A sacrificial pile group, a sacrificial pile and a sacrificial pile group positioning method

Abstract

This application discloses a sacrificial pile group, sacrificial piles, and a method for positioning the sacrificial pile group, belonging to the field of bridge foundation protection and water flow control technology. The sacrificial pile group is located on the upstream side of the bridge pier and consists of a guiding zone far from the pier and a return flow reflection zone adjacent to the pier. A kinetic energy dissipation zone is formed between the two zones. Through flow diversion, return flow counter-current, and turbulent collision, the kinetic energy of the water flow is dissipated step by step, suppressing downflow and horseshoe vortices around the pier, and synergistically mitigating scouring and erosion of the pier foundation. The sacrificial pile is a cylindrical structure with openings along the water flow direction, which can divide the incoming flow and suppress turbulent superposition. The openings use non-uniform cross-section flow channels to accelerate the water flow. Multiple sets of openings can be set to adapt to water level fluctuations, and active thrust components such as shaftless pumps can be integrated to form a combined active and passive flow control structure. The sacrificial pile adopts a modular combination design of fixed sections, pile body sections, perforated sections, and pile top sections, which is convenient to connect and highly versatile. The positioning method uses prefabricated land-based positioning and bearing reference components as a unified platform. After precise placement of connectors, the entire pile group is sunk into place, achieving high-precision positioning and stable installation. This application offers high protection efficiency and strong adaptability to various working conditions, effectively improving the erosion and abrasion resistance of bridge foundations and reducing operation and maintenance costs.

Description

Technical Field

[0001] This application belongs to the field of bridge foundation protection and water flow control technology, and in particular relates to a sacrificial pile group based on passive flow control, the sacrificial piles that make up the pile group, and a high-precision positioning method for the sacrificial pile group. Background Technology

[0002] Bridges, as vital transportation hubs spanning rivers and straits, are of paramount importance in terms of safety and durability. Bridge piers and their foundations, as the supporting structures of bridges, bear the environmental loads of water flow and floating debris over long periods. Among these, localized scouring and water erosion around the pier foundations are two key factors threatening bridge safety. Localized scouring refers to the drastic changes in flow velocity and flow pattern that occur when water flows around the piers, such as… Figure 6 As shown, a downflow forms around the pier, especially in front of it, eroding the silt and sand on the pier bed and creating scour pits. As these scour pits deepen, the embedment depth and effective support capacity of the pier foundation are weakened, potentially leading to foundation exposure, hollowing out, or even instability and failure. Water flow erosion refers to the continuous impact and wear of solid particles such as silt and gravel carried by the water flow on the surface of the pier foundation and protective structures under the drive of high-speed water flow. This long-term physical abrasion gradually weakens the effective cross-section of structural components, reducing their load-bearing capacity. Especially for concrete structures, this accelerates steel corrosion and significantly shortens the structure's service life.

[0003] To address the scouring and abrasion problems of bridge pier foundations, existing technologies have proposed various protective measures, but all have significant limitations. Traditional rigid protection (such as riprap and geotextile concrete) can partially stabilize the riverbed, but it alters the flow field, inducing edge scouring, and is difficult to resist abrasion, requiring frequent maintenance. Flexible protection (such as geotextile sand sheets) lacks strength and durability, and is prone to failure under harsh hydrological conditions. Furthermore, methods involving altering the foundation structure or installing diversion facilities are limited in application due to high costs or the inability to effectively suppress harmful eddies around the pier. The sacrificial pile technology, which has received considerable attention in recent years, can mitigate localized scouring by interfering with the flow, but its design still has fundamental flaws. Existing solutions have a single protective objective, focusing only on scouring control while neglecting abrasion protection; their turbulence effects may even exacerbate the abrasion of the structure by sediment. Simultaneously, fixed structural parameters make it difficult to adapt to varying flow rates, lacking refined diversion and graded energy dissipation designs for different flow velocity levels, resulting in insufficient protection efficiency under different hydrological conditions. Therefore, there is an urgent need for a new type of protective structure that can resist erosion and abrasion in a coordinated manner and has adaptive flow control capabilities. Summary of the Invention

[0004] A sacrificial pile group is composed of several sacrificial piles installed on the water-facing side of a bridge pier. The sacrificial pile group includes two functional zones composed of sacrificial piles: a guiding zone and a backflow reflection zone. The sacrificial pile group on the side away from the bridge pier is the guiding zone, and the one adjacent to the bridge pier is the backflow reflection zone. The guiding zone guides the water flow to the backflow reflection zone, and the backflow reflection zone reflects the water flow to the guiding zone, forming a kinetic energy dissipation zone between the guiding zone and the backflow reflection zone to reduce the kinetic energy of the water flow.

[0005] Furthermore, the sacrificial pile group, the guide area sacrificial pile group, can be composed of several sacrificial piles arranged in a triangular shape.

[0006] Furthermore, the sacrificial pile group is characterized in that: the sacrificial pile group in the backflow reflection zone is arranged in any one of the following curved shapes: parabola, elliptic curve, catenary, or hyperbola.

[0007] Furthermore, a passive flow-controlled sacrificial pile is provided, wherein the sacrificial pile body is a columnar structure and has an opening in the same direction as the water flow. The incoming flow passing through the sacrificial pile is divided into two wing-shaped flow and a straight flow passing through the opening, so as to suppress the generation of downflow in front of the pile and thereby eliminate the turbulent superposition effect of downflow and horseshoe vortex.

[0008] Furthermore, in a passive flow-controlled sacrificial pile, the flow channel of the opening is a non-uniform cross-section flow channel, used to accelerate the straight-through water flow through the opening.

[0009] Furthermore, a passive flow-control type sacrificial pile is provided, wherein the number of holes in the sacrificial pile is more than two, in order to adapt to water level fluctuations during the wet and dry seasons.

