Synchronous pile pressing construction method for pier and abutment fixed connection double piles for pile foundation reinforcement

Abstract

The invention provides a synchronous pile pressing construction method for abutment fixedly connected double piles for pile foundation reinforcement. The synchronous pile pressing construction method comprises the following steps that S1, investigation is conducted; s2, tubular pile production; s3, cutting is conducted, specifically, a surface layer at the corresponding position of the wharf platform is cut off, a construction window is formed, and a working space is provided for follow-up construction; s4, pile sinking; s5, portal frame installation is conducted, specifically, the portal frame is installed on the wharf platform on the two sides of the construction window with the steel pipe piles as the center, the portal frame and the wharf platform form an integrated structure, and two sets of oil cylinders on the portal frame are located at the tops of the two steel pipe piles correspondingly and are parallel to the steel pipe piles; s6, primary pile pressing; s7, manufacturing a fixed connection abutment; s8, secondary pile pressing is conducted; s9, reinforcing piers are manufactured at the tops of the steel pipe piles; and S10, dismounting the portal frame. The synchronous pile pressing construction method for the abutment fixedly-connected double piles for pile foundation reinforcement is simple in construction, convenient and fast to operate, low in construction site requirement, short in construction period, low in cost, high in construction safety and suitable for various old wharf pile foundation reinforcement reconstruction projects.

Description

Technical Field

[0001] This invention relates to a wharf reinforcement method, and more particularly to a synchronous pile driving construction method for fixed double piles of piers and abutments for pile foundation reinforcement. Background Technology

[0002] A high-pile wharf is a type of open hydraulic structure supported by pile foundations. It is mainly used for port construction under soft soil foundation conditions. Its core feature is that the pile foundation driven into the soil and the superstructure form an integral whole. The superstructure directly bears the load (mainly vertical and horizontal loads) and transmits it to the pile foundation. The pile foundation penetrates deep into the bearing layer of the foundation and supports the superstructure.

[0003] Common pile foundation types include straight piles and inclined piles. Straight piles mainly bear vertical loads, while inclined piles mainly bear horizontal loads. A reasonable combination of straight and inclined piles ensures the stability of the overall structure. With the development of the shipping industry, to adapt to the trend of larger ships, optimize cargo matching, conserve shoreline resources, and revitalize idle wharf resources, some old wharves can enhance their port competitiveness at a lower cost and faster speed through renovation and reconstruction.

[0004] During the renovation of high-pile wharves, the original structure often fails to meet the requirements for horizontal bearing capacity, necessitating pile foundation reinforcement. Due to construction constraints, inclined pile driving is often difficult to implement. To enhance the horizontal load bearing capacity of the pile foundation, the common method is to arrange many straight piles, relying on quantity. However, this method has disadvantages such as requiring a large number of piles, high cost, and long construction period.

[0005] Currently, conventional pile driving machinery is designed for the early stages of new construction projects and in open working environments. For example, static pressure pile drivers, which are commonly used for pile driving in civil engineering projects, require large open spaces for construction; pile driving vessels need sufficient open water to ensure their safe operation.

[0006] In summary, when supplementing existing piers with additional piles, the lack of sufficiently open water makes it difficult for piling vessels to operate. Onshore hydraulic static pile drivers are often constrained by existing buildings and equipment on the pier platform, as well as the platform's load-bearing capacity, also making operation difficult. Furthermore, existing piling vessels and hydraulic static pile drivers are only capable of driving single piles. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a synchronous pile driving construction method for pier-type fixed double piles for pile foundation reinforcement that is simple in process, convenient in operation, has low requirements for construction site, stable in structure, and can effectively improve the horizontal bearing capacity.

[0008] This invention provides a synchronous pile driving construction method for fixed double piles in piers for pile foundation reinforcement, comprising the following steps: S1. Survey: Conduct a survey of the construction conditions for the wharf to be constructed. S2. Production: Determine the pile locations and specifications and quantity of steel pipe piles 9 based on the construction conditions and scope, and carry out the production of steel pipe piles 9. S3. Cutting: The surface layer at the corresponding position of the dock platform 3 is cut off to form a construction window 30 and provide working space for subsequent construction. S4. Piling: Using lifting equipment, two steel pipe piles 9 are hoisted to the top of the construction window 30 in sequence. After adjusting their position and verticality, they are slowly lowered. The lower end of the steel pipe pile 9 sinks into the seabed mud layer under its own weight and is initially fixed. S5. Gantry frame installation: With the steel pipe pile 9 as the center, install the gantry frame on the dock platform 3 on both sides of the construction window and make the gantry frame and the dock platform 3 form an integral structure. Make the two sets of hydraulic cylinders 2 on the gantry frame located on the top of the two steel pipe piles 9 respectively and parallel to the steel pipe piles 9. S6. One-time pile driving: A pressure plate is set on the top of the steel pipe pile 9, and two sets of hydraulic cylinders 2 drive the two steel pipe piles 9 synchronously, so that the two steel pipe piles are driven into the first elevation at the same time. S7. Construction of the fixed pier: Weld the fixed pier between the two steel pipe piles 9 to form an integral structure with the two steel pipe piles 9. S8. Secondary pile driving: The two steel pipe piles are driven synchronously by two sets of hydraulic cylinders 2, pressing the fixed pier 91 underwater and driving the two steel pipe piles synchronously to the final elevation. S9. Construct a reinforcing pier 92 on top of the steel pipe pile 9; S10. Dismantle the gantry frame.

