Pile foundation structure for V-shaped pier rigid frame bridge and construction method of pile foundation structure

Abstract

The invention provides a pile foundation structure for a V-shaped pier rigid frame bridge and a construction method thereof.The pile foundation structure comprises a bearing platform and a plurality of pile foundations arranged at the bottom of the bearing platform, each pile foundation comprises a vertical section embedded and fixed into a bearing stratum, the top of each vertical section is provided with a hole shrinkage connecting section, and the top of each hole shrinkage connecting section is anchored into the bearing platform; and a high-damping elastic coating sleeve is arranged outside the high-damping elastic coating sleeve, and forms a local flexible area at the joint of the pile foundation and the bearing platform. The flexible tuning area made of the high-damping elastomer material is arranged on the upper section of the pile body, so that the equivalent bending rigidity of the area is effectively reduced, the pile foundation can actively adapt to longitudinal deformation caused by temperature change, shrinkage creep and the like while bearing vertical load and horizontal thrust transmitted by the V-shaped pier, and the stability of the pile foundation is improved. Secondary internal force in the bearing platform and the pile body is obviously reduced, concrete cracking is avoided, and the structural durability is improved.

Description

Technical Field

[0001] This invention relates to the field of V-shaped pier rigid frame bridge construction, and in particular to a pile foundation structure for V-shaped pier rigid frame bridges and its construction method. Background Technology

[0002] V-shaped pier rigid frame bridges have been increasingly widely used in bridge engineering in recent years due to their lightweight and beautiful shape, reasonable structural stress distribution, and ability to effectively reduce the height of the main beam and improve the span capacity. However, while V-shaped piers efficiently transfer the superstructure load to the foundation, they also bring about a prominent contradiction in the substructure, which needs to balance high bearing capacity with good longitudinal deformation adaptability.

[0003] Currently, the project mainly relies on two passive coping methods: one is to significantly increase the bending stiffness of the pile foundation and the rotational constraint stiffness of the pile cap to "bear" the huge horizontal thrust and bending moment transmitted from the V-shaped pier, and supplement it with the passive earth pressure provided by the soil around the pile to balance part of the horizontal force. Although this method is technically mature, it leads to a significant increase in the cross-sectional size and reinforcement of the pile foundation, large material consumption, high construction difficulty, and poor economy. Moreover, excessive structural stiffness will severely restrict the free deformation of the superstructure caused by temperature changes, which will generate significant secondary internal forces in the pile body and pile cap, and there is a risk of concrete cracking and durability deterioration.

[0004] Another approach is to enhance the system's flexibility by increasing the free length of the pile foundation to accommodate longitudinal displacement. This usually requires large-scale dredging of the riverbed or seabed. However, such measures not only have high initial engineering costs and significant ecological disturbance, but also make it difficult to maintain the dredging effect in the long term. After siltation, the free length of the pile foundation decreases, and the deformation adaptability deteriorates rapidly. Furthermore, continuous dredging and maintenance costs are required.

[0005] The conventional methods mentioned above have failed to fundamentally reconcile the inherent conflict between bearing capacity and deformation adaptability. Therefore, a pile foundation structure and its construction method for V-shaped pier rigid frame bridges are proposed to solve the above problems. Summary of the Invention

[0006] The main objective of this invention is to provide a pile foundation structure and its construction method for V-shaped pier rigid frame bridges, solving the problems in the prior art where excessive pile foundation stiffness leads to significant secondary internal forces and easy cracking under the influence of temperature and other factors, or poor economy and maintenance difficulties caused by excessive reliance on dredging to increase free length.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a pile foundation structure for a V-shaped pier rigid frame bridge and its construction method, including a pile cap and a plurality of pile foundations set at the bottom of the pile cap. The pile foundation includes a vertical section embedded in the bearing layer, and a reduced diameter connecting section is provided at the top of the vertical section. The top of the reduced diameter connecting section is anchored to the pile cap, and a high-damping elastic covering sleeve is provided on its exterior, which forms a local flexible zone at the connection between the pile foundation and the pile cap.

[0008] In the preferred embodiment, the high-damping elastic covering sleeve includes an annular filling cavity located outside the reduced-diameter connecting section. The annular filling cavity is filled with a high-damping elastomer material. A gap is provided between the outer wall of the annular filling cavity and the bottom of the bearing platform. The top of the high-damping elastomer material inside the cavity abuts against the bottom surface of the bearing platform.