[0010] A modular sacrificial pile, wherein the modular sacrificial pile is composed of at least one fixed section and at least one pile body section connected in a modular combination by a reusable mechanical fastening connection structure.

[0011] A composite flow-controlled sacrificial pile, wherein the pile body is a columnar structure and has at least one opening aligned with the direction of water flow. The opening contains an active thrust assembly that enhances the velocity and directionality of the water flow through the pile.

[0012] Furthermore, in a composite flow-controlled sacrificial pile, the active thrust assembly is a shaftless pump thruster, the thrust direction of which is consistent with the direction of water flow through the opening; the conduit shell of the shaftless pump thruster is fixedly connected to the inner wall of the opening.

[0013] A method for locating a group of sacrificial piles involves first determining the size of the sacrificial piles in the group based on hydrological conditions.

[0014] Further, determine the pile location layout based on the sacrificial pile functional area, and confirm the sacrificial pile installation position on the positioning bearing reference component on land according to the installation layout. Based on the confirmed installation position, construct a connector or sacrificial pile that is compatible with the sacrificial pile fixing section on the positioning bearing reference component. Sink the prefabricated positioning bearing reference component to the predetermined position on the riverbed in front of the bridge pier.

[0015] The beneficial effects of this application are: The sacrificial pile group forms a three-level functional zone upstream of the bridge pier: a guiding zone, a backflow reflection zone, and a kinetic energy dissipation zone. Through diversion and bypassing, backflow counter-impact, and turbulent collision, the kinetic energy of the water flow is dissipated step by step, which greatly reduces the effective impact energy flowing towards the bridge pier, suppresses the formation and superposition of horseshoe vortices, downflow, and complex turbulence, and significantly reduces the scouring and abrasion damage to the bridge pier foundation and the riprap around the pier.

[0016] Setting through-holes in the water level fluctuation zone of the sacrificial pile can induce some water flow to pass through the pile, thereby suppressing the downflow and horseshoe vortex generation in front of the pile from the source, eliminating the superposition effect of turbulence, reducing the complexity of turbulence at the pile tail, and avoiding concentrated scouring of the riverbed and bridge piers by local strong turbulence.

[0017] By integrating shaftless pump thrusters and other active thrust components within the opening, a combined active and passive control structure is formed. The drive power can be dynamically adjusted according to real-time flow velocity and flow rate, solving the problem of the pure passive flow control effect being greatly reduced with hydrological fluctuations. It can maintain the optimal energy dissipation and protection effect under conditions of high and low flow velocities and large water level changes.

[0018] The sacrificial pile adopts a standardized modular design with fixed sections, pile body sections, perforated sections, and pile top sections, which can be freely assembled to suit rivers with different water depths and varying water levels, greatly improving the versatility of the structure; it adopts detachable connections such as threads, flanges, and tenon and mortise locking pins, which facilitates later maintenance, replacement and upgrades, reducing the total life cycle project cost. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of this application; Figure 2 This is a schematic diagram of the opening section in this application; Figure 3 This is a schematic diagram of the shaftless pump pusher device used in this application; Figure 4 Schematic diagram of the structural reference member for positioning the sacrificial pile group; Figure 5 Cross-sectional view of the connection part for positioning the bearing reference component; Figure 6 A schematic diagram illustrating the principle of water erosion around bridge piers; Figure 7 A comparison chart of scour depth; Figure descriptions: 1. Guide zone; 2. Return flow reflection zone; 3. Opening; 4. Positioning bearing reference element; 5. Threaded pile; 6. Flange connection seat; 7. Conduit shell; 8. Stator; 9. Rotor; 10. Hydrodynamic bearing; 11. Blade. Detailed Implementation Example 1

[0020] To address the problems mentioned in the background art, this embodiment provides a sacrificial pile group protection structure that utilizes active protection and passive flow control of sacrificial pile groups to resist scour and abrasion of bridge pier foundations.

[0021] The sacrificial piles consist of multiple piles arranged according to functional zones on the upstream side of the pier, i.e., upstream of the pier. The minimum effective distance between the sacrificial piles and the pier is typically 1.5–4.5 times the diameter of the pier. Those skilled in the art can freely adjust this distance based on hydrological conditions and the pier structure.

[0022] According to the passive flow control method disclosed in this application, the functional areas of the sacrificial pile group are mainly divided into a guiding area 1, a return flow reflection area 2, and a kinetic energy dissipation area formed between the two functional areas through their synergistic effect.

[0023] like Figure 1 As shown, the guiding zone 1 is composed of at least a single sacrificial pile, which is located on the side of the sacrificial pile group away from the pier. Its main function is to block the water flow and passively separate the water flow on both sides of the sacrificial pile to form a flow around it. Under the action of the streamline compression zone at the tail of the sacrificial pile in this functional zone, the separated water flow is introduced into the return reflection zone 2.

[0024] As shown in Figure 1, the backflow reflection zone 2 is formed by a number of sacrificial piles and is located between the bridge pier and the guide zone 1. The sacrificial piles of the backflow reflection zone 2 are arranged in at least one of the following curved shapes: parabola, elliptic curve, catenary, hyperbola, or any pile group arrangement that can reflect the diverted water flow of the guide zone 1 back to the guide zone 1, so that the water flow is reflected and a backflow is formed.

[0025] The wake generated by the guide zone 1 collides with the return flow reflected back to the guide zone 1 by the return flow reflection zone 2, and the two functional zones collide to dissipate the kinetic energy flowing toward the bridge pier, forming a kinetic energy dissipation area.

