CN114855707A - Silt-promoting repair device and method for local erosion pit - Google Patents

Abstract

The invention provides a silt-promoting repairing device and method for a partial scour pit, comprising: a skeleton, the skeleton is arranged around the pier, and the inner ring of the skeleton is fixed on the pier; a fixing device is used to make the skeleton and the surrounding of the pier The bottom bed is fixed; the floating body is set on the skeleton, and the floating body is used to provide buoyancy for the skeleton; the mesh part is set on the skeleton, and the mesh part completely covers the opening of the scour pit, so as to increase the flow of submerged current and eddy current movement around the pier. Resistance, weaken the strength of the water flow under the mesh part, reduce the sand carrying capacity of the water flow under the mesh part, so that the incoming sand quickly falls into the net through the mesh part of the mesh part and accumulates; the mesh part is placed in the water for neutral buoyancy. . The invention fundamentally eliminates the root cause of scouring, avoids the harm caused by scouring, reduces the difficulty of installation, and greatly reduces the construction cost; the underwater weight of the device is light, and does not significantly increase the amount of water acting on piles and other foundations. load, so there is no need to increase the requirements for the bearing capacity of the foundation.

Description

A silt-promoting repair device and method for partial scour pit

technical field

The invention relates to the field of water conservancy and ocean engineering, in particular to a silt-promoting repairing device and method for local scour pits.

Background technique

Pile piers are the foundation of bridges, wharves, offshore platforms, and offshore wind power. They are now widely seen in rivers, lakes and seas, and will continue to emerge with economic and social development. However, local erosion around the piers often endangers the safety of the superstructure. Therefore, it is necessary to take corresponding anti-scour measures.

After long-term research, scholars at home and abroad have developed numerous measures to solve the problem of local scour of piles and piers, which can be roughly divided into three categories: 1) Passive protection is also called physical protection, that is, to improve the anti-scour ability of bed bedding; The main measures are: riprap protection, expansion of bridge pier foundation protection, concrete hinge row protection, filled concrete mold bag protection, four-corner concrete block protection, etc.; 2) Active protection is also called deceleration and non-rush protection, that is, reducing the impact of downward water flow and horseshoe-shaped vortex. For the erosion of sediment around the pile, the measures mainly include: protection of the retaining ring, partial or overall opening protection of the bridge pier, protection of the piles in front of the pier, protection of the submerged wing wall in front of the pier, etc.; 3) The local resistance increase and silting protection method, not only So that the bottom bed does not scour, and it also plays a role in promoting siltation, mainly including: tetrahedral permeable frame, triangular net silting-promoting and anti-scouring device, biological and artificial aquatic plants promoting silting and scouring, and silting-promoting floating curtain device. However, the existing passive protection methods have their own shortcomings, such as high engineering cost and easy to cause secondary flushing; active protection methods have the problem of being difficult to adapt to the frequent changes in the height and flow direction of the natural bed, or change the bearing structure form, The applicable conditions are limited, or the installation and construction are difficult, and the hydrodynamic load on the structure is increased. The above-mentioned local resistance-increasing and silting-promoting methods also have limited protection ability in high-velocity environments, and some methods lack the ability to cope with flow direction changes. and many other deficiencies.

For example, after searching, it was found that the Chinese Patent Application Publication No. 108468353A provides a flexible scour protection structure for marine engineering infrastructure, including multiple protection units and connecting cables, and the multiple protection units are connected by the connecting cables. Connected to form a flexible scour protection surface laid on the seabed; the protection unit has a cavity penetrating the upper and lower surfaces of the protection unit, or the outer side of the protection unit has a groove and is connected by a cable between the multiple protection units After the connection, a cavity penetrating the flexible scouring protective surface is formed by the groove, so that the flexible scouring protective surface is densely distributed through the cavity of the flexible scouring protective surface. The selection range of the said protective monomer includes prefabricated concrete blocks and waste tires. The selection range of the protection unit includes precast concrete blocks, the flexible erosion protection surface includes at least a plurality of precast concrete blocks, the precast concrete blocks have cavities penetrating the upper and lower surfaces of the precast concrete blocks, or the The outer side is provided with a groove, and a cavity penetrating the flexible scouring protective surface is formed by the groove after the plurality of protective units are connected by connecting cables. The cavity is a concave cavity with a concave side wall. Obviously, the weight of the protective structure is very heavy, not only is the construction difficult and the cost is high, but also the total underwater weight transmitted to the marine engineering foundation is large, which increases the foundation's need for the bearing capacity of the foundation. stability. In addition, although these groove structures increase the local frictional resistance and reduce the overall flow velocity of the near flow, they also increase the turbulence intensity near the bottom, and a large number of vortices are generated near the grooves, and these vortices will It directly rolls up a large amount of bottom sand and increases the suspension ability of the water flow to the sediment. Therefore, the protective structure will not only not play a good role in promoting siltation, but will increase the scouring ability.