[0009] In the preferred embodiment, the outer diameter of the high-damping elastic covering sleeve is the same as the outer diameter of the vertical section, and the radial thickness and height of the annular filling cavity are determined according to the volume and shear deformation requirements of the high-damping elastomer material required at the location of the pile foundation.

[0010] In the preferred embodiment, the vertical section, the reduced diameter connecting section, and the annular filling cavity are composed of an outer steel casing and a necked inner steel casing. The outer steel casing extends vertically along the pile body to form the outer shell of the vertical section. The necked inner steel casing is coaxially sleeved on its top. The top of the necked inner steel casing is higher than the outer steel casing. Together, they constitute the outer shell of the reduced diameter connecting section. The cavity formed between the necked inner steel casing and the outer steel casing is an annular filling cavity. The outer steel casing and the necked inner steel casing are equipped with variable diameter cast-in-place piles, forming an integrated vertical section and a necked connection section. The top of the steel cage inside the variable diameter cast-in-place pile extends out from the top of the necked inner steel casing and is used for anchoring to the pile cap.

[0011] In the preferred embodiment, the necked inner steel casing includes a tapered cylinder that is wider at the bottom and narrower at the top, and a narrow-diameter vertical cylinder connected to the narrow opening at the top of the tapered cylinder.

[0012] In the preferred embodiment, a sealing ring is provided on the outside of the wide opening at the bottom of the conical cylinder to seal the bottom of the annular filling cavity. The sealing ring is adapted to the inner diameter of the outer steel casing, and a sealing ring is fitted on its outside.

[0013] The method includes: S1. The outer steel casing is gradually lowered to the designed pile position, and then holes are drilled inside the outer steel casing. S2. The reinforcing cage of the variable diameter cast-in-place pile is hoisted into the outer steel casing and is coaxial with its center line. The necked inner steel casing is installed into the outer steel casing by a step-by-step hoisting and assembly method with the reinforcing cage or a pre-assembled overall hoisting method. After installation, the top of the necked inner steel casing is higher than the top surface of the outer steel casing. S3. The bottom of the closed annular filling cavity is sealed, and underwater concrete is poured into the inner steel casing of the constricted neck and the outer steel casing of the conduit through the insertion of the guide pipe until it reaches the top surface of the inner steel casing of the constricted neck, thereby forming a variable diameter cast-in-place pile. S4. Seal the top of the annular filling cavity, ensuring the sealing height meets the molding height of the high-damping elastomer material, and install an injection pipe and an exhaust overflow pipe. Then, perform a pressure or vacuum test on the annular filling cavity. S5. Press the high-damping elastomer material into the injection tube at a uniform speed, and after pressing, allow it to fully solidify and form a high-damping elastic covering sleeve.

[0014] In the preferred embodiment, the high-damping elastomer material is injected into the annular filling cavity through an injection device, which includes a sealing cover covering the top of the annular filling cavity to seal it, multiple retractable injection pipes extending through the sealing cover into the annular filling cavity, multiple exhaust overflow pipes set on the sealing cover, a lifting mechanism set on the outside of the sealing cover for controlling the raising and lowering of the injection pipes, and an anti-detachment block for temporarily fixing the sealing cover and the variable-diameter injection pile through the reinforcing cage.

[0015] In the preferred embodiment, the sealing cover includes a closed annular groove-shaped cover that can be fitted onto the outside of the outer steel casing, the diameter of its central hole being adapted to the outer diameter of the necked inner steel casing, and a lifting annular groove-shaped cover that is suspended on the top of the necked inner steel casing is provided thereon. The anti-loosening bolt block is specifically inserted under the lowest stirrup at the end of the steel cage and presses on the hoisting annular trough-shaped cover; The horizontal ring plate of the closed annular groove cover is provided with multiple intersecting telescopic holes and vent holes. The injection pipe is telescopically installed in the telescopic hole, and a sealing ring is provided between the two. The vent overflow pipe is connected and installed on the vent hole. The bottom of the expansion joint is provided with a fitting groove with a diameter larger than that of the expansion joint, and a fitting sealing ring is installed in the fitting groove. The bottom end of the injection pipe is provided with a fitting ring that can fit into the fitting groove.