[0026] To reduce the turbulent characteristics of water flow that directly impacts the bridge piers, suppress the formation and superposition of complex flow patterns, and generate a safe wake zone of sufficient range, so as to prevent complex turbulent flow from scouring and wearing the bridge piers and damaging the riprap around the piers.

[0027] Furthermore, the sacrificial pile group in the guide area 1 can be composed of several sacrificial piles arranged in a triangular shape.

[0028] As shown in Figure 7, to compare the improvement effect of this embodiment with that of unprotected and traditional sacrificial piles in terms of scour depth, the applicant conducted an experiment to verify the following: The test tank was 16.7 m long, 0.8 m wide, and 0.8 m deep, with a maximum flow rate of 0.1 m³ / s and a maximum wave height of 0.2 m; the fluid velocity was measured using a Doppler point velocity meter with a measurement accuracy of ±1 mm / s. Both the model pier and the sacrificial pile were made of acrylic glass, with the pier model having a diameter of 0.1 m and a height of 0.8 m, and the sacrificial pile model having a diameter of 0.05 m and a height of 0.8 m. The model sand used was standard sand with a median particle size of d50 = 0.15 mm, a saturated density of 2.0 g / cm³, and a dry density of 1.6 g / cm³. The experiment was conducted under constant flow conditions with a water depth of 0.2 m, a sand depth of 0.2 m, and a flow velocity of 0.3 m / s. The three working conditions correspond to "unprotected," "traditional sacrificial pile," and "this application," respectively, and the experimental results are shown in Figure 7.

[0029] As shown in Figure 7, under the unprotected condition, the maximum local scour depth of the bridge pier foundation is 5.2 cm; under the traditional sacrificial pile condition, the maximum local scour depth is 2.1 cm; and under the condition described in this application, the maximum local scour depth is only 1.2 cm. This demonstrates that the sacrificial pile group protection structure of this application achieves highly efficient protection of the bridge foundation. Example 2

[0030] A sacrificial pile used in Embodiment 1 is described as cylindrical (circular cross-section). In practical applications, the cross-sectional shape of the sacrificial pile is not limited to a circle; it can also be replaced by an ellipse, square, polygonal, teardrop-shaped (wing-shaped), or a combination of a circular arc on the water-facing side and a flat surface on the water-repellent side. As long as the pile structure can effectively block water flow, guide the flow pattern, and induce backflow, it falls within the protection scope of this invention. Example 3

[0031] This embodiment is an improvement on the sacrificial pile structure in Embodiment 1. For example... Figure 6 As shown, when the water flow comes into contact with the sacrificial pile, a downflow and a horseshoe vortex will be formed on its upstream side. The turbulent characteristics of these two types of water flow will be superimposed in the wake region of the sacrificial pile, which will aggravate the complexity of the tail turbulence and thus affect the protection effect.

[0032] To avoid the above problems, such as Figure 1 and 2 As shown in this embodiment, a through hole is opened in the water level fluctuation area of ​​the sacrificial pile. Through this through hole 3, part of the water flow that would have formed a downflow is induced to pass directly through the pile, thereby suppressing the generation of downflow from the source, thus eliminating the turbulent superposition effect of downflow and horseshoe vortex, and reducing the complexity of tail turbulence.

[0033] Applying the perforated sacrificial pile of this embodiment to the sacrificial pile group in the backflow reflection zone 2 of Embodiment 1 reduces the complexity of turbulence at the tail of the pile. Example 4

[0034] Based on the technical solution of Embodiment 1, the dissipation zone is formed by the synergistic effect of the water flow regulated by the guiding zone 1 and the return flow reflection zone 2, and its water flow velocity directly determines the hydrodynamic dissipation effect. Based on this technical feature, this embodiment applies the sacrificial pile with opening 3 described in Embodiment 3 to the guiding zone 1. While reducing the downflow on the upstream side of the pile, the incoming flow from the guiding pile passes through the opening 3, dividing the sacrificial pile wake into two parts: the through-pile flow and the bypass flow. This allows the wake of the guiding zone 1 to converge with the return flow at a higher velocity in the dissipation zone, thereby improving the energy dissipation efficiency of the kinetic energy dissipation zone.

[0035] Furthermore, to further increase the velocity of the water flowing through opening 3, the sacrificial pile's opening 3 channel is a non-uniform cross-section flow channel with equal diameters at both ends and a gradually narrowing configuration that converges inward in the middle. The diameter of the opening on the water-facing side is consistent with that on the back water-facing side, and a contracting cross-section is formed in the middle section of the channel. According to the fluid continuity equation and the Venturi effect, when water flows through this contracting channel, the flow cross-sectional area decreases, and the water flow velocity is actively increased, achieving a water flow acceleration effect.

[0036] or The sacrificial pile with opening 3 is applied to the guide zone 1. The flow channel of the sacrificial pile with opening 3 adopts a non-uniform cross-section flow channel with a gradually narrowing structure, which has a large diameter on the upstream side and a small diameter on the downstream side. The flow channel continuously narrows inward along the direction of water flow. According to the fluid continuity equation and the Venturi effect, the cross-section of the water flow continuously decreases as the water flows through this gradually narrowing flow channel, and the water flow is forcibly accelerated. This structure reduces the downflow and horseshoe vortex on the upstream side of the pile, while the laminar flow in front of the guide pile accelerates through the opening 3, dividing the wake of the sacrificial pile into high-speed penetrating water flow and conventional bypass flow. This allows the wake of the guide zone 1 to meet and collide with the backflow in the dissipation zone at a higher velocity, strengthening the momentum exchange intensity between water flows and significantly improving the hydrodynamic dissipation efficiency. Example 5

[0037] This embodiment is a further improvement on the aforementioned sacrificial pile embodiment with opening 3. Fixed spiral blades are set in the straight-through opening 3 or the tapered non-uniform cross-section flow channel of the sacrificial pile. The fixed spiral blades are evenly distributed along the circumference of the inner wall of the opening 3. The blades are spiral in shape and fixedly connected to the inner wall of the opening 3. The blades extend toward the center of the opening 3.

