Bend torrent beach weir multiple anti-scour flow regulating device and construction method

Abstract

The application relates to the technical field of cofferdam protection of water conservancy projects, and provides a multi-directional scouring prevention and flow regulation device for a curved torrent river beach cofferdam and a construction method. A standard unit body of the device is composed of upper and lower circular arc-shaped fixed steel plates, a louvered multi-directional flow guide cover, a vein bionic bifurcation channel diffusion and energy dissipation body and an elastic flow velocity control grid which are sequentially arranged from outside to inside and fixed between the two circular arc-shaped fixed steel plates. The arc-shaped blades of the louvered multi-directional flow guide cover are hingedly installed through adjusting shafts, can be self-adaptively deflected to guide multi-directional incoming flow. The vein bionic bifurcation channel diffusion and energy dissipation body is internally provided with a main channel and multi-stage bifurcated branch channel, can gradually decompose and reduce kinetic energy of water flow. The rubber elastic grid of the elastic flow velocity control grid makes outflow uniform and suppresses pressure pulsation. The standard unit bodies are vertically spliced through splicing mechanisms, and connected with a steel sheet pile ton bag cofferdam through a connecting and fixing mechanism.

Description

Technical Field

[0001] This invention belongs to the field of cofferdam protection technology in water conservancy projects, specifically relating to a multi-directional anti-scour and flow-regulating device and construction method for a cofferdam on a meandering, fast-flowing riverbed. Background Technology

[0002] When constructing bridge foundations or hydraulic facilities in complex hydrological areas such as meandering riverbeds, composite cofferdam structures using sheet piles combined with ton bags are often employed. These structures must withstand the continuous scouring action of the river during construction. Especially in meandering river sections, the headwaters, corners, and sheet pile joints of the cofferdam are susceptible to repeated, concentrated scouring by multidirectional, uneven rapid flows due to centrifugal force and turbulent water flow. Over time, the filler material in the ton bags gradually leaks out, and the sheet pile feet are hollowed out, seriously threatening the overall stability of the cofferdam structure and construction safety.

[0003] Currently, protective measures against the aforementioned scouring problem mainly rely on passive protection methods such as dumping large amounts of riprap or laying geotextiles outside the cofferdam. These passive protection methods have the following technical problems.

[0004] First, it requires a large amount of materials, resulting in high construction costs. Furthermore, the large amount of dumped riprap may occupy the river's cross-section, affecting its flood control capacity. Second, it has poor adaptability to complex, multi-directional water flow. The direction of water flow in meandering river sections continuously changes with water level and flow rate. Fixed-shape riprap protection cannot effectively resist scouring from different directions, easily leading to localized failure. Third, the passive protection structure itself is unstable under rapid current scouring; riprap is frequently washed away and geotextile is often lifted, requiring repeated filling and repair, resulting in a large maintenance workload. Fourth, the above-mentioned protection methods are general-purpose measures, lacking specialized design for the characteristics of sheet pile and ton bag cofferdam structures. Their adaptability to the cofferdam carrier is insufficient, failing to achieve precise protection of scour-prone areas. Fifth, traditional passive protection methods rely solely on increasing resistance to resist scouring, without regulating the scouring flow itself from a hydrodynamic perspective, thus failing to reduce scouring intensity at its source.

[0005] Therefore, there is an urgent need to develop a local scour protection device and its construction method that can be closely integrated with steel sheet pile ton bag cofferdam structures, can actively dissipate and rectify energy, can be quickly installed and disassembled, and is economical and efficient. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies in the anti-scour measures of steel sheet pile ton bag cofferdams on curved and fast-flowing riverbanks, such as being passive and inefficient, having poor adaptability to multi-directional water flow, and being insufficiently compatible with the cofferdam carrier. This invention provides a multi-directional anti-scour rectification device and construction method for cofferdams on curved and fast-flowing riverbanks.

[0007] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention proposes a multi-directional anti-scouring and flow-regulating device for a cofferdam on a meandering, fast-flowing riverbank, comprising a standard unit body. The standard unit body is formed by connecting two upper and lower arc-shaped fixed steel plates and, fixed between the two plates, sequentially arranged from the outside to the inside, a louvered multi-directional flow guide hood, a leaf-vein-inspired bifurcation channel diffusion energy dissipator, and an elastic flow velocity control grid. The direction from the outside to the inside is from away from the sheet piles to closer to the sheet piles. Adjacent standard unit bodies are rigidly spliced ​​vertically through a splicing mechanism. The spliced ​​device is connected to a sheet pile ton bag cofferdam via a connecting and fixing mechanism. The louvered multi-directional air guide includes multiple air guide units spaced apart along the arc length direction of two upper and lower arc-shaped fixed steel plates. Each air guide unit includes an arc-shaped blade, a vertical adjustment shaft connected to the arc-shaped blade, and fixing components at both ends of the adjustment shaft. The fixing components hinge the adjustment shaft to the upper and lower arc-shaped fixed steel plates, so that the arc-shaped blade rotates around the adjustment shaft to adaptively adjust the direction. The leaf vein-inspired bifurcation channel diffusion energy dissipation body is a three-dimensional mesh structure with vertical spacing, including multiple layers of energy dissipation and diffusion channels. Each layer of energy dissipation and diffusion channels includes multiple main channels and bifurcation tributary channels connected to the main channels. The front end of the main channel is the inlet end, which faces the outlet end of the louvered multi-guide hood. The outlet ends of the main channels and / or the bifurcation tributary channels are respectively connected to or oriented towards the elastic flow velocity control grid. The elastic flow rate control grid includes a stainless steel frame and a rubber elastic grid fixed to the stainless steel frame in a rectangular mesh pattern.

