An assembled bridge pier scouring prevention device and method

Abstract

This invention discloses a prefabricated anti-scour device and method for bridge piers. The anti-scour device includes a support cylinder, an upper protective component, and a lower protective component. The upper protective component is annular, with its inner circumferential edges fixed to the top of the support cylinder. The lower protective component is divided into a semi-circular truncated cone and a conical portion. The outer side of the semi-circular truncated cone is a partially frustum-shaped surface, smaller at the top and larger at the bottom. The cross-sectional area of ​​the conical portion gradually decreases in the direction away from the semi-circular truncated cone. During operation, the support cylinder, upper protective component, and lower protective component are fitted onto the outer side of the bottom of the bridge pier. The semi-circular truncated cone faces the direction of water flow. The upper protective component blocks the downward jet formed by the water flow impacting the bridge pier. The lower protective component provides protection at the junction of the bridge pier and the riverbed sediment. This invention, by setting up the upper and lower protective components, prevents the downward jet generated by the water flow impacting the bridge pier from directly impacting the junction of the bridge pier and the riverbed. This avoids the jet from impacting and damaging the sand and gravel in the riverbed, thereby affecting the stability of the bridge pier.

Description

Technical Field

[0001] This invention belongs to the technical field of bridge pier anti-scour devices, specifically relating to a prefabricated bridge pier anti-scour device and method. Background Technology

[0002] The safety and stability of bridge pile foundations in complex water flow environments depend not only on the stress conditions within those environments but also on the reduced bearing capacity caused by shallower pile depths due to water scouring. Furthermore, numerous surveys and statistical results indicate that one of the main causes of bridge damage is the reduction in pier depth due to localized scouring of the pier foundation.

[0003] like Figure 1 As shown, constructing pile structures in a flowing water environment significantly alters the flow field around the structure, creating a complex and variable three-dimensional flow regime. Downflow and horseshoe vortices form in front of the piles, while a wake vortex forms behind them. The formation and movement of the horseshoe vortex and wake vortex enhance the transport capacity of materials on the riverbed surface, resulting in significant localized scour pits in the bridge pile foundations. This reduces the effective embedment depth of the bridge pile foundations in the riverbed soil, leading to a decrease in the bearing capacity of the pile foundations and greatly affecting the safety and stability of the bridge. Furthermore, in mountainous cities where the water flow velocity is even greater, the impact of water scour on bridge safety and stability is even more severe. Summary of the Invention

[0004] The purpose of this invention is to provide a prefabricated bridge pier anti-scour device and method.

[0005] In a first aspect, the present invention provides a prefabricated bridge pier anti-scour device, comprising a support cylinder, an upper protective component, and a lower protective component; the upper protective component is annular, and its inner circumferential edge is fixed to the top of the support cylinder; the lower protective component is divided into a semi-circular truncated section and a pointed conical section; the top edges of the semi-circular truncated section and the pointed conical section together form a circular connecting edge; the circular connecting edge is fixed to the bottom edge of the support cylinder; the outer side of the semi-circular truncated section is a partially frustum-shaped surface with a smaller top and a larger bottom; the cross-sectional area of ​​the pointed conical section gradually decreases in the direction away from the semi-circular truncated section; the bridge pier anti-scour device is formed by multiple protective units; adjacent protective units are detachably connected.

[0006] During operation, the support cylinder, upper protective component, and lower protective component are fitted onto the outer side of the bottom of the pier; the semi-circular truncated section faces the direction of water flow; the upper protective component blocks the downward jet formed by the water flow impacting the pier; the lower protective component protects the connection between the pier and the riverbed sediment, inhibiting the formation of horseshoe vortices.

[0007] Preferably, the tip of the cone portion is located in the same plane as the bottom edge of the truncated cone portion.

[0008] Preferably, the semi-circular frustum and the pointed cone of the lower protective member each occupy a 180° central angle range of the lower protective member.

[0009] Preferably, the bottom radius of the semicircular frustum is greater than the top radius; the cone angle of the outer side of the semicircular frustum is 30°-60°.

[0010] Preferably, the height of the support cylinder is 0.6d to 1.2d; where d is the inner diameter of the support cylinder.