SUMMARY OF THE INVENTION

Aiming at the defects in the prior art, the purpose of the present invention is to provide a silt-promoting repairing device and method for partial scour pits.

A first aspect of the present invention provides a silt-promoting repair device for a partial scour pit, comprising:

a skeleton, the skeleton is arranged around the pier, and the inner ring of the skeleton is fixed on the pier;

a fixing device for fixing the frame to the subbed around the pier;

a floating body arranged on the skeleton, the floating body is used to provide buoyancy for the skeleton;

A net-shaped member arranged on the skeleton, and the net-shaped member completely covers the opening of the scour pit, so as to increase the resistance of the downflow and eddy current movement around the pier, and weaken the water flow under the net-shaped member The strength reduces the sand-carrying ability of the water flow under the mesh member, so that the incoming sand quickly falls into the net through the mesh of the mesh member and accumulates; the mesh member is in a neutral buoyancy state when placed in water.

Preferably, the mesh component adopts a specific gravity close to that of water, and its underwater weight is light, thereby minimizing the total weight of the entire repair device and ensuring that the load transferred by the repair device to the pier will not be significantly increased , and is made of high-strength engineering materials with anti-corrosion and anti-ultraviolet rays.

Preferably, the aperture of the mesh component is 5d ₉₅ to 500d ₉₅ , so as to ensure that the sand particles can fall through the mesh holes smoothly, wherein d ₉₅ is that the sediment particles smaller than the particle size in the incoming sand account for 95% of the the weight of.

Preferably, the porosity of the mesh component is 20% to 80%, so as to ensure that the incoming sand particles will basically fall under the mesh through the mesh holes, and the incoming sand will not continuously accumulate on the mesh when suspended in the air.

Preferably, the thickness of the mesh component: 1 cm-10 cm.

Preferably, connecting portions are provided around and in the middle of the net-shaped member, and the net-shaped member is connected to the frame through the connecting portions.

Preferably, the mesh component is composed of several fan-shaped meshes or strips spliced into one, or the mesh component adopts a circular flexible mesh, so as to better adapt to the elliptical shape of the scouring pit, and give the repairing device a better performance. Manufacturing and construction bring convenience.

Preferably, the hole shape of the mesh member is circular or square.

Preferably, the fixing device includes:

Several ground anchors, the ground anchors are buried below the bottom surface to prevent them from being exposed by the water flow. Once the ground anchors are exposed, the anchoring force of the ground anchors will be significantly reduced, thereby causing instability and damage of the repair device;

A cable, one end of the cable is connected with the ground anchor, and the other end of the cable is connected with the frame.

Preferably, the skeleton includes:

an inner ring, the inner ring is tightly sleeved on the pile pier, and is close to one end of the bottom bed surface, and the pile pier is used as a support of the repairing device;

The outer ring is arranged on the periphery of the maximum scour range of the pile pier. Several grid keels are arranged between the outer ring and the inner ring, and the grid keels form a ring-shaped platform for fixing and installing the mesh parts.

A second aspect of the present invention provides a method for promoting silting and repairing a partial scour pit, which is carried out by using the above-mentioned silting-promoting and repairing device for a partial scour pit.

Preferably, the silting-promoting repair method for local scour pits includes:

Fix the skeleton at the position of the maximum scour range around the pier corresponding to the bed plane;

The floating body is installed below the frame, and the long axis of the floating body is reversed toward the incoming flow;

The mesh member is fixed on the skeleton, so that the opening of the scour pit is completely covered, so as to increase the resistance of the downflow and eddy current movement around the pile, weaken the water flow intensity under the mesh member, and reduce the mesh The sand-carrying ability of the water flow under the component makes the incoming sand quickly fall into the net through the mesh of the mesh component and accumulate;

The fixing device is determined according to the overall scouring changes of the bottom bed, the subsoil conditions, the geometrical and physical parameters of the water flow wave elements, the skeleton and the mesh parts. connected to the backbone.