[0008] Furthermore, the leaf vein biomimetic bifurcation channel diffusion energy dissipator also includes a plurality of vertical upper and lower fixed steel plate support rods spaced apart along the arc length direction of the upper and lower arc-shaped fixed steel plates, with the upper and lower ends of each upper and lower fixed steel plate support rod connected to the upper and lower arc-shaped fixed steel plates respectively; the front end of the main channel is connected to the upper and lower fixed steel plate support rods.

[0009] Furthermore, the cross-section of the main channel and the branch channel is a circular pipe, and the outlet end of the main channel is thermally fused to the elastic flow velocity control grid.

[0010] Furthermore, the splicing mechanism includes a stainless steel butt flange and connecting bolts for stacking and connecting the arc-shaped fixed steel plates of vertically adjacent standard units.

[0011] Furthermore, the sheet pile ton bag cofferdam includes sheet piles; the connecting and fixing mechanism includes a connecting rod, a fixing base, and anchor bolts; one end of the connecting rod is connected to an arc-shaped fixing steel plate through anchor bolts, and the other end is connected to the sheet pile through the fixing base.

[0012] Furthermore, the sheet pile ton bag cofferdam also includes a ton bag; the connecting and fixing mechanism also includes a drill rod; the ton bag is located between the standard unit and the sheet pile; one end of the drill rod is connected to the arc-shaped fixing steel plate, and the other end is inserted into the ton bag.

[0013] Furthermore, the standard unit is positioned at the corner of the sheet pile ton bag cofferdam.

[0014] Furthermore, the water-facing surface of the arc-shaped blade is configured as an arc-shaped curved surface.

[0015] Secondly, the present invention also proposes a construction method for a multi-directional anti-scour and rectification device for a cofferdam on a winding, fast-flowing riverbank, wherein the device is the aforementioned multi-directional anti-scour and rectification device; the construction method includes the following steps: S1. Hydrological survey and installation location determination before construction: Conduct on-site measurements of the river level, flow velocity and flow direction of the meandering and rapid riverbed, and analyze the scour risk area around the cofferdam; S2. Design of Cofferdam Pretreatment and Installation Parameters: Based on the structural parameters of the steel sheet pile ton bag cofferdam, the construction plan of the island building platform, and the water flow, riverbed topography and scour characteristics of the construction area, determine the installation location and depth of the anti-scour rectification device, and determine the number of standard unit connections, combination method and installation location according to the draft of the installation location. S3. Standard unit assembly: The standard unit of the designed number of units, including the louvered multi-guide fairing, the leaf vein bionic bifurcation channel diffusion energy dissipator, the elastic flow velocity control grid and the upper and lower arc-shaped fixed steel plates, are fixedly spliced ​​in the prefabrication site on the shore. S4. Graded Installation and Fixing: Based on the installation position of the standard unit, the fixing base of the connecting and fixing mechanism is installed on the steel sheet piles of the steel sheet pile ton bag cofferdam; the standard unit is hoisted layer by layer, and the arc-shaped fixing steel plates of the vertically adjacent standard unit are superimposed and connected through the splicing mechanism. The standard unit and the fixing base are connected through the connecting rod and anchor bolt of the connecting and fixing mechanism, and one end of the connecting rod of the connecting and fixing mechanism is connected to the arc-shaped fixing steel plate of the standard unit, and the other end is inserted into the ton bag of the steel sheet pile ton bag cofferdam.

[0016] Furthermore, in step S4, the method further includes placing a ton bag between the standard unit and the sheet pile, connecting one end of the drill rod to the arc-shaped fixing steel plate of the standard unit, and inserting the other end of the drill rod into the ton bag.