[0016] In the preferred embodiment, the lifting mechanism includes an extension ring disposed outside the closed annular groove-shaped cover. The extension ring has multiple mounting holes, in which a lifting telescopic cylinder is installed. A lifting ring is installed on the telescopic end of the top of the lifting telescopic cylinder. The diameter of the central hole of the lifting ring is larger than the outer diameter of the annular groove-shaped cover being lifted. The top of the injection pipe is fixed through and fixed to the lifting ring.

[0017] This invention provides a pile foundation structure and construction method for a V-shaped pier rigid frame bridge. By setting a flexible tuning zone composed of a high-damping elastomer material in the upper part of the pile body, the equivalent bending stiffness of this region is effectively reduced. This allows the pile foundation to actively adapt to longitudinal deformation caused by temperature changes, shrinkage, and creep while bearing the vertical load and horizontal thrust transmitted by the V-shaped pier. This significantly reduces secondary internal forces in the pile cap and pile body, prevents concrete cracking, and improves structural durability. The high-damping elastomer material can efficiently dissipate the energy input by earthquakes or wind vibrations during shear deformation, enhancing... The bridge's overall seismic and wind resistance is excellent. The combined structure of the outer steel casing and the necked inner steel casing not only provides reliable restraint for the reinforced concrete core but also provides a stable installation interface for the high-damping cladding, ensuring structural reliability. This structure decouples and optimizes the complex compression-bending coupling forces in space, achieving a balance between high vertical bearing capacity and adaptability to large longitudinal deformation. It eliminates the need to significantly increase the size of the pile foundation or carry out large-scale riverbed dredging, significantly reducing material usage and construction difficulty, saving project costs, and requiring virtually no maintenance in the later stages, demonstrating outstanding economic efficiency and sustainability. Attached Figure Description

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is an overall structural diagram of the V-shaped pier rigid frame bridge of the present invention; Figure 2 This is a diagram showing the connection structure between the foundation cap and the pile foundation of this invention; Figure 3 This is a cross-sectional structural diagram of the pile foundation of the present invention; Figure 4 This is a top view of the pile foundation structure of the present invention; Figure 5 This is a structural diagram of the necked inner steel casing of the present invention; Figure 6 This is a half-sectional view of the necked inner steel casing of the present invention; Figure 7 This is a structural diagram of the connection between the grouting device of the present invention and the pile foundation; Figure 8 This is the present invention. Figure 7 A half-section structural diagram; Figure 9 This is a structural diagram of the infusion device of the present invention; Figure 10 This is the present invention. Figure 9 A half-section structural diagram; Figure 11 This is a half-sectional view of the injection device of the present invention in the lifting state; Figure 12 This is a structural diagram of the sealing cover of the present invention; Figure 13 This is the present invention. Figure 12 A half-section structural diagram; Figure 14 This is a structural diagram of the initial state of the infusion device of the present invention; Figure 15 This is a structural diagram of the injection device of the present invention in the state of injection completion; Figure 16 This is the present invention. Figure 15 Enlarged view of the A-structure.

[0019] In the diagram: Pile foundation 1; Vertical section 10; Outer steel casing 101; Narrow-necked inner steel casing 102; Narrow-diameter vertical cylinder 1020; Conical cylinder 1022; Variable diameter cast-in-place pile 103; Narrow-diameter connecting section 11; High-damping elastic covering sleeve 12; Annular filling cavity 120; High-damping elastomer material 121; Foundation 2; V-shaped rigid frame 3; Grouting device 4; Sealing cover 40; Closed annular groove cover 401; Lifting annular groove cover 402; Extension ring 403; Mounting hole 4031; Grouting pipe 41; Expansion hole 410; Fitting groove 411; Extrusion fitting sealing ring 4110; Fitting ring 412; Exhaust overflow pipe 42; Exhaust hole 420; Lifting mechanism 43; Lifting ring 430; Telescopic cylinder 431; Anti-detachment block 44. Detailed Implementation

[0020] Example 1 like Figures 1-6 As shown, a pile foundation structure for a V-shaped pier rigid frame bridge includes a V-shaped rigid frame 3, a pile cap 2 disposed at the bottom of the V-shaped rigid frame 3, and a plurality of piles 1 disposed at the bottom of the pile cap 2. The piles 1 are embedded in the bearing layer to provide vertical bearing capacity and resistance to horizontal forces.

