtain information on its slope gradient, the morphology of the slope trench, the particle size distribution of the slope debris, and its mechanical properties. Based on the slope information, morphological information, particle size distribution information and mechanical property information, the design parameters of the stepped pool structure, which were pre-constructed through debris flow interception tests, are determined by calling the stepped pool structure design model. The design parameters include step height, pool depth, horizontal layout spacing and step rise-span ratio. Based on the design parameters and root reinforcement parameters of the pre-selected slope protection plants, the stability of the terrace structure under high sediment runoff is verified. The verification includes the increase in shear strength provided by the plant roots to the soil at the foot of the terrace arch. When the verification results meet the preset safety threshold, the design parameters are used to implement the drainage structure engineering of the target slope.

[0008] In some possible implementations, the particle size distribution information of the slope debris includes the median particle size d of the debris slope. 50 The stepped pool structure design model determines the step height H and horizontal spacing L based on the following expressions: in, The slope angle of the target slope is represented by J, which corresponds to the tangent value at the toe of the target slope.

[0009] In some possible implementations, the morphological information of the slope trench includes the trench width W; the pool depth h is determined in the terraced pool structure design model based on the following expression: Among them, Q f This indicates the design flood flow rate for the rainy season.

[0010] In some possible implementations, the mechanical property information of the slope debris includes the debris flow yield stress. The stepped span ratio is determined in the stepped pool structure design model based on the following expression. : in, This represents the stiffness coefficient of the debris flow. This represents the stiffness coefficient of the debris flow slurry. This indicates the volume concentration of coarse particles in the debris flow. This indicates the limiting volume concentration of coarse particles in the debris flow.

[0011] Among some possible implementations, for on-site sampling, the stiffness coefficient of the debris flow slurry, the volume concentration and limiting volume concentration of coarse particles in the debris flow are determined by indoor rheological tests, and the median particle size of the debris slope is determined based on sieve analysis.

[0012] In some possible implementations, the steps of the terraced pool structure are arched structures convex towards the direction of water flow. The verification process includes calculating the horizontal thrust F of the arched structure based on the following expression. H Accounting: Where q represents the uniformly distributed vertical load of the debris flow acting on the horizontal projection of the arched steps, K represents the debris flow turbulence correction coefficient, C represents the flow resistance coefficient, ρ represents the density of the debris flow, and V represents the calculated velocity of the debris flow.

[0013] In some possible implementations, the pre-selected slope protection plants are water-tolerant, deep-rooted plants.

[0014] Second aspect This application provides a drainage structure for debris slopes, which is based on a stepped pool structure. The design parameters of the stepped pool structure are determined by the drainage structure design method described in any of the implementations of the first aspect above.

[0015] In some possible implementations, in actual drainage structure engineering, the bottom of the deep pool of the stepped pool structure is provided with a roughened bed surface composed of large-diameter boulders to reduce the intensity of water flow scouring and inhibit downcutting erosion.

[0016] In some possible implementations, in actual drainage structure engineering, a nutrient zone composed of fine-grained silt is provided around the perimeter of the terraced pool structure near the foot of the stepped arch, in order to synergistically stimulate the nutrient and water tropism of the roots of the pre-selected slope protection plants.

[0017] The technical solution provided in this application, by combining field survey data of debris slopes with a stepped drainage structure design model constructed based on debris flow interception tests, achieves scientific quantification and precise adaptation of drainage structure parameters, effectively overcoming the problems of easy siltation, insufficient energy dissipation, and structural instability of traditional stepped drainage structures under high sediment content and high flow velocity runoff conditions. By incorporating the shear strength increment provided by the root system of pre-selected slope protection plants to the stepped arch foot soil in the stability calculation, ecological measures are deeply integrated into the structural safety design system, which not only improves the anti-sliding and anti-scour properties of key parts of the arch foot. The system not only solves the technical challenge of maintaining the long-term stability of stepped structures on debris slopes lacking bedrock support, but also naturally possesses the functions of graded energy dissipation, sediment settling, and local water storage. Combined with the utilization of fine-particle silt by plant roots, some of the silt is transformed into ecological matrix rather than an obstacle that needs to be removed. Thus, while ensuring efficient drainage and disaster prevention, it also achieves on-site retention, purification, and ecological reuse of rainwater resources, significantly enhancing the sustainability, long-term effectiveness, and eco-friendliness of debris slope treatment projects in ecologically fragile areas such as cold and arid regions. Attached Figure Description

[0018] Figure 1 A flowchart illustrating a drainage structure design method for a debris slope according to an embodiment of this application; Figure 2 A schematic longitudinal section of a stepped pool structure provided in one embodiment of this application; Figure 3 This is a top view illustration of a stepped pool structure provided in one embodiment of this application. Detailed Implementation

[0019] To make the purpose, technical solution and advantages of this application clearer, the technical solution of this application will be described in detail below.

