Evaluation method and application of self-desilting efficiency of gap dams, and gap dam design method

Abstract

The present invention discloses a method for evaluating the self-desilting efficacy of a slit dam and its application, as well as a method for designing a slit dam. In view of the defect that the prior art does not have a technical solution related to the self-desilting efficacy of a sand retaining dam, the present invention provides a method for evaluating the self-desilting efficacy of a slit dam. The evaluation method starts with the heavy characteristic parameters of the scouring and erosion of the deposits in front of the dam by hydrodynamics, constructs a series of mathematical models and corresponding thresholds, and first completes the classification of the self-desilting effect of the slit dam, dividing it into surface scouring type and groove erosion type, thereby solving the problems of measuring the self-recovery reservoir capacity, self-recovery expansion rate, and reservoir capacity recovery capacity classification. The slit dam design method of the present invention provides an optimal verification technology for the opening structure parameters of the combination of slit width and opening rate, guiding the design and implementation of the self-desilting capability of the slit dam in actual engineering. The present invention improves the scientific nature of the research on the automatic desilting function of the permeable sand retaining dam.

Description

Technical Field

[0001] The present invention relates to a debris flow disaster prevention project, and in particular to a method for evaluating the self-desilting efficacy of a slit dam and its application, as well as a slit dam design method. The invention belongs to the technical field of water conservancy engineering and the technical field of data processing methods specifically suitable for specific functions. Background Art

[0002] When debris flow dams accumulate silt in front of the dam during operation, the debris flow deposits stored in the reservoir can be partially or completely transported downstream with the water under the scouring and erosion generated by daily hydrodynamics, achieving automatic silt removal. This phenomenon is called self-silting of the dam. In debris flow control projects, permeable dams have a self-silting function. While improving the safety of the dam body during operation, they can also alleviate the urgency of silt removal projects in front of the dam to a certain extent. Therefore, they have gradually replaced traditional solid dams and become the more widely used type of dam in control projects. Among various types of permeable dams, slot dams have become one of the most widely used permeable dam types because they can take into account the advantages of permeability and simple structure.

[0003] Although the prior art has observed the self-silting phenomenon of permeable sand-control dams in operation, and recognized that self-silting is a unique performance of permeable sand-control dams, which has the specific advantages of increasing effective storage capacity, extending the service life of the project, and reducing the amount of manual silting work and total costs, and has also partially described the self-silting process of sediments upstream of the grid dam, and at the same time recognized that not all permeable sand-control dams have good self-silting effects, the prior art still lacks research on the self-silting efficacy of permeable sand-control dams.

[0004] The existing paper "Evaluation of the Self-Dredging Effect and Effectiveness of Transparent Debris Flow Dams" (Huang Diwen et al., People's Yangtze River, March 2025) discloses the performance characteristics and effectiveness of self-dredging in transparent debris flow dams, based on field survey data from 154 transparent debris flow dams. The paper demonstrates that self-dredging can reduce the longitudinal slope of the accumulation within the reservoir, while also causing surface coarsening and gully erosion of debris flow deposits. A self-dredging effect classification matrix was constructed, identifying key factors influencing self-dredging: longitudinal slope of the backfill, rainfall intensity, and relative aperture. However, this paper is still a research finding based on scientific observation and does not identify technical issues related to self-dredging effectiveness, nor does it provide corresponding technical solutions.

[0005] In fact, existing research on the self-dredging efficacy of permeable sand dams has reached a certain consensus, but further research is needed to integrate these findings with engineering practice to identify technical issues, develop technical solutions, and resolve these issues, thereby promoting the transfer of scientific discoveries into engineering practice. Based on existing technologies, new technical issues should be addressed and raised. Specifically, how can a scientific evaluation scheme for self-dredging efficacy be established, in addition to field measurements and empirical descriptions? Furthermore, how can this approach, through the development of a scientific evaluation scheme for self-dredging, expand the scope of scientific research and technical solution development in the field of slit dams? Summary of the Invention

[0006] The purpose of the present invention is to address the deficiencies of the existing technology and provide an evaluation and measurement technology for the self-dredging efficacy of a slit dam during operation, as well as a design method based on this technology to enhance the self-dredging function of the slit dam.

[0007] To achieve the above objectives, the present invention provides a method for evaluating the self-desilting efficacy of a slit dam, and its technical solution is as follows.

[0008] A method for evaluating the effectiveness of self-desilting of gap dams.

