Complicated riverbed special-shaped steel casing reinforced deep water pile foundation, pile foundation structure and construction method

Abstract

The application discloses a complex riverbed special-shaped steel casing reinforced deep water pile foundation, a pile foundation structure and a construction method, and belongs to the technical field of bridge reinforcement. The scheme comprises a construction platform, a support assembly and a radial adjusting mechanism, and the casing assembly is composed of an upper rigid casing and a lower flexible casing. During construction, the adjusting mechanism drives the frame unit to move in the radial direction, the enclosed hole diameter is changed to adapt to different pile diameters, after the casing is lowered, the lower flexible casing supports the flexible skin by using the lining framework, and is self-adapted to the irregular riverbed contour. The application can adapt to different pile diameters by using the variable-diameter tool, solves the sealing problem of the inclined riverbed by using the flexible casing, realizes full water operation, does not need a diver to seal underwater, effectively prevents concrete from leaking, and significantly improves the construction efficiency and safety.

Description

Technical Field

[0001] This invention belongs to the field of bridge and hydraulic structure construction technology in civil engineering, specifically relating to a complex riverbed special-shaped steel casing reinforcement method for deep-water pile foundations, pile foundation structure and construction method for reinforcing existing pile foundations in deep-water environments and complex sloping riverbeds. Background Technology

[0002] In the long-term operation and maintenance of hydraulic structures such as bridges and wharves, reinforcing existing pile foundations located in deep-water environments is a critical task. Conventional reinforcement methods typically require installing a casing around the existing pile foundation and pouring concrete between the casing and the pile foundation.

[0003] However, existing technologies face significant technical bottlenecks when dealing with deep water, rapid currents, and riverbeds with irregular slopes or complex contours:

[0004] 1. Conflict between sealing performance and pile quality: Traditional casings are mostly integral rigid steel structures, whose flat bottoms cannot effectively fit against sloping or uneven riverbed surfaces, resulting in large gaps at the bottom of the casing. During underwater concrete pouring, cement slurry easily leaks through these gaps, not only wasting materials but also causing segregation of the reinforced concrete layer, and even "honeycomb surface" or voids, seriously affecting the reinforcement strength.

[0005] 2. High Construction Risks and Costs: To solve the problem of grout leakage at the bottom, current construction methods often rely on divers to perform underwater bagging and sand and gravel filling for sealing operations. Deep-water operations are not only inefficient and costly, but also expose divers to extremely high personal safety risks.

[0006] 3. Poor equipment versatility: Traditional casing positioning frames or guide frames are usually welded and fixed for specific pile diameters, lacking adjustability. When dealing with existing pile foundations of different diameters, it is often necessary to reprocess or replace the entire set of tooling, resulting in long construction preparation cycles and low equipment reuse rates.

[0007] Therefore, there is an urgent need for a deep-water pile foundation reinforcement technology and equipment that can adapt to complex riverbed contours, provide effective sealing, and be installed quickly and accurately. Summary of the Invention

[0008] The purpose of this application is to address the problems existing in the prior art, such as the inability of existing rigid casings to adapt to complex sloping riverbeds, leading to severe grout leakage during concrete pouring, and the inability of matching construction tools to adapt to changes in pile diameter, forcing construction to rely heavily on high-risk and low-efficiency underwater sealing operations by divers. This application provides a combined irregular casing structure with "upper rigid + lower flexible" design. The flexible bottom opening of the inner lining skeleton adapts to the riverbed, and is combined with a variable diameter construction system based on a slider radial drive separated frame unit, realizing non-diving operation and tooling standardization for deep-water pile foundation reinforcement.

[0009] To achieve the above objectives, this invention discloses a method for reinforcing deep-water pile foundations with irregularly shaped steel casings in complex riverbeds, comprising:

[0010] A support assembly is configured to be installed on a construction platform on water, and the support assembly is provided with a ring base;

[0011] The radial adjustment mechanism includes several sets of adjustment components distributed along the circumference and installed on the annular base, as well as an upper frame assembled from several independent frame units; the radial adjustment components are configured to drive the corresponding frame units to move radially back and forth to change the range of the inner diameter formed by the upper frame, thereby adapting to existing pile foundations of different diameters.