[0020] As described in the background section, debris slopes (such as strongly weathered slopes in arid and cold regions, landslide deposits, and collapse deposits) are generally characterized by loose structure, high porosity, and high permeability. Under the influence of heavy rainfall or snowmelt, they are prone to forming surface runoff with high sediment content and high flow velocity. This type of flow often exhibits non-Newtonian fluid characteristics and also has precursory properties of debris flows. It not only has strong scouring force but also easily causes siltation of drainage channels, thereby inducing secondary soil erosion, shallow landslides, and even debris flow disasters. Therefore, scientifically designing drainage structures with efficient drainage, sediment regulation, and energy dissipation functions for such slopes is of great significance for improving slope stability and disaster prevention capabilities.

[0021] In developing this invention, the inventors discovered that while existing tiered drainage structures are effective in conventional slope management, they still have significant limitations when dealing with debris slopes. Specifically, existing tiered drainage structures are mostly designed based on clear water flow or low-sediment flow, focusing on energy dissipation and resistance enhancement, but failing to fully consider the impact of high-concentration sediment on rheological characteristics, deposition behavior, and flow capacity. This leads to siltation and blockage, a sharp drop in drainage efficiency, and even structural failure during actual operation. Furthermore, they lack mechanisms for the coordinated utilization of rainwater resources. Especially in cold and arid regions with highly weathered slopes, water resources are extremely scarce, and ecological restoration is difficult. Traditional drainage structures only aim to drain water away, making it difficult to effectively retain, purify, or guide rainwater for local ecological replenishment, thus missing the opportunity to transform hazardous runoff into ecological resources.

[0022] Based on in-depth consideration of the above-mentioned needs and practical research and analysis, the inventors discovered that naturally developed terraced pool structures have high energy dissipation efficiency for water flow, and their deep pool sections also have water storage functions. In other words, the terraced arrangement can effectively impede high-sediment-laden water flow and enhance sediment retention, making it an effective integrated drainage and water storage structure. Based on this, the inventors further conducted extensive research on the dimensions and spatial arrangement of natural terraced pool structures, analyzed their geometric configuration characteristics, and artificially simulated terraced pool structures to conduct debris flow interception experiments. This research investigated the influence of the size, shape, and spacing of the terraced pool structure under different debris gradations and slope gradients, thereby summarizing and deriving a terraced pool structure design model. Based on this, a drainage structure design method for debris slopes was proposed. Based on the characteristics of the target slope, a terraced pool structure was used to specifically implement the drainage structure design for the target debris slope, scientifically guiding the implementation of related projects and realizing an integrated drainage and water storage structure that simulates the natural state, achieving the goal of effectively impeding high-sediment-laden water flow and enhancing sediment retention.

[0023] In one embodiment, such as Figure 1 As shown, the drainage structure design method for debris slopes proposed in this application includes: Step S110: Investigate the target slope to obtain information on the slope gradient, the morphology of the slope trench, the particle size distribution of the slope debris, and the mechanical properties of the target slope.

[0024] In practice, slope angle information can be obtained through technologies such as total station, UAV photogrammetry, or lidar, such as obtaining the slope parameters corresponding to the slope angle. In reality, debris slopes often have gullies, which are areas where rainfall converges and concentrates on the slope surface. In the technical solution of this application, the terrace structure is arranged on the slope gully. The morphological information of the slope gully is mainly the gully width W, which can be quantitatively determined by combining field surveying with three-dimensional terrain modeling. The particle size distribution and mechanical properties information of the slope debris can be obtained by sampling the debris on the target slope and determining the required particle size distribution and mechanical properties information based on relevant experimental measurements.