[0009] First, conduct on-site surveys of the gap dam and trench to obtain basic engineering data;

[0010] Secondly, calculate the heavy feature parameters A , heavy feature parameters A According to the model expression of formula 1,

[0011] Formula 1

[0012] Where, c f - The fluid density of the hydrodynamic conditions in the dam front ditch, in kN / m 3 , determined according to the basic engineering data,

[0013] g - Gravitational acceleration constant, unit: m / s 2 ,

[0014] r d - Density of debris flow accumulation in the reservoir, unit: t / m 3 , determined according to basic engineering data;

[0015] Secondly, calculate the discriminant parameters of the self-desilting effect of the gap dam F , discriminant parameters F According to the model expression of formula 2,

[0016] Formula 2

[0017] Where,b - The width of the gap dam, in meters, is determined based on the basic engineering data.

[0018] d max - The maximum particle size of debris flow intercepted by the gap dam, in meters, is determined based on the basic engineering data.

[0019] l - Slit dam opening ratio, %, determined based on engineering basic data.

[0020] F r - Froude number of fluid motion in the ditch in front of the dam under hydrodynamic conditions, dimensionless parameter,

[0021] v f - Average flow velocity of the fluid in the ditch in front of the dam under hydrodynamic conditions, in m / s, determined based on basic engineering data.

[0022] h f - Average depth of fluid flow in the ditch in front of the dam under hydrodynamic conditions, in meters, determined based on basic engineering data.

[0023] i - The accumulation slope of debris flow accumulation body in the reservoir, in degrees, based on basic engineering data;

[0024] Finally, according to the discriminant parameters F Evaluate the type of self-desilting effect of the gap dam,

[0025] like F <0.28, the self-desilting effect of the gap dam belongs to the surface scouring type;

[0026] like F ≥0.28, the self-desilting effect of the gap dam belongs to the gully erosion type.

[0027] The above-mentioned evaluation method of the self-dredging efficacy of the gap dam starts from the conditional judgment of the self-dredging function of the gap dam, that is, it fundamentally considers whether the debris flow deposits intercepted in the reservoir can be transported to the downstream with the water due to the scouring and erosion of the water flow under the hydrodynamic conditions. The hydrodynamic conditions are characterized by the gravity relationship between the debris flow deposits in the reservoir in front of the dam and the water flow in front of the dam. It is compared with the macro- and micro-structural characteristics of the deposits caused by the accumulation formation mechanism as a variable to investigate the removal of the surface of the deposits by scouring and erosion with the water flow. The gravity characteristic parameter A is designed as the first-level observation variable for the evaluation of the self-dredging efficacy of the gap dam. On this basis, a discriminant model for the self-dredging efficacy of the gap dam is constructed by combining theoretical derivation, engineering practice survey data, and indoor simulation experiment measurement data. The discriminant parameter F Quantify the effectiveness types of self-desilting of gap dams.

[0028] The assessment method divides the self-desilting effect of the gap dam into two types, one corresponding to each gap dam type: F A dam with a slurry ratio less than 0.28 is a surface-scouring, self-dredging, and gap dam. Its self-dredging effect is generated by the planar erosion of debris flow deposits within the reservoir. During dam operation, scouring can significantly coarsen the surface particles of the deposits. However, due to hydrodynamic conditions and the macro- and microstructural characteristics of the deposits due to their formation mechanism, the erosion base level of the deposits is difficult to lower, and a dominant erosion path cannot be established, resulting in a cumulative erosion depth. Therefore, after the debris flow is intercepted and accumulated in front of the dam, the self-dredging effect can be relatively stably demonstrated under the hydrodynamic conditions of approximately one hydrological year. F A dam with a slit dam depth of ≥0.28 is considered a groove-erosion, self-dredging dam. Its self-dredging effect is generated by water undercutting and lateral erosion. During dam operation, the hydrodynamic forces in front of the dam coarsen the surface particles of the deposit, further forming distinct erosion grooves. The erosion base level gradually decreases, ultimately establishing a dominant erosion path. Along this dominant erosion path, erosion achieves a relatively stable cumulative effect over time, maintaining the overall erosion depth over a longer period. Therefore, after debris flow is intercepted and accumulated in front of the dam, the self-dredging effect can be stably demonstrated over approximately one to two hydrological years of hydrodynamic conditions.

[0029] Based on the evaluation and classification of the self-desilting effect of the gap dam, the self-recovery storage capacity Δ V . Self-recovery storage capacity Δ V It refers to the storage capacity that can be automatically restored by the gap dam under the action of self-dredging.