[0012] The lower frame is composed of several frame units and is connected to the upper frame by connecting rods;

[0013] The guardrails are vertically installed through the upper and lower frames; and

[0014] The irregular casing assembly is configured to be fixed to the periphery of the existing pile foundation by means of retaining rods; the irregular casing assembly includes an upper rigid casing and a lower flexible casing connected to the bottom of the upper rigid casing, the lower flexible casing being constructed to have flexible deformation capability to conform to the irregular riverbed contour.

[0015] Furthermore, the adjustment assembly includes a support plate, a slider, and a clamping component;

[0016] The bearing plate is fixedly installed on the annular base, and the slider is slidably mounted on the bearing plate;

[0017] The clamping element is connected to the slider and clamps the fixed frame unit;

[0018] The sliding of the slider causes the clamping parts and frame units to move radially relative to the support plate.

[0019] Furthermore, the clamping component includes an outer fixing component and an inner fixing component, and the frame unit of the upper frame is clamped between the outer fixing component and the inner fixing component;

[0020] The frame units are not connected to each other, and the diameter of the virtual circumference they enclose is changed by the synchronous drive of the radial adjustment mechanism.

[0021] Furthermore, the support assembly includes several fixed brackets, which include a beam structure and a column structure; the annular base includes an outer ring and an inner ring installed on the beam structure, and a reinforcing connector is connected between the outer ring and the inner ring, the reinforcing connector being constructed as a grid strip.

[0022] Furthermore, the lower flexible casing includes a flexible outer skin and an inner lining skeleton; the flexible outer skin is made of high-strength fiber cloth or rigid canvas, and the inner lining skeleton is a flexible steel wire skeleton. The lower flexible casing is connected to the inner wall structure of the upper rigid casing through the inner lining skeleton.

[0023] Furthermore, the guardrail is connected to the upper and lower frames in a matching interlocking manner, and the guardrail is used to apply lateral clamping force to the irregularly shaped casing assembly to achieve fixation.

[0024] Furthermore, the circumference of the lower frame adapts synchronously with the adjustment of the upper frame, and the upper and lower frames remain coaxially aligned in the vertical direction.

[0025] A construction method for reinforcing deep-water pile foundations using the complex riverbed irregular steel casing construction system described above includes the following steps:

[0026] S1. Assemble the support components and ring base on the construction platform;

[0027] S2. Install the radial adjustment mechanism and connect the frame unit of the upper frame to the adjustment assembly;

[0028] S3. The drive adjustment component moves the frame unit radially to adjust the inner diameter of the upper frame so that it adapts to and fits the outer dimensions of the existing pile foundation.

[0029] S4. Connect the upper frame and the lower frame with connecting rods, and install the guardrails;

[0030] S5. Lower the irregularly shaped casing assembly along the gap between the existing pile foundation and the frame unit, and fix it with the retaining rod;

[0031] S6. Make the bottom of the lower flexible casing contact and deform under pressure to conform to the contour of the riverbed, forming a closed cavity between the irregular casing assembly and the existing pile foundation;

[0032] S7. Pour concrete into the closed cavity.

[0033] Furthermore, in step S6, the inner lining skeleton of the lower flexible casing is used to support the flexible outer skin, so that it maintains its shape stability under the lateral pressure of concrete pouring; and / or, an underwater camera device is used to assist in judging the fit between the bottom of the lower flexible casing and the riverbed contour.

[0034] A complex riverbed irregular steel casing reinforcement deep-water pile foundation structure includes:

[0035] Existing pile foundations, standing in water on a sloping or irregular riverbed surface;

[0036] An irregularly shaped casing is installed around the existing pile foundation; the irregularly shaped casing includes an upper rigid casing at the top and a lower flexible casing at the bottom; the bottom opening shape of the lower flexible casing adaptively deforms to conform to the contour of the riverbed and fits tightly to it; and

[0037] A concrete reinforcement layer is filled and solidified in the cavity between the irregularly shaped casing and the existing pile foundation.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0039] 1. Excellent adaptive sealing performance (solving the problem of grout leakage): By setting up a "lower flexible casing" (outer fiber / canvas + inner flexible steel wire skeleton), its flexible deformation capability can automatically conform to and closely fit the irregular sloping riverbed contour when it is lowered to the bottom. Combined with the lateral pressure of concrete, it achieves self-sealing, which completely solves the problem of poor reinforcement quality caused by grout leakage at the bottom of the rigid casing.