[0011] Secondly, this invention provides a prefabricated bridge pier anti-scour device and method, comprising a support cylinder, an upper protective component, and a lower protective component; the upper protective component is annular, with its inner circumferential edges fixed to the top of the support cylinder; the lower protective component is divided into a frustum section and an annular section. The inner ring edge of the annular section is fixed to the outer edge of the bottom of the frustum section; the bottom diameter of the frustum section is larger than the top diameter, and the cone angle of the outer surface of the frustum section is 30°-60°. This bridge pier anti-scour device is formed by multiple protective units; adjacent protective units are detachably connected.

[0012] During operation, the support cylinder, upper protective component, and lower protective component are fitted onto the outer side of the bottom of the pier; the upper protective component blocks the downward jet formed by the water flow impacting the pier; the lower protective component guides the water flow upward along the outer side of the truncated cone section, avoiding direct impact at the connection between the pier and the riverbed.

[0013] Preferably, the inner edge of the top of the upper protective member is consistent with the shape of the top edge of the support cylinder and is welded and fixed; the inner edge of the lower protective member is consistent with the shape of the bottom edge of the support cylinder and is welded and fixed.

[0014] Preferably, the number of protective units is two; the support cylinder is divided into two semi-cylindrical structures; the upper protective component is divided into two upper semi-circular rings; the lower protective component is divided into two semi-circular frustums and two lower semi-circular rings; the adjacent side edges of the two upper semi-circular rings and the adjacent side edges of the two lower semi-circular rings are detachably connected by a fixing component; the fixing component includes a connector; the two ends of the connector are fixed to the two upper semi-circular rings respectively, or the two ends of the connector are fixed to the two lower semi-circular rings respectively.

[0015] Preferably, the fixing component further includes two bolts, and the two ends of the connector are fixed by the two bolts respectively.

[0016] Thirdly, the present invention provides a method for preventing erosion of bridge piers, comprising the following steps:

[0017] Step 1: Assemble the various protective units of the prefabricated pier scour protection device on the top of the pier to be protected, so that the protective units surround the top of the pier.

[0018] Step 2: Release the assembled and fixed protective units so that the anti-scouring device for the bridge pier composed of the protective units sinks to the bottom of the water, providing protection for the bottom of the bridge pier and reducing the scouring loss of silt at the connection between the bridge pier and the riverbed.

[0019] The beneficial effects of this invention are:

[0020] 1. The present invention provides a semi-circular truncated section below the support cylinder. The outer side of the semi-circular truncated section guides the water flow impacting the semi-circular truncated section to flow upward and cancels out the downward jet formed by the support cylinder; thereby reducing the generation of jets towards the riverbed and thus reducing the erosion of the riverbed sand and gravel around the bridge pier.

[0021] 2. The present invention provides a pointed cone on the side of the bridge pier away from the impact of the water flow. The inclined surface of the pointed cone guides the water flow to the tip of the pointed cone, thereby reducing the flow range of the water flow on both sides of the bridge pier when the water flow impacts the bridge pier, thus reducing the erosion of the riverbed on both sides of the bridge pier by the water flow.

[0022] 3. In Embodiment 2 of the present invention, a support cylinder is fitted at the bottom of the pier, and upper and lower protective components are installed at the top and bottom of the support cylinder. The upper and lower semi-circular protective rings block the jet generated when the water flow impacts, thereby preventing the jet from eroding the sand and gravel in the riverbed around the pier and thus affecting the stability of the pier. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the concave structure formed at the connection between the bridge pier and the riverbed under normal conditions due to water erosion.

[0024] Figure 2 This is a schematic diagram of the overall structure of Embodiment 1 of the present invention;

[0025] Figure 3 This is a schematic diagram of water flow scouring after the device is installed on the bridge pier according to Embodiment 1 of the present invention;

[0026] Figure 4 This is a schematic diagram of the overall structure of Embodiment 2 of the present invention;

[0027] Figure 5 This is a schematic diagram of water flow scouring after the device is installed on the bridge pier according to Embodiment 2 of the present invention;

[0028] Figure 6 This is a schematic diagram of the structure for fixing the fixing component and the lower protective component in Embodiment 2 of the present invention;

[0029] Figure 7 This is a comparative schematic diagram showing the riverbed scouring of the bridge piers with and without the device installed, according to various embodiments of the present invention.

[0030] Figure 8 This is a bottom-view diagram comparing riverbed scouring with and without the device installed on the bridge piers according to various embodiments of the present invention.

[0031] Figure 9 This is a comparative schematic diagram showing the scouring of bridge piers with and without the device installed according to various embodiments of the present invention.