[0017] The beneficial effects of this invention are as follows: The arc-shaped blades of the louvered multi-directional flow guide cover are hinged to two upper and lower arc-shaped fixed steel plates, allowing for adaptive deflection under the impact of water flow from different directions. The arc-shaped curved surface of the blades increases the interception and guidance range of the incoming flow, unifying the multi-directional flow towards the energy dissipator, thus solving the problem of poor adaptability of traditional fixed protective structures to multi-directional water flow. The leaf vein-inspired bifurcation channel diffusion energy dissipator draws on the bifurcation transport principle of plant leaf veins. Its main channel and multi-level bifurcation tributary channels form a three-dimensional mesh structure that decomposes the concentrated water flow guided by the flow guide cover into multiple fine streams through progressively bifurcation circular pipes. Each stream gradually reduces its kinetic energy under the action of pipe wall friction and flow diffusion. The free ends of the bifurcation tributary channels allow the kinetic energy of the diverted water to be fully dissipated at the free ends, resulting in an energy dissipation efficiency far higher than that of traditional single-channel or simple grid energy dissipation methods. The rubber elastic grid of the elastic flow velocity control grid is made of rubber material, which has good elastic deformation capacity. When water flows through the rectangular mesh holes, the slight elastic deformation of the rubber elastic grid can absorb and buffer the pressure pulsation of the water flow, so that the water flow velocity acting on the steel sheet piles and ton bag structure is uniform and the pulsation amplitude is significantly reduced. The three-stage structure of the standard unit body undertakes the functions of guiding and diverting the flow, dissipating energy in stages, and homogenizing and rectifying the flow. By gradually reducing the impact intensity of the water flow, the local scouring effect of the cofferdam is suppressed at the source, avoiding damage phenomena such as loss of ton bag filler and hollowing out of the steel sheet pile feet.

[0018] The rectifying device of this invention uses standard unit cells as basic modules. These standard unit cells are rigidly connected vertically via a splicing mechanism, allowing for flexible combinations based on the scour risk level at different depths on the upstream side of the cofferdam. The number of standard unit cells and the splicing length can be adjusted according to the actual water depth and scour risk on site. They can be freely spliced ​​along depth and length directions, making them suitable for island-building platforms of different sizes and complex scour risk areas in meandering rapids. The device is rigidly connected to the cofferdam structure via a connecting and fixing mechanism, ensuring a strong and reliable connection without damaging the original cofferdam structure. The modular design results in a high degree of standardization in the device's manufacturing, high on-site installation efficiency, and a short construction cycle. All components of the device are disassembled and recyclable, and can be reused after cleaning and maintenance, reducing engineering material costs. Compared to the traditional passive protection method of massively dumping riprap, this invention does not occupy the river's cross-sectional area and does not affect the river's flood discharge capacity. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the multi-directional anti-scouring and rectifying device for cofferdams on winding, fast-flowing riverbanks according to the present invention.

[0020] Figure 2 This is a top view of the multi-directional anti-scouring and flow-rectifying device for a cofferdam on a winding, fast-flowing riverbank, according to the present invention.

[0021] Figure 3This is a schematic diagram of the structure of the louvered multi-directional airflow cover of the present invention.

[0022] Figure 4 This is a schematic diagram of the structure of the leaf vein biomimetic bifurcation channel diffusion energy dissipator of the present invention.

[0023] Figure 5 This is a schematic diagram of the structure of the elastic flow velocity control grid of the present invention.

[0024] Figure 6 This is a side view schematic diagram of the vertically adjacent standard unit splicing and connection with the steel sheet pile ton bag cofferdam of the present invention.

[0025] Figure 7 This is a flowchart of the construction method steps of the present invention.

[0026] Figure 8 This is a three-dimensional structural diagram of the multi-directional anti-scour and straightening device for a meandering, fast-flowing riverbank cofferdam of the present invention, installed on a sheet pile ton bag cofferdam.

[0027] In the picture: 100 - Steel sheet pile ton bag cofferdam; 110 - Steel sheet pile; 120 - Ton bag; 200 - Louvered multi-directional air guide fairing; 210 - Curved blades; 220 - Adjustment shaft; 230 - Fixing assembly; 300 - Leaf vein-inspired bifurcation channel diffusion energy dissipator; 310 - Bifurcation branch channel; 320 - Upper and lower fixed steel plate support rod; 330 - Small bolt; 400 - Flexible flow control grille; 410 - Rubber flexible grille; 420 - Stainless steel frame; 500 - Assembly mechanism; 510 - Stainless steel butt flange; 520 - Connecting bolts; 600 - Connecting and fixing mechanism; 610 - Connecting rod; 620 - Fixing base; 630 - Anchor bolt; 640 - Drill rod; 700 - Arc-shaped fixed steel plate. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] like Figures 1 to 8 As shown, this invention provides a multi-directional anti-scour and flow-regulating device for cofferdams in meandering, fast-flowing riverbeds, suitable for localized active scour protection on the water-facing side of sheet pile ton-bag type island cofferdams in meandering, fast-flowing riverbed environments. The device is installed in the water flow at the front end of the sheet pile 110.