[0030] The self-recovery storage capacity Δ of surface scouring type self-desilting and groove erosion type self-desilting is calculated according to the models of Equation 3 and Equation 4 respectively. V 1 and Δ V 2. Among them, V is the designed storage capacity of the gap dam (unit: m 3 ).

[0031] Formula 3

[0032] Formula 4

[0033] Further optimization of the evaluation method of the self-dredging effect of the gap dam is to calculate the self-recovery expansion rate of the gap dam E .index E In addition to its absolute value, it can also be used to evaluate the self-desilting performance level of the gap dam. Based on the survey data of gap dam engineering practice, this paper provides a set of specific grading standards: E ≤5% means weak performance, 5%< E ≤15% is medium performance, 15%< E≤30% indicates strong performance, E >30% indicates strong performance.

[0034] Formula 5

[0035] The above-mentioned evaluation method of self-desilting effect of gap dam can be used to evaluate the self-desilting effect of gap dam in design, in addition to evaluating the gap dam that has been built. ,in α It is the channel slope at the dam site, unit: °.

[0036] The present invention also provides an application scheme of the above-mentioned method for evaluating the self-desilting efficacy of a slit dam, which is specifically as follows.

[0037] The application of the above-mentioned method for evaluating the self-desilting effectiveness of a slot dam is applied to the design of the structural parameters of the slot dam.

[0038] The most significant technical advantage of a slot dam over traditional solid retaining dams lies in its self-desilting capability. Based on the analysis of the self-desilting principle and the self-recovery reservoir capacity calculations presented in this paper, groove-erosion slot dams exhibit superior self-desilting capabilities compared to surface-scour slot dams. This paper, building on the aforementioned slot dam self-desilting efficacy evaluation method, also provides a slot dam design method. This design method guides the design of slot dam structural parameters, resulting in a slot dam designed as a groove-erosion slot dam with more optimal self-desilting capabilities.

[0039] A method for designing a slot dam, which is implemented using the above-mentioned slot dam self-desilting efficacy evaluation method, is a slot dam of the gully erosion type; conducting a field survey of the slot dam and the gully to obtain basic engineering data, and using the basic engineering data to calculate and determine parameters A With parameters F r value, will A 、 F r 、 d max Substitute into the model in formula 6 to determine the opening structural parameters of the groove erosion type gap dam ( b , l ) design value, longitudinal slope of debris flow accumulation body in the reservoir , α is the channel slope at the dam site, in degrees,

[0040] Formula 6

[0041] Among the structural parameters of the gap dam, the gap width b , opening rate l 、 b / d maxIt is a key parameter related to the permeability of the slit dam opening. d max It belongs to engineering environment data, not design object parameters, so this design method is based on ( b , l ) is used as the target combination of design parameters of the opening structure parameters, and is verified by the formula 6 model to control the discrimination parameters of the design gap dam. F ≥0.28, which means it has the function of self-dredging of gully erosion type and belongs to the gully erosion type gap dam.

[0042] The above-mentioned gap dam design method can further increase the gap dam self-recovery expansion rate E Incorporate into the design parameter verification process. Specifically, the determined engineering basic data also includes the self-recovery expansion rate of the groove erosion type gap dam design E′ , in the A 、 F r 、 d max When substituting into the model 6 for verification, E′ Substitute into formula 5 and calculate in parallel with formula 4 to determine whether the designed self-recovery expansion rate is met. E′ Slot dam opening structural parameters ( b , l ) design value. The self-desilting performance level can also be included in the design parameter verification process. Specifically, the determined engineering basic data also includes the design self-desilting performance level of the groove erosion type gap dam. A 、 F r 、 d max When substituting into the model 6 for verification, the corresponding E Substitute the value into formula 5 and verify it in parallel with formula 4 to determine the opening structural parameters of the gap dam that meets the designed self-desilting performance level ( b , l ) design value.

[0043] The field investigation referred to in this technology includes various geological surveys, reconnaissance, mapping, and measurement work at the alluvial fan site at the outlet of the river channel where the project is located, as well as existing simulation experiments, testing experiments, observation experiments, and analysis experiments in the field, as well as the acquisition of historical disaster records, relevant technical specifications, and empirical methods and data acquisition for reference. The data obtained from the field investigation is collectively referred to as the basic engineering data of this technical solution.