[0025] Specifically, the particle size distribution information of the slope debris here includes the median particle size d of the debris slope. 50 In practice, on-site sampling can be conducted, and the median particle size of the debris slope can be determined based on sieve analysis. The mechanical properties of the slope debris include the debris flow yield stress. In practice, high-sediment-laden runoff formed on debris slopes under heavy rainfall or snowmelt conditions often exhibits non-Newtonian fluid behavior. Its initiation and movement are controlled by yield stress. Directly measuring the yield stress of debris flows in the field is difficult and has poor repeatability. In this application, the stiffness coefficient of the debris flow slurry, the volume concentration of coarse particles in the debris flow, and the limiting volume concentration are determined through indoor rheological tests to indirectly determine this information. For example, the yield stress of the debris flow is determined based on the following expression. : (1) (2) In expressions (1) and (2), This represents the stiffness coefficient of the debris flow. This represents the stiffness coefficient of the debris flow slurry. This indicates the volume concentration of coarse particles in the debris flow. This represents the limiting volume concentration of coarse particles in a debris flow. It should be noted that the above expression is a generalized engineering application formula and does not involve unit calculations.

[0026] Next, step S120 is performed. Based on the slope information, morphological information, particle size distribution information and mechanical property information determined in step S110, the design parameters of the stepped pool structure, which were pre-constructed through debris flow interception tests, are called to determine the design parameters of the stepped pool. The design parameters here include the step height, pool depth, horizontal spacing and step rise-span ratio.

[0027] Specifically, such as Figure 2 As shown, in the stepped pool structure design model summarized in this application, the step height H and horizontal spacing L are determined based on the following expressions: (3) (4) In expressions (3) and (4), The slope angle of the target slope is represented by J, which corresponds to the tangent at the toe of the target slope (slope gradient). 50 (Unit m) represents the median particle size. Similarly, these expressions are generalized engineering application formulas and do not involve unit calculations. For example, in an implementation scenario, the slope of the target slope is 26 degrees, the median particle size is 0.5m, H is determined to be 0.8m, and L is approximately 1.23m.

[0028] Specifically, such as Figure 2 As shown, in the stepped pool structure design model summarized in this application, the pool depth (or deep pool depth) h is also determined based on the following expression: (5) In expression (5), Q f Indicates the design flood discharge during the rainy season (m³). 3 / s), the trench width W is in meters. Similarly, the expression here is a generalized engineering application formula and does not involve unit calculation.

[0029] And it's easy to understand that the length of the deep pool here is also L.

[0030] In addition, such as Figure 3 As shown, an arched structure convex towards the direction of water flow ( Figure 3 (The arrow on the left in the diagram indicates the direction of water flow.) It possesses natural stability in the lateral direction. It effectively constrains the lateral diffusion of water flow, concentrating it in the central part of the steps and reducing erosion of the slopes or boundaries on both sides. The water flow diffuses on the arched surface and forms a hydraulic jump when converging at the edge of the next step, which helps to disperse and reduce the energy of the water flow. Therefore, in this application, the steps in the stepped pool structure are arched. Accordingly, the stepped pool structure design model summarized in this application also determines the step rise-span ratio based on the following expression. : (6) Expression (6) is also an engineering application formula, where d represents the sag (i.e., the arch height) and does not involve unit calculation.

[0031] Based on step S120, step S130 is performed. According to the design parameters and the root reinforcement parameters of the pre-selected slope protection plants, the stability of the terraced structure under high sediment load runoff is verified. This verification includes the increase in shear strength provided by the plant roots to the foot of the terraced arch. Specifically, the root reinforcement parameters include the internal friction angle φ and cohesion C of the root-soil composite, which can be pre-determined through geotechnical tests using undisturbed or reconstituted soil samples containing the corresponding plant roots, employing direct shear or triaxial shear tests.

[0032] It should be noted that, as mentioned earlier, the use of an arched structure allows water flow to diffuse on the arched surface and form a hydraulic jump when converging at the edge of the next step, which helps to disperse and reduce the energy of the water flow. However, the arch foot of the arched step requires a deep and resistant bedrock as a support point, which is generally not available in actual debris slopes. Considering the loose accumulation of debris slopes, the lack of a stable bearing layer, the urgent need for ecological restoration, and the high cost and poor durability of traditional engineering retaining structures, this application adopts ecological measures as a technical means to stabilize the structure. The reinforcement effect of the root system of resilient plants is used to enhance the overall erosion and sliding stability of the stepped structure.

[0033] In other words, based on the above-mentioned terrace structure design, this application combines artificially guided plant configuration during engineering implementation, utilizing the reinforcement and anchoring effect of the root system to ensure structural stability (e.g., by planting slope protection plants, the plant root system formed in the soil at the foot of the terrace arch is used to enhance the overall shear strength of the terrace structure).