[0032] Among them: 1. Fixing component; 1-1. Connecting component; 1-2. Bolt; 2. Protective unit; 2-1. Support cylinder; 2-2. Upper protective component; 2-2-1. Upper semi-circular ring guard; 2-3. Lower protective component; 2-3-1. Semi-circular frustum; 2-3-2. Conical part; 2-3-3. Lower semi-circular ring guard. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings.

[0034] Example 1

[0035] like Figure 2 As shown, a prefabricated bridge pier anti-scour device includes two protective units 2 and multiple fixing components 1; the two protective units 2 surround the outer surface of the bridge pier; the adjacent sides of the two protective units 2 are detachably connected. Each protective unit 2 includes a semi-cylinder, an upper semi-circular ring 2-2-1, a truncated cone portion 2-3-1, and a pointed cone portion 2-3-2. The two semi-cylinders can be closed to form a complete cylindrical support tube 2-1; the two upper semi-circular rings 2-2-1 can be closed to form a complete annular upper protective member 2-2; the truncated cone portion 2-3-1 and the pointed cone portion 2-3-2 can be closed to form a complete lower protective member 2-3.

[0036] The height of the semi-cylinder is twice the radius of the pier. The inner diameter of the semi-cylinder is slightly larger than the diameter of the pier, facilitating the sliding of the two semi-cylinders along the pier surface after installation. The diameter of the pier is 1m-10m. The inner ring edge of the upper semi-circular retaining ring 2-2-1 is welded and fixed to the top edge of the semi-cylinder. The outer side of the semi-circular frustum 2-3-1 is a partially frustum-shaped surface, smaller at the top and larger at the bottom. The top edge of the semi-circular frustum 2-3-1 is welded and fixed to the bottom edge of the semi-cylinder. The outer surface of the pointed cone 2-3-2 is triangular. The top edges of the semi-circular frustum 2-3-1 and the pointed cone 2-3-2 together form a circular connecting edge. The circular connecting edge is fixed to the bottom edge of the support cylinder. The distance from the tip of the pointed cone 2-6 to the axis of the support cylinder is equal to three times the radius of the support cylinder 2-1.

[0037] In use, the semi-cylinders in the two protective units 2 enclose the pier on the water surface; and the two upper semi-circular rings 2-2-1 are fixed together by multiple fixing components 1 to form the upper protective member 2-2 surrounding the pier. The truncated cone portion 2-3-1 and the pointed cone portion 2-3-2 will enclose to form the lower protective member 2-3. At this time, the truncated cone portion 2-3-1 faces the direction of the water flow impacting the pier. The cross-sectional area of ​​the pointed cone portion 2-3-2 gradually decreases in the direction away from the truncated cone portion 2-3-1; the tip of the pointed cone portion 2-3-2 is in the same plane as the bottom edge of the truncated cone portion 2-3-1. After fixing, the support cylinder 2-1 slides down along the outer surface of the pier until it sinks to the junction of the pier and the riverbed.

[0038] The working principle of this invention is as follows:

[0039] like Figure 3 As shown, the water flow impacting the bridge piers forms a flow around the piers to both sides, as well as a jet parallel to the pier axis downwards. The upper semi-circular retaining ring 2-2-1 blocks this downward jet, preventing it from impacting the riverbed, reducing the depth of sand and gravel in the riverbed, and affecting the stability of the bridge piers.

[0040] The water flow impacting the support cylinder 2-1 forms water flows towards both sides of the pier, as well as a jet stream downwards along the surface of the support cylinder 2-1. The water flow impacting the semi-circular truncated cone 2-3-1 forms water flows upwards along the outer surface of the semi-circular truncated cone 2-3-1, as well as water flows towards both sides of the semi-circular truncated cone 2-3-1. The jet stream formed by the support cylinder 2-1 and the upward water flow along the outer surface of the semi-circular truncated cone 2-3-1 impact each other; this avoids the jet stream directly impacting the connection between the pier and the riverbed, but rather acts on the connection between the support cylinder 2-1 and the semi-circular truncated cone 2-3-1. This reduces the damage of the jet stream to the silt at the connection between the pier and the riverbed. At the same time, the water flow towards both sides of the semi-circular truncated cone 2-3-1 is guided by the pointed cone 2-3-2, directed towards the tip of the pointed cone 2-3-2; this reduces the scouring of the riverbed sand and gravel on both sides of the pier by the water flow.