[0030] The basic unit of the rectifier is the standard unit. The standard unit consists of two upper and lower arc-shaped fixed steel plates 700, and a series of components fixed between them, arranged sequentially from the outside to the inside: a louvered multi-directional flow guide shroud 200, a leaf vein-inspired bifurcation channel diffuser and energy dissipator 300, and an elastic velocity control grid 400. The direction from the outside to the inside is from furthest from the sheet pile 110 to closest to it; that is, the louvered multi-directional flow guide shroud 200 is furthest from the sheet pile 110, and the elastic velocity control grid 400 is closest to it. The standard unit has a total depth of 150cm, a width of 100cm, and a thickness of 50cm.

[0031] like Figure 3 As shown, the louvered multi-directional flow guide hood 200 is located at the front end of the standard unit, that is, on the side furthest from the steel sheet pile 110. It is the first-stage structure of the flow rectifier to receive the impact of water flow and is used to receive and guide the impact water flow from different directions.

[0032] The louvered multi-directional fairing 200 includes multiple fairing units spaced apart along the arc length of two upper and lower arc-shaped fixed steel plates 700. Each fairing unit includes an arc-shaped blade 210, a vertical adjusting shaft 220 disposed at one vertical end of the arc-shaped blade 210, and fixing components 230 disposed at both ends of the adjusting shaft 220. The fixing components 230 are used to hinge the adjusting shaft 220 to the upper and lower arc-shaped fixed steel plates 700, thereby realizing the rotational connection of the arc-shaped blade 210 around the adjusting shaft 220.

[0033] The upstream surface of the arc-shaped blade 210 is designed as an arc-shaped curved surface, made of lightweight and high-strength PVC material, with an average width of 25cm, a length of approximately 100cm, and a thickness of 1cm. The arc-shaped curved surface design increases the interception and guidance range of the arc-shaped blade 210 for water flows impacting from different horizontal angles. A standard unit has a total of 7 arc-shaped blades 210, which are hinged to the upper and lower arc-shaped fixed steel plates 700 via the fixing assembly 230 through the adjusting shaft 220.

[0034] The connected arc-shaped blades 210 can rotate around the adjusting shaft 220. When water flows from directly in front, the arc-shaped blades 210 maintain their initial state under the symmetrical action of the water pressure, and the water flows through the gap between adjacent arc-shaped blades 210 into the leaf vein-inspired bifurcation channel diffuser 300. When water flows from the left or right, the arc-shaped blades 210 deflect around the adjusting shaft 220 at a corresponding angle under the asymmetrical pressure of the water flow. The deflected arc-shaped blades 210 guide the oblique incoming flow, directing it towards the inlet of the leaf vein-inspired bifurcation channel diffuser 300. The arc-shaped blades 210 adaptively adjust their rotation angle according to different water flow directions and impact forces, with an adjustment limit range of 0 to 160 degrees of left and right oscillation. When the water flow direction changes, the arc-shaped blades 210 automatically adjust their deflection angle under the new water pressure, achieving adaptive guidance of water flows impacting from different directions without manual intervention. This adaptive adjustment capability enables the rectifier to effectively cope with the complex working conditions of frequent changes in the direction of water flow in meandering river sections.

[0035] like Figure 4 As shown, the leaf vein-inspired bifurcation channel diffusion energy dissipator 300 is located between the louvered multi-directional flow guide hood 200 and the elastic flow velocity control grid 400. It is the core energy dissipation structure of the rectifier, and its design inspiration comes from the bifurcation transport structure of plant leaf veins.

[0036] The leaf vein-inspired bifurcation channel diffusion energy dissipator 300 is a three-dimensional mesh structure, comprising multiple upper and lower fixed steel plate support rods 320 spaced apart along the arc length of two upper and lower arc-shaped fixed steel plates 700 as a support framework. The upper and lower ends of each upper and lower fixed steel plate support rod 320 are connected to the upper and lower arc-shaped fixed steel plates 700, respectively. The upper and lower fixed steel plate support rods 320 are distributed on the outer arc edge of the arc-shaped fixed steel plates 700.

[0037] The leaf vein-inspired bifurcation channel energy dissipator 300 consists of a main channel and multi-level bifurcation branch channels 310. The channel cross-section is a circular pipe type with a radius of 1.5cm, and is made of lightweight, high-strength PVC material. A standard unit has 5 to 6 layers of energy dissipation and diffusion channels along the depth direction, i.e., the height direction, and each layer includes multiple main channels at the same horizontal height.