[0038] Preferably, there are at least three fixed helical blades.

[0039] After entering the flow channel through the large-diameter inlet on the upstream side of the sacrificial pile, the water first undergoes initial acceleration within the narrowing culvert. Subsequently, as it flows through the fixed helical blades, the blades guide and rectify the water flow, converting the circumferential rotational component into an axial flow component. Simultaneously, the flow pattern is further regulated, eddies and pulsations are eliminated, preventing turbulent interference within the opening 3. Through the synergistic effect of the narrowing flow channel and the fixed helical blades, the water exiting the small opening on the downstream side forms a high-speed, stable, and straight axial jet. This reduces the downflow and horseshoe vortex in front of the pile while significantly improving the directionality and velocity uniformity of the water flow through the pile. This makes the high-speed laminar component in the wake more stable and the velocity difference more significant, leading to a more intense momentum exchange with the backflow in the dissipation zone. This further improves the hydrodynamic dissipation efficiency and enhances the synergistic protection against scour and erosion of the bridge pier foundation. Example 6

[0040] In the above embodiments, the sacrificial piles or pile groups all employ passive flow control methods such as passive guidance, passive diversion, passive acceleration, passive reflection, and passive dissipation, which constitute a fully passive flow control scheme. The flow control effect of this fully passive scheme depends entirely on hydrological conditions, including water flow velocity. When hydrological conditions fluctuate (such as excessively high or low flow velocity), its flow control energy dissipation effect will weaken accordingly, making it difficult to adapt to complex and ever-changing river hydrological conditions.

[0041] Therefore, based on the aforementioned embodiments, this embodiment proposes a sacrificial pile with an active-passive composite flow control structure. Through the synergistic effect of the active flow control component and the passive flow control structure, it solves the problems of poor adaptability and unstable effect of the all-passive scheme, and further improves the flow control energy dissipation efficiency and the reliability of pier protection.

[0042] In this embodiment, the sacrificial pile has an active thrust assembly arranged axially along the opening 3 within the opening 3 of the sacrificial pile described in the previous embodiment. The active thrust assembly can be an electric propeller or a shaftless pump-jet propulsion device. To clearly illustrate the technical solution, this embodiment uses a shaftless pump-jet propulsion device as the active thrust assembly for detailed explanation, as shaftless pump-jet propulsion devices are typically designed for underwater operation and possess inherent waterproofing capabilities. Methods such as using epoxy resin or other waterproof sealing designs around the stator 8 coils are common waterproofing techniques for underwater drive devices and are existing technologies, not involving any of the technical improvements described in this application. Therefore, this application will not elaborate further on these methods.

[0043] The shaftless pump thruster is installed inside the opening 3 of the sacrificial pile. Its thrust direction is consistent with the direction of water flow through the opening 3, ensuring that the active drive and passive flow guidance directions work in tandem and avoiding flow turbulence caused by directional conflict. The conduit shell 7 of the shaftless pump thruster is fixedly connected to the inner wall of the opening 3. The fixing method can be adhesive connection, fastener connection, or interference fit or tight fit embedding connection to ensure a firm connection, reliable sealing, and suitability for underwater working environment.

[0044] like Figure 3 As shown, a stator 8 for driving the rotor 9 is fixedly installed on the inner edge of the conduit housing 7. Two end faces of the stator 8 inside the conduit housing 7 are also provided with dynamic pressure bearings 10 to support the rotor 9, ensuring that the rotor 9 can rotate smoothly at high speed within the electromagnetic field ring formed by the stator 8, reducing frictional losses during rotor rotation, and improving the operational stability and service life of the device. The rotor 9 has a ring structure, with at least two helical blades 11 extending towards the center of the rotor 9 on its inner wall. The helical blades 11 are fixed at equal intervals on the inner edge of the rotor 9, and the arrangement angle of the blades 11 is adapted to the water flow direction to maximize the water flow driving efficiency.

[0045] The stator 8 is wound with enameled wire to generate an electromagnetic field. The lead-out end of the enameled wire is connected to a waterproof cable through an insulated connection. The waterproof cable provides power to the stator 8, thereby driving the rotor 9 to rotate. The insulated connection is preferably sealed with adhesive to ensure that the connection between the lead-out end and the waterproof cable is insulated and waterproof, preventing short circuits caused by underwater immersion and ensuring the stable operation of the shaftless pump pusher.

[0046] Furthermore, to achieve energy self-sufficiency and reduce dependence on external power supply, solar panels can be installed on the top of the sacrificial pile. The solar panels are electrically connected to waterproof cables through energy storage modules to convert solar energy into electrical energy and store it, providing the power to drive the rotor 9 of the shaftless pump pusher. This is suitable for application scenarios in remote river channels where there is no external power supply, thus improving the practicality and applicability of the device.