[0040] 2. Extremely high tooling versatility (solving the problem of variable diameter): An innovative "adjustable frame system" driven by a slider is designed. The outer fasteners and inner fixing parts clamp independent "frame units," and the diameter of the "virtual circle" enclosed by the frame units is changed by radial sliding. This design allows the same set of construction equipment to adapt to existing pile foundations of different diameters, eliminating the need to customize molds for each pile, and significantly reducing equipment costs and construction time.

[0041] 3. Significantly improves construction safety and efficiency (solves diving problems): The entire system (including the positioning, diameter adjustment and fixing of the casing) can be completed on the water construction platform. The self-adhesive characteristics of the flexible casing eliminate the need for underwater manual sealing, greatly reducing or even eliminating high-risk underwater operations by divers, and significantly improving construction safety.

[0042] 4. Stable and reliable structure: The rigid base, consisting of an outer ring, an inner ring, and grid strips (reinforcing ribs), combined with the clamping and fixing of the retaining rods, forms a multi-layered high-rigidity support network that can effectively resist the impact of deep water flow and the lateral pressure during concrete pouring, ensuring the stability of the construction process. Attached Figure Description

[0043] Figure 1 This is a three-dimensional schematic diagram of the construction of deep-water pile foundation reinforced with irregularly shaped steel casing for complex riverbeds, according to an embodiment of the present invention.

[0044] Figure 2 for Figure 1 Enlarged view of node A in the middle;

[0045] Figure 3This is a top view of the construction of deep-water pile foundation reinforced with irregularly shaped steel casing for complex riverbeds, according to an embodiment of the present invention.

[0046] Figure 4 for Figure 3 Enlarged view of node B in the middle.

[0047] In the diagram: 1. Existing pile foundation; 2. Riverbed surface; 3. Upper rigid casing; 4. Lower flexible casing; 5. Construction platform; 6. Fixed support; 7. Upper crossbeam; 8. Lower crossbeam; 9. Vertical plate; 10. Vertical rod; 11. Inner ring; 12. Outer ring; 13. Grating strip; 14. Support plate; 15. Sliding block; 16. External fastener; 17. Internal fastener; 18. Upper frame; 19. Lower frame; 20. Frame unit; 21. Connecting rod; 22. Enclosure rod. Detailed Implementation

[0048] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0049] Those skilled in the art should understand that, in the disclosure of this application, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limitations on this application.

[0050] Example 1: Construction System for Deep-Water Pile Foundation Reinforced with Irregularly Shaped Steel Casings in Complex Riverbeds

[0051] like Figures 1 to 4 As shown, the present invention provides a construction system for reinforcing deep-water pile foundations with irregularly shaped steel casings in complex riverbeds. This system is constructed in the aquatic environment surrounding the existing pile foundation 1, especially for deep-water environments where the riverbed surface 2 is sloping or has an irregular contour.

[0052] The construction system mainly includes support components, radial adjustment mechanisms, and special-shaped casing components.

[0053] The supporting components include a construction platform 5 and fixed supports 6. The construction platform 5 is a construction vessel or a temporary floating platform erected around the existing pile foundation 1 to provide a site for water-based operations. The fixed supports 6 consist of several groups (e.g., four or more, evenly distributed) installed on the construction platform 5. Specifically, the fixed supports 6 include an upper crossbeam 7, a lower crossbeam 8, uprights 9, and vertical rods 10. These components are welded or bolted together to form a robust, rigid frame to withstand subsequent construction loads.

[0054] To establish the basis for radial adjustment, an annular base is installed on the lower crossbeam 8 of the fixed bracket 6. This annular base consists of a concentric outer ring 12 and an inner ring 11. A grid strip 13 (also known as a reinforcing connector) is connected between the outer ring 12 and the inner ring 11 for connection and reinforcement. The grid strip 13 not only enhances the rigidity of the rings but also serves as a maintenance passage for operators.