[0044] Compared with the existing technology, the beneficial effects of the present invention are: (1) The present invention decomposes the evaluation of the self-dredging efficacy of the slit dam into three hierarchically related technical problems: how to achieve the self-dredging effect, how much reservoir capacity is restored by self-dredging, and how much the reservoir capacity restored by self-dredging improves the overall operating capacity of the slit dam. Thus, the evaluation of the self-dredging efficacy of the slit dam is transformed into a scientific observation and calculation problem, which can move from the level of experience summary thinking to the level of technical solution implementation. (2) The method for evaluating the self-dredging efficacy of the slit dam of the present invention first starts from the key variables of the hydrodynamic scouring, erosion and removal of the deposits in front of the dam, and constructs the heavy characteristic parameter A and the discrimination parameter F The model and the discrimination threshold are used to solve the classification problem of the self-dredging effect of the slit dam. The classification of the self-dredging effect is also used to complete the classification of the self-dredging efficacy and the classification of the slit dam, which serves as the basis for further efficacy evaluation. The self-recovery storage capacity calculation model of the slit dam further solves the problem of calculating the storage capacity that can be restored by the two types of slit dams under the action of self-dredging. On this basis, the quantitative ratio of the storage capacity recovery capacity to the operating storage capacity of the slit dam and the grading of the storage capacity recovery capacity are solved, and the contribution of the self-dredging effect to the operational safety of the dam body is measured. (3) Based on the technical solution for the evaluation of the self-dredging efficacy of the slit dam, the slit dam design method of the present invention can guide the design of the structural parameters of the slit dam, provide the optimization technology of the opening structure parameters, make the self-dredging capacity of the slit dam a "designable object", and can be quantitatively obtained and improved through engineering design, thereby enhancing the technical advantages of the slit dam in actual engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a flow chart of the method for evaluating the effectiveness of self-dredging of gap dams.

[0046] Figure 2 It is a schematic diagram of the flow chart of the gap dam design method (showing three routes). DETAILED DESCRIPTION

[0047] The preferred embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0048] Figure 1 It is a flow chart of the method for evaluating the effectiveness of self-dredging of gap dams.

[0049] In the following embodiments, the classification of data in Table 1, Table 2, and Table 3 is not a strict classification of types, but is only for the purpose of making the meaning of the listed data clear and easy to read.

[0050] Example 1

[0051] The method of the present invention is used to evaluate the self-desilting effect of a certain gap dam in service and to calculate the self-recovery storage capacity.

[0052] A debris flow gully is located on the left bank of the Yala River in Kangding City, Ganzi Prefecture, Sichuan Province. A residential area is located on an accumulation fan at the mouth of the gully. The gully basin has a long fan-shaped plan view, a feather-shaped drainage system, and a drainage area of ​​25.88 km. 2 The main gully is 9.18 km long, with an average bed gradient of 310‰. The gully bed is generally steep, with well-developed bends. Branch gullies are concentrated on the left side of the gully, with significant incision depths. Above 4,000 meters above sea level, grasslands dominate the landscape. This area is also subject to strong frost weathering, with some bedrock exposed or weathering products accumulated. The gully has experienced flash floods and debris flows in the accumulation fan area, causing overtopping hazards. To manage the mountainous environment, a gap dam was constructed within the main gully, designed to meet a P = 2% (50-year return rate) standard.

[0053] Conduct on-site investigations of the gap dam and channel to obtain basic engineering data (Table 1).

[0054] Table 1 Basic data of the project in Example 1

[0055]

[0056] Using engineering basic data, calculate the heavy characteristic parameters according to the model in formula 1 A ,have A = 0.50. Then according to the formula 2 model, the Froude number of fluid motion is calculated as F r =0.98, efficacy discrimination parameter F =0.19.

[0057] F =0.19<0.28, it is judged that the self-desilting effect of the gap dam belongs to the surface scouring type, that is, the gap dam is a surface scouring self-desilting type gap dam.

[0058] Then, according to the model of formula 4, the effective storage capacity Δ increased by the self-desilting effect during the operation of the gap dam is calculated. V 1. Calculate Δ V 1=0.014*10 4 m 3 . Self-recovery expansion rate E =Δ V 1 / V =0.36%.

[0059] The assessment shows that the self-dredging effect of the gap dam is regulated by the surface erosion of the debris flow accumulation body in the reservoir by the water flow in front of the dam. After the debris flow is intercepted and accumulated in front of the dam, the self-dredging and capacity expansion effect can be manifested under the hydrodynamic conditions of about one hydrological year.

[0060] Example 2

[0061] The method of the present invention is used to evaluate the self-desilting effect of a proposed gap dam and calculate the self-recovery storage capacity.