Preferably, in order to increase the stability of the repair device and further reduce its engineering cost, before the fixing of the skeleton at the position of the maximum scour range around the pile pier corresponding to the bed plane, the method further includes:

Predict the lowest elevation of the subbed at the position of the pile pier before construction, and fix the inner ring of the skeleton on the outer wall of the pier at the predicted lowest elevation to prevent the overall lowering of the subbed caused by seasonal changes in water and sand conditions. Causes the overhang of the skeleton and mesh parts to be too high;

According to the predicted minimum elevation, the set height for embedding the fixture into the bottom bed is determined, that is, the fixture is buried below the lowest elevation of the bottom bed.

The working mechanism of the above-mentioned device of the present invention: the opening of the existing scouring pit (or the position where the scouring pit may appear) is completely covered with a mesh member with geometric features, and the strength of incoming water and sand before and after covering is not only basic It does not change, and the coverage of the mesh component will lead to a significant reduction in the flow velocity in the scour pit below it; when the upstream sand reaches the mesh component, it will quickly pass through its mesh and fall into the scour pit, and the falling sediment will be due to the weakening of the flow strength It will not be washed out of the pit, but will be permanently deposited in the pit; before the scour pit under the mesh component is not filled with silt, the suspended part of the mesh component will not accumulate sediment significantly. Therefore, the skeleton and the mesh component The force transmitted to the pier is limited and will not endanger the safety of the pier; the continuous sand deposition upstream makes the scour pit continuously smaller until a new scour and silt balance is established. At this time, the local scour of the pile pier becomes very limited and the pile Pier erosion is effectively protected.

Compared with the prior art, the present invention has at least one of the following beneficial effects:

The above-mentioned device of the present invention can fully cover the existing scour pit or the maximum scour range around the pile pier by setting the mesh member, thereby increasing the resistance of the undercurrent and eddy current movement around the pile pier, and weakening the water flow intensity under the mesh member. That is, it blocks the flow of water that reaches under the mesh component, reduces the sand carrying capacity of the water flow under the mesh, and makes the incoming sand quickly fall into the scour pit under the mesh from the mesh, and the mesh component will not accumulate significantly before it is suspended. Sediment, the sediment in the pit is continuously deposited, and the depth of the original scour pit is gradually reduced, and the local scour degree of the pile pier is controlled within a limited range, which fundamentally eliminates the root cause of scouring and avoids the harm caused by scouring; in addition, The underwater weight of the silt-promoting repair device is light, and the load acting on the piles and other foundations will not be significantly increased, and the requirements for the bearing capacity of the foundation will not be significantly increased.

All components of the device of the present invention are prefabricated in the factory and assembled on site, which reduces the difficulty of installation, greatly reduces the construction cost, and provides guarantee for the infrastructure construction of bridges, wharves, offshore platforms and offshore wind power.

Description of drawings

Other features, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments with reference to the following drawings:

1 is a schematic structural diagram of a silt-promoting repair device for a partial scour pit according to a preferred embodiment of the present invention;

The symbols in the figure are respectively indicated as: 1 is the skeleton, 2 is the floating body, 3 is the mesh member, 4 is the connecting part, 5 is the cable, and 6 is the ground anchor.

Detailed ways

The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

Example 1

Assuming that a 2m diameter pier standing upright in the river channel forms a 6m deep scour pit under the action of water flow, and the scour pit radius is 30m. The scour has posed a threat to the safety of the pier and needs to be protected from scour. Referring to FIG. 1 , this embodiment provides a silting-promoting repair device for partial scour pits, which includes a frame 1 , a fixing device, a floating body 2 and a mesh component 3 .

Referring to FIG. 1 , the frame 1 is arranged around the pier, and the inner ring of the frame 1 is fixed on the pier.

The fixing device is used to fix the frame 1 with the bed around the pier to prevent the frame 1 from being washed away by water currents and waves.

The floating body 2 is arranged on the frame 1, and the floating body 2 is used to provide buoyancy for the frame 1 and reduce the load imposed by the device on the pile pier. As a preferred way, the floating body 2 can be made of anti-corrosion, anti-ultraviolet, and foamed polymer materials, the shape is an ellipsoid, and the density is 0.2 times that of water.