[0055] A radial adjustment mechanism is installed on the aforementioned annular base to accommodate existing pile foundations 1 of different diameters. Specifically, a bearing plate 14 is installed on the outer ring 12 and the inner ring 11, and a slider 15 is provided on the bearing plate 14. The slider 15 is configured to slide radially back and forth along the bearing plate 14 (i.e., move in a direction pointing towards or away from the center of the existing pile foundation 1). A clamping member is connected to the slider 15, which includes an outer fixing member 16 and an inner fixing member 17.

[0056] The upper frame 18 is mounted on the support plate 14 and located between the outer fixing member 16 and the inner fixing member 17. It is worth noting that the upper frame 18 is not an indivisible monolithic ring, but rather assembled from several independent frame units 20. The outer fixing member 16 and the inner fixing member 17 together clamp the frame units 20 of the upper frame 18. When the drive slider 15 slides radially, it causes the outer fixing member 16 and the inner fixing member 17 to move synchronously, thereby pushing and pulling the frame units 20 to perform radial displacement. By synchronously adjusting the sliders 15 in all directions, the inner diameter range of the virtual circumference formed by the several frame units 20 can be changed, thus adapting to different pile diameters.

[0057] To maintain the verticality of the casing, a lower frame 19 is also provided in the system. The lower frame 19 is also composed of several frame units 20. The upper frame 18 is connected to the lower frame 19 through a connecting rod 21, so that the lower frame 19 can adjust its circumference synchronously with the upper frame 18 and maintain coaxial alignment in the vertical direction.

[0058] The guardrail 22 is a long rod that runs vertically through the frame, and it is fitted into the pre-drilled holes or slots in the upper frame 18 and the lower frame 19. The main function of the guardrail 22 is to provide inward lateral clamping force to fix the irregularly shaped casing assembly.

[0059] The irregular-shaped casing assembly includes an upper rigid casing 3 at the top and a lower flexible casing 4 connected to the bottom. The upper rigid casing 3 is typically made of rolled steel plate and has high structural strength. The lower flexible casing 4 is constructed to have flexible deformation capabilities to conform to the irregular contours of the riverbed. In this preferred embodiment, the lower flexible casing 4 includes a flexible outer skin and an inner lining skeleton; the flexible outer skin is made of high-strength fiber cloth or rigid canvas, which has good seepage prevention and tear resistance; the inner lining skeleton is a flexible steel wire skeleton, which can both support the outer skin to maintain its cylindrical shape and allow it to undergo compressive deformation under axial pressure. The lower flexible casing 4 is connected and fixed to the inner wall structure of the upper rigid casing 3 through the inner lining skeleton.

[0060] Example 2: Construction Method

[0061] Based on the construction system described in Embodiment 1, the present invention also provides a construction method for reinforcing deep-water pile foundations with irregularly shaped steel casings in complex riverbeds, specifically including the following steps:

[0062] S1. Constructing a construction platform 5: Depending on the site's hydrological conditions, choose to moor the construction vessel or construct a temporary water platform with steel pipe piles around the existing pile foundation 1.

[0063] S2. Install fixed supports 6: Weld or bolt several sets of fixed supports 6 on the construction platform 5. Each set of fixed supports 6 includes an upper crossbeam 7, a lower crossbeam 8, a vertical plate 9 and a vertical rod 10 to ensure the stability of the supports.

[0064] S3. Mounting base: Install the outer ring 12 and the inner ring 11 on the lower crossbeam 8 of the fixed bracket 6, and weld the grid strip 13 between them to form a high-rigidity ring support structure.

[0065] S4. Install the adjustment components: Lay the support plate 14 and slider 15 on the outer ring 12 and inner ring 11, and connect the outer fixing part 16 and the inner fixing part 17 to the slider 15.

[0066] S5. Install the upper frame 18: Place the upper frame 18, which consists of several frame units 20, on the support plate 14, ensuring that each frame unit 20 is placed between the corresponding outer fastener 16 and inner fastener 17.

