Pile foundation scouring comprehensive protection structure

Abstract

The utility model discloses a pile foundation scouring comprehensive protection structure which comprises a steel pipe pile and a scouring pit around a pile foundation of the steel pipe pile, and further comprises a three-maintenance ring which is fixed to a riverbed, used for limiting water flow around the pile foundation in a protection ring cavity, located on the outer side of the steel pipe pile and spaced from the steel pipe pile by a certain distance. The rear end of the three-maintenance ring is provided with an opening used for guiding water flow in a cavity of the retainer to flow out, the outer wall of the three-maintenance ring is two sections of S-shaped curved surfaces which are in smooth transition and are not equal in wall thickness, the upper curved surface is a curved surface protruding towards the outer side, and the lower curved surface is a curved surface recessed towards the inner side. Erosion of horseshoe vortexes to a riverbed is reduced, and therefore the pile foundation scouring depth is greatly reduced.

Description

Technical Field

[0001] This utility model belongs to the field of steel pipe pile protection technology, and in particular relates to a comprehensive protection structure for pile foundation scour. Background Technology

[0002] Bridge piers placed in flowing water can cause erosion of the riverbed around their foundations, a phenomenon commonly known as scouring. If scouring extends to the bottom of the pier foundation, the structural integrity of the pier and the safety of the bridge may be threatened. The flow behavior around the pier exhibits three-dimensional separation. In the upstream region of the pier, due to the formation of a pressure gradient, some fluid is transported downwards to the riverbed, forming horseshoe vortices that surround the front and sides of the pier. Meanwhile, the remaining flow and horseshoe vortices, after bypassing the pier, experience streamline contraction, leading to an increase in flow velocity. Finally, the wake vortex, or Reynolds number-dependent eddy, rotates around the vertical axis and alternately separates downstream of the pier.

[0003] Existing anti-scour measures are generally flat plate guards, which are horizontal discs installed on bridge piers, usually two to four times the diameter of the pier. They work by blocking or shielding horseshoe vortices. However, the problem with flat plate guards is that while they reduce scour in some locations, they also cause scour in others, thus limiting their effectiveness in reducing scour.

[0004] Therefore, it is urgent to solve the above problems. Utility Model Content

[0005] Purpose of the utility model: The purpose of this utility model is to provide a comprehensive protection structure for pile foundation scour, which reduces the erosion of the riverbed by horseshoe vortices, thereby significantly reducing the scour depth of the pile foundation.

[0006] Technical Solution: To achieve the above objectives, this utility model discloses a comprehensive protection structure for pile foundation scour, including steel pipe piles and scour pits around the pile foundations. The structure is characterized by further including geotextile covering the scour pits and a three-layer protective ring fixed to the riverbed to confine the water flow around the pile foundation within a protective ring cavity. The three-layer protective ring is located outside the steel pipe piles and spaced a certain distance apart. An opening is provided at the rear end of the three-layer protective ring to guide the water flow out of the protective ring cavity. The outer wall of the three-layer protective ring consists of two smoothly transitioning S-shaped curved surfaces with non-uniform wall thicknesses. The upper curved surface is a convex surface to the outside, and the lower curved surface is a concave surface to the inside.

[0007] Optionally, the included angle of the opening is 60° to 120°, and the included angle of the opening is symmetrically arranged with the steel pipe pile as the center.

[0008] Optionally, the inner arc diameter of the upper curved surface is Φ0.11D, where D is the diameter of the steel pipe pile.

[0009] Optionally, the inner arc diameter of the lower curved surface is Φ0.21D, where D is the diameter of the steel pipe pile.

[0010] Optionally, the bottom diameter of the three maintenance rings is 3.33D, where D is the diameter of the steel pipe pile.

[0011] Optionally, the three protective rings are fixedly connected to the riverbed via an annular base, wherein a drainage outlet is provided on the annular base at a position corresponding to the opening of the three protective rings.

[0012] Optionally, the equation of the outer arc surface of the S-shaped surface is y = 0.007x. 3 +0.0053x 2 -0.0046x, where the origin is the lowest point on the outer side of the three maintenance rings.

[0013] Optionally, the height of the three protective rings is 0.32D, and the distance between the apex of the three protective rings and the outer side of the steel pipe pile is 0.21D, where D is the diameter of the steel pipe pile.

[0014] Optionally, the flushing pit is filled with geotextile concrete and fine sand, and the flushing pit is covered with geotextile.

[0015] Optionally, a riprap layer is laid on top of the geotextile, and the riprap layer is located upstream of the three maintenance rings.

