A multi-stage barrier net flow control component

Abstract

This disclosure provides a multi-stage barrier net flow control component. The multi-stage barrier net flow control component includes: a first barrier net device and a second barrier net device. The first barrier net device includes: a first flexible protective net and multiple first anchor cables. The first flexible protective net is arranged on the downstream slope of a debris flow dam, with both sides of the first flexible protective net positioned at the junction of the debris flow dam and the two bank slopes. The first flexible protective net has multiple first mesh openings. One end of each of the multiple first anchor cables is fixed to one side of the first flexible protective net, and the other end of each of the multiple first anchor cables is fixed to the bank slopes on both sides of the debris flow dam. The flexible protective net has high flexibility and can mitigate the enormous impact force brought by floods and the movement of large particles from the dam body. To ensure the stability of the first flexible protective net, a second barrier net device is added to intercept most of the sediment transported downstream during the breach, automatically pressing down the downstream dam slope and increasing the stability of the remaining dam body.

Description

Technical Field

[0001] This disclosure relates to the field of emergency response to debris flow blocking rivers and landslide dams, and in particular to a multi-stage barrier net flow control component. Background Technology

[0002] Debris flows, as one of the most common mountain disasters, severely restrict economic development in debris flow-prone areas. In recent years, with the increasing frequency of extreme weather events such as heavy rainfall, strong snowmelt, and high-intensity earthquakes, large-scale debris flows are highly likely to occur in the basins of major rivers in high mountain and canyon areas. When debris flows enter the main river, they can quickly block the river channel, forming a barrier dam of considerable height. As the water level upstream of the barrier dam continues to rise, a barrier lake with high risk can form. Once the barrier lake breaches, it will create a powerful and destructive flood, causing severe damage downstream.

[0003] Currently, in emergency response to landslide dams, the main methods used are excavating initial spillway channels or manual blasting to reduce the dam's height, thereby decreasing reservoir capacity and ultimately lowering the outburst flood peak. However, for debris flow dams, the subsidence of machinery and manpower on the dam poses serious safety hazards. Even blasting techniques are not always effective; for example, the Zhouqu landslide dam in August 2010 was blasted with unsatisfactory results because debris flow dams still possess considerable plasticity. Therefore, there is an urgent need for a device that can effectively control the outburst flood peak.

[0004] Public content

[0005] To address the problems of existing technologies, this disclosure provides a multi-stage barrier net flow control device. The technical solution is as follows:

[0006] On one hand, this disclosure provides a multi-stage barrier net flow control component, which includes: a first barrier net device and a second barrier net device. The first barrier net device includes: a first flexible protective net and a plurality of first anchor cables. The first flexible protective net is arranged on the dam slope downstream of the debris flow landslide dam, and both sides of the first flexible protective net are arranged at the junction of the debris flow landslide dam and the two bank slopes. The first flexible protective net is provided with a plurality of first mesh holes. One end of the plurality of first anchor cables is fixed to both sides of the first flexible protective net, and the other end of the plurality of first anchor cables is fixed to the bank slopes on both sides of the debris flow landslide dam.

[0007] The second barrier net device includes: a second flexible protective net, a barrier frame, and multiple second anchor cables. The second flexible protective net is arranged downstream of the first flexible protective net at intervals, and both sides of the second flexible protective net are arranged at the junction of the debris flow dam and the bank slopes on both sides. One end of each of the multiple second anchor cables is fixed to both sides of the second flexible protective net, and the other end of each of the multiple second anchor cables is fixed to the bank slopes on both sides of the debris flow dam. The second flexible protective net is inclined towards one side of the first flexible protective net. The bottom of the second flexible protective net is connected to one side of the barrier frame. The barrier frame is arranged between the second flexible protective net and the first flexible protective net, and the angle α between the second flexible protective net and the barrier frame is less than 45°. The second flexible protective net has multiple second mesh openings, and a rigid protective net is installed on the barrier frame.

[0008] Specifically, the first flexible protective netting is laid at a height of H on the dam slope. F0 H F0 =H D -H b +h, where H D H represents the height of the debris flow dam. b is the corresponding final depth of the breach, and h is the reserved safety freeboard.

[0009] Furthermore, h is 0.5m.

[0010] Furthermore, the second flexible protective net is laid at half the height of the first flexible protective net.

[0011] Specifically, pressure-reducing rings are laid on both the first flexible protective net and the second flexible protective net.

[0012] Specifically, the size of both the first mesh and the second mesh is less than or equal to D. 80 D 80 This refers to the particle size of the dam body when the cumulative mass percentage is 80%.