[0067] S6. Adjusting the aperture: Based on the actual diameter of the existing pile foundation 1 and the required reinforcement layer thickness, simultaneously drive the sliders 15 in all directions, causing the outer fixing member 16 and the inner fixing member 17 to move, thereby clamping and driving the frame unit 20 to slide radially. By adjusting the position of the frame unit 20, the inner diameter enclosed by the upper frame 18 is changed to adapt to construction requirements.

[0068] S7. Connecting the lower frame 19: The adjusted upper frame 18 is connected to the lower frame 19, which is composed of lower frame units, through the connecting rod 21 to form a three-dimensional guide cage structure.

[0069] S8. Install guardrail 22: Install guardrail 22 through the upper frame 18 and the lower frame 19.

[0070] S9. Install the casing: Lower the pre-assembled upper rigid casing 3 and lower flexible casing 4 from the top along the gap between the existing pile foundation 1 and the retaining rod 22. During the lowering process, the casing is fixed by tightening the retaining rod 22. When the bottom of the lower flexible casing 4 contacts the riverbed surface 2, continue to apply downward pressure, using the inner lining skeleton of the lower flexible casing 4 to support the flexible outer skin, causing it to deform under pressure, thereby tightly fitting the irregular contour of the riverbed surface 2. At this time, the fitting status can be observed with the help of an underwater camera to ensure good sealing. A closed cavity is formed between the upper rigid casing 3, the lower flexible casing 4 and the existing pile foundation 1.

[0071] S10. Concrete Pouring: Underwater non-dispersible concrete is poured into the closed cavity. The lower flexible casing 4 expands further outward under the lateral pressure of the internal concrete and presses against the riverbed surface 2, effectively preventing grout leakage. After the concrete hardens, a reinforcement layer is formed, completing the reinforcement of the existing pile foundation 1. Finally, the construction components such as the slider 15 and frame unit 20 can be removed for reuse.

[0072] Example 3: Reinforced Deep-Water Pile Foundation Structure

[0073] This embodiment describes the final product structure constructed by the above method. For example... Figure 1 As shown, the complex riverbed reinforced deep-water pile foundation with irregularly shaped steel casing includes an existing pile foundation 1 located in the water, on a sloping riverbed surface 2. An irregularly shaped casing is installed around the existing pile foundation 1, consisting of an upper rigid casing 3 and a lower flexible casing 4. The bottom opening of the lower flexible casing 4 has adaptively deformed to conform to the contour of the riverbed surface 2, fitting tightly without any obvious gaps. A concrete reinforcement layer is filled and solidified within the annular cavity formed between the upper rigid casing 3, the lower flexible casing 4, and the existing pile foundation 1. This reinforcement layer encloses the portion of the existing pile foundation 1 above the riverbed surface 2, significantly improving the pile foundation's bearing capacity and durability.

[0074] The parts not described in detail in this application are prior art, and therefore are not described in detail in this application.

[0075] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0076] Although this document uses terms such as "etc." extensively, the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the nature of this application; interpreting them as any additional limitation would be contrary to the spirit of this application.

[0077] This application is not limited to the above-described preferred embodiments. Anyone can derive other products in various forms under the guidance of this application. However, regardless of any changes made to their shape or structure, any technical solution that is the same as or similar to that of this application falls within the protection scope of this application.