[0034] Specifically, the selected slope protection plants here are water-tolerant, deep-rooted plants, such as Amorpha fruticosa, Juniperus sabina, Caragana korshinskii, and Bermuda grass.

[0035] The above verification process includes calculating the horizontal thrust F of the arch structure based on the following expression. H Accounting: (7) (8) In expressions (7) and (8), q represents the uniformly distributed vertical load of the debris flow acting on the horizontal projection of the arched steps, K represents the debris flow turbulence correction coefficient, C represents the flow resistance coefficient, and ρ represents the density of the debris flow (unit: kg / m³). 3 V represents the calculated velocity of debris flow (unit: m / s). Generally, the actual average velocity at the step should be used. If field measurement data is lacking, it can be calculated by combining the design flood flow observed at the hydrological station with the cross-sectional area at the step.

[0036] It should also be noted that, regarding the turbulence correction coefficient K for debris flow, considering the non-ideal uniformity of actual debris flow (such as turbulence and velocity fluctuations in natural channels), such as the steady debris flow in artificial channels, K = 0.9~1.0. However, when the debris flow is turbulent and has many eddies, K can be taken as 1.3~1.5. In practice, it is generally necessary to combine the on-site hydrological observation data for correction. The drag coefficient C is closely related to the cross-sectional shape and surface roughness of the step, and is a key parameter affecting the accuracy of impact force calculation. In application, for the case of arc-shaped cross-section, C = 0.8~1.2 (0.8 when the surface is smooth, and 1.0~1.2 when the surface has concrete laitance or attachments).

[0037] Based on the obtained horizontal thrust, targeted reinforcement of the arch foot is carried out to improve the stability of the arched staircase.

[0038] Specifically, F is calculated according to equation (7). H This application proposes a method based on the joint verification of soil bearing capacity and plant root anchoring capacity to ensure the overall stability of the arched stepped structure.

[0039] First, the soil in the arch foot area has its own anti-sliding resistance R. s It can be determined according to the classical soil shear strength criterion, as shown in the following expression (9): (9) In expression (9), Indicates effective cohesion. Indicates the effective internal friction angle. Let A represent the effective stress and A be the potential slip surface area.

[0040] Based on this, the enhancement of soil strength after adding roots includes two aspects: the shear strength of the root-soil composite itself, and the additional anchoring resistance provided by the roots.

[0041] Specifically, the shear strength of the root-soil composite formed in the arch foot region can be expressed as: (10) In expression (10), This indicates the contribution of the root reinforcement effect.

[0042] It can be calculated based on the Wu model or its improved form, and its expression is as follows: (11) In expression (11), This represents the tensile strength of the i-th root system. Indicates the angle between the root system and the shear plane. This represents the area of ​​the shear surface.

[0043] Combining the above incremental terms, the anti-sliding bearing capacity after root reinforcement can be obtained: (12) The additional anchoring resistance provided by the root system refers to the pull-out and shear resistance contribution of the root system itself, in addition to the increase in soil strength. It can be estimated using the following expression: (13) In expression (13), Indicates the root diameter. Indicates the effective anchorage length of the root system. This indicates the root-soil interface adhesion force.

[0044] Furthermore, considering both the shear strength and additional anchoring force provided by the root system, the total influence of the root system on soil strength enhancement can be summarized as follows: (14) Furthermore, considering the horizontal force exerted by the water flow on the plant stem, according to the drag force formula in fluid mechanics, this force can be expressed as: (15) In expression (15), Represents the drag coefficient of the water flow; for a cylindrical stem, the Reynolds number Re = 10. 3- 10 5 When the water flow drag coefficient is between 0.8 and 2.0, the coefficient decreases as the flow velocity increases; A represents the frontal area.

[0045] Then, in step S130, stability verification is performed based on the following safety factor expression, in conjunction with expressions (7) to (15): (16) In expression (16), This represents the safety threshold determined based on experience in slope stability engineering and design specifications, and is generally taken as 1.3-1.5.

[0046] Based on step S130, step S140 is performed. If the verification result meets the preset safety threshold, the design parameters are used to implement the drainage structure project of the target slope. If it does not meet the threshold, the sag-to-span ratio parameter in the design parameters can be adjusted and the verification is performed again until the verification is passed.