[0016] Beneficial effects: Compared with the prior art, this utility model has the following advantages: This utility model suppresses horseshoe vortices and protects the high-velocity area on the side of the bridge pier through a comprehensive protection measure based on three protective rings. The three protective rings allow horseshoe vortices to circulate within them, while guiding and controlling them. The horseshoe vortices will not escape from the sides of the protective rings, nor will they interfere with the flow, thereby reducing their erosion of the riverbed and significantly reducing the scour depth of the pile foundation. In this utility model, the large outer diameter of the protective rings acts as a shield, preventing the erosive force generated by the accelerated flow from reaching the riverbed near the bridge pier. Other protective materials in this utility model are geotextiles, crushed stone, and geotextile concrete, which have simple construction technology, low overall cost, and good economic benefits. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of this utility model;

[0018] Figure 2 This is a schematic diagram showing the dimensions of the three maintenance rings in this utility model;

[0019] Figure 3 This is the front view of the three maintenance rings in this utility model. Detailed Implementation

[0020] The technical solution of this utility model will be further described below with reference to the accompanying drawings.

[0021] like Figure 1 , Figure 2 and Figure 3 As shown, a comprehensive protection structure for pile foundation scour includes a three-ring retaining ring 3, a circular base 5, a concrete geotextile bag 7, fine sand 8, geotextile 9, and a riprap layer 10. The three-ring retaining ring 3 is fixed to the riverbed 2, and a steel pipe pile 1 is installed on the riverbed 2. Scour pits are formed around the pile foundation of the steel pipe pile 1. The three-ring retaining ring 3 is used to confine the water flow around the pile foundation within the retaining ring cavity. The three-ring retaining ring 3 is located outside the steel pipe pile and is spaced a certain distance from the steel pipe pile. An opening 4 is provided at the rear end of the three-ring retaining ring 3 to guide the water flow out of the retaining ring cavity, thereby facilitating the horseshoe vortex within the retaining ring cavity. The included angle of the opening 4 is 60° to 120°, and the included angle of the opening 4 is symmetrically arranged with the steel pipe pile as the center. The included angle of the opening 4 refers to the angle formed by the two sides of the opening and the center of the steel pipe pile. The included angle of the opening 4 is preferably 90°. The outer wall of the three-maintain ring 3 consists of two smoothly transitioning S-shaped curved surfaces with non-uniform wall thicknesses. The upper curved surface is a convex surface with an inner arc diameter of Φ0.11D, where D is the diameter of the steel pipe pile. The lower curved surface is a concave surface with an inner arc diameter of Φ0.21D. The bottom diameter of the three-maintain ring 3 is 3.33D, the height of the three-maintain ring 3 is 0.32D, and the distance between the vertex of the three-maintain ring (3) and the outer side of the steel pipe pile 1 is 0.21D. The equation of the outer arc surface of the S-shaped curved surface is y = 0.007x. 3 +0.0053x 2 -0.0046x, where the origin O is the lowest point on the outer side of the three protective rings. In this invention, the three protective rings confine the water flow within the ring cavity until it reaches both sides of the pier; subsequently, the flow within the cavity is guided upwards, exiting from the rear of the protective ring and being transported downstream, thus away from the critical area around the pier. In this invention, horseshoe vortices are controlled, secondary horseshoe vortices are eliminated, and the flow accelerated through the protective rings is significantly reduced, thereby significantly reducing the shear stress in the riverbed.

[0022] The three-layer retaining ring 3 is fixedly connected to the riverbed 2 via a circular base 5. A drainage outlet 6 is provided on the circular base 5 at a position corresponding to the opening of the three-layer retaining ring. The circular base 5 can be made of concrete or reinforced concrete. At least one pair of lifting rings are also provided on the outer wall of the three-layer retaining ring 3, arranged in the retaining ring placement area 11. The scour pit is filled with geotextile concrete 7 and fine sand 8. The thickness of the geotextile concrete 7 is 30-60 cm. The geotextile concrete 7 and fine sand 8 are used to fill the scour pit around the pile foundation. A geotextile 9 is placed over the scour pit. A riprap layer 10 is laid on top of the geotextile 9, and the riprap layer 10 is U-shaped. The geotextile 9 is a 50 kN / m woven geotextile, and its laying range can completely cover the scour pit around the pile foundation. The riprap layer 10 is made of bagged stones or directly dumped. The stone size of the riprap layer 10 is 40-60cm. The riprap layer 10 fills the scour pit smoothly, and the filling height does not exceed the natural height of the riverbed. The lifting ring can be connected to a steel cable. The lifting ring is used to place the three-maintenance ring into the steel pipe pile through the steel cable connection. Subsequently, it is integrally cast with the circular base to fix it to the riverbed. Then, geotextile is laid around the scour pit on the riverbed and temporarily fixed with crushed stones or bagged sand. After the diver goes underwater to check, crushed stones are thrown by a long-arm excavator or open barge to lay the riprap layer. The formwork concrete construction involved in this utility model usually adopts the "lay-then-pour method". Concrete is pumped into the underwater-laid formwork bag through a hose using a concrete pump on the ship. First, the diver goes underwater to check the laid formwork bag. Underwater, the hose is inserted into the sleeve of the formwork bag. After the sleeve is filled with concrete, the pump pipe is moved to the next sleeve to continue filling. After the pump pipe is removed from the sleeve, the sleeve is immediately tied. Finally, it is confirmed that the concrete formwork bag has been successfully filled and the filling quality of the formwork bag is checked.