Claims

1. A construction system for reinforcing deep-water pile foundations with irregularly shaped steel casings in complex riverbeds, characterized in that, include: A support assembly is configured to be installed on a construction platform (5) on water, and the support assembly is provided with an annular base; The radial adjustment mechanism includes several sets of adjustment components distributed circumferentially and installed on the annular base, and an upper frame (18) assembled from several independent frame units (20); the radial adjustment mechanism is configured to drive the corresponding frame unit (20) to reciprocate radially to change the inner diameter range enclosed by the upper frame (18), thereby adapting to existing pile foundations (1) of different diameters; the adjustment components include a bearing plate (14), a slider (15), and a clamping member; the bearing plate (14) is fixedly installed on the annular base, and the slider (15) is slidably disposed on the bearing plate (14). 14) The clamping member is connected to the slider (15) and clamps and fixes the frame unit (20); the sliding of the slider (15) causes the clamping member and the frame unit (20) to move radially relative to the support plate (14); the clamping member includes an outer fixing member (16) and an inner fixing member (17), and the frame unit (20) of the upper frame (18) is clamped between the outer fixing member (16) and the inner fixing member (17); the frame units (20) are not connected to each other, and the virtual circumference diameter enclosed by them is changed by the synchronous drive of the radial adjustment mechanism; The lower frame (19) is composed of several frame units (20) and is connected to the upper frame (18) by a connecting rod (21); The guardrail (22) is vertically installed through the upper frame (18) and the lower frame (19); and The irregular casing assembly is configured to be fixed to the periphery of the existing pile foundation (1) by the retaining rod (22); the irregular casing assembly includes an upper rigid casing (3) and a lower flexible casing (4) connected to the bottom of the upper rigid casing (3). The lower flexible casing (4) is constructed to have flexible deformation capability to conform to the irregular riverbed contour. The lower flexible casing (4) includes a flexible outer skin and an inner lining skeleton. The flexible outer skin is made of high-strength fiber cloth or hard canvas, and the inner lining skeleton is a flexible steel wire skeleton. The lower flexible casing (4) is connected to the inner wall structure of the upper rigid casing (3) through the inner lining skeleton.

2. The construction system for reinforcing deep-water pile foundations with irregularly shaped steel casings in complex riverbeds according to claim 1, characterized in that, The support assembly includes several fixed brackets (6), the fixed brackets (6) include a beam structure and a column structure; the annular base includes an outer ring (12) and an inner ring (11) installed on the beam structure, and a reinforcing connector is connected between the outer ring (12) and the inner ring (11), the reinforcing connector being constructed as a grid strip (13).

3. The construction system for reinforcing deep-water pile foundations with irregularly shaped steel casings in complex riverbeds according to claim 1, characterized in that, The guardrail (22) is connected to the upper frame (18) and the lower frame (19) by a matching interlocking connection. The guardrail (22) is used to apply a lateral clamping force to the irregular-shaped protective cylinder assembly to achieve fixation.

4. The construction system for reinforcing deep-water pile foundations with irregularly shaped steel casings in complex riverbeds according to claim 1, characterized in that, The circumference of the lower frame (19) adapts synchronously with the adjustment of the upper frame (18), and the upper frame (18) and the lower frame (19) remain coaxially aligned in the vertical direction.

5. A construction method using the complex riverbed irregular steel casing reinforcement deep-water pile foundation construction system as described in any one of claims 1 to 4, characterized in that, Includes the following steps: S1. Assemble the support components and the annular base on the construction platform (5); S2. Install the radial adjustment mechanism and connect the frame unit (20) of the upper frame (18) to the adjustment assembly; S3. Drive the adjustment component to move the frame unit (20) radially and adjust the inner diameter of the upper frame (18) to adapt to and fit the outer dimensions of the existing pile foundation (1). S4. Connect the upper frame (18) and the lower frame (19) through the connecting rod (21), and install the guardrail (22). S5. Lower the irregular casing assembly along the gap between the existing pile foundation (1) and the frame unit (20), and fix it with the retaining rod (22); S6. Make the bottom of the lower flexible casing (4) contact and be deformed by pressure to fit the contour of the riverbed, forming a closed cavity between the irregular casing assembly and the existing pile foundation (1); S7. Pour concrete into the enclosed cavity.

6. The construction method according to claim 5, characterized in that, In step S6, the inner lining skeleton of the lower flexible casing (4) is used to support the flexible outer skin, so that it maintains its shape stability under the lateral pressure of concrete pouring; the underwater camera device is used to help determine the fit between the bottom of the lower flexible casing (4) and the riverbed contour.

7. A complex riverbed irregular-shaped steel casing reinforced deep-water pile foundation structure obtained by the construction method described in claim 5, characterized in that, include: There are existing pile foundations (1), which stand in the water on a sloping or irregular riverbed surface (2); A special-shaped casing is arranged around the existing pile foundation (1); the special-shaped casing includes an upper rigid casing (3) at the top and a lower flexible casing (4) at the bottom; the bottom opening shape of the lower flexible casing (4) adapts to the contour of the riverbed surface (2) and fits it tightly; and A concrete reinforcement layer is filled and solidified in the cavity between the irregular casing and the existing pile foundation (1).

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