[0041] Example 2

[0042] like Figure 4 As shown, a prefabricated bridge pier anti-scouring device includes two protective units 2 and multiple fixing components 1; the two protective units 2 surround the outer surface of the bridge pier; the adjacent sides of the two protective units 2 are detachably connected.

[0043] The protective unit 2 includes a semi-cylinder, an upper semi-circular ring 2-2-1, a truncated cone section 2-3-1, and a lower semi-circular ring 2-3-3. The two semi-cylinders can be joined to form a complete support cylinder 2-1 with a lower truncated cone shape and an upper cylindrical shape. The two upper semi-circular rings 2-2-1 can be joined to form a complete annular upper protective member 2-2. The two truncated cone sections 2-3-1 can be joined to form a complete truncated cone segment. The two lower semi-circular rings can be joined to form a complete annular segment. The truncated cone segment and the annular segment together constitute the lower protective member 2-3.

[0044] The height of the semi-cylinder is twice the radius of the pier. The inner diameter of the semi-cylinder is slightly larger than the diameter of the pier to facilitate the sliding of the two semi-cylinders along the surface of the pier after installation. The diameter of the pier is 1m-10m. The inner edge of the upper semi-circular retaining ring 2-2-1 is welded and fixed to the top edge of the semi-cylinder.

[0045] The outer surface of the semi-circular frustum 2-3-1 is shaped like a partially frustum, smaller at the top and larger at the bottom. The top edge of the semi-circular frustum 2-3-1 is welded and fixed to the bottom edge of the semi-cylinder. The outer diameter of the bottom of the semi-circular frustum 2-3-1 is twice the inner diameter of the semi-cylinder. The cone angle of the outer surface of the semi-circular frustum 2-3-1 is 30°-60°. The inner ring edge of the lower semi-circular retaining ring 2-3-3 is welded and fixed to the outer edge of the bottom of the semi-circular frustum 2-3-1.

[0046] The adjacent side edges of the two upper semicircular ring guards 2-2-1 and the adjacent side edges of the two lower semicircular ring guards 2-3-3 are connected by mounting and fixing components 1.

[0047] like Figure 4 As shown, the fixing component 1 includes a connecting part 1-1 and two bolts 1-2. The two ends of the connecting part 1-1 are respectively mounted on two upper semi-circular retaining rings 2-2-1 or two lower semi-circular retaining rings 2-3-3. The connecting part 1-1 is fixed to the upper semi-circular retaining rings 2-2-1 and the lower semi-circular retaining rings 2-3-3 by the bolts 1-2.

[0048] In use, the semi-cylinders in the two protective units 2 enclose the bridge pier on the water surface; and the two upper semi-circular rings 2-2-1 are fixed together by multiple fixing components 1 to form the upper protective component 2-2 surrounding the bridge pier, and the two lower semi-circular rings 2-3-3 are fixed together. The two semi-circular truncated sections 2-3-1 and the two lower semi-circular rings 2-3-3 form the lower protective component 2-3 surrounding the bridge pier. After fixing, the support cylinder 2-1 slides down along the outer surface of the bridge pier until it sinks to the junction of the bridge pier and the riverbed.

[0049] The working principle of this invention is as follows:

[0050] like Figure 5As shown, the water flow impacting the bridge piers forms a flow around the piers to both sides, as well as a jet parallel to the pier axis downwards. The upper semi-circular retaining ring 2-2-1 blocks this downward jet, preventing it from impacting the riverbed, reducing the depth of sand and gravel in the riverbed, and affecting the stability of the bridge piers.

[0051] The water flow impacting the support cylinder 2-1 forms a flow around the pier on both sides, as well as a jet stream downwards along the surface of the support cylinder 2-1. The water flow impacting the semi-circular truncated section 2-3-1 of the lower protective member 2-3 forms a flow around the pier on both sides, as well as a flow stream upwards along the outer surface of the semi-circular truncated section 2-3-1. The jet stream formed on the support cylinder 2-1 and the upward flow stream along the outer surface of the semi-circular truncated section 2-3-1 interact and impact each other, preventing the jet stream from directly impacting the connection between the pier and the riverbed, but instead acting at the connection between the support cylinder 2-1 and the semi-circular truncated section 2-3-1. At the same time, the lower semi-circular protective ring 2-3-3 will suppress the horseshoe-shaped vortex formed at the connection between the pier and the riverbed sediment.