[0038] The front end of each main channel, away from the sheet pile 110, is connected to the upper and lower fixed steel plate support rods 320 via small bolts 330. The entrance of the main channel is not blocked by the small bolts 330, which can be replaced by cable ties. The rear end of each main channel is heat-fused to the elastic flow control grid 400. Each main channel has branching channels 310 on both sides, both of which are circular pipes. The other end of each branching channel 310 is either a free end or connected to an adjacent main channel. The total horizontal span of the channels is approximately 25cm, and different channels are connected by heat-fused PVC material. Specifically, there are multiple main channels, spaced apart along the arc length of the arc-shaped fixed steel plate 700. The entrance of each main channel is near the arc-shaped blade 210, and the exit of each main channel is near the rubber elastic grid 410. Multiple branch channels 310 are provided on both sides of the main channel or between two adjacent main channels. Each main channel is connected to multiple branch channels 310 at intervals along its length. The multiple branch channels 310 are arranged in a zigzag shape along the arc length of the arc-shaped fixed steel plate 700. The end of the outermost branch channel 310 is the outlet end of the branch channel 310, and the inlet end of the branch channel 310 is connected to the main channel. Thus, when water enters the main channel, part of it enters the branch channels 310 on both sides of the main channel. Under the diversion effect of the branch channels 310, the water flows into the adjacent main channels, and so on, until it flows out from the free end of the outermost branch channel 310. Of course, some water flows directly into the main channel from the inlet and flows out from its outlet.

[0039] After being guided by the louvered multi-directional flow guide hood 200, the water flow enters the main channel and is gradually broken down into multiple fine streams at each branching point. The cross-sectional area of ​​each branching channel 310 remains constant, while the number of branching channels 310 increases progressively along the water flow direction, gradually increasing the total flow area and creating a diffusion effect. At the channel branching points, the water flow changes direction and energy is redistributed, resulting in a decrease in flow velocity during diffusion. Simultaneously, frictional resistance is generated between the water flow and the pipe wall as it flows within the circular pipe, continuously converting the kinetic energy of the water flow into heat energy, which is then dissipated. The free ends of the branching channels 310 allow for sufficient dissipation of the kinetic energy of the split water flow. The energy dissipation through channel branching, wall friction, and free end dissipation significantly reduces the flow velocity of the water flow after passing through the leaf vein-inspired bifurcation channel diffusion energy dissipation body 300, effectively reducing the impact kinetic energy.

[0040] like Figure 5As shown, the elastic flow velocity control grid 400 is located at the end of the standard unit, i.e., on the side closest to the sheet pile 110, connected to the rear of the leaf vein-inspired bifurcation channel diffuser energy dissipator 300. It is arc-shaped and positioned on the inner arc edge of the arc-shaped fixed steel plate 700. The elastic flow velocity control grid 400 is the third-stage treatment structure of the rectification device, responsible for the final homogenization and pulsation suppression of the water flow after initial rectification by the leaf vein-inspired bifurcation channel diffuser energy dissipator 300.

[0041] The elastic flow velocity control grid 400 is made of a rubber elastic grid 410 and a stainless steel frame 420. The rubber elastic grid 410 is a rectangular mesh, and the mesh size is set to 1 cm based on the relationship between water flow area and flow velocity to maximize energy dissipation. The rubber elastic grid 410 is fixed to the stainless steel frame 420 and can be connected to the front end of the leaf vein-inspired bifurcated channel diffusion energy dissipator 300 by bolts or heat fusion.

[0042] When the water flow after passing through the leaf vein-inspired bifurcation channel energy dissipator 300 passes through the elastic velocity control grid 400, the rectangular mesh openings of the rubber elastic grid 410 generate uniform resistance to the water flow, making the flow velocity through each opening more consistent. This eliminates the velocity differences remaining due to the incomplete uniformity of outflow from each channel within the leaf vein-inspired bifurcation channel energy dissipator 300. Simultaneously, when residual pressure pulsations in the water flow act on the rubber elastic grid 410, the elastic properties of the rubber material cause the grid to undergo slight elastic deformation, converting a portion of the pulsating energy into elastic potential energy, which is released at a lower frequency during rebound, thus buffering and weakening the pressure pulsations. After passing through the elastic velocity control grid 400, the water flow that ultimately flows out and acts on the sheet piles 110 and the ton bag 120 structure is stable and controllable, significantly reducing the scouring effect on the cofferdam structure.

[0043] like Figure 1 and Figure 6 As shown, two arc-shaped fixed steel plates 700 are respectively set on the upper and lower sides of the standard unit body, both in an arc shape. The two arc-shaped fixed steel plates 700 are connected to each hood unit of the louvered multi-directional air guide hood 200 through the fixing component 230. The upper and lower ends of the upper and lower fixed steel plate support rods 320 are respectively connected to the two arc-shaped fixed steel plates 700 to support the leaf vein biomimetic bifurcation channel diffusion energy dissipator 300. The stainless steel frame 420 of the elastic flow velocity control grid 400 is fixedly connected to the inner arc edge of the arc-shaped fixed steel plates 700, thereby combining the louvered multi-directional air guide hood 200, the leaf vein biomimetic bifurcation channel diffusion energy dissipator 300 and the elastic flow velocity control grid 400 into a compact standard unit body.