[0013] Specifically, both the first mesh and the second mesh are regular hexagons.

[0014] Specifically, the distance L between the bottom of the first flexible protective net and the bottom of the second flexible protective net is greater than or equal to 15m.

[0015] Specifically, the rigid protective net is provided with multiple third mesh holes, and the maximum aperture of the third mesh hole is no greater than 1.5m.

[0016] Specifically, protective support ropes are provided on the edges of the first flexible protective net and the second flexible protective net.

[0017] The beneficial effects of the technical solution provided in this disclosure are as follows: This invention provides a multi-stage barrier net flow control component. The first and second flexible protective nets are characterized by low cost, easy transportation, easy installation, high flexibility, and high strength. In particular, the high flexibility can alleviate the huge impact force brought by floods and the movement of large particles in the dam body. In order to ensure the stability of the first flexible protective net, a second barrier net device needs to be added at a certain distance downstream. After intercepting most of the sediment transported downstream during the breach, it automatically presses down the downstream dam slope and increases the stability of the remaining dam body. In addition, a rigid protective net is set on the barrier frame of the second barrier net device, and the barrier frame is connected to the second flexible protective net as a whole. On the one hand, the barrier frame can use its own weight to drive the second barrier net device to fall into the bottom of the river channel, effectively intercepting sediment particles. On the other hand, after the sediment transported to the barrier frame during the breach is deposited, it will automatically press down the barrier frame, which can effectively constrain the lower boundary of the barrier frame and prevent sediment from forming a transport channel from the lower boundary of the barrier frame, thereby effectively controlling the downstream movement of sediment. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the main structure of the multi-level barrier net flow control component provided in this embodiment of the disclosure;

[0020] Figure 2 This is a side view of the multi-level barrier net flow control assembly provided in this embodiment of the present disclosure;

[0021] Figure 3 It is a pressure-reducing ring on the first flexible protective net provided in the embodiments of this disclosure. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0023] Example

[0024] This invention provides a multi-level barrier network flow control component, such as... Figure 1 and Figure 2As shown, the multi-stage barrier net flow control component includes: a first barrier net device 1 and a second barrier net device 2. The first barrier net device 1 includes: a first flexible protective net 3 and multiple first anchor cables 4. The first flexible protective net 3 is arranged on the dam slope a downstream of the debris flow landslide dam, and the two sides of the first flexible protective net 3 are arranged at the junction of the debris flow landslide dam and the two bank slopes. The first flexible protective net 3 is provided with multiple first mesh holes 3a. One end of the multiple first anchor cables 4 is fixed to both sides of the first flexible protective net 3, and the other end of the multiple first anchor cables 4 is fixed to the bank slopes on both sides of the debris flow landslide dam.

[0025] The second barrier net device 2 includes: a second flexible protective net 5, a barrier frame 6, and multiple second anchor cables 7. The second flexible protective net 5 is arranged downstream of the first flexible protective net 3 at intervals, and the two sides of the second flexible protective net 5 are arranged at the junction of the debris flow dam and the two bank slopes. One end of the multiple second anchor cables 7 is fixed to the two sides of the second flexible protective net 5, and the other end of the multiple second anchor cables 7 is fixed to the bank slopes on both sides of the debris flow dam. The second flexible protective net 5 is inclined to one side of the first flexible protective net 3. The bottom of the second flexible protective net 5 is connected to one side of the barrier frame 6. The barrier frame 6 is arranged between the second flexible protective net 5 and the first flexible protective net 3, and the angle α between the second flexible protective net 5 and the barrier frame 6 is less than 45°. The second flexible protective net 5 is provided with multiple second mesh holes 5a, and a rigid protective net 6a is installed on the barrier frame 6.

[0026] To improve the stability of the second barrier net device 2, the second flexible protective net 5 needs to be tilted upstream at a certain angle. This included angle α is determined according to the natural angle of repose of the sediment after the breach, and it can be less than 45°.

[0027] In practice, high-strength steel cables can be used to fix the left and right boundaries with anchor bolts.

[0028] Multiple first anchor cables 4 and multiple second anchor cables 7 can also be fixed to surrounding structures that can resist strong traction forces. The spacing between two adjacent first anchor cables 4 should preferably be 3 to 5 meters. The spacing between two adjacent second anchor cables 7 should preferably be 3 to 5 meters.

[0029] Specifically, the first flexible protective net 3 is laid at a height of H on dam slope a. F0 H F0 =H D -H b +h, where H D H represents the height of the debris flow dam. b Where H represents the final depth of the corresponding breach, and h is the reserved safety freeboard. For ease of construction, if the calculated H... F0 When the result is not an integer, it must be selected by rounding up.