[0047] Furthermore, during the implementation of the drainage structure project, on-site layout and earthwork excavation were carried out based on the determined step height, pool depth, horizontal layout spacing, and step span ratio to construct the step section. At the corresponding downstream position of the step, a deep pool section was excavated and constructed. Simultaneously, in the step arch foot area, pre-selected deep-rooted stress-resistant slope protection plants (such as Amorpha fruticosa, Caragana korshinskii, or Juniperus sabina) were planted according to the design. This allows their roots to extend directionally into the moist area of ​​the deep pool through water-oriented guidance during subsequent growth, forming a three-dimensional reinforcement and anchorage for key stress-bearing parts.

[0048] After construction, this tiered drainage structure can achieve energy dissipation through cascading of high-sediment-laden runoff, sediment settling and retention, and localized water storage and reuse. Furthermore, the tiered structure is designed to be permeable and porous, allowing fine sediment particles to settle and combine with plant roots. The accumulated sediment is primarily fine-grained, high-quality soil, which can serve as a substrate for plant growth. Therefore, partial sedimentation is necessary and does not require complete removal. Sand removal only needs to remove the portion exceeding the critical height that significantly impacts water storage capacity. Selective sand removal is only performed when the sedimentation height in the deep pool exceeds a preset critical water storage threshold (e.g., 75% of the pool depth), thus ensuring the long-term operational efficiency of the system and the synergistic improvement of its ecological functions.

[0049] The technical solution provided in this application, by combining field survey data of debris slopes with a stepped drainage structure design model constructed based on debris flow interception tests, achieves scientific quantification and precise adaptation of drainage structure parameters, effectively overcoming the problems of easy siltation, insufficient energy dissipation, and structural instability of traditional stepped drainage structures under high sediment content and high flow velocity runoff conditions. By incorporating the shear strength increment provided by the root system of pre-selected slope protection plants to the stepped arch foot soil in the stability calculation, ecological measures are deeply integrated into the structural safety design system, which not only improves the anti-sliding and anti-scour properties of key parts of the arch foot. The system not only solves the technical challenge of maintaining the long-term stability of stepped structures on debris slopes lacking bedrock support, but also naturally possesses the functions of graded energy dissipation, sediment settling, and local water storage. Combined with the utilization of fine-particle silt by plant roots, some of the silt is transformed into ecological matrix rather than an obstacle that needs to be removed. Thus, while ensuring efficient drainage and disaster prevention, it also achieves on-site retention, purification, and ecological reuse of rainwater resources, significantly enhancing the sustainability, long-term effectiveness, and eco-friendliness of debris slope treatment projects in ecologically fragile areas such as cold and arid regions.

[0050] In one embodiment, this application also proposes a drainage structure for debris slopes, which is based on a stepped pool structure. The design parameters of the stepped pool structure are determined by the drainage structure design method in any of the above embodiments.

[0051] Furthermore, in the actual implementation of the drainage structure, the bottom of the deep pool in the stepped pool structure is equipped with a roughened bed surface composed of large-diameter boulders to reduce the intensity of water flow scouring and inhibit downcutting erosion. In this way, increasing the surface roughness can significantly dissipate the kinetic energy of the cascading water flow, slow down the near-bottom flow velocity, and at the same time increase the critical velocity for sediment initiation, effectively preventing the continuous erosion and downcutting of the original soil at the bottom of the pool by high-sediment-laden runoff. In addition, the pores between the roughened layers can accommodate some fine-particle sediments, preventing the bed surface from being completely silted up, maintaining long-term energy dissipation and flow passage functions, thereby ensuring the geometric stability and engineering durability of the stepped pool structure under the action of multiple rainstorms or snowmelt events.

[0052] Furthermore, in the actual implementation of the drainage structure project, the deep pool of the terraced pool structure is surrounded by a nutrient zone composed of fine-grained silt near the foot of the stepped arch, in order to synergistically stimulate the nutrient and water tropism of the roots of the pre-selected slope protection plants.