[0021] The pile foundation 1 includes a vertical section 10 embedded in the bearing layer. The top of the vertical section 10 is provided with an integrally formed reduced-diameter connecting section 11, the top of which is anchored to the pile cap 2. A high-damping elastic covering sleeve 12 is provided on its exterior. Under horizontal load, the high-damping elastic covering sleeve 12 undergoes shear deformation, forming a low-stiffness, high-damping local flexible zone in the upper part of the pile body, which significantly reduces the equivalent bending stiffness of this section. This flexible zone alleviates the deformation incoordination between the pile cap 2 and the pile body on the one hand, and maintains the effective transfer of load on the other hand, thereby achieving coordinated tuning of the stress and deformation of the pile foundation system. The local flexible zone absorbs most of the bending energy caused by temperature deformation, reduces the bending moment transferred to the lower pile body and root, and improves the durability of the pile foundation.

[0022] Furthermore, the high-damping elastic covering sleeve 12 includes an annular filling cavity 120 located outside the reduced diameter connecting section 11. The annular filling cavity 120 is filled with a high-damping elastomer material 121. A gap is provided between the outer wall of the annular filling cavity 120 and the bottom of the support 2, while the top of the high-damping elastomer material 121 inside it abuts against the bottom surface of the support 2.

[0023] In this embodiment, the high-damping elastomer material 121 is a high-damping rubber body or a polyurethane prepolymer or other similar material.

[0024] This design allows the high-damping elastomer material 121 to absorb and dissipate vibration energy through shear deformation when the pile top is subjected to horizontal loads. At the same time, the gaps avoid rigid constraints, thus forming a controllable flexible connection between the pile body and the pile cap 2. This not only effectively reduces the equivalent bending stiffness of the upper part of the pile body and coordinates the deformation difference between the pile cap 2 and the pile foundation 1, but also significantly improves the energy dissipation capacity and deformation adaptability of the pile foundation system while ensuring the vertical bearing capacity.

[0025] In addition, the outer diameter of the high-damping elastic sleeve 12 is the same as the outer diameter of the vertical section 10 to maintain the continuity of the pile body shape and avoid stress concentration. The radial thickness and height of the annular filling cavity 120 are determined according to the volume and shear deformation requirements of the high-damping elastic material 121 required at the location of the pile foundation 1, so as to adapt to the specific connection position and stress conditions of the pile foundation 1 and the pile cap 2 in the actual project, and ensure that the flexible tuning zone is accurately arranged at the key part of the pile top.

[0026] In the preferred embodiment, the vertical section 10, the reduced diameter connecting section 11, and the annular filling cavity 120 are composed of an outer steel casing 101 and a necked inner steel casing 102. The outer steel casing 101 extends vertically along the pile body to form the outer shell of the vertical section 10, and the smaller-diameter necked inner steel casing 102 is coaxially sleeved at its top. Together, they constitute the outer shell of the reduced diameter connecting section 11, achieving a smooth transition of the pile body cross section. At the same time, the cavity formed between the necked inner steel casing 102 and the outer steel casing 101 is the annular filling cavity 120.

[0027] The top of the constricted inner steel casing 102 is higher than the outer steel casing 101. While connecting with the bearing platform 2, it forms a gap between the outer wall of the annular filling cavity 120 and the bottom of the bearing platform 2, and at the same time allows the high-damping elastomer material 121 to abut against the bottom of the bearing platform 2.

[0028] The outer steel casing 101 and the necked inner steel casing 102 are equipped with variable diameter cast-in-place piles 103, thus forming an integrated vertical section 10 and a necked connecting section 11. The top of the reinforcing cage inside the variable diameter cast-in-place pile 103 passes through the top of the necked inner steel casing 102 and is anchored to the pile cap 2, ensuring that the pile body still has good structural continuity, bending bearing capacity and load transfer capacity in the variable cross-section area.