[0030] Furthermore, h can be 0.5m.

[0031] Furthermore, the laying height of the second flexible protective net 5 can be half the laying height of the first flexible protective net 3.

[0032] Specifically, the distance L between the bottom of the first flexible protective net 3 and the bottom of the second flexible protective net 5 is greater than or equal to 15m.

[0033] To ensure sufficient thickness of sediment deposits to weigh down the main retaining mesh, the height H of the secondary retaining mesh is... F1 The secondary barrier net is 1 / 2 of the main retaining net. The distance L from the downstream boundary of the debris flow dam is calculated based on the total erosion V caused by dam failure. D Perform the calculation:

[0034] Based on the final breach shape simulated by the dam-break model, the total erosion V of the dam body is calculated according to geometric relationships. D Based on the actual terrain, and assuming different L values, calculate the total reservoir capacity V2 of the secondary dam, where the siltation gradient of the reservoir area is selected from 2° to 5°. When V2 = kV D When L is calculated, it represents the distance between the designed secondary barrier net and the downstream boundary of the debris flow dam. If L is not an integer, it is rounded up to the nearest integer. In the formula, k is the designed sediment interception rate of the secondary barrier net, taking into account suspended mass transport and allowable transport rate, and is taken as (0.6~0.8). If the calculated distance L is less than 20m, L is taken as 20m.

[0035] like Figure 3 As shown, pressure-reducing rings 8 can be laid on both the first flexible protective net 3 and the second flexible protective net 5.

[0036] Furthermore, protective netting support ropes 9 are respectively provided at the edges of the first flexible protective netting 3 and the second flexible protective netting 5. These support ropes 9 can further reinforce the first flexible protective netting 3 and the second flexible protective netting 5.

[0037] Specifically, the dimensions of the first mesh 3a and the second mesh 5a are both less than or equal to D. 80 D 80 This refers to the particle size of the dam body when the cumulative mass percentage is 80%.

[0038] To effectively contain material within the dam and keep the residual dam height within the design range, the mesh size design of the first flexible protective net 3 and the second flexible protective net 5 is a crucial design parameter. Particles smaller than the mesh opening diameter can easily pass through the first flexible protective net 3 and the second flexible protective net 5. As the diameter of the first mesh 3a and the second mesh 5a increases, less material is contained, making it more likely that the residual dam height will fall below the design value, resulting in a final breach flood peak flow exceeding the maximum flood discharge standard of the downstream river channel.

[0039] The method for determining the diameters of the first mesh 3a and the second mesh 5a is as follows: Based on field investigation, determine the full gradation curve of the dam body particle composition, and then look up the particle size (D) corresponding to a cumulative mass percentage of 80%. 80 The diameters of both the first mesh 3a and the second mesh 5a must be less than or equal to D. 80 The specific dimensions can be selected by combining the manufacturer's production standards, provided that the above conditions are met.

[0040] Specifically, both the first mesh 3a and the second mesh 5a can be regular hexagons. The regular hexagonal first mesh 3a and the second mesh 5a respectively give the first flexible protective net 3 and the second flexible protective net 5 better tensile strength and enable them to withstand larger compressive loads.

[0041] Specifically, the rigid protective net 6a is provided with multiple third mesh openings, the maximum diameter of which is no greater than 1.5m. The width of the retaining frame 6 is no greater than 1.5m, and its length (along the main river channel direction b) should not be less than 15m.

[0042] Specifically, the width of the second flexible protective net 5 is equal to the width of the debris flow dam.

[0043] When using the multi-stage barrier net flow control component provided in the embodiments of the invention to control the flow of debris flow dams, it is first determined whether the multi-stage barrier net flow control component provided in the embodiments of the invention needs to be deployed, as follows:

[0044] After a debris flow dam occurs, it is crucial to obtain the basic parameters of the dam and the downstream river flood control standards as quickly as possible through satellite remote sensing imagery, drone aerial photography, or on-site investigation. These parameters mainly include: water level-reservoir capacity curve, dam height, dam body particle size distribution, and downstream river flood control standards (maximum allowable flood discharge Q). max ).

[0045] Predict the maximum peak flow Q under the condition of natural collapse of debris flow dam. P The DB-IWHR-2018 software proposed by Academician Chen Zuyu was used to simulate the outburst flow process of the debris flow dam, and the peak outburst flow rate Q was obtained. P The simulation method of the software refers to the "DB-IWHR-2018 User Manual for Dam Break Flood Analysis". When basic data is insufficient, the corresponding formula for calculating the peak discharge of the dam break can be used for calculation.