[0009] Furthermore, in step S6, at the first elevation, the installation position of the fixed pier is close to the wharf platform surface.

[0010] Furthermore, during the primary or secondary pile driving process, when the hydraulic cylinder 2 reaches its maximum stroke, the hydraulic cylinder 2 resets and places one or more replacement piles 8 on top of the steel pipe pile 9.

[0011] Furthermore, each set of cylinders 2 includes one or more cylinders arranged in parallel and of the same specifications.

[0012] Furthermore, all cylinders 2 are driven by the same hydraulic pump station, ensuring that the output pressure of each cylinder 2 is synchronized with its stroke.

[0013] Furthermore, the connection point between the gantry and the wharf platform, the axis of the hydraulic cylinder 2, and the axis of the steel pipe pile 9 are located in the same plane.

[0014] Furthermore, the fixed pier 91 is a box-type structure welded from steel plates. The box-type structure is equipped with reinforcing bars, and a pouring hole 910 is opened at the top of the box-type structure. Concrete is poured into the box-type structure to form reinforced concrete.

[0015] Furthermore, the gantry frame includes a crossbeam 13 and support units symmetrically fixed at both ends of the crossbeam 13. The support unit includes a longitudinal beam 12 fixedly connected to the crossbeam 13 and support legs 11 disposed at both ends of the longitudinal beam 12. The bottom of the support leg 11 is provided with a support base plate 14. The support base plate 14 is provided with mounting holes 140 and can be fixedly connected to the dock platform 3 by anchor bolts. The bottom surface of the longitudinal beam 12 is provided with one or more hydraulic cylinders 2. The hydraulic cylinders 2, the longitudinal beam 12 and the support legs 11 are located in the same plane.

[0016] Furthermore, the outrigger 11 is inclined to the surface of the dock platform.

[0017] Furthermore, each set of hydraulic cylinders 2 consists of two cylinders, and the center distance between the two cylinders is L=De, where D is the outer diameter of the steel pipe pile and e is the wall thickness of the steel pipe pile 9.

[0018] This invention relates to a synchronous pile driving method for reinforcing piers with double piles, applicable to the pile foundation reinforcement of existing wharves. It is adaptable to most wharf platform operating environments, overcoming the limitations of existing single-pile driving machines, and allows for phased synchronous pile driving of two steel pipe piles. The double-pile pier reinforcement can be completed above water first, followed by synchronous pile driving of both piles to a designated underwater location. This avoids the disadvantages of underwater construction, such as high difficulty, quality control challenges, and high costs, achieving controllable and inspectable construction quality, cost reduction and efficiency improvement, and shortened construction period. This synchronous pile driving method for reinforcing piers with double piles is simple to construct, convenient to operate, requires minimal site conditions, has a short construction period and low cost, and offers high construction safety. It is suitable for various old wharf pile foundation reinforcement and renovation projects. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the gantry frame structure; Figure 2 This is a schematic diagram of the gantry frame from another angle. Figure 3 This is a schematic diagram showing the installation location of the gantry crane; Figure 4 This is a structural schematic diagram of the support base plate of the gantry frame; Figure 5 This is a schematic diagram of a double-pile structure; Figure 6 This is a cross-sectional view of a double-pile structure; In the diagram: 11. Support leg, 12. Longitudinal beam, 13. Cross beam, 14. Support base plate, 140. Mounting hole, 2. Hydraulic cylinder, 3. Wharf platform, 30. Construction window, 8. Replacement pile, 9. Steel pipe pile, 91. Fixed pier, 910. Pouring hole, 92. Reinforced pier. Detailed Implementation

[0020] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0021] See Figures 1-6 This invention provides a synchronous pile driving construction method for fixed double piles in piers for pile foundation reinforcement, comprising the following steps: S1. Survey: Conduct a survey of the construction conditions for the wharf to be constructed. The survey included geological survey, environmental survey, and facility survey; During geological surveys, specialized geological drilling equipment is used to conduct layered sampling and analysis of the geology of the wharf area and surrounding seabed. This clarifies the physical and mechanical properties of each soil layer, such as bearing capacity, compression modulus, and internal friction angle, providing a precise basis for the selection of steel pipe piles and the calculation of pile driving force. Simultaneously, underwater topographic mapping technology can be used to create detailed underwater topographic maps, marking the location, depth, and distribution of seabed obstacles to avoid problems such as pile jamming and misalignment during pile driving.

