Cable-stayed bridge main girder dismantling method based on self-balancing hydraulic jack stress self-adaption

Abstract

The application discloses a kind of based on self-balancing hydraulic jack stress self-adapting cable-stayed bridge girder dismantling method, first, bridge deck accessory structure and paving layer are dismantled, support is erected below main girder and support component is laid out, then self-balancing system and vibration suppression device are set in specified beam section;Then grade is released and corresponding cable-stayed cable is dismantled, diamond rope saw is used to accurately cut closure section and each beam section, cooperate with steel wedge to ensure that cutting is smooth;Afterwards, beam section dismantling, hoisting operation are circulated and advanced, support system is adjusted simultaneously to maintain structural stability;Finally, block cutting hoisting is carried out on 0X# beam section and other key positions, and full-bridge dismantling is completed.The method of the application optimizes traditional four-point statically indeterminate support to three-point statically determinate support system, forms isobaric support unit by parallel connection of two groups of oil cylinders, cooperates with closed-loop hydraulic system with energy accumulator, can self-adaptively compensate beam body sagging and upwarp displacement, realizes beam body stress smooth release, effectively avoids structural disturbance, improves construction safety and efficiency.

Description

Technical Field

[0001] This invention belongs to the field of bridge demolition technology, and more specifically, relates to a method for demolishing the main beam of a cable-stayed bridge based on stress self-adaptation of a self-balancing hydraulic jack. Background Technology

[0002] With the upgrading of urban infrastructure and the optimization of transportation networks, the demolition of existing cable-stayed bridges is increasing. As a complex bridge structure with a long span and high self-weight, the demolition of cable-stayed bridges is characterized by complicated procedures, complex stress, and high safety risks. Among these, the stability of the beam segment support system is the core key to ensuring the safety of the entire demolition process.

[0003] Currently, the industry generally adopts a segmented cutting and dismantling method for the demolition of cable-stayed bridges. This involves cutting and separating the main beams according to the original construction segments or design-defined blocks, and then lifting them off the site using hoisting equipment to gradually complete the demolition of the entire bridge. However, due to the enormous self-weight of the main beams of cable-stayed bridges, and the gradual release of prestress and continuous changes in stress state during the cutting process, coupled with the influence of factors such as construction site conditions, aging of existing structures, and track flatness deviations, the beam segment support system needs to continuously withstand dynamic loads, placing extremely high demands on its stability and adaptability.

[0004] In existing technologies, the support methods for beam segments during the demolition of cable-stayed bridges mostly employ rigid support structures such as steel piers, jacks, and ordinary jacks. The inherent drawback of such rigid support structures is that their support height and force are fixed, making them unable to adapt to the minute deformations that occur during beam cutting and prestress release. They are also ill-equipped to handle stress distribution changes caused by track unevenness and beam center of gravity shifts. This easily leads to uneven stress at the support points, resulting in problems such as localized overload, support detachment, or structural instability. In severe cases, it can cause beam cracking and overturning, posing a significant threat to construction safety.

[0005] Furthermore, during the dismantling of cable-stayed bridges, the tensioning of the stay cables is a crucial process affecting the stress state of the beam. As the main load-bearing components of the main beam, the tensioning process of the stay cables causes abrupt changes in the beam's stress system, leading to a redistribution of stress and resulting in deformations such as upward tilting, downward deflection, or lateral swaying at the beam ends. If the support system cannot respond to these stress changes and deformations in real time, and cannot dynamically adjust and compensate for the support force in a timely manner, it will further exacerbate the stress imbalance of the beam, easily causing beam torsion, local structural damage, and even safety accidents such as hoisting jamming and equipment damage. In addition, traditional rigid support systems lack effective stress monitoring and automatic control mechanisms, requiring real-time observation and manual adjustment. This not only increases the intensity of manual labor but also results in low adjustment accuracy and slow response speed, failing to meet the real-time and precision requirements of the support system under complex dismantling conditions. Summary of the Invention

[0006] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a method for dismantling the main girder of a cable-stayed bridge based on stress self-adaptive self-balancing hydraulic jacks. The traditional four-point statically indeterminate support system is optimized into a three-point statically determinate support system. Two sets of hydraulic cylinders are connected in parallel to form an isobaric support unit. Combined with a closed-loop hydraulic system with an accumulator, it can adaptively compensate for the downward and upward displacement of the girder. Pressure sensors enable automatic pressure stabilization and overload protection, ensuring support stability. Construction employs a "first close the closure section, then the standard girder section, and place a jack for every two girder sections dismantled" approach. The cable-stayed bridge employs a cyclical process where multiple pairs of stay cables are released after the main tower is dismantled, and then the bridge is dismantled in sections from top to bottom. Block 0 is hoisted in sections after the main tower is dismantled, gradually releasing internal forces. The closure section uses an inverted V-shaped cutting line and steel wedge design, combined with fixed pre-jacking force and diamond wire saw static cutting to avoid jamming and structural disturbance. At the same time, a self-balancing system and vibration damping device are installed in the closure section and adjacent beam sections to constrain beam displacement and vibration. The overall process is standardized and reusable, taking into account construction safety, precision and efficiency, and is suitable for the dismantling of cable-stayed bridge main beams under complex working conditions.