The mesh member 3 is arranged on the skeleton 1, and the mesh member 3 completely covers the opening of the scour pit, so as to increase the resistance of the downflow and eddy current movement around the pier, weaken the water flow intensity under the mesh member 3, and reduce the mesh member 3. The sand-carrying ability of the water flow makes the incoming sand quickly fall into the net through the mesh of the mesh part 3 and accumulate; the mesh part 3 is in a neutral buoyancy state when placed in the water. As a preferred way, the mesh member 3 can be made of high-strength modified HDPE material that is anti-corrosion and anti-ultraviolet. ₉₅ (ie 5 mm, d ₉₅ =0.1 mm), porosity: 0.3; mesh thickness: 3 cm. The mesh component 3 adopts a specific gravity close to that of water, so that it is light in weight underwater, thereby minimizing the total weight of the entire repair device and ensuring that the load transferred by the repair device to the pier will not be significantly increased.

In other preferred embodiments, the mesh member 3 is provided with a connection portion 4 , and the mesh member 3 is connected to the frame 1 through the connection portion 4 . The connection part 4 can be snapped or bundled. The buckle can be made of modified PVC material.

In other preferred embodiments, the mesh member 3 is circular, the mesh member 3 is composed of several fan-shaped meshes spliced into one, and each neutral mesh 3 is closely arranged with each other to prevent the mesh member 3 from not being laid on the The place. The circular mesh part 3 assembled by several fan-shaped meshes can better adapt to the elliptical shape of the scouring pit, which brings convenience to the manufacture and construction of the repair device.

In other preferred embodiments, the hole shape of the mesh member 3 is circular or square.

In other preferred embodiments, the aperture of the mesh member 3 is 5d ₉₅ to 500d ₉₅ to ensure that the sand particles can fall through the mesh holes smoothly, wherein d ₉₅ is the ratio of 95% of the particles in the bed sand to this particle size Small; porosity: 20% to 80%, to ensure that the sand particles will basically fall to the bottom of the net through the mesh, and the sand will not accumulate continuously on the net when it is suspended. Thickness of the mesh member 3: 1 cm to 10 cm.

In other preferred embodiments, the fixing device includes several ground anchors 6 and cables 5, wherein several ground anchors 6 are buried under the bottom surface to prevent them from being exposed by the water flow. Once exposed, the anchoring force of the ground anchors will be reduced. significantly reduced, resulting in the instability and damage of the repair device; the ground anchor 6 uses dynamic torpedo anchors, the number of anchors is 32, the anchor length is 1m, and the cross-sectional diameter is 12cm. One end of the cable 5 is tied to the ground anchor 6, and the other end of the cable 5 is tied to the frame 1 to prevent the frame 1 from being washed away by water currents and waves. The cable 5 is a 5mm thick ultra-high molecular polyethylene rope. The stability of the ground anchor 6 is the key to the success or failure of the protection project. The selection, size, current situation and burial depth of the 6 types of ground anchors should be determined according to the optimization and calculation of the overall scour change of the ground bed, the sediment conditions, the current wave elements, the geometric and physical parameters of the skeleton 1 and the neutral grid, and the economic budget. After optimization calculation, it is determined that the ground anchor 6 is buried below 5m of the bottom bed. The ground anchor 6 is a stationary component fixed on the bottom bed, and can use dynamic torpedo anchors, Hall anchors, concrete piers, stones and sandbags.

In other preferred embodiments, the skeleton 1 includes an inner ring, an outer ring and several mesh keels, wherein the inner ring is tightly sleeved on the pile pier, and is close to one end of the bed surface, and the pile pier is used as the repair device. A support; the diameter of the inner ring can be 2m; the outer ring is arranged on the periphery of the inner ring, and a number of grid keels are arranged between the outer ring and the inner ring, and a number of grid keels form a ring-shaped platform for fixing and installing mesh components 3 . The skeleton 1 is made of HDPE material clad steel pipe, and the specific gravity distribution is relatively uniform. The length of the radial keel strips of the skeleton 1 is 30m, 16 in total, φ=100mm; in addition to the inner and outer rings, there are also 20 circles in the middle, φ=30mm.

In another embodiment, a method for promoting silting and repairing a partial scour pit is provided, which is carried out by using the above-mentioned device for promoting silting and repairing a partial scour pit.

The silt-promoting repair methods for local scour pits include:

Fix the frame 1 at the position of the maximum scour range around the pier corresponding to the bed plane.

The floating body 2 is installed under the frame 1, and the long axis of the floating body 2 is reversed toward the incoming flow.