[0022] During environmental surveys, hydrological conditions such as tides, currents, and waves in the construction area are monitored, and data such as water level changes, flow velocity, and direction at different times are recorded to determine reasonable time windows for pile driving operations, ensuring construction safety and quality. Simultaneously, the ecological environment of the surrounding sea area can be investigated, including the types, distribution, and activity patterns of marine life, to formulate corresponding environmental protection measures, such as setting up pollution barriers and controlling construction noise, to reduce the impact on the marine ecosystem.

[0023] During the facility survey, the structural integrity of the existing wharf platform is inspected, including the damage and load-bearing capacity of the wharf deck, beams, and pile foundations. Its ability to withstand the new pile driving construction is assessed, and the existing wharf is reinforced if necessary. Simultaneously, the distribution of underground pipelines and cables within the construction area is investigated, a pipeline distribution map is drawn, and protective measures are implemented during construction to avoid damage to the pipelines.

[0024] S2. Production: Determine the pile locations and specifications and quantity of steel pipe piles 9 based on the construction conditions and scope, and carry out the production of steel pipe piles 9. Specifically, based on the survey results and the overall planning of the wharf construction, a three-dimensional model was established using BIM technology to simulate the layout of the steel pipe piles, optimize the pile spacing and arrangement, ensure uniform stress on the pile foundation, and meet the wharf's load-bearing requirements.

[0025] At the same time, taking into account the functions of the wharf, such as the tonnage of ships berthing and the weight of cargo loaded and unloaded, the specifications of the steel pipe piles are accurately calculated, including pile diameter, wall thickness, and length, to ensure the strength and stability of the steel pipe piles.

[0026] During the production of steel pipe piles, strict control is exercised over the quality of raw materials. The material and specifications of the steel are inspected to ensure they meet design requirements. Welding quality control is strengthened by employing advanced welding processes and equipment, and non-destructive testing of the welds, such as ultrasonic testing and X-ray testing, to ensure weld quality meets standards.

[0027] Finally, the completed steel pipe piles are subjected to anti-corrosion treatment. Based on the corrosion characteristics of the marine environment, appropriate anti-corrosion coatings and anti-corrosion processes are selected to improve the service life of the steel pipe piles.

[0028] S3. Cutting: The surface layer at the corresponding position of the dock platform 3 is cut off to form a construction window 30 and provide working space for subsequent construction. Based on the layout of the steel pipe piles and the operating space of the construction equipment, the size and shape of the construction window are precisely calculated to ensure that the construction window can meet the requirements of pile driving and pressing operations while minimizing damage to the original wharf platform structure. Cutting equipment, such as diamond wire saws and plasma cutters, is used to cut the surface layer of the wharf platform. Protective railings and warning signs are installed around the cut construction window to prevent personnel and objects from falling. At the same time, the edges of the construction window can be ground to remove sharp corners and avoid scratching personnel or damaging equipment during construction.

[0029] S4. Piling: Using lifting equipment, two steel pipe piles 9 are hoisted to the top of the construction window 30 in sequence. After adjusting their position and verticality, they are slowly lowered. The steel pipe piles 9 sink into the seabed mud layer under their own weight and achieve initial fixation. Based on the weight and length of the steel pipe piles and the conditions of the construction site, select appropriate lifting equipment, such as cranes or floating cranes, to ensure that the lifting capacity and operating range of the lifting equipment meet the construction requirements. Before hoisting, conduct a comprehensive inspection and debugging of the lifting equipment, including the hoisting mechanism, luffing mechanism, and slewing mechanism of the crane, to ensure that the equipment operates normally.

[0030] Positioning and guiding devices, such as guide frames and positioning piles, can be installed above the construction window to assist in the precise positioning of the steel pipe piles. During the hoisting process, measuring equipment such as total stations and levels can be used to monitor the verticality of the steel pipe piles in real time. By adjusting the lifting point position of the hoisting equipment and the lowering speed of the steel pipe piles, the verticality deviation of the steel pipe piles can be kept within the allowable range. After the steel pipe piles have sunk to the initial fixed position, a second measurement and inspection should be conducted to confirm that the position and verticality of the steel pipe piles meet the requirements before proceeding with subsequent construction.