[0047] The sacrificial pile of the active-passive composite flow control structure described in this embodiment achieves its technical effect based on the following technical means: First, the opening 3 of the sacrificial pile adopts the straight-through or tapered structure of the aforementioned embodiment, which can realize the passive guidance and passive acceleration of the water flow. Through flow channel convergence, the water flow is initially accelerated and its flow pattern is regulated, laying the foundation for active drive and continuing the advantages of the all-passive scheme in terms of simple structure and high durability. Second, the shaftless pump thrust device installed in the opening 3 serves as an active thrust component. Its thrust direction is consistent with the water flow direction. Based on passive acceleration, the stator 8 drives the rotor 9 and helical blades to rotate at high speed, applying active thrust to the water flow, further... First, the pressure energy of the water flow is converted into kinetic energy, significantly improving the velocity and directionality of the water flow through the pile. Second, the dynamic pressure bearing 10 ensures the smooth rotation of the rotor 9, reducing water flow disturbance. Combined with the equidistant arrangement of the spiral blades, it can effectively eliminate the swirling and turbulent flow in the opening 3, making the water flow through the pile form a high-speed, stable axial jet. Finally, the dual power supply mode of the solar panel and the external waterproof cable ensures that the shaftless pump thruster can be stably powered under different working conditions. The rotor speed can be dynamically adjusted according to real-time hydrological conditions (such as changes in water flow velocity and flow rate), thereby adjusting the magnitude of the active thrust, so that the flow control effect is always in the optimal state. Example 7

[0048] This embodiment improves upon the aforementioned sacrificial pile with three openings. To address the issue of flow control failure of a single opening with three openings due to significant fluctuations in water level during the high and low water periods of the river, a sacrificial pile structure with multiple openings with three openings and multiple gradients is proposed to achieve stable flow control and energy dissipation throughout the entire water level cycle, thereby enhancing the adaptability of the bridge pier protection under various working conditions.

[0049] like Figure 1 As shown in the illustration, the sacrificial pile in this embodiment has two or more through-holes 3 along its height. The layout of the through-holes 3 completely covers the entire water level fluctuation area between the highest water level (high water level during the wet season) and the lowest water level (low water level during the dry season), ensuring that there are through-holes 3 at corresponding heights in an effective flow-through state regardless of whether the water level is high during the wet season or low during the dry season. This prevents a single through-hole 3 from becoming ineffective due to water level fluctuations causing it to detach from the water flow. The shape of the through-hole 3 is not limited to the circular hole shown in this embodiment; it can be flexibly replaced according to actual flow control needs, including but not limited to: elongated slits, elliptical holes, rhomboid holes, irregular polygonal holes, etc. Different through-hole 3 forms can adapt to different flow control needs: for example, elongated slits can achieve continuous flow guidance along the pile height, elliptical holes can improve the flow rate in a specific direction, and rhomboid holes can enhance the effect of suppressing flow diversion and turbulence.

[0050] Furthermore, the shape of the energy dissipation opening 3 in the water level fluctuation zone is not limited to the circular opening shown in this embodiment. It can be flexibly replaced according to actual flow control needs, including but not limited to: elongated slits, elliptical openings, rhomboid openings, irregular polygonal openings, etc. Different opening forms 3 can adapt to different flow control needs: for example, elongated slits can achieve continuous flow guidance along the pile height, elliptical openings can improve the flow rate in a specific direction, and rhomboid openings can enhance the effect of suppressing flow diversion turbulence.

[0051] To accommodate the water flow velocity distribution characteristics along the pile height, the aperture size and distribution density of the opening 3 in this embodiment can vary gradually along the pile height. Typical designs include two types: 1. Top-dense and bottom-sparse: The water flow velocity is high and the scouring force is strong in the lower part of the pile (near the riverbed), so small-diameter, high-density openings are used to enhance the diversion and eddy suppression effect; the water flow velocity is relatively low in the upper part of the pile (high water level area), so large-diameter, low-density openings are used to reduce the loss of pile structural strength while ensuring the diversion effect.

[0052] 2. Dense at the top and sparse at the bottom: For working conditions with frequent water level fluctuations and severe turbulence in the upper part of the water flow, a three-row arrangement of openings with high density at the top and low density at the bottom is adopted to prioritize the suppression of horseshoe vortices and downflow in the high water level area, which is suitable for the protection needs of strong flow during the high water season.

[0053] During the high-water season, the upper opening 3 of the pile is in the water flow. Through the diversion and guidance effect of the opening 3, the downward flow in front of the pile and the formation of horseshoe vortices are suppressed. At the same time, the incoming flow is guided through the pile, and the wake is separated into laminar flow and around flow, thus achieving flow control and energy dissipation. During the low-water season, the lower opening 3 of the pile receives the water flow, continuing the flow control effects of diversion, vortex suppression, and acceleration, ensuring that the sacrificial pile is always in an effective working state throughout the entire water level cycle. At the same time, the gradient hole diameter and density design can be specifically matched to the water flow velocity at different pile height positions, maximizing flow control efficiency and avoiding structural waste caused by ineffective openings 3.

[0054] The sacrificial pile can be set in the guide zone 1 or the backflow reflection zone 2 of the sacrificial pile group described in this application, as needed. Example 8

[0055] Based on the aforementioned multi-gradient perforated sacrificial pile, this embodiment proposes a modular and combinable sacrificial pile structure to meet the differentiated needs of different river hydrological depths and water level fluctuation ranges. Through the flexible assembly of functional segments, the sacrificial pile structure can be precisely adapted to hydrological conditions, thereby improving the versatility and economy of engineering applications.

[0056] In this embodiment, the sacrificial pile is divided into four independent functional segments along the pile height. Each segment adopts a standardized interface design and can be freely combined and assembled according to the actual hydrological depth and water level fluctuation range. Fixed section (pile bottom section): Located at the lowest end of the sacrificial pile, it is used for anchoring to the riverbed foundation and providing stable support for the entire pile. The internal structure of the section is solid, and the riverbed fixing scheme is selected according to the riverbed structure.

[0057] Pile body section (standard section): A solid standard section without openings, used to adjust the overall pile length of the sacrificial pile to adapt to the hydrological depth requirements of different river channels. The section uses the same material as the fixed section to ensure the overall structural strength of the pile. Multiple pile body sections can be connected in series according to depth requirements to flexibly adjust the total pile height.