[0029] In a preferred embodiment, the necked inner steel casing 102 includes a tapered cylinder 1022 that is wider at the bottom and narrower at the top, and a narrow-diameter vertical cylinder 1020 that is connected to the narrow opening at the top of the tapered cylinder 1022.

[0030] In the preferred embodiment, a sealing ring 1021 is provided on the outside of the wide opening at the bottom of the conical cylinder 1022. The sealing ring 1021 is adapted to the inner diameter of the outer steel casing 101, and a sealing ring is fitted on its outside, so as to seal the bottom of the annular filling cavity 120, which facilitates the casting and grouting of the variable diameter cast-in-place pile 103 and the high damping elastic covering sleeve 12.

[0031] Example 2 To further illustrate with reference to Example 1, a construction method for a pile foundation structure of a V-shaped pier rigid frame bridge is provided, the method comprising: S1. Process the outer steel casing 101 and the necked inner steel casing 102 respectively. The outer diameter of the necked inner steel casing 102 is smaller than the inner diameter of the outer steel casing 101, and its length is designed so that its top is higher than the top surface of the outer steel casing 101 after installation. The specific outer diameter of the necked inner steel casing 102 is determined according to the required size of the annular filling cavity 120.

[0032] S2. Using a large crane or vibratory hammer, the outer steel casing 101 is gradually lowered to the designed pile position. Then, a hole of the designed diameter is drilled in the center of the outer steel casing 101 using a rotary drilling rig or impact drill. During the drilling process, a pile head guide device is set to ensure that the drilling is concentric with the steel pipe. The drilling depth must exceed the designed elevation of the pile bottom, that is, below the embedment point, to reach the bearing layer. Then, the hole is cleaned until the sediment thickness meets the standard.

[0033] S3. Process the reinforcing cage of the variable diameter cast-in-place pile 103 and hoist it into the outer steel casing 101. During the hoisting process, ensure that the reinforcing cage is located in the center of the steel pipe and maintain the designed gap with the inner wall of the steel pipe. The necked inner steel casing 102 is installed into the outer steel casing 101 by a step-by-step hoisting and assembly method with the reinforcing cage or a pre-assembled overall hoisting method, thereby forming an annular filling cavity 120 between the outer steel casing 101 and the necked inner steel casing 102. After installation, the top of the necked inner steel casing 102 is higher than the top surface of the outer steel casing 101, and the top of the reinforcing cage passes through the necked inner steel casing 102. The necked inner steel casing 102 is fixed in the outer steel casing 101 by the reinforcing cage.

[0034] The assembly method after the step-by-step hoisting is as follows: After the steel cage is hoisted, the necked inner steel casing 102 is hoisted separately to the top of the outer steel casing 101 and fitted onto the outside of the upper section of the narrowed diameter of the steel cage. Then, it is fixed to the steel cage and the outer steel casing 101 by welding or mechanical connectors.

[0035] The pre-assembled overall hoisting method is as follows: the necked inner steel casing 102 is pre-installed and fixed to the outer periphery of the upper section of the narrowed diameter of the steel cage, and then hoisted into the outer steel casing 101 synchronously with the steel cage to achieve integrated positioning.

[0036] S4. The bottom of the closed annular filling cavity 120 is sealed, and underwater concrete is poured into the constricted inner steel casing 102 and the outer steel casing 101 of the conduit through the insertion of the conduit until it reaches the top surface of the constricted inner steel casing 102, thereby forming a variable diameter cast-in-place pile 103.

[0037] S5. Seal the top of the annular filling cavity 120, ensuring that the sealing height meets the molding height of the high-damping elastomer material 121. Then, install the injection pipe 41 and the exhaust overflow pipe 42. Finally, perform a pressure or vacuum test on the annular filling cavity 120 to ensure that the annular filling cavity 120 is sealed and leak-free.

[0038] S6. Using specialized mixing and grouting equipment, the high-damping elastomer material 121 is uniformly pressed into the grouting pipe 41. After pressing, according to the material characteristics, constant temperature and pressure conditions are maintained to allow it to fully solidify and form a uniform and continuous flexible interlayer, thus completing the construction of a single pile foundation 1.