[0031] Since the steel pipe pile 9 itself has a certain weight, and since the seabed mud layer has a certain fluidity, under the weight of the steel pipe pile 9, its lower end can sink into the seabed for a certain length, thus achieving the initial fixation of the steel pipe pile 9.

[0032] S5. Gantry frame installation: With the steel pipe pile 9 as the center, install the gantry frame on the dock platform 3 on both sides of the construction window and make the gantry frame and the dock platform 3 form an integrated structure. After the gantry frame is installed, the corresponding hydraulic cylinder sets for the steel pipe sets are installed at the corresponding positions on the gantry frame. The two sets of hydraulic cylinders 2 are located at the top of the two steel pipe piles 9 and are parallel to the steel pipe piles 9. Based on the specifications of the steel pipe piles, the required pile driving force, and the construction site conditions, a specialized design for the gantry frame is carried out to ensure that the strength, rigidity, and stability of the gantry frame meet the construction requirements. High-quality steel is selected for the fabrication of the gantry frame, and processing and assembly are carried out strictly in accordance with the design drawings. The welding quality of the gantry frame is rigorously inspected.

[0033] The gantry crane is hoisted onto the dock platform on both sides of the construction window using lifting equipment. The position and level of the gantry crane are adjusted to ensure a firm connection between the gantry crane and the dock platform. The gantry crane and the dock platform are then integrated into a single structure through welding or bolting, providing a reliable support foundation for subsequent pile driving.

[0034] Perform hydraulic system debugging on the cylinders on the gantry, check parameters such as cylinder extension and retraction speed and pressure, and ensure that the cylinders operate smoothly and have good synchronization.

[0035] S6. One-time pile driving: A pressure plate is set on the top of the steel pipe pile 9, and two sets of hydraulic cylinders 2 drive the two steel pipe piles 9 synchronously, so that the two steel pipe piles are driven into the first elevation at the same time. Based on the top dimensions of the steel pipe pile and the required driving force, a suitable pressure plate is designed to ensure that the contact area between the pressure plate and the top of the steel pipe pile is uniform, thus avoiding excessive local stress that could lead to deformation of the steel pipe pile.

[0036] During pile driving, the pile driving force and displacement of the two sets of hydraulic cylinders are monitored in real time to ensure that the pile driving speed and penetration of the two steel pipe piles are kept synchronized.

[0037] Meanwhile, during the pile driving process, the elevation and verticality of the steel pipe piles are measured regularly, and the pile driving parameters are adjusted in a timely manner to ensure that the steel pipe piles are driven into the primary elevation simultaneously.

[0038] Real-time analysis of pile driving data is conducted, and the pile driving construction process is adjusted in a timely manner based on geological conditions and the settlement of steel pipe piles to ensure construction quality and safety.

[0039] S7. Construction of the fixed pier: Weld the fixed pier between the two steel pipe piles 9 to form an integral structure with the two steel pipe piles 9. Based on the spacing of the steel pipe piles, the stress conditions, and the usage requirements of the wharf, the structural design of the fixed piers is carried out. The shape, size, and reinforcement method of the piers are reasonably selected to ensure that the connection between the fixed piers and the steel pipe piles is firm and the overall stress is uniform.

[0040] Before welding, the welding area should be cleaned and pre-treated to remove impurities such as oil and rust. Appropriate welding technology and materials should be used, and welding should be carried out in strict accordance with the welding process specifications. Parameters such as welding current, voltage, and welding speed should be controlled to ensure welding quality. Non-destructive testing, such as ultrasonic testing and magnetic particle testing, should be performed on the welded joint to promptly detect and address welding defects and ensure the connection quality between the fixed pier and the steel pipe pile.

[0041] After the fixed piers are manufactured, their surfaces are treated with anti-corrosion coatings and processes similar to those used for steel pipe piles to improve their corrosion resistance.

[0042] Once the fixed pier 91 is welded, the two steel pipe piles 9 form a double-pile structure that is fixed to the pier 91, thus forming an integral structure.

[0043] S8. Secondary pile driving: Two sets of hydraulic cylinders 2 continue to drive the two steel pipe piles synchronously, pressing the fixed pier 91 underwater, and finally driving the two steel pipe piles synchronously to the final elevation. Once the steel pipe piles have been driven to their final elevation, the pile driving operation is stopped, and the elevation and verticality of the steel pipe piles are precisely measured to confirm that they meet the design requirements.

[0044] S9. After the hydraulic cylinder is reset and the replacement pile on the steel pipe pile is removed, a reinforcing pier 92 is made on the top of the steel pipe pile 9. The reinforcing pier forms an integral part with the original wharf platform. S10. Dismantle the gantry frame and clean it up. Construction is complete.