[0058] Perforated section (functional section): This is the core flow control functional section. The section has through-holes 3. The form, diameter, and distribution density of the perforations can follow any of the perforation 3 technical solutions described in the previous embodiments, covering the entire water level fluctuation area from the wet season to the dry season, and realizing the passive flow control functions of diversion, eddy suppression, acceleration, and energy dissipation. One or more perforated sections can be selected in series according to the water level fluctuation range to accurately match the water level line of the target protection area. Alternatively, the number of perforated sections can be fixed to accommodate the water level fluctuation range.

[0059] Top section (capping section): Located at the top of the sacrificial pile, it is used for structural capping of the top of the pile. It can be integrated with additional devices such as solar panels, sensors, shaftless pump power supply modules, etc., as needed. It is also compatible with extended functions such as active flow control and status monitoring, while optimizing the flow characteristics around the pile top and reducing the formation of top eddies.

[0060] In some cases, the combined sacrificial pile described in this embodiment is modularly assembled using either "1 fixed section + several pile body sections + several perforated sections + 1 pile top section" or "1 fixed section + several pile body sections". The connection method for each functional segment can be the following reusable mechanical fastening connection structure to ensure connection reliability under underwater conditions: 1. Threaded connection (preferred solution): The upper and lower end faces of each segment are equipped with standardized internal / external thread interfaces. The threads are trapezoidal or sawtooth threads, which have high self-locking performance and impact resistance. During assembly, the rigid connection between segments is achieved by screwing them together. At the same time, underwater special sealant is applied to the thread contact surface to prevent water from seeping in and causing corrosion.

[0061] 2. Flange fastening connection: Each segment end face is equipped with an integrated flange, and bolt holes are evenly distributed along the circumference of the flange. High-strength stainless steel bolts and nuts are used to achieve fastening connection between segments. A waterproof sealing gasket is set on the flange contact surface to improve sealing performance. It is suitable for large-diameter, high-load sacrificial pile structures.

[0062] 3. Mortise and tenon + locking pin connection: The end face of the segment is equipped with a tenon and mortise structure. During assembly, the segment is positioned by the mortise and tenon, and then a transverse locking pin is inserted to lock it. The connection structure is simple and easy to disassemble and assemble, and is suitable for the rapid construction and later maintenance and replacement of small and medium-sized sacrificial piles.

[0063] In terms of adaptability to hydrological conditions, this embodiment uses the following methods for rivers with deep water levels and large water level fluctuations: 1 fixed section + multiple pile sections (adapting to the total depth) + multiple perforated sections (covering the entire water level fluctuation zone), achieving full-depth flow control protection through the series connection of multiple perforated sections; for rivers with shallow water levels and small water level fluctuations: 1 fixed section + a small number of pile sections + 1 perforated section (precisely covering the water level line), reducing redundant structures and lowering engineering costs; for rivers with dynamically changing hydrological conditions: the pile length and perforation range can be flexibly adjusted by increasing or decreasing the number of pile sections and perforated sections, without the need to recast the entire pile, adapting to changes in working conditions after river regulation and water level control.

[0064] Based on the aspect of extended function adaptation, this embodiment can seamlessly connect with the aforementioned active flow control scheme: a shaftless pump pusher device is integrated in the opening 3 of the perforated section, and active drive is achieved through the power supply module of the pile top section, forming a modular active-passive composite flow control sacrificial pile; at the same time, the perforated section can be replaced individually, which facilitates the maintenance and upgrading of the shaftless pump pusher device in the later stage, and significantly reduces the operation and maintenance costs; and by selecting different pile top sections, additional devices such as solar panels, sensors, and shaftless pump pusher power supply modules can be integrated according to needs to adapt to extended functions such as active flow control and status monitoring.

[0065] In this embodiment, the hydrological adaptability is extremely strong. Through the flexible combination of functional segments, it can accurately match the hydrological depth and water level fluctuation range of different rivers, solving the problem that traditional integrated sacrificial piles cannot adapt to multiple working conditions, and significantly improving versatility. Example 9

[0066] The sacrificial pile group described in this application achieves precise flow regulation through the coordinated operation of multiple functional areas such as the guiding zone 1 and the return flow reflection zone 2. The relative positional relationship of each functional area (the pile group in the guiding zone 1 and the pile group in the return flow reflection zone 2) directly determines the synergistic effect of water flow guidance, reflection, and dissipation, placing high demands on the positioning accuracy of the pile group. If the positioning deviation of the pile group in each functional area is too large, it will lead to the deviation of the water flow guidance direction and abnormal return flow reflection angle, significantly weakening the flow control and energy dissipation efficiency and failing to achieve effective protection for the bridge pier foundation. Therefore, this embodiment provides a high-precision positioning construction method and corresponding structure for the sacrificial pile group to ensure that the relative position of the pile group in each functional area meets the design requirements and guarantees the overall flow regulation and protection effectiveness of the pile group.

[0067] The sacrificial pile group construction method described in this embodiment is based on "precise positioning via land prefabrication, overall underwater immersion and fixation, and modular assembly". Relying on prefabricated slabs or caissons as positioning benchmarks, it achieves synchronous and precise positioning of the pile groups in the guidance zone 1 and the backflow reflection zone 2. The specific construction steps and structure are as follows: Overall positioning structure and design of sacrificial pile group The sacrificial pile group described in this embodiment includes a pile group in the guiding zone 1 and a pile group in the backflow reflection zone 2. These two types of pile groups are arranged at preset intervals and angles on the upstream side of the bridge pier, forming a coordinated flow regulation system. To ensure the relative positional accuracy of the two types of pile groups, a structural form of "positioning bearing reference component + modular pile body" is adopted. The positioning bearing reference component 4 is made of reinforced concrete precast slab or steel structure caisson, serving as a unified positioning foundation for the pile groups in the guiding zone 1 and backflow reflection zone 2, avoiding deviations caused by individual positioning of pile groups in each area.