[0044] like Figure 6As shown, the splicing mechanism 500 is located at the connection interface of the standard unit body, used to splice multiple standard unit bodies vertically, i.e., along the water depth direction. The splicing mechanism 500 includes a stainless steel butt flange 510 and connecting bolts 520 mounted on the arc-shaped fixing steel plate 700 of the standard unit body. During splicing, the stainless steel butt flange 510 at the bottom of the arc-shaped fixing steel plate 700 of the upper standard unit body aligns and fits against the top surface of the arc-shaped fixing steel plate 700 of the lower standard unit body. The connecting bolts 520 are then tightened through corresponding holes, achieving a rigid connection between adjacent standard unit bodies. After multiple standard unit bodies are vertically spliced, a continuous protective assembly covering the required water depth range is formed, enabling rapid splicing, expansion, and disassembly of multiple standard unit bodies in the 100-meter depth direction of the sheet pile cofferdam.

[0045] like Figure 6 As shown, the connecting and fixing mechanism 600 is used to connect the assembled device to the sheet pile ton bag cofferdam 100. Two connecting and fixing mechanisms 600 are respectively provided at the end of each standard unit, that is, on the side near the sheet pile 110. The connecting and fixing mechanism 600 includes a connecting rod 610, a fixing base 620, an anchor bolt 630, and a drill rod 640, which are set on the upper and lower arc-shaped fixing steel plates 700.

[0046] One end of the connecting rod 610 is fixedly connected to the arc-shaped fixed steel plate 700 via anchor bolts 630, and the other end is connected to the fixed base 620. The fixed base 620 is a clamp-type structure, which is clamped and fixed to the outer wall of the sheet pile 110. During installation, the clamp position of the fixed base 620 is adjusted and the base bolts are tightened to achieve a rigid connection between the connecting rod 610, the fixed base 620, and the sheet pile 110. One end of the drill rod 640 is fixedly connected to the arc-shaped fixed steel plate 700, and the other end is inserted into the ton bag 120 for anchoring.

[0047] In practical applications, based on the distribution of scour hazard areas on the upstream side of the cofferdam, protective assemblies can be installed at scour-prone locations such as the head of the flow, corners, and sheet pile joints. Each protective assembly consists of several standard units joined together by a splicing mechanism, with the number of units determined by the water depth range at that location. The protective units can be freely spliced ​​along both depth and length, making them suitable for complex scour risk areas such as island platforms of different sizes and meandering rapid current zones, forming continuous protective zones targeting scour hazard areas at different water depths.

[0048] like Figure 7 As shown, the construction method of the rectifier device of the present invention includes the following steps.

[0049] S1. Hydrological survey and installation location determination before construction. Conduct on-site measurements of river level, flow velocity, and flow direction in the meandering, fast-flowing riverbed, analyze the scour risk area around the cofferdam, and identify the most severe local locations and depths of scour.

[0050] S2. Cofferdam Pretreatment and Installation Parameter Design. Based on the structural parameters of the sheet pile ton-bag cofferdam 100, the island construction platform plan, and the water flow, riverbed topography, and scour characteristics of the construction area, the installation location and depth of the scour control device are determined. According to the draft at the installation location, the number of standard unit connections, the combination method, and the installation position are determined. The riverbed in the scour hazard area is surveyed; if local soft soil layers exist, crushed stone replacement is used. Fixed bases 620 are installed at predetermined positions on the outer wall of the sheet piles 110, and drill rods 640 are installed on the surface of the ton-bags 120.

[0051] S3. Modular assembly of standard unit components. At the onshore prefabrication site, prefabricate the louvered multi-directional flow guide shroud 200, the leaf vein-inspired bifurcated channel diffuser and energy dissipator 300, and the elastic flow velocity control grid 400 according to the design drawings. Securely connect these three components to the upper and lower arc-shaped fixing steel plates 700 to form the designed number of standard unit bodies. After assembly, check whether the arc-shaped blades 210 rotate smoothly and flexibly around the adjusting shaft 220, whether the channels of the leaf vein-inspired bifurcated channel diffuser and energy dissipator 300 are unobstructed, and whether the rubber elastic grid 410 is securely installed.

[0052] S4. Graded Installation and Fixing. A floating crane is used to hoist the bottom protective unit to the bottom of the cofferdam on the water-facing side, allowing the anti-slip teeth of the load-bearing bracket to engage with the crushed stone cushion layer of the island-building platform. The position of the clamps on the fixing base 620 is adjusted, and the base bolts are tightened to achieve a rigid connection between the connecting rod 610, the fixing base 620, and the sheet pile 110. The connecting rod 610 is fixedly connected to the arc-shaped fixing steel plate 700 using anchor bolts 630. Standard units are hoisted layer by layer along the water flow depth direction. The upper and lower standard units are docked and locked together using the stainless steel butt flange 510 of the splicing mechanism 500 and the connecting bolts 520, ensuring a tight fit of the transverse overlap grooves and a splicing gap of less than 1 cm.