[0045] When constructing old wharves, the existing wharf platform and surrounding area often have limited space, making it extremely difficult for large construction equipment to enter and operate. This construction method relies on the existing wharf platform as the operating base, requiring only the cutting of small construction windows at corresponding locations on the wharf platform to carry out the work, without the need for large-scale site leveling or the creation of new construction access routes around the wharf.

[0046] This method involves first constructing the fixed piers on the water, then pressing the entire double-pile structure underwater. This eliminates the need for complex underwater welding and pouring operations, improving construction efficiency, shortening the construction period, and significantly reducing construction difficulty and cost. Traditional double-pile fixed pier construction requires underwater welding and other critical processes. Underwater welding not only demands extremely high skill levels from welders but also presents challenges such as low visibility, difficulty in controlling welding quality, and significant safety risks for workers. This method transfers the pier construction process to the surface dock platform, allowing workers to complete welding operations in a stable environment, ensuring better welding quality and avoiding the safety risks associated with underwater operations, such as drowning and decompression sickness. Furthermore, equipment debugging, material transportation, and construction management are more convenient on the water, effectively improving construction efficiency.

[0047] Conventional pile driving methods typically require driving and pressing each pile individually, a cumbersome and time-consuming process. This method uses two sets of hydraulic cylinders on a gantry crane to simultaneously drive two steel pipe piles, completing the penetration of both piles in a single operation, significantly reducing repetitive pile driving steps. After driving the piles to the designated elevation in the first operation, the anchoring pier is constructed directly above water, followed by a second round of simultaneous pile driving to press the anchored double-pile structure underwater to the final elevation. Compared to traditional methods, this method offers a more compact construction process, avoiding the time-consuming steps of frequent equipment relocation and adjustment during pile-by-pile construction, effectively shortening the construction cycle.

[0048] In conventional double-pile anchorage construction, key processes such as welding and pouring are mostly carried out underwater, making them concealed works with significant challenges in quality inspection. Inspections are limited to underwater cameras and divers' exploration, making it difficult to comprehensively and accurately assess construction quality. This method transfers the anchorage fabrication to the water, making the entire construction process visible. Welding quality and concrete pouring quality can be rigorously inspected using conventional methods such as visual observation and non-destructive testing, allowing for timely detection and remediation of quality defects and significantly reducing construction difficulty.

[0049] Traditional pile replacement methods require a large number of straight piles to meet the horizontal load-bearing capacity requirements of pile foundations, leading to a significant increase in pile foundation material costs and a greater investment of construction equipment and manpower. This method, through the use of double piles connected to piers, significantly improves the bearing capacity and structural stiffness of a single pile foundation, and can significantly reduce the number of replacement piles while achieving the same bearing capacity requirements. Furthermore, the reduction in the number of replacement piles also correspondingly reduces the frequency and operating costs of lifting equipment and pile driving equipment, further saving construction costs.

[0050] Finally, wharf construction projects often need to be carried out while ensuring the normal operation of the wharf. The longer the construction period, the greater the impact on wharf operations and the greater the operational losses. This method, by simplifying the construction process and improving construction efficiency, effectively shortens the construction period and can quickly restore the wharf's normal usability. The shortened construction period also reduces management costs and safety risk costs during the construction process, further improving the overall economic benefits of the project.

[0051] To further facilitate the welding of the fixed pier 91, in this embodiment, the installation position of the fixed pier is close to the wharf platform surface when the first pile driving is completed.

[0052] The fixed-position pier is installed close to the wharf platform, allowing workers to operate directly near the platform without the need for complex high-altitude or underwater work platforms. Workers enjoy stable standing positions and ample hand space, enabling more precise control of welding angles and speeds, significantly reducing the difficulty of welding operations. In traditional underwater or high-altitude welding scenarios, workers require diving equipment or suspended cages, restricting their movement and compromising welding accuracy. This solution allows workers to operate close to the wharf platform, making construction convenient and safe. Welding operations on water and at heights face numerous safety risks, such as drowning, electric shock, and decompression sickness in underwater welding, and falls and falling objects in high-altitude welding. This solution transfers welding operations to the vicinity of the wharf platform, completely avoiding the safety risks of complex underwater environments and high-altitude operations. Furthermore, the wharf platform offers a wide field of vision and good ventilation, allowing for the timely removal of harmful gases generated during welding, effectively protecting worker health and reducing occupational hazards.