[0068] Fixed connectors are pre-installed on the positioning bearing reference component 4. The distribution and spacing of the connectors are strictly determined according to the design layout parameters of the pile group of the guide zone 1 and the return flow reflection zone 2. This ensures that after the pile group of the guide zone 1 and the pile group of the return flow reflection zone 2 are installed, their relative positions, spacing and angles meet the flow control design requirements, ensuring that the water flow can accurately enter the return flow reflection zone 2 after being guided by the guide zone 1 to achieve reflection and energy dissipation.

[0069] Land prefabrication and fixed connection arrangement In the early stages of construction, the positioning and bearing reference component 4 (precast slab or caisson) was prefabricated at the land prefabrication yard, and the precise arrangement of the fixing connectors was completed at the same time. The specific steps are as follows: 1. Precast positioning and bearing reference components 4: Based on the hydrological conditions of the construction area, riverbed geology, and pile group design dimensions, precast reinforced concrete slabs or steel structure caissons. The precast slabs can be made of cast reinforced concrete to ensure sufficient load-bearing capacity and erosion resistance; the caissons are made of corrosion-resistant steel structure welded together, and internal compartments can be installed to facilitate attitude control during floating and sinking.

[0070] 2. Arrangement of Fixed Connectors: Based on the pile layout drawings of the pile groups in the guiding zone 1 and the return flow reflection zone 2, fixed connectors are precisely pre-embedded or fixedly installed on the top surface of the precast slab or the top surface inside the caisson. The fixed connectors are threaded piles 5 or flange connecting seats 6 that are compatible with the threaded holes at the bottom of the sacrificial pile fixing section. Their placement is precisely determined using laser projection, a total station, or other planar positioning and marking methods to ensure that the relative positions of each connector are completely consistent with the pile group design parameters.

[0071] Alternatively, sacrificial piles can be directly fixed on the positioning bearing reference component 4 to form a pre-set pile group structure.

[0072] 3. Fixing and protection of connectors: The fixing connectors are cast in one piece with the precast slab / caisson (precast slab) or welded (caisson). Furthermore, the connection end faces of the connectors can be waterproofed and corrosion-proofed by applying underwater special sealant and anti-corrosion coating to prevent underwater water immersion and silt erosion from causing connector failure.

[0073] Underwater placement and positioning of the positioning bearing reference component 4 Based on the water depth, flow velocity, and riverbed topography of the construction area, either the precast slab sinking method or the caisson floating and sinking method will be selected to accurately sink the precast positioning and bearing reference component 4 to the predetermined position on the riverbed in front of the bridge pier. Specifically, there are two schemes: Option 1: Precast slab sinking method 1. Precast slab transportation and positioning: The precast slabs prefabricated on land are transported to the construction water area by flatbed transport ships. A crane and a total station positioning system are used to slowly lower the precast slabs to the design elevation position of the riverbed in front of the bridge piers. During the lowering process, the posture of the precast slabs is adjusted in real time to ensure that their levelness meets the requirements.

[0074] 2. Riverbed foundation treatment: If the riverbed contains silt or loose sand, the sinking area must be dredged and compacted first, or a cushion layer (such as a crushed stone cushion layer) must be laid to prevent the precast slabs from sinking or shifting; if the riverbed is a hard rock layer, anti-slip protrusions can be set at the bottom of the precast slabs to enhance their anti-slip ability.

[0075] 3. Fixing the reference component: After the precast slab is in place, several guide piles are driven into its perimeter. The guide piles penetrate into the riverbed rock layer by no less than 1.5m. The guide piles are fixed to the precast slab through connectors to further improve the anti-overturning and anti-sliding performance of the precast slab and ensure its stability as a positioning reference.

[0076] Option 2: Caisson floating and sinking method 1. Caisson floating and positioning: The steel structure caisson is floated to the predetermined position above the riverbed in front of the bridge pier by tugboats. During the floating process, the attitude of the caisson is controlled by the anchoring system to avoid displacement due to water flow impact.

[0077] 2. Caisson sinking and positioning: Water is slowly injected into the compartments inside the caisson, and the caisson is gradually sunk by the gravity of the water. During the sinking process, the position and level of the caisson are monitored in real time. The water volume of each compartment is adjusted to ensure that the caisson sinks smoothly until the bottom plate of the caisson is in line with the designed position of the riverbed.

[0078] 3. Caisson stabilization treatment: After the caisson is in place, plain concrete or gravel is filled inside to enhance the overall weight and stability of the caisson; at the same time, the gap between the caisson and the riverbed is sealed to prevent the water flow from eroding the riverbed and causing the caisson to shift, thus forming a stable pile group positioning platform.

[0079] Modular installation of sacrificial pile groups After the positioning and bearing reference component 4 is securely in place, the installation of the sacrificial pile group in the guide zone 1 and the return flow reflection zone 2 is completed according to the steps of "fixed section connection - segment assembly - pile group formation", as follows: 1. Fixed Section Connection: The fixed section of the sacrificial pile (using the same fixed section structure as the aforementioned modular combined sacrificial pile) is securely connected to the pre-set connector on the positioning bearing reference component 4 via a threaded connection. The threaded connection uses a trapezoidal thread. After screwing in, underwater special sealant is applied to ensure a firm and waterproof seal. At the same time, the verticality of the fixed section is calibrated using a total station or other planar positioning and marking instruments.

[0080] 2. Pile segment assembly: Based on the designed pile length and hydrological conditions, the pile body segment, the perforated segment (the perforated segment with multi-gradient opening 3 is selected for the pile group in the guide zone 1, and the perforated segment with the appropriate reflection function is selected for the pile group in the backflow reflection zone 2) and the pile top segment are connected in sequence above the fixed segment. Each segment is fastened with threads or flanges. During the assembly process, the verticality and relative position of the pile body are calibrated in real time to ensure that the spacing and angle of the pile groups in the guide zone 1 and backflow reflection zone 2 meet the design requirements.