[0053] S5. Overall Commissioning and Optimization. At the onshore prefabrication site, based on the measured water flow direction, the initial deflection angle of the arc-shaped blades 210 is pre-adjusted to ensure the angle between their upstream direction and the measured water flow direction is 10 to 15 degrees before hoisting and fixing. After installation, the water flow velocity in front of and behind the cofferdam's upstream protection assembly is compared to verify whether the rectification and energy dissipation effect meets expectations. If the scour hazard area is found to exceed expectations, standard units can be added to expand the protection coverage.

[0054] S6. Equipment Dismantling and Recycling. After the main construction of the island-building platform and cofferdam is completed, first remove the connecting bolts 520 and stainless steel butt flanges 510 of the splicing mechanism 500, then loosen the fixed base 620 and anchor bolts 630. Use a floating crane to lift each standard unit layer by layer and transport it to the shore. Clean the dismantled standard units to remove surface silt and rust. Lubricate and maintain the adjusting shaft 220 of the arc-shaped blade 210, unclog and inspect the channels of the leaf vein bionic bifurcation channel diffuser energy dissipator 300, and test the deformation and wear of the rubber elastic grid 410. Standard units that pass maintenance and inspection are stored for reuse in subsequent projects. Restore the water-facing side of the cofferdam and the edge of the island-building platform, and clean up waste generated during construction.

[0055] When water flows in a meandering, rapid riverbed impacts the upstream side of a cofferdam from different directions, it first comes into contact with the louvered multi-directional flow guide shroud 200. The curved surface of the arc-shaped blades 210 acts as an initial converging agent on the upstream side of the flow. Under the impact of the water flow, the arc-shaped blades 210 adaptively deflect around the regulating axis 220, guiding the multi-directional flow into a basically consistent direction and entering the leaf vein-inspired bifurcation channel diffusion energy dissipator 300. This is the first stage of treatment, and its main function is to normalize the direction of the multi-directional flow and reduce the directional differences in the impact of the water flow.

[0056] Guided by the louvered multi-directional flow guide hood 200, the water flows into the main channel of the leaf vein-inspired bifurcation channel diffusion energy dissipator 300. Subsequently, at each bifurcation point, it is gradually broken down into multiple fine streams, each flowing within its respective bifurcation branch channel 310. The channel bifurcation causes abrupt changes in direction and vortex formation in the water flow at the bifurcation points, consuming kinetic energy. The circular pipe wall further increases the flow resistance, continuously converting the kinetic energy of the water into heat energy. The free ends of the bifurcation branch channels 310 allow the split water flow to fully diffuse and dissipate energy at the outlet. This is the second stage of treatment, its main function being to significantly reduce the impact kinetic energy of the water flow.

[0057] After being treated by the leaf vein-inspired bifurcated channel diffusion energy dissipator 300, the water flow converges into the elastic velocity control grid 400. As it passes through the rectangular mesh openings of the rubber elastic grid 410, it is further homogenized, with the elastic deformation of the rubber material absorbing residual pressure pulsations. This is the third stage of treatment, whose main function is to ensure a uniform velocity field and stable pressure field in the outflowing water.

[0058] The above three-stage structure sequentially performs the functions of directional guidance, kinetic energy reduction, and flow field homogenization, forming a complete active energy dissipation and rectification process. Ultimately, it makes the water flow acting on the sheet pile 110 and ton bag 120 structures stable and controllable, effectively protecting the structural safety of the sheet pile ton bag cofferdam 100.

[0059] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A multi-directional anti-scouring and flow-regulating device for cofferdams on meandering, fast-flowing riverbanks, characterized in that, The system includes a standard unit, which is formed by connecting two upper and lower arc-shaped fixed steel plates and a louvered multi-directional flow guide hood, a leaf vein-inspired bifurcation channel diffusion energy dissipator, and an elastic flow velocity control grid, which are arranged sequentially from the outside to the inside between the two arc-shaped fixed steel plates. The direction from the outside to the inside is from away from the steel sheet pile to closer to the steel sheet pile. Adjacent standard units are rigidly spliced ​​vertically by a splicing mechanism. The spliced ​​device is connected to the steel sheet pile ton bag cofferdam by a connecting and fixing mechanism. The louvered multi-directional air guide includes multiple air guide units spaced apart along the arc length direction of two upper and lower arc-shaped fixed steel plates. Each air guide unit includes an arc-shaped blade, a vertical adjustment shaft connected to the arc-shaped blade, and fixing components at both ends of the adjustment shaft. The fixing components hinge the adjustment shaft to the upper and lower arc-shaped fixed steel plates, so that the arc-shaped blade rotates around the adjustment shaft to adaptively adjust the direction. The leaf vein-inspired bifurcation channel diffusion energy dissipation body is a three-dimensional mesh structure with vertical spacing, including multiple layers of energy dissipation and diffusion channels. Each layer of energy dissipation and diffusion channels includes multiple main channels and bifurcation tributary channels connected to the main channels. The front end of the main channel is the inlet end, which faces the outlet end of the louvered multi-guide hood. The outlet ends of the main channels and the bifurcation tributary channels are respectively connected to or oriented towards the elastic flow velocity control grid. The elastic flow rate control grid includes a stainless steel frame and a rubber elastic grid fixed to the stainless steel frame in a rectangular mesh pattern. The leaf vein biomimetic bifurcation channel diffusion energy dissipator also includes multiple vertical upper and lower fixed steel plate support rods spaced apart along the arc length direction of the upper and lower arc-shaped fixed steel plates, with the upper and lower ends of each upper and lower fixed steel plate support rod connected to the upper and lower arc-shaped fixed steel plates respectively; the front end of the main channel is connected to the upper and lower fixed steel plate support rods. The main channel and the branch channel have circular cross-sections, and the outlet end of the main channel is thermally fused to the elastic flow velocity control grid.