[0052] The scouring and sediment volume changes of the riverbed were simulated with and without the anti-scouring devices described in Examples 1 and 2. The initial sediment thickness of the riverbed was 5m, the pier radius was 2.5m, the radius of the retaining ring was 5m, the ratio of the support cylinder height to the support cylinder radius was 2, and the water flow velocity was 2m / s. The simulation was performed using the FLUENT module of the finite element software ANSYS. After 20 time steps, the model reached a steady state. The simulation results are as follows. Figure 7 As shown in the figure; parts (a), (b), and (c) correspond to the bridge piers without anti-scour devices and the bridge piers equipped with the anti-scour devices described in Embodiments 1 and 2, respectively; Figure 8 Parts (d), (e), and (f) correspond to the bridge piers without anti-scour devices and the bridge piers equipped with anti-scour devices as described in Examples 1 and 2, respectively. Figure 7 , 8 In the diagram, the darker the color, the shallower the silt layer, and the more severe the erosion of the riverbed.

[0053] The simulation results are as follows Figure 9 As shown; Figure 9 Parts (g), (h), and (i) correspond to the bridge piers without anti-scour devices and the bridge piers equipped with anti-scour devices as described in Examples 1 and 2, respectively. Figure 9 In the diagram, the color indicates the proportion of sand and gravel per unit volume; the darker the color, the less sand and mud it contains.

[0054] The changes in the thickness of mud and sand on the front, rear, left and right sides of the bridge pier without protection or with the anti-scouring devices described in Examples 1 and 2 are shown in Table 1 below.

[0055] Table 1 Comparison of Riverbed Sediment Thickness After Erosion

[0056]

[0057] Combination Figure 7-9 As shown in Table 1, both Examples 1 and 2 can maintain a greater thickness of silt at the connection between the bridge pier and the riverbed under the scouring of water flow, and Example 1 achieves the best anti-scouring effect.

Claims

1. A prefabricated bridge pier anti-scouring device, characterized in that: It includes a support cylinder (2-1), an upper protective component (2-2), and a lower protective component (2-3); the upper protective component (2-2) is annular, and its inner circumferential edge is fixed to the top of the support cylinder (2-1); the lower protective component (2-3) is divided into a semi-circular frustum (2-3-1) and a conical part (2-3-2); the top edges of the semi-circular frustum (2-3-1) and the conical part (2-3-2) enclose to form a circular connecting edge; the circular connecting edge is fixed to the bottom edge of the support cylinder (2-1); the outer side of the semi-circular frustum (2-3-1) is a partially frustum-shaped surface with a smaller top and a larger bottom; the cross-sectional area of ​​the conical part (2-3-2) gradually decreases in the direction away from the semi-circular frustum (2-3-1); the bridge pier anti-scouring device is formed by multiple protective units (2); two adjacent protective units (2) are detachably connected; The tip of the conical portion (2-3-2) is in the same plane as the bottom edge of the truncated cone portion (2-3-1); the truncated cone portion (2-3-1) and the conical portion (2-3-2) of the lower protective member (2-3) each occupy a 180° central angle range of the lower protective member (2-3); the bottom radius of the truncated cone portion (2-3-1) is greater than the top radius; the cone angle of the outer side of the truncated cone portion (2-3-1) is 30° to 60°; the height of the support cylinder (2-1) is 0.6d to 1.2d; d is the inner diameter of the support cylinder (2-1); During operation, the support cylinder (2-1), the upper protective component (2-2), and the lower protective component (2-3) are fitted onto the outer side of the bottom of the pier; the semi-circular truncated section (2-3-1) faces the direction of water flow; the upper protective component (2-2) blocks the downward jet formed by the impact of water flow on the pier; the lower protective component (2-3) inhibits the formation of horseshoe-shaped vortices at the junction of the pier and the riverbed sediment, and protects the junction of the pier and the riverbed sediment.

2. A method for protecting bridge piers from erosion, characterized in that: Includes the following steps: Step 1: Assemble the various protective units (2) that make up the prefabricated bridge pier anti-scour device as described in claim 1 on the top of the bridge pier to be protected, so that each protective unit (2) surrounds the top of the bridge pier. Step 2: Release the assembled and fixed protective units (2) so that the anti-scouring device for the pier composed of the protective units (2) sinks to the bottom of the water, providing protection for the bottom of the pier and reducing the scouring loss of mud and sand at the connection between the pier and the riverbed.

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