[0023] Unlike traditional retaining ring designs where flow circulates along the riverbed surface, this invention circulates the flow within cavities of the retaining ring. This circulation forms horseshoe vortices, which typically propagate around the front of the piers but are now confined within the retaining ring cavities until the water reaches the sides of the piers. The flow within the three retaining ring cavities is guided upwards, exiting from the rear of the retaining ring and being transported downstream, thus away from the critical area around the piers. A U-shaped riprap layer is located on the upstream side of the three retaining rings, laid on top of the geotextile within the scour pit area around the pile foundation. Concrete-filled geotextile bags are used to fill the scour pits around the pile foundations, located below the geotextile and riprap layer. Concrete or cement mortar is injected into the geotextile bags using a high-pressure pump, and after solidification, it forms a monolithic geotextile bag structure with a certain strength. This invention directly solves the problem of horseshoe vortex formation caused by scouring, and can be installed without damaging the structural integrity of the bridge pier. It is convenient to construct, has good application effect, and is highly adaptable. It has been widely used in the pile foundation protection of cross-sea bridges. The protective layers are tightly bonded and have good integrity, which can effectively improve the scouring resistance.

Claims

1. A comprehensive protection structure against scour of a pile foundation, comprising a steel pipe pile (1) and a scour pit around the pile foundation of the steel pipe pile, characterized in that, The utility model also comprises a three-dimensional fender (3) fixed on the riverbed (2) and used for limiting the water flow around the pile foundation into the fender cavity, the three-dimensional fender (3) is located outside the steel pipe pile and is spaced apart from the steel pipe pile, the rear end of the three-dimensional fender (3) is provided with an opening (4) for guiding the water flow out of the fender cavity, the outer wall of the three-dimensional fender (3) is a S-shaped curved surface with two sections of smooth transition and non-equal wall thickness, the upper curved surface is a curved surface protruding outward, and the lower curved surface is a curved surface recessed inward.

2. A scour protection structure according to claim 1, wherein, The included angle of the opening (4) is 60°-120°, and the opening (4) is symmetrically arranged with the steel pipe pile as the center.

3. The pile foundation scour comprehensive protection structure according to claim 1, characterized in that, The diameter of the inner arc surface of the upper curved surface is Φ0.11D, wherein D is the diameter of the steel pipe pile.

4. The pile foundation scour comprehensive protection structure according to claim 1, characterized in that, The diameter of the inner arc surface of the lower curved surface is Φ0.21D, wherein D is the diameter of the steel pipe pile.

5. The pile foundation scour comprehensive protection structure according to claim 1, characterized in that, The bottom diameter of the three-dimensional fender (3) is 3.33D, wherein D is the diameter of the steel pipe pile.

6. The pile foundation scour comprehensive protection structure according to claim 1, characterized in that, The three-dimensional fender (3) is fixedly connected with the riverbed (2) through a circular ring base (5), and the circular ring base (5) is provided with a drainage port (6) at a position corresponding to the opening of the three-dimensional fender.

7. The pile foundation scour comprehensive protection structure according to claim 1, characterized in that, The equation of the outer arc of the S-shaped surface is y = 0.007x 3 + 0.0053x 2 - 0.0046x, wherein the origin O is the outermost bottom point of the three-dimensional retaining ring.

8. The pile foundation scour comprehensive protection structure according to claim 1, characterized in that, The height of the three-dimensional fender (3) is 0.32D, and the distance between the top of the three-dimensional fender (3) and the outer side of the steel pipe pile (1) is 0.21D, wherein D is the diameter of the steel pipe pile.

9. The pile foundation scour comprehensive protection structure according to claim 1, characterized in that, The scour pit is filled with mold bag concrete (7) and fine sand (8), and a geotextile (9) is arranged on the scour pit.

10. A scour protection structure according to claim 9, wherein, A riprap layer (10) is arranged above the geotextile (9), and the riprap layer (10) is located upstream of the three-dimensional fender (3).

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