[0062] A debris flow gully is located in Xide County, Liangshan Prefecture, Sichuan Province. It is a tributary of the Reshui River, a first-level tributary on the left bank of the Anning River. Residential villages are distributed in the relatively flat areas such as the alluvial fan and gully. The gully basin has a long strip shape in the plane, with a drainage area of ​​9.20 km. 2 The main ditch is 7.08 km long, with an average gradient of 169‰. The basin's overall topography is high in the southeast and low in the northwest. The area is rich in loose sediments, and the terrain is fragmented, with numerous ravines and deep gullies. To manage the mountainous environment, a slit dam is planned for the middle and lower reaches of the ditch's flow area.

[0063] Conduct on-site investigations of the gap dam and channel to obtain basic engineering data (Table 2).

[0064] Table 2 Basic data of the project of Example 2

[0065]

[0066] Since the gap dam is a proposed project, the accumulation slope of the debris flow accumulation body in the reservoir i according to Determine the specific value of tan i =(tan α ) / 2, there is i =4.5°. Density r d According to industry experience, the value is generally taken as 2.1 t / m 3 ~2.3 t / m 3 , in this case the value r d =2.1 t / m 3 .

[0067] Using basic engineering data, according to formula 1 and formula 2, we can calculate: A =0.52, F r =0.85, F =0.39>0.28; Then, according to the model of formula 5, the self-recovery storage capacity of the gap dam during its operation is calculated as follows: V 2=1.047*10 4 m 3 .

[0068] The evaluation shows that according to the engineering design, the self-dredging effect of the dam belongs to the groove erosion type, that is, the dam is a groove erosion self-dredging type dam. This shows that the self-dredging effect of the dam is regulated by the relatively long-term downcutting and lateral erosion of the water flow in front of the dam. After the debris flow is intercepted and accumulated in front of the dam, it can achieve self-dredging and expansion under the hydrodynamic conditions of about 1 to 2 hydrological years, and the self-recovery expansion rate is 1. E =Δ V 2 / V =31.73%.

[0069] Example 3

[0070] The method for measuring the self-recovery storage capacity of a slot dam of the present invention is applied to the design of the opening structural parameters of the slot dam.

[0071] Figure 2 It is a schematic diagram of the flow chart of the gap dam design method (showing three routes).

[0072] A debris flow gully is a tributary of the left bank of the Kule River, a tributary of the Yalong River, with a drainage area of ​​6.90 km. 2 The main ditch is 4.95 km long, with an average gradient of 289‰ in the main ditch bed. The basin's overall topography is steep-to-gentle. The slopes on both sides of the main tributaries are steep, with well-developed gullies on the slopes. The basin's overall morphology is broad-leaved. Numerous residential buildings and farmland are located at the ditch entrance, with residential areas primarily located to the left of the alluvial fan. According to field surveys and remote sensing interpretation, the basin is rich in material resources, with a total loose solid material source of approximately 105.0×10 4 m 3 The kinetic reserve that may participate in debris flow activities is 39.8×10 4 m 3 To improve the mountain environment, a slot dam is planned to be constructed within the gully. The project is designed to be a self-draining slot dam for gully erosion, with the self-draining performance design standard meeting the "strong" level.

[0073] Conduct on-site investigations of the gap dam and channel to obtain basic engineering data (Table 3).

[0074] Table 3 Basic data of the project in Example 3

[0075]

[0076] Debris flow accumulation slope in the reservoir i The same method as in Example 2 is used to determine the specific value of tan i =0.6*(tan α ),have i =5°. Density r d =2.1 t / m 3 .

[0077] Using engineering basic data, according to the formula 1 model and the formula 2 model F r Function model, calculated and determined A =0.55, F r =0.90, and then d max =0.70m and substitute them into the model of formula 6 for parameter verification; at the same time, the 15%< E ≤30% is substituted into formula 5 and verified in parallel with formula 4. Verification confirms that when the gap dam opening structure parameters ( b , l ) takes the value (0.8m, 0.34), equation 6 is satisfied; and this design condition ( b , l ), the self-recovery expansion rate E =Δ V / V =Δ V 2 / V =27.6%, meeting the design standard.