[0053] Meanwhile, the stable working environment near the dock platform is unaffected by external factors such as water flow, waves, and wind, allowing welding parameters to remain stable and preventing defects such as porosity, cracks, and lack of fusion in the weld due to environmental fluctuations. Furthermore, workers can clearly observe the weld pool in real time and adjust welding techniques promptly to ensure aesthetically pleasing and high-quality welds. For critical welds, non-destructive testing can be performed at any time during the welding process to promptly identify and repair quality issues, ensuring the welding quality of the fixed piers and steel pipe piles from the source.

[0054] During construction, there is no need to build underwater or high-altitude operating platforms, saving significant costs in platform construction materials and labor. Furthermore, improved welding quality reduces rework costs due to weld defects, while increased welding efficiency shortens the project duration and reduces time costs associated with equipment rental and labor. In addition, the improved safety of the working environment reduces the probability of accidents, preventing economic losses and project delays caused by incidents.

[0055] In this embodiment, the fixed pier 91 is a box-type structure welded from steel plates. Specifically, the box-type structure includes two side plates, a top plate, and a bottom plate. The two side plates are parallel to each other and are fixedly attached between two steel pipe piles 9. The distance between the two side plates is basically the same as the diameter of the steel pipe piles 9. The top plate and the bottom plate are fixed to the top and bottom surfaces of the side plates, respectively. An arc-shaped groove with the same diameter as the steel pipe pile is opened at the end of the top plate and the bottom plate for fitting the outer wall of the steel pipe pile. A sealed space is formed between the top plate, the bottom plate, the side plates, and the two steel pipe piles. A reinforcing cage is provided in the sealed space. A pouring hole 910 is opened at the top of the box-type structure. Concrete is poured into the box-type structure to form a reinforced concrete structure. The fixed pier abutment uses a box-type structure to tightly connect two steel pipe piles into a whole, changing the traditional mode of independent force bearing by a single pile. When subjected to horizontal loads, the two steel pipe piles can transfer stress to each other through the box structure, jointly resisting horizontal thrust. This significantly increases the overall horizontal bearing capacity of the pile foundation compared to a single pile, avoiding tilting, breakage, and other damage caused by concentrated stress on a single pile, effectively ensuring the stability of the wharf structure. The welded steel plate box structure itself has good deformation resistance. After the internal reinforced concrete is poured, a steel plate-reinforced concrete composite structure is formed, further enhancing the overall rigidity of the fixed pier abutment. The steel plate can restrain the lateral deformation of the concrete, giving full play to the compressive strength of the concrete; the internal steel cage enhances the tensile and shear resistance of the structure, making the fixed pier abutment less prone to bending, cracking, and other deformations when subjected to complex loads.

[0056] In this application, during the primary or secondary pile driving process, when the hydraulic cylinder 2 reaches its maximum stroke, it resets and places one or more replacement piles 8 on top of the steel pipe pile 9. In pile foundation reinforcement construction, the final penetration depth of the steel pipe pile is often large, while the stroke of a single hydraulic cylinder has a physical limit. By resetting the hydraulic cylinder when it reaches its maximum stroke and adding replacement piles, multiple replacement piles can be sequentially connected to the top of the steel pipe pile, effectively extending the working length at the top of the steel pipe pile. This allows the hydraulic cylinder to continuously apply pressure to the steel pipe pile until the design elevation is reached. This effectively solves the contradiction between insufficient hydraulic cylinder stroke and the required pile driving depth, eliminating the need to replace with a dedicated hydraulic cylinder with a larger stroke, significantly reducing the difficulty and cost of equipment selection. The replacement piles are made of high-strength steel, possessing good compressive strength and structural stability, and can evenly transmit the pile driving force of the hydraulic cylinder to the top of the steel pipe pile. During the pile driving process, the replacement piles avoid localized stress concentration caused by repeated direct contact between the hydraulic cylinder and the top of the steel pipe pile, reducing the risk of deformation and damage to the top of the steel pipe pile. Meanwhile, by precisely controlling the flatness and verticality of the replacement piles, it can be ensured that the pile driving force is always transmitted along the axis of the steel pipe pile, avoiding the tilting or displacement of the steel pipe pile due to force deviation, and ensuring that the verticality and penetration accuracy of the pile foundation meet the design requirements.

[0057] Using replacement piles eliminates the need for large-stroke specialized hydraulic cylinders, allowing for deep pile driving operations using standard-sized cylinders, thus reducing equipment procurement costs. Furthermore, the cylinders operate within their rated stroke, significantly reducing wear and malfunction probability, extending equipment maintenance cycles, and minimizing maintenance costs and downtime. Additionally, replacement piles are reusable and can be reused across multiple projects, further reducing the overall cost of renovation and construction.