[0053] Specifically, during the initial to mid-stages of the terraced pool operation, fine-grained sediment carried by high-sediment-laden runoff settles within the deep pool and gradually accumulates in the low-velocity zone at the pool's edge, forming a fertile surface layer with a certain organic matter content and water retention capacity. During construction, this high-quality silt can be artificially guided to be concentrated and laid on the outer side of the deep pool within the range from the arch foot of the terrace, forming a ring-shaped or strip-shaped nutrient zone. This nutrient zone not only improves the local soil nutrient level and water retention capacity but also overlaps with the moist zone formed by the deep pool's water storage, jointly constituting a water-nutrient composite gradient field. This effectively induces the roots of deep-rooted plants such as Amorpha fruticosa and Caragana korshinskii to preferentially extend and grow towards the key stress area of ​​the arch foot, enhancing the reinforcement density and anchoring depth of the roots on potential slip surfaces or scour weak zones, thereby improving the overall anti-slip stability and scour durability of the terraced structure.

[0054] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0055] It is understood that the same or similar parts in the above embodiments can be referred to each other, and the contents not described in detail in some embodiments can be referred to the same or similar contents in other embodiments.

[0056] It should be noted that in the description of this application, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this application, unless otherwise stated, "a plurality of" means at least two.

[0057] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the function involved, as will be understood by those skilled in the art to which embodiments of this application pertain.

[0058] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0059] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A method for designing drainage structures for debris slopes, characterized in that, include: The target slope is investigated to obtain information on its slope gradient, the morphology of the slope trench, the particle size distribution of the slope debris, and its mechanical properties. Based on the slope information, morphological information, particle size distribution information and mechanical property information, the design parameters of the stepped pool structure, which were pre-constructed through debris flow interception tests, are determined by calling the stepped pool structure design model. The design parameters include step height, pool depth, horizontal layout spacing and step rise-span ratio. Based on the design parameters and root reinforcement parameters of the pre-selected slope protection plants, the stability of the terrace structure under high sediment runoff is verified. The verification includes the increase in shear strength provided by the plant roots to the soil at the foot of the terrace arch. When the verification results meet the preset safety threshold, the design parameters are used to implement the drainage structure engineering of the target slope.

2. The drainage structure design method according to claim 1, wherein, The particle size distribution information of the slope debris includes the median particle size d of the debris slope. 50 The stepped pool structure design model determines the step height H and horizontal spacing L based on the following expressions: in, The slope angle of the target slope is represented by J, which corresponds to the tangent value at the toe of the target slope.

3. The drainage structure design method according to claim 2, wherein, The morphological information of the slope trench includes the trench width W; the depth h of the pool is determined in the terraced pool structure design model based on the following expression: Among them, Q f This indicates the design flood flow rate for the rainy season.

4. The drainage structure design method according to claim 3, wherein, The mechanical properties of the slope debris include the debris flow yield stress. The stepped span ratio is determined in the stepped pool structure design model based on the following expression. : in, This represents the stiffness coefficient of the debris flow. This represents the stiffness coefficient of the debris flow slurry. This indicates the volume concentration of coarse particles in the debris flow. This indicates the limiting volume concentration of coarse particles in the debris flow.

5. The drainage structure design method according to claim 4, wherein, For on-site sampling, the stiffness coefficient of the debris flow slurry, the volume concentration and limiting volume concentration of coarse particles in the debris flow were determined by indoor rheological tests, and the median particle size of the debris slope was determined based on sieve analysis.

6. The drainage structure design method according to claim 4, wherein, The stepped structure of the terraced pool is an arched structure convex towards the direction of water flow. The verification process includes calculating the horizontal thrust F of the arched structure based on the following expression. H Accounting: Where q represents the uniformly distributed vertical load of the debris flow acting on the horizontal projection of the arched steps, K represents the debris flow turbulence correction coefficient, C represents the flow resistance coefficient, ρ represents the density of the debris flow, and V represents the calculated velocity of the debris flow.

7. The drainage structure design method according to claim 1, wherein, The selected slope protection plants are deep-rooted plants that are tolerant of waterlogging.

8. A drainage structure for debris slopes, characterized in that, The drainage structure is based on a stepped pool structure, and the design parameters of the stepped pool structure are determined by the drainage structure design method according to any one of claims 1 to 7.

9. The drainage structure according to claim 8, wherein, In actual drainage structure engineering implementation, the bottom of the deep pool of the stepped pool structure is provided with a roughened bed surface composed of large-diameter boulders to reduce the intensity of water flow scouring and inhibit downcutting erosion.

10. The drainage structure according to claim 8, wherein, In the actual implementation of drainage structure engineering, a nutrient zone composed of fine-grained silt is provided around the perimeter of the terraced pool structure near the foot of the stepped arch, in order to synergistically stimulate the nutrient and water tropism of the root system of the pre-selected slope protection plants.

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