Claims

1. A method for evaluating the effectiveness of self-dredging of a slit dam, characterized by: First, conduct on-site surveys of the gap dam and trench to obtain basic engineering data; Secondly, calculate the heavy feature parameters A , heavy feature parameters A According to the model expression of formula 1, Formula 1 Where, γ f - The fluid density of the hydrodynamic conditions in the dam front ditch, in kN / m 3 , determined according to the basic engineering data, g - Gravitational acceleration constant, unit: m / s 2 , ρ d - Density of debris flow accumulation in the reservoir, unit: t / m 3 , determined according to basic engineering data; Secondly, calculate the discriminant parameters of the self-desilting effect of the gap dam F , discriminant parameters F According to the model expression of formula 2, Formula 2 Where, b - The width of the gap dam, in meters, is determined based on the basic engineering data. d max - The maximum particle size of debris flow intercepted by the gap dam, in meters, is determined based on the basic engineering data. λ - Slit dam opening ratio, %, determined based on engineering basic data. F r - Froude number of fluid motion in the ditch in front of the dam under hydrodynamic conditions, dimensionless parameter, v f - Average flow velocity of the fluid in the ditch in front of the dam under hydrodynamic conditions, in m / s, determined based on basic engineering data. h f - Average depth of fluid flow in the ditch in front of the dam under hydrodynamic conditions, in meters, determined based on basic engineering data. θ - The accumulation slope of debris flow accumulation body in the reservoir, in degrees, based on basic engineering data; Finally, according to the discriminant parameters F Evaluate the type of self-desilting effect of the gap dam, like F <0.28, the self-desilting effect of the gap dam belongs to the surface scouring type, and the self-recovery storage capacity of the gap dam is calculated according to the model of formula 3; like F ≥0.28, the self-desilting effect of the gap dam belongs to the gully erosion type, and the self-recovery storage capacity of the gap dam is calculated according to the model of formula 4; Formula 3 Formula 4 Where, Δ V 1. Δ V 2 - the self-recovery storage capacity of the surface scour self-dredging type gap dam and the self-recovery storage capacity of the groove erosion desilting type gap dam, respectively, in m 3 , V - Design storage capacity of the gap dam, unit: m 3 , determined based on basic engineering data.

2. The method for evaluating the self-dredging efficacy of a slit dam according to claim 1, characterized in that: Calculate the self-recovery expansion rate of the gap dam according to formula 5 E , Formula 5.

3. The method for evaluating the self-dredging efficacy of a slit dam according to claim 2, wherein: By indicator E Evaluation of the self-desilting performance level of the gap dam: E ≤5% means weak performance, 5%< E ≤15% is medium performance, 15%< E ≤30% indicates strong performance, E >30% indicates strong performance.

4. The method for evaluating the self-dredging efficacy of a slit dam according to any one of claims 1 to 3, characterized in that: If the gap dam is a proposed project, the longitudinal slope of the debris flow accumulation body in the reservoir , α It is the channel slope at the dam site, unit: °.

5. The method for evaluating the self-dredging efficacy of a slit dam according to claim 4, characterized in that: It is used in the structural parameter design of gap dam.

6. The method for evaluating the self-dredging efficacy of a slit dam according to claim 5, characterized in that: It is used in the design of the structural parameters of the slot dam opening.

7. A method for designing a slot dam, implemented using the method for evaluating the self-dredging efficacy of a slot dam according to claim 1, characterized in that: It is a groove erosion type gap dam; carry out on-site investigation of gap dam and channel, obtain basic engineering data, and use the basic engineering data to calculate and determine parameters A With parameters F r value, will A 、 F r 、 d max Substitute into the model in formula 6 to determine the opening structural parameters of the groove erosion type gap dam ( b , λ ) design value, longitudinal slope of debris flow accumulation body in the reservoir , α is the channel slope at the dam site, in degrees, Formula 6.

8. The method for designing a slot dam according to claim 7, wherein: The method for evaluating the self-dredging effect of the slit dam according to claim 2 is used to achieve the above. The engineering basic data also includes the self-recovery expansion rate of the groove erosion type slit dam design. E′ , in the A 、 F r 、 d max When substituting into the model 6 for verification, E′ Substitute into formula 5 and calculate in parallel with formula 4 to determine whether the designed self-recovery expansion rate is met. E′ Slot dam opening structural parameters ( b , λ ) design value.

9. The method for designing a slot dam according to claim 7, wherein: The method for evaluating the self-dredging performance of the slit dam according to claim 3 is used to achieve the above. The engineering basic data also includes the self-dredging performance level of the groove erosion type slit dam. A 、 F r 、 d max When substituting into the model 6 for verification, the corresponding E Substitute the value into formula 5 and verify it in parallel with formula 4 to determine the opening structural parameters of the gap dam that meets the designed self-desilting performance level ( b , λ ) design value.

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