[0039] S7. After completing the construction of all pile foundations 1, hoist the shell of the pier cap 2 into place, and slowly press the top of the high-damping elastomer material 121 down until the shell of the pier cap 2 reaches the design elevation. At this time, the high-damping elastomer material 121 is compressed and closely abuts against the bottom surface of the pier cap 2. At the same time, the top of the steel cage of the variable diameter cast-in-place pile 103 is inserted into the shell of the pier cap 2 to fix the shell of the pier cap 2. The construction of the pier cap 2 and the V-shaped rigid frame 3 on it is then completed.

[0040] Example 3 Further explanation in conjunction with Example 2, such as Figures 5-16 To achieve the injection of the high-damping elastomer material 121 in Embodiment 2, this embodiment also proposes an injection device 4, which includes a sealing cover 40 covering the top of the annular filling cavity 120 to seal it, a plurality of retractable injection pipes 41 extending through the sealing cover 40 into the annular filling cavity 120, a plurality of exhaust overflow pipes 42 disposed on the sealing cover 40, a lifting mechanism 43 disposed outside the sealing cover 40 and used to control the lifting and lowering of the injection pipes 41, and an anti-detachment block 44 for temporarily fixing the sealing cover 40 and the variable-diameter injection pile 103 through the reinforcing cage.

[0041] With this design, the annular filling cavity 120 can be filled through the injection pipe 41. During the injection process, the injection pipe 41 is raised synchronously with the liquid level in the cavity by the lifting mechanism, thereby filling the high-damping elastomer material 121 by pouring. This avoids the formation of unwanted air bubbles or voids in the high-damping elastomer material 121, which would affect its performance. The exhaust overflow pipe 42 at the top is used to directly exhaust the air. When the exhaust overflow pipe 42 overflows the high-damping elastomer material 121, the high-damping elastomer material 121 is poured.

[0042] The sealing cover 40 includes a closed annular groove-shaped cover 401 that can be fitted onto the outside of the outer steel casing 101. The diameter of its central hole is adapted to the outer diameter of the necked inner steel casing 102, and a hoisting annular groove-shaped cover 402 is provided on it and suspended on the top of the necked inner steel casing 102.

[0043] Both the closed annular groove cover 401 and the hoisting annular groove cover 402 are composed of a horizontal ring plate and a side wall extending downward along its outer edge. The depth of the closed annular groove cover 401 meets the requirements of the molding height of the high-damping elastomer material 121 after installation.

[0044] With this design, the closed annular groove cover 401 can be fitted onto the top of the outer steel casing 101 to seal it. At the same time, the annular groove cover 402 can be hoisted onto the necked inner steel casing 102, thereby fixing the closing height of the closed annular groove cover 401. The central hole of the hoisted annular groove cover 402 can avoid interference with the variable diameter cast-in-place pile 103.

[0045] It should be noted that sealing rings are provided at the connection between the closed annular groove cover 401 and the outer steel casing 101, and at the connection between the hoisted annular groove cover 402 and the necked inner steel casing 102.

[0046] The anti-loosening bolt block 44 is specifically inserted under the lowest stirrup at the end of the steel cage and presses on the hoisting annular trough cover 402.

[0047] The horizontal ring plate of the closed annular groove cover 401 is provided with a plurality of intersecting telescopic holes 410 and vent holes 420. The injection pipe 41 is telescopically installed in the telescopic hole 410, and a sealing ring is provided between the two. The vent overflow pipe 42 is connected to the vent hole 420.

[0048] The bottom of the telescopic hole 410 is provided with a fitting groove 411 with a diameter larger than that of the hole. A fitting sealing ring 4110 is installed in the fitting groove 411. The bottom end of the injection pipe 41 is provided with a fitting ring 412 that can fit into the fitting groove 411.

[0049] With this design, when the injection tube 41 is raised to the top, the fitting ring 412 fits into the fitting groove 411, thereby forming a flat bottom of the closed annular groove-shaped cover 401 and squeezing the fitting sealing ring 4110 to form a sealing structure, ensuring the subsequent pressure holding process.

[0050] In a preferred embodiment, the lifting mechanism 43 includes an extension ring 403 disposed outside the closed annular groove-shaped cover 401. The extension ring 403 is provided with a plurality of mounting holes 4031, and a lifting telescopic cylinder 431 is installed in the mounting holes 4031. In this embodiment, the lifting telescopic cylinder 431 is a hydraulic cylinder. A lifting ring 430 is installed on the telescopic end at the top of the lifting telescopic cylinder 431. The diameter of the central hole of the lifting ring 430 is larger than the outer diameter of the hoisting annular groove-shaped cover 402. The top of the injection pipe 41 is fixed through and fixed on the lifting ring 430.