2. The multi-directional anti-scouring and flow-regulating device for cofferdams on winding, fast-flowing riverbanks according to claim 1, characterized in that, The splicing mechanism includes a stainless steel butt flange and connecting bolts for connecting the overlapping arc-shaped fixed steel plates of vertically adjacent standard units.

3. The multi-directional anti-scouring and flow-rectifying device for cofferdams on winding, fast-flowing riverbanks according to claim 1, characterized in that, The sheet pile ton bag cofferdam includes sheet piles; the connecting and fixing mechanism includes a connecting rod, a fixing base and anchor bolts; one end of the connecting rod is connected to an arc-shaped fixing steel plate through anchor bolts, and the other end is connected to the sheet pile through the fixing base.

4. The multi-directional anti-scouring and flow-rectifying device for cofferdams on winding, fast-flowing riverbanks according to claim 3, characterized in that, The sheet pile ton bag cofferdam also includes a ton bag; the connecting and fixing mechanism also includes a drill rod; the ton bag is located between the standard unit and the sheet pile; one end of the drill rod is connected to the arc-shaped fixing steel plate, and the other end is inserted into the ton bag.

5. The multi-directional anti-scouring and flow-regulating device for cofferdams on winding, fast-flowing riverbanks according to claim 1, characterized in that, The standard unit is located at the corner of the sheet pile ton bag cofferdam.

6. The multi-directional anti-scouring and flow-regulating device for cofferdams on winding, fast-flowing riverbanks according to claim 1, characterized in that, The water-facing surface of the arc-shaped blade is set as an arc-shaped curved surface.

7. A construction method for a multi-directional anti-scour and flow-regulating device for a cofferdam on a meandering, fast-flowing riverbed, characterized in that, The device is the multi-directional anti-scouring and rectifying device according to any one of claims 1-6; the construction method includes the following steps: S1. Hydrological survey and installation location determination before construction: Conduct on-site measurements of the river level, flow velocity and flow direction of the meandering and rapid riverbed, and analyze the scour risk area around the cofferdam; S2. Design of Cofferdam Pretreatment and Installation Parameters: Based on the structural parameters of the steel sheet pile ton bag cofferdam, the construction plan of the island building platform, and the water flow, riverbed topography and scour characteristics of the construction area, determine the installation location and depth of the anti-scour rectification device, and determine the number of standard unit connections, combination method and installation location according to the draft of the installation location. S3. Standard unit assembly: The standard unit of the designed quantity of louvered multi-guide fairing, leaf vein bionic bifurcation channel diffusion energy dissipator, elastic flow velocity control grid and upper and lower arc-shaped fixed steel plates are fixedly spliced ​​in the prefabrication site on the shore. S4. Graded Installation and Fixing: Based on the installation position of the standard unit, the fixing base of the connecting and fixing mechanism is installed on the steel sheet piles of the steel sheet pile ton bag cofferdam; the standard unit is hoisted layer by layer, and the arc-shaped fixing steel plates of the vertically adjacent standard unit are superimposed and connected through the splicing mechanism. The standard unit and the fixing base are connected through the connecting rod and anchor bolt of the connecting and fixing mechanism, and one end of the connecting rod of the connecting and fixing mechanism is connected to the arc-shaped fixing steel plate of the standard unit, and the other end is inserted into the ton bag of the steel sheet pile ton bag cofferdam.

8. The construction method of the multi-directional anti-scour and flow-rectifying device for cofferdams on winding, fast-flowing riverbanks according to claim 7, characterized in that, S4 further includes placing a ton bag between the standard unit and the sheet pile, connecting one end of the drill rod to the arc-shaped fixing steel plate of the standard unit, and inserting the other end of the drill rod into the ton bag.

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