[0081] The sacrificial pile group construction method and structure in this embodiment, addressing the high positioning accuracy requirements of the coordinated flow regulation of the guide zone 1 and the return flow reflection zone 2, achieves the following beneficial effects through the core concept of "precise positioning via land prefabrication and overall underwater immersion and fixation": 1. Positioning accuracy meets standards: The arrangement of fixed connectors is transferred to the land prefabrication stage to avoid positioning deviations caused by the complex underwater environment. This ensures that the relative positions, spacing, and angles of the pile groups in the guidance zone 1 and the return flow reflection zone 2 meet the design requirements, guaranteeing the synergistic effect of water flow guidance, reflection, and dissipation. This solves the problems of large positioning deviations and poor flow regulation effects of pile groups in traditional construction.

[0082] 2. Improved construction efficiency: The positioning and bearing reference component 4 and the fixed connecting component adopt land prefabrication and modular operation, which greatly reduces the underwater operation time and construction difficulty, and reduces construction costs; the two sinking schemes of prefabricated slabs and caissons can be adapted to different hydrological and geological conditions, and have strong versatility.

[0083] 3. Strong structural stability: Using precast slabs or caissons as a unified positioning benchmark, it provides rigid support for the sacrificial pile group, effectively resisting the impact and displacement of high-velocity water flow, ensuring that the pile group can maintain stable positioning under different hydrological conditions such as high water season and low water season, and continuously play its role in flow regulation and protection.

[0084] 4. Convenient operation and maintenance: The modular pile body and detachable connection methods such as threads and flanges facilitate the inspection and replacement of individual piles and sections in the later stage; the integrity of the positioning reference components facilitates the monitoring and adjustment of the positioning accuracy of the pile group in the later stage, reducing the operation and maintenance cost throughout the entire life cycle. Example 10

[0085] The materials used for sacrificial piles described in this application are not limited to reinforced concrete or steel pipe piles; steel-concrete composite structures, polymer composite materials (such as fiberglass reinforced plastic (FRP) pipes), prestressed concrete pipe piles (PHC), or corrosion-resistant alloy materials may also be used. Furthermore, the pile surface may be coated with an anti-abrasion coating (such as polyurea or epoxy resin mortar) to further enhance its anti-abrasion capabilities.

Claims

1. A group of sacrificial piles, wherein the group of sacrificial piles consists of a plurality of sacrificial piles disposed on the water-facing side of a bridge pier, characterized in that: The sacrificial pile group includes at least two functional zones composed of sacrificial piles: a guiding zone and a backflow reflection zone. The sacrificial pile group on the side away from the pier is the guiding zone, and the one adjacent to the pier is the backflow reflection zone. The guiding zone guides the water flow to the backflow reflection zone, and the backflow reflection zone reflects the water flow to the guiding zone, forming a kinetic energy dissipation zone between the guiding zone and the backflow reflection zone to reduce the kinetic energy of the water flow.

2. The sacrificial pile group as described in claim 1, characterized in that: The sacrificial pile group in the guidance area can be composed of several sacrificial piles arranged in a triangular shape.

3. The sacrificial pile group as described in claim 1, characterized in that: The sacrificial pile group in the backflow reflection zone is arranged in any one of the following curve types: parabola, elliptic curve, catenary, or hyperbola.

4. A passive flow-control type sacrificial pile used in claim 1, 2 or 3, wherein the sacrificial pile body is a columnar structure, characterized in that: The sacrificial pile has an opening aligned with the direction of water flow, which divides the incoming flow through the sacrificial pile into two wing-shaped flows and a straight flow through the opening, thereby suppressing the generation of downflow in front of the pile and eliminating the superposition effect of turbulence between downflow and horseshoe vortex.

5. The passive flow-controlled sacrificial pile as described in claim 4, characterized in that: The flow channel of the opening is a non-uniform cross-section flow channel, which is used to accelerate the straight flow of water through the opening.

6. The passive flow-controlled sacrificial pile as described in claim 4, characterized in that: The number of holes in the sacrificial piles is more than two, in order to adapt to water level fluctuations during the wet and dry seasons.

7. A modular sacrificial pile used in claim 1, 2 or 3, wherein the modular sacrificial pile is composed of at least one fixed section and at least one pile body section combined in a modular manner and connected by a reusable mechanical fastening connection structure.

8. A composite flow-control type sacrificial pile used in claim 1, 2 or 3, wherein the composite flow-control type sacrificial pile body is a cylindrical structure, and the pile body is provided with at least one opening aligned with the water flow direction, characterized in that: The opening is equipped with an active thrust assembly that enhances the flow velocity and directionality of the water flow through the pile.

9. The composite flow-controlled sacrificial pile as described in claim 8, characterized in that: The active thrust assembly uses a shaftless pump thruster, whose thrust direction is consistent with the direction of water flow through the opening; the outer shell of the shaftless pump thruster is fixedly connected to the inner wall of the opening.

10. A method for locating a group of sacrificial piles, firstly determining the dimensions of the sacrificial piles in the group based on hydrological conditions; characterized in that, Further, determine the pile location layout based on the sacrificial pile functional area, and confirm the sacrificial pile installation position on the positioning bearing reference component on land according to the installation layout. Based on the confirmed installation position, construct a connector or sacrificial pile that is compatible with the sacrificial pile fixing section on the positioning bearing reference component. Sink the prefabricated positioning bearing reference component to the predetermined position on the riverbed in front of the bridge pier.

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