[0058] In this application, each set of hydraulic cylinders 2 includes one or more hydraulic cylinders arranged in parallel and of the same specifications, which can ensure the synchronous pile driving action of multiple hydraulic cylinders, avoid the excessive settlement difference of the two piles due to the lag in response of a single hydraulic cylinder or pressure fluctuation, and provide structural protection for the synchronous settlement of the two piles; in this embodiment, all hydraulic cylinders 2 are driven by the same hydraulic pump station, which can ensure the synchronization of the output pressure and stroke of each hydraulic cylinder 2.

[0059] In this embodiment, the connection point between the gantry and the wharf platform, the axis of the hydraulic cylinder 2, and the axis of the steel pipe pile 9 are located in the same plane. When the connection point between the gantry and the wharf platform, the axis of the hydraulic cylinder, and the axis of the steel pipe pile are located in the same plane, the pile driving force applied by the hydraulic cylinder can be transmitted sequentially to the steel pipe pile in a straight line, and finally transmitted to the seabed soil layer through the steel pipe pile. This straight force transmission path avoids secondary stresses such as additional bending moment and shear force caused by the deviation of the force transmission direction, ensuring that the gantry, hydraulic cylinder, steel pipe pile, and each structural component of the wharf platform only bear axial pressure or tension, which conforms to the optimal stress state of material mechanics. If the three components (cylinder, hydraulic cylinder, and steel pipe pile) are not on the same plane, the hydraulic cylinder's driving force will generate a torsional moment in the gantry structure, causing local overload on the gantry components and increasing the risk of structural deformation or even damage. In this design, the gantry primarily bears axial pressure, significantly improving material strength utilization and allowing for a lighter design that reduces steel consumption. During the driving process, the coplanarity of the hydraulic cylinder axis and the steel pipe pile axis ensures that the driving force is always applied along the central axis of the steel pipe pile, effectively preventing tilting due to uneven stress. Simultaneously, the connection point between the gantry and the wharf platform is on the same plane, ensuring the gantry's installation accuracy and preventing cylinder position displacement due to gantry tilt. During construction, when monitoring the verticality of the steel pipe pile using equipment such as a total station, the coplanar structure facilitates real-time adjustment of the hydraulic cylinder position, ensuring the steel pipe pile remains vertical at all times.

[0060] The gantry frame in this embodiment includes a crossbeam 13 and two support units, which are symmetrically fixed at both ends of the crossbeam 13. Each support unit includes a longitudinal beam 12 and legs 11. The longitudinal beam 12 is fixedly connected to the crossbeam, and the legs 11 are fixedly connected to both sides of the longitudinal beam 12. A support base plate 14 is provided at the bottom of the legs 11. The support base plate 14 can fit against the bottom surface. At the same time, the support base plate 14 is provided with several mounting holes 140, which can be fixedly connected to the dock platform by anchor bolts, thereby fixing the gantry frame to the dock platform. One or more hydraulic cylinders 2 are provided on the bottom surface of the longitudinal beam 12, preferably two, and the two hydraulic cylinders 2, the longitudinal beam 12, and the legs 11 are located in the same plane. The crossbeam, longitudinal beam, and legs can be made of square steel, round steel, or I-beam.

[0061] In this embodiment, the support leg 11 is inclined to the dock platform surface, which can increase the distance between the two support legs 11 and the bottom connection point. On the one hand, it can improve the overall installation stability of the gantry frame, and on the other hand, it can expand the lateral span of the overall support base of the gantry frame, so that the main structure of the gantry frame avoids the construction window area and avoids the gantry frame from interfering with the construction area.

[0062] To improve the stability of pile driving, in this embodiment, each set of hydraulic cylinders 2 consists of two cylinders, and the center distance between the two cylinders is L=De, where D is the outer diameter of the steel pipe pile and e is the wall thickness of the steel pipe pile 9. During pile driving, the contact point between the hydraulic cylinder 2 and the steel pipe pile 9 is located at the center of the side wall end of the steel pipe pile 9, and the two pile driving points and the axis of the steel pipe pile 9 are coplanar. This ensures that the pile driving points of the two hydraulic cylinders are accurately located at the center of the side wall end of the steel pipe pile. At this time, the point of application of the pile driving force coincides with the neutral axis of the steel pipe pile wall, avoiding local stress concentration in the pile body caused by the eccentricity of the pile driving force. The two hydraulic cylinders apply pressure synchronously, and the pile driving point is coplanar with the axis of the steel pipe pile, so that the resultant force of the pile driving force is always transmitted along the axis of the steel pipe pile, avoiding torsional moment caused by uneven force on one side. In traditional single-point pile driving, the contact point between the hydraulic cylinder and the pile top is prone to offset due to the flatness of the pile top, resulting in pile torsion, increasing the frictional resistance between the pile body and the soil layer, and even causing the pile body to tilt. The symmetrical pressure application by the dual hydraulic cylinders can automatically offset minor contact deviations, ensuring that the pile remains vertical. Simultaneously, the symmetrical pressure application by the dual hydraulic cylinders makes the force on the gantry more even, reducing the risk of tilting or instability due to excessive force on one side.