[0051] With this design, the lifting ring 430 can be lifted by lifting the telescopic cylinder 431, thereby driving the injection pipe 41 to be lifted synchronously until the fitting ring 412 is fitted into the corresponding fitting groove 411.

[0052] In use, the grouting device 4 is hoisted onto the outer steel casing 101 and the necked inner steel casing 102, and the top of the reinforcing cage of the variable diameter cast-in-place pile 103 is made to pass through the central hole of the grouting device 4. Then, the anti-detachment block 44 is inserted into the reinforcing cage to press down the grouting device 4. Then, the exhaust overflow pipe 42 is closed and the annular filling cavity 120 is sealed through the grouting pipe 41. After the test is completed, the grouting pipe 41 is connected to the mixing and grouting equipment to grout the high damping elastomer material 121. During the grouting process, the grouting pipe 41 is gradually lifted by the lifting mechanism 43 until the fitting ring 412 is fitted into the corresponding fitting groove 411. When the high damping elastomer material 121 overflows from the exhaust overflow pipe 42, the grouting is completed. The exhaust overflow pipe 42 is closed and constant temperature and pressure conditions are maintained to allow the high damping elastomer material 121 to fully solidify and form.

[0053] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A pile foundation structure for a V-shaped pier rigid frame bridge, comprising a pile cap (2) and multiple pile foundations (1) disposed at the bottom of the pile cap (2), characterized in that: The pile foundation (1) includes a vertical section (10) embedded in the bearing layer. A reduced diameter connecting section (11) is provided at the top of the vertical section (10). The top of the reduced diameter connecting section (11) is anchored to the pile cap (2), and a high-damping elastic covering sleeve (12) is provided on its exterior, which forms a local flexible zone at the connection between the pile foundation (1) and the pile cap (2).

2. The pile foundation structure for a V-shaped pier rigid frame bridge according to claim 1, characterized in that: The high-damping elastic sheath (12) includes an annular filling cavity (120) located outside the reduced diameter connecting section (11). The annular filling cavity (120) is filled with a high-damping elastomer material (121). A gap is provided between the outer wall of the annular filling cavity (120) and the bottom of the support (2). The top of the high-damping elastomer material (121) inside it abuts against the bottom surface of the support (2).

3. The pile foundation structure for a V-shaped pier rigid frame bridge according to claim 2, characterized in that: The outer diameter of the high-damping elastic covering sleeve (12) is the same as the outer diameter of the vertical section (10). The radial thickness and height of the annular filling cavity (120) are determined according to the volume and shear deformation requirements of the high-damping elastomer material (121) required at the location of the pile foundation (1).

4. The pile foundation structure for a V-shaped pier rigid frame bridge according to claim 2 or 3, characterized in that: The vertical section (10), the reduced diameter connecting section (11), and the annular filling cavity (120) are composed of an outer steel casing (101) and a necked inner steel casing (102). The outer steel casing (101) extends vertically along the pile body to form the outer shell of the vertical section (10). The necked inner steel casing (102) is coaxially sleeved on its top. The top of the necked inner steel casing (102) is higher than the outer steel casing (101). The two together constitute the outer shell of the reduced diameter connecting section (11). The cavity formed between the necked inner steel casing (102) and the outer steel casing (101) is the annular filling cavity (120). The outer steel casing (101) and the necked inner steel casing (102) are equipped with variable diameter cast-in-place piles (103), forming an integrated vertical section (10) and a necked connecting section (11). The top of the steel cage inside the variable diameter cast-in-place pile (103) passes through the top of the necked inner steel casing (102) and is used to anchor to the pile cap (2).

5. The pile foundation structure for a V-shaped pier rigid frame bridge according to claim 4, characterized in that: The necked inner steel casing (102) includes a tapered cylinder (1022) that is wider at the bottom and narrower at the top, and a narrow-diameter vertical cylinder (1020) connected to the narrow opening at the top of the tapered cylinder (1022).