[0046] If Q p ≥Q max Then a multi-level barrier network flow control component needs to be deployed; if Q p ≤Q amx Therefore, there is no need to deploy multi-level barrier network flow control components.

[0047] The multi-level barrier net flow control component provided in this embodiment of the invention is subjected to actual flow control operation as follows:

[0048] A large-scale debris flow event occurred in a certain area, completely blocking the main river channel and forming a debris flow dam. Based on on-site investigation, remote sensing imagery, and drone aerial photography, fundamental data of this debris flow dam were obtained, providing crucial support for the design of the multi-stage retaining system proposed in this invention, which allows for partial collapse of the debris flow dam. Specific data are as follows:

[0049] The debris flow dam is 30m high (base elevation 2560m, crest elevation 2590m), 35m wide at the crest, with an upstream slope of 13° and a downstream slope of 10°. Several villages, roads, bridges, and power stations are located within 200km of the downstream river channel. If this debris flow dam were to breach, it would pose a significant threat to the downstream area. The basic input parameters for dam-break simulation using DB-IWHR-2018 are shown in Table 1 (for detailed calculation procedures and methods, please refer to the "DB-IWHR-2018 Calculation Manual").

[0050] Table 1 shows the basic input parameters required for calculating the hydrograph of a debris flow dam break flood using DB-IWHR-2018.

[0051]

[0052]

[0053] Referring to Table 1, determine whether the multi-stage barrier network flow control component provided in this embodiment of the invention needs to be deployed. Specifically, the failure flow process of the debris flow dam is simulated using the DB-IWHR-2018 software proposed by Academician Chen Zuyu. Assuming complete dam failure, the peak failure flow rate Q is obtained. P It is 6646.98m 3 / s.

[0054] According to the flood control standards of the downstream river channel, the maximum allowable peak flow (safe peak flow) Q is... max 5500m 3 / s. Q p ≥Q max Therefore, it is necessary to deploy multi-level barrier network flow control components.

[0055] The particle size distribution curve of the dam body was obtained based on field investigation, and then the particle size (D) corresponding to a cumulative mass percentage of 80% was determined. 80 The diameter is 4.4 cm. In this embodiment, both the first mesh 3a and the second mesh 5a are regular hexagons, and the diameters of the first mesh 3a and the second mesh 5a must be less than or equal to D. 80Based on the manufacturer's production standards, the diameters of the first mesh 3a and the second mesh 5a were selected to be 5.0 cm, and pressure-reducing rings 8 were added to the first flexible protective net 3 and the second flexible protective net 5 respectively. The pressure-reducing rings 8 can effectively buffer and reduce the kinetic energy generated by sudden particle impacts.

[0056] The laying height of the first flexible protective net 3 on the downstream dam slope is determined as follows:

[0057] Based on the simulated breach flow process described above, assuming different final breach bottom elevations, the corresponding breach peak flow is calculated. When the final breach bottom elevation is 2577.70m, the calculated breach peak flow is 5495.98m. 3 / s, approximately equal to the maximum flood discharge of the downstream river channel of 5500 m³ / s. 3 / s; at this time, the corresponding breach depth H b The length of the breach is 12.3m, and the final width at the bottom of the breach is 44.34m.

[0058] Therefore, the height H of the flexible protective netting laid on the downstream dam slope surface can be calculated. F0 :

[0059] H F0 =H D -H b +h=30-12.3+0.5=18.2m

[0060] In the formula, H F0 The height at which the first flexible protective net 3 is laid on the downstream dam slope surface;

[0061] H b This corresponds to the final depth of the breach;

[0062] H D The height of the debris flow dam;

[0063] h represents the reserved safety freeboard, which is set at 0.5m.

[0064] For ease of construction, if the calculated H F0 When H is not an integer, it must be selected by rounding up. Therefore, in this embodiment, H F It is 19m.

[0065] To improve the stability of the second flexible protective net 5, the second flexible protective net 5 needs to be tilted upstream at a certain angle. This included angle α is determined according to the natural angle of repose of the sediment after the breach. According to the field investigation, the natural angle of repose of the sediment after the breach is calculated to be 30°, so the included angle α is 30°.

[0066] To ensure sufficient thickness of sediment deposits to weigh down the first flexible protective netting 3, the second flexible protective netting 5 is laid at a height H. F1 The laying height of the first flexible protective net 3 is 1 / 2, i.e., H F1 = 9.5m, using the rounding up method, therefore, in this embodiment H F1 It is 10m.