The mesh member 3 is fixed on the skeleton 1, so that the opening of the scour pit is completely covered, so as to increase the resistance of the downflow and eddy current movement around the pier, weaken the water flow intensity under the mesh member 3, and reduce the water flow under the mesh member 3. The ability to carry sand makes the incoming sand quickly fall into the net through the mesh of the mesh component 3 and accumulate.

The fixing device is determined according to the overall scouring change of the bottom bed, the sediment condition, the water flow wave elements, the geometrical and physical parameters of the skeleton 1 and the mesh part 3. After the determination, the fixing device is buried below the set height of the bed surface, and the fixing device is installed. Connect to Skeleton 1.

Preferably, in order to increase the stability of the repair device and further reduce its engineering cost, before the frame 1 is fixed at the position of the maximum scour range around the pile pier corresponding to the bed plane, the method further includes:

Predict the lowest elevation of the subbed at the position of the pier before construction, and fix the inner ring of frame 1 to the outer wall of the pier at the predicted lowest elevation to prevent the overall undercut of the subbed caused by seasonal changes in water and sediment conditions. The overhang of the frame 1 and the mesh part 3 is too high.

According to the predicted minimum elevation, determine the set height of the fixture to be buried in the bottom surface, that is, to bury the fixture below the lowest elevation of the bottom surface, so as to prevent the ground anchor 6 from being washed and leaking due to seasonal changes in water and sand conditions and losing the anchor. fixed effect.

After the above repair method is implemented, the depth of the original scour pit is significantly reduced to less than about 1m, and the safety of the pile pier is guaranteed. In addition, the underwater weight of the silt-promoting repair device is light, and the load acting on the pile with a diameter of 2 m will not be significantly increased, and the requirement for the bearing capacity of the foundation will not be significantly increased.

Example 2

Assuming that the pile has been standing in the ocean with a bed sediment d ₉₅ of 0.2mm and a diameter of 5m, a scour pit with a depth of 12m may be formed under the action of sea current and wave scouring, and the obvious scour range is 80m in radius. Pile safety poses a threat, and anti-scour protection is required in the early stage of pile construction. Referring to FIG. 1 , this embodiment provides a silt-promoting repair device for a partial scour pit, which includes a frame 1 , a fixing device, a floating body 2 and a mesh member 3 .

The skeleton 1 is a hollow rod made of cast iron, the skeleton 1 is arranged around the pile, and the inner ring is fixedly arranged on the outer wall of the pile.

The fixing device provides cables 5 to fix the frame 1 to the bed around the pile, preventing the frame 1 from being washed away by currents and waves.

The floating body 2 is arranged on the frame 1, and the floating body 2 is used to provide buoyancy for the frame 1 and reduce the load imposed by the device on the pile pier. As a preferred way, the floating body 2 can be made of anti-corrosion and anti-ultraviolet foamed polymer material, the shape is an ellipsoid, and the density is 0.3 times that of water.

The mesh part 3 is a circular ring with an inner diameter of 5m and an outer diameter of 80m made of anti-corrosion and UV-resistant Kevlar material. The specific gravity of the mesh part 3 is 1.1 times that of water, the mesh distribution is uniform, and the diameter of the mesh rope is 3mm, the pore size is 6mm, and the porosity is about 0.5. The mesh component 3 is fixed on the skeleton 1 with a strapping belt, and the mesh component 3 completely covers the potential scour range around the pile, so as to weaken the water flow intensity under the net, reduce the sand carrying capacity of the wave flow under the net, and make the sand flow. It quickly falls into the net through the mesh and accumulates.

The fixing device includes several ground anchors 6 and cables 5, among which several ground anchors 6 are buried 1m below the bottom surface; the ground anchors 6 are selected from concrete blocks, the number of ground anchors 6 is 32, and the size of the concrete block is 0.5m*0.5m* 0.5m, the cross-section diameter is 12cm. One end of the cable 5 is tied to the ground anchor 6, and the other end of the cable 5 is tied to the frame 1 to prevent the frame 1 from being washed away by water currents and waves. The cable 5 uses a 3mm thick Kevlar rope.

After the above method is implemented, the safety of upright piles with a diameter of 5m in the ocean will be guaranteed. In addition, the underwater weight of the silt-promoting repair device is light, and the load acting on the pile is not significantly increased, and the requirement for the bearing capacity of the foundation is not significantly increased.

Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various variations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims (10)

1. The utility model provides a promote silt prosthetic devices of local scouring pit which characterized in that includes:

the framework is arranged around the pile pier in a surrounding mode, and the inner ring of the framework is fixed on the pile pier;

the fixing device is used for fixing the framework and a bottom bed around the pile pier;

the floating body is arranged on the framework and used for providing buoyancy for the framework;

the mesh-shaped component is arranged on the framework and completely covers the pithead of the scouring pit so as to increase the resistance of the submerged flow and the vortex motion around the pile pier, weaken the water flow strength under the mesh-shaped component and reduce the sand-carrying capacity of the water flow under the mesh-shaped component, so that the incoming sand quickly falls under the mesh through the meshes of the mesh-shaped component and is deposited; the net-shaped component is placed in water and is in a neutral buoyancy state.

2. The silt-promoting repair device for the local scoured pits according to claim 1, wherein the net-shaped component is made of high-strength engineering materials with specific gravity close to that of water, corrosion resistance and ultraviolet resistance;

the pore diameter of the reticular component is as follows: 5d ₉₅ ～500d ₉₅ Wherein d is ₉₅ The sand particles smaller than the grain diameter in the sand account for 95 percent of the weight;

the porosity of the mesh component is as follows: 20 to 80 percent;

thickness of the mesh member: 1 cm-10 cm.

3. The silt-promoting repair apparatus for local scour pits according to claim 2, wherein the net-shaped member is provided with connecting parts at the periphery and in the middle, and the net-shaped member is connected with the framework through the connecting parts.

4. The silt-promoting repair device for local scour pits according to claim 3, wherein the net-shaped part is formed by splicing a plurality of fan-shaped grids or strips into a whole, or a circular ring-shaped flexible net is adopted as the net-shaped part.

5. The apparatus for promoting silt restoration of a partially flushed pit according to claim 2, wherein the mesh openings of the mesh member are circular or square holes.

6. The apparatus for silt-promoting repair of locally scoured pits according to claim 1, wherein the securing means comprises:

the ground anchors are buried below the bottom bed surface;

and one end of the cable is connected with the ground anchor, and the other end of the cable is connected with the framework.

7. The apparatus for accelerated siltation repair of a partially eroded pit according to claim 1, wherein said skeleton comprises:

the inner ring is tightly sleeved at one end of the pile pier close to the bottom bed surface;

the outer ring is arranged on the periphery of the maximum scouring range of the pile pier, a plurality of grid keels are arranged between the outer ring and the inner ring, and the grid keels form an annular platform and are used for fixing and installing the net-shaped component.

8. A method for promoting siltation repair of a partially eroded pit, which is carried out by using the device for promoting siltation repair of a partially eroded pit according to any one of claims 1 to 7.

9. The method for promoting siltation repair of a locally flushed pit according to claim 8, comprising:

fixing the framework on the position of the maximum scouring range around the pile pier corresponding to the bottom bed plane;

installing a floating body below the framework, and enabling a long axis of the floating body to face the incoming flow in a reverse direction;

fixing a net-shaped component on the framework to enable the pithead of the scouring pit to be completely covered so as to increase the resistance of the submerged flow and the vortex motion around the pile pier, weaken the water flow strength under the net-shaped component and reduce the sand-carrying capacity of the water flow under the net-shaped component, so that the incoming sand can quickly fall under the net through the meshes of the net-shaped component to deposit;

determining a fixing device according to the whole scouring change condition of the bottom bed, the bottom material condition, the water flow wave elements, the geometric and physical parameters of the framework and the net-shaped part, embedding the fixing device below the set height of the bottom bed surface after determination, and connecting the fixing device with the framework.

10. The method for promoting siltation repair of a locally eroded pit according to claim 8, wherein before the step of fixing the framework at the position of the maximum erosion range around the pile pier corresponding to the bed bottom plane, the method further comprises:

predicting the lowest elevation of the bottom bed where the pile pier is located before construction, and fixing the inner ring of the framework on the outer wall of the pile pier at the predicted lowest elevation so as to prevent the overhigh suspension height of the framework and the net-shaped part caused by integral undercutting of the bottom bed due to seasonal changes of water and sand conditions;

and determining the set height of the fixing device embedded in the bottom bed surface according to the predicted lowest elevation, namely, the set height of the fixing device embedded in the bottom bed surface is lower than the lowest elevation.

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