6. The pile foundation structure for a V-shaped pier rigid frame bridge according to claim 5, characterized in that: The tapered cylinder (1022) has a sealing ring (1021) on the outside of the wide opening at the bottom for sealing the bottom of the annular filling cavity (120). The sealing ring (1021) is adapted to the inner diameter of the outer steel casing (101) and is fitted with a sealing ring on its outside.

7. The construction method for the pile foundation structure of a V-shaped pier rigid frame bridge according to any one of claims 4-6, characterized in that: The method includes: S1. The outer steel casing (101) is gradually lowered to the designed pile position, and then holes are formed inside the outer steel casing (101); S2. The reinforcing cage of the variable diameter cast-in-place pile (103) is hoisted into the outer steel casing (101) and coaxial with its center line. The necked inner steel casing (102) is installed into the outer steel casing (101) by a step-by-step hoisting and assembly method with the reinforcing cage or a pre-assembled overall hoisting method. After the necked inner steel casing (102) is installed, the top of it is higher than the top surface of the outer steel casing (101). S3. The bottom of the closed annular filling cavity (120) is sealed, and underwater concrete is poured into the constricted inner steel casing (102) and the outer steel casing (101) through the conduit until it reaches the top surface of the constricted inner steel casing (102), thereby forming a variable diameter cast-in-place pile (103). S4. The top of the annular filling cavity (120) is closed, and the closing height meets the molding height of the high damping elastomer material (121). An injection pipe (41) and an exhaust overflow pipe (42) are set. Then, the annular filling cavity (120) is subjected to pressure or vacuum testing. S5. Press the high-damping elastomer material (121) into the injection tube (41) at a uniform speed, and after pressing, allow it to fully solidify and form a high-damping elastic covering sleeve (12).

8. The construction method for the pile foundation structure of a V-shaped pier rigid frame bridge according to claim 7, characterized in that: The high-damping elastomer material (121) is injected into the annular filling cavity (120) through the injection device (4). The cavity includes a sealing cover (40) covering the top of the annular filling cavity (120) to seal it, multiple injection pipes (41) that are retractable and extend through the sealing cover (40) into the annular filling cavity (120), multiple exhaust overflow pipes (42) provided on the sealing cover (40), a lifting mechanism (43) provided on the outside of the sealing cover (40) for controlling the lifting and lowering of the injection pipes (41), and an anti-detachment block (44) for temporarily fixing the sealing cover (40) and the variable diameter injection pile (103) through the steel cage.

9. The construction method for the pile foundation structure of a V-shaped pier rigid frame bridge according to claim 8, characterized in that: The sealing cover (40) includes a closed annular groove cover (401) that can be fitted onto the outside of the outer steel casing (101), the diameter of its central hole is adapted to the outer diameter of the necked inner steel casing (102), and a lifting annular groove cover (402) is provided on it and suspended on the top of the necked inner steel casing (102). The anti-loosening block (44) is specifically inserted under the lowest stirrup at the end of the steel cage and pressed on the hoisting annular trough cover (402); The horizontal ring plate of the closed annular groove cover (401) is provided with multiple intersecting telescopic holes (410) and vent holes (420). The injection pipe (41) is telescopically installed in the telescopic hole (410), and a sealing ring is provided between the two. The vent overflow pipe (42) is connected to the vent hole (420). The bottom of the expansion hole (410) is provided with a fitting groove (411) with a diameter larger than that of the expansion hole (410), and a fitting sealing ring (4110) is installed in the fitting groove (411). The bottom end of the injection pipe (41) is provided with a fitting ring (412) that can fit into the fitting groove (411).

10. The construction method for the pile foundation structure of a V-shaped pier rigid frame bridge according to claim 9, characterized in that: The lifting mechanism (43) includes an extension ring (403) disposed outside the closed annular groove cover (401). The extension ring (403) is provided with multiple mounting holes (4031). A lifting telescopic cylinder (431) is installed in the mounting hole (4031). A lifting ring (430) is installed on the telescopic end of the top of the lifting telescopic cylinder (431). The diameter of the central hole of the lifting ring (430) is larger than the outer diameter of the hoisting annular groove cover (402). The top of the injection pipe (41) is fixed through the lifting ring (430).

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