[0063] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A synchronous pile driving construction method for fixed double piles in piers for pile foundation reinforcement, characterized in that, Includes the following steps: S1. Survey: Conduct a survey of the construction conditions for the wharf to be constructed. S2. Production: Determine the pile locations, specifications, and quantities of steel pipe piles based on construction conditions and scope, and carry out the production of steel pipe piles. S3. Cutting: The surface layer of the corresponding location on the dock platform is cut off to form a construction window and provide working space for subsequent construction. S4. Piling: Using lifting equipment, two steel pipe piles are hoisted to the top of the construction window in sequence. After adjusting their position and verticality, they are slowly lowered. The lower end of the steel pipe pile sinks into the seabed mud layer under its own weight and is initially fixed. S5. Gantry crane installation: With the steel pipe pile as the center, install the gantry crane on the dock platform on both sides of the construction window and make the gantry crane and the dock platform form an integrated structure. Make the two sets of hydraulic cylinders on the gantry crane located on the top of the two steel pipe piles and parallel to the steel pipe piles. S6. One-time pile driving: A pressure plate is set on the top of the steel pipe pile, and two sets of hydraulic cylinders drive the two steel pipe piles synchronously, so that the two steel pipe piles are driven into the first elevation at the same time. S7. Construction of fixed pier: Weld a fixed pier between two steel pipe piles. The two steel pipe piles are fixedly connected through the fixed pier and form an integral structure. S8. Secondary pile driving: Two sets of hydraulic cylinders are used to drive the two steel pipe piles synchronously, pressing the fixed pier into the water and driving the two steel pipe piles into the final elevation simultaneously. S9. Construct a reinforcing pier on top of the steel pipe pile; S10. Dismantle the gantry frame.

2. The synchronous pile driving construction method for pier-supported double piles for pile foundation reinforcement as described in claim 1, characterized in that: In step S6, at the first elevation, the installation position of the fixed pier is close to the wharf platform surface.

3. The synchronous pile driving construction method for pier-supported double piles for pile foundation reinforcement as described in claim 1, characterized in that: During a single or double pile driving process, when the hydraulic cylinder reaches its maximum stroke, the cylinder resets and one or more replacement piles are placed on top of the steel pipe pile.

4. The synchronous pile driving construction method for pier-supported double piles for pile foundation reinforcement as described in claim 1, characterized in that: Each group of hydraulic cylinders includes one or more hydraulic cylinders arranged in parallel and of the same specifications.

5. The synchronous pile driving construction method for pier-supported double piles for pile foundation reinforcement as described in claim 1, characterized in that: All cylinders are driven by the same hydraulic pump station, ensuring that the output pressure of each cylinder is synchronized with its stroke.

6. The synchronous pile driving construction method for pier-supported double piles for pile foundation reinforcement as described in claim 1, characterized in that: The connection point between the gantry and the wharf platform, the axis of the hydraulic cylinder, and the axis of the steel pipe pile are all located in the same plane.

7. The synchronous pile driving construction method for pier-supported double piles for pile foundation reinforcement as described in claim 1, characterized in that: The fixed pier is a box-type structure welded from steel plates. The box-type structure contains reinforcing bars, and a pouring hole is opened at the top of the box-type structure. Concrete is poured into the box-type structure to form reinforced concrete.

8. The synchronous pile driving construction method for pier-supported double piles for pile foundation reinforcement as described in claim 1, characterized in that: The gantry includes a crossbeam and support units symmetrically fixed at both ends of the crossbeam. Each support unit includes a longitudinal beam fixedly connected to the crossbeam and legs disposed at both ends of the longitudinal beam. The bottom of each leg is provided with a support base plate, which has mounting holes and can be fixedly connected to the dock platform by anchor bolts. One or more hydraulic cylinders are provided on the bottom surface of the longitudinal beam, and the hydraulic cylinders, the longitudinal beam, and the legs are located in the same plane.

9. The synchronous pile driving construction method for pier-supported double piles for pile foundation reinforcement as described in claim 1, characterized in that: The outriggers are inclined to the dock platform surface.

10. The synchronous pile driving construction method for pier-supported double piles for pile foundation reinforcement as described in claim 1, characterized in that: Each set of hydraulic cylinders consists of two cylinders, and the center distance between the two cylinders is L=De, where D is the outer diameter of the steel pipe pile and e is the wall thickness of the steel pipe pile.

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