[0067] The distance L between the second flexible protective net 5 and the downstream boundary of the debris flow dam (the bottom of the first flexible protective net 3) is calculated according to the total erosion V caused by the dam failure. D Perform the calculation:

[0068] Based on the final breach shape simulated by the dam break model (the final width at the bottom of the breach is 44.34m, and the left and right slopes of the breach are 40°), the total erosion V of the dam body is calculated based on geometric relationships. D ≈32 764m 3 .

[0069] Based on the actual terrain, and assuming different L values, the total reservoir capacity V2 of the secondary dam is calculated, where the siltation gradient of the reservoir area is calculated as 3°.

[0070] When L = 19.6m, the total reservoir capacity of the secondary dam is V2 = 22,934m³. 3 0.7V D In (0.6~0.7)V D Since the value is within the specified range, we round up to the nearest integer, taking L = 20.0m.

[0071] This invention provides a multi-stage barrier net flow control component. The first and second flexible protective nets are characterized by low cost, easy transportation, easy installation, high flexibility, and high strength. In particular, the high flexibility can mitigate the enormous impact force brought about by floods and the movement of large particles in the dam body. To ensure the stability of the first flexible protective net, a second barrier net device needs to be added at a certain distance downstream. This intercepts most of the sediment transported downstream during the breach and automatically presses down on the downstream dam slope. In addition, a rigid protective net is set on the barrier frame of the second barrier net device, and the barrier frame is integrated with the second flexible protective net. On the one hand, the barrier frame can use its own weight to drive the second barrier net device to the bottom of the river channel, effectively intercepting sediment particles. On the other hand, after the sediment transported to the barrier frame during the breach is deposited, it will automatically press down on the barrier frame, effectively constraining the lower boundary of the barrier frame and preventing sediment from forming a transport channel from the lower boundary of the barrier frame, thereby effectively controlling the downstream movement of sediment.

[0072] The above description is merely an optional embodiment of this disclosure and is not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A multi-stage barrier net flow control component, characterized in that, The multi-stage barrier net flow control component includes: a first barrier net device and a second barrier net device. The first barrier net device includes: a first flexible protective net and multiple first anchor cables. The first flexible protective net is arranged on the dam slope downstream of the debris flow landslide dam, and the two sides of the first flexible protective net are arranged at the junction of the debris flow landslide dam and the two bank slopes. The first flexible protective net has multiple first mesh openings. One end of each of the multiple first anchor cables is fixed to both sides of the first flexible protective net, and the other end of each of the multiple first anchor cables is fixed to the bank slopes on both sides of the debris flow landslide dam. The laying height of the first flexible protective net on the dam slope is HF0, where HF0 = HD - Hb + h, HD is the height of the debris flow landslide dam, Hb is the corresponding final breach depth, and h is the reserved safety freeboard. The second barrier net device includes: a second flexible protective net, a barrier frame, and multiple second anchor cables. The second flexible protective net is arranged at intervals downstream of the first flexible protective net, and both sides of the second flexible protective net are arranged at the junction of the debris flow dam and the bank slopes on both sides. One end of each of the multiple second anchor cables is fixed to both sides of the second flexible protective net, and the other end of each of the multiple second anchor cables is fixed to the bank slopes on both sides of the debris flow dam. The second flexible protective net is inclined towards one side of the first flexible protective net. The bottom of the second flexible protective net is connected to one side of the barrier frame. The barrier frame is arranged between the second flexible protective net and the first flexible protective net, and the angle α between the second flexible protective net and the barrier frame is less than 45°. The second flexible protective net has multiple second mesh openings, and a rigid protective net is installed on the barrier frame. The second flexible protective net is laid at half the height of the first flexible protective net; Both the first and second flexible protective nets are equipped with pressure-reducing rings.

2. The multi-stage barrier net flow control component according to claim 1, characterized in that, h is 0.5m.

3. The multi-stage barrier net flow control component according to claim 1, characterized in that, The size of both the first mesh and the second mesh is less than or equal to D80, where D80 is the particle size of the dam body particles corresponding to a cumulative mass percentage of 80%.

4. The multi-stage barrier net flow control component according to claim 1, characterized in that, Both the first mesh and the second mesh are regular hexagons.

5. The multi-stage barrier net flow control component according to claim 1, characterized in that, The distance L between the bottom of the first flexible protective net and the bottom of the second flexible protective net is greater than or equal to 15m.

6. The multi-stage barrier net flow control component according to claim 1, characterized in that, The rigid protective net is provided with multiple third mesh holes, and the maximum aperture of the third mesh hole is no greater than 1.5m.

7. The multi-stage barrier net flow control component according to claim 1, characterized in that, The edges of the first and second flexible protective nets are respectively provided with protective net support ropes.

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