[0007] To achieve the above objectives, a method for dismantling the main girder of a cable-stayed bridge based on stress self-adaptation using a self-balancing hydraulic jack, according to the present invention, includes the following steps: S100: First, remove the bridge deck ancillary structures and bridge deck pavement layer, and erect scaffolds under the main beams of the cable-stayed bridge and the main beams of the continuous beam bridge. Support components are installed between the 6L# and 7L# beam segments of the main beams of the continuous beam bridge and the closure section, 28X# to 31X# beam segments of the main beams of the cable-stayed bridge and the scaffolds. S200: Self-balancing systems are installed between the 7L# beam segment of the main beam of the continuous beam bridge, the closure segment of the main beam of the cable-stayed bridge, and the 31X# beam segment and the support. At the same time, vibration damping devices are installed between the closure segment and the top of the main beam of the continuous beam bridge. S300: Implement multiple rounds of graded tension release for cables #14 and #15, gradually releasing cable force until complete unloading, and then disconnect the anchorage connection between cables #14 and #15 and the main beam of the continuous beam bridge and the main beam of the cable-stayed bridge; S400: Using specialized cutting equipment, the closure section is cut according to the preset cutting line, and then the closure section is lifted and moved as a whole by hoisting equipment to complete the dismantling of the closure section; S500: Install support components between the 26X# to 27X# beam segments of the main girder of the cable-stayed bridge and the support frame. Perform graded tensioning of the 13# cable-stayed cable until the cable force is completely unloaded. Then, release the anchorage connection between the 13# cable-stayed cable and the main girder of the cable-stayed bridge. Remove the self-balancing system under the 7L# beam segment of the continuous beam main girder and install it between the 30X# beam segment and the support frame. Use cutting equipment to cut the 31X# and 30X# beam segments sequentially along the preset cutting line. After cutting, use hoisting equipment to lift the two beam segments away from the support frame. S600: Move the support components located at the bottom of beam segments 31X# and 30X# to the bottom of beam segments 24X# and 25X#. Implement graded tensioning of cable 12# until the cable force is completely unloaded. Then, remove the anchorage connection between cable 12# and the main beam of the cable-stayed bridge. Move the self-balancing system at the bottom of beam segments 31X# and 30X# to the bottom of beam segments 28X# and 29X#. Use cutting equipment to cut beam segments 28X# and 29X# sequentially along the preset cutting line. After cutting, use hoisting equipment to lift the two beam segments away from the support. S700: Repeat the construction procedure of step S500 above, and cyclically advance the beam segment demolition operation until the demolition of beam segment 6X# and beam segment 7X# is completed; S800: Install support components between beam segments 0X# and 1X# and the support frame. Move the self-balancing system located at the bottom of beam segments 6X# and 7X# to the bottom of beam segments 4X# and 5X#. Use cutting equipment to cut beam segments 4X# and 5X# sequentially along the preset cutting line. Repeat the aforementioned demolition process until beam segments 1X# and 2X# are demolished. Use cutting equipment to longitudinally cut beam segment 0# into multiple blocks. Use hoisting equipment to lift the multiple blocks off the support frame to complete the overall demolition work.

[0008] Furthermore, the bridge deck ancillary structures of the cable-stayed bridge include streetlights, guardrails, and expansion joints. The removal of the streetlights, guardrails, and expansion joints is carried out gradually from the top of the bridge piers to the mid-span, completing the unloading and removal of the bridge deck ancillary facilities.

[0009] Furthermore, the support components are located at the four corners of the bottom of the beam segment, and include steel supports, prefabricated unloading blocks, several steel plates, and rubber plates. The steel supports are located on the top of the secondary longitudinal beam at the top of the support, and the top of the steel supports is provided with prefabricated unloading blocks. Several steel plates are provided on the top of the prefabricated unloading blocks, and a rubber plate is provided between the steel plates and the bottom of the main beam. The steel supports include steel pipes, and steel plates are welded to the top and bottom of the steel pipes.

[0010] Furthermore, step S400 specifically includes the following steps: S410: Use specialized cutting equipment to perform cutting operations along the pre-set cutting line between the closure section and the 7L# beam segment of the main beam of the continuous beam bridge; S420: After the above cutting is completed, the vibration damping device is then removed; S430: Continue to use special cutting equipment to carry out cutting operations along the preset cutting line between the closure section and the 31X# beam segment of the cable-stayed bridge main beam; S440: After all cutting operations are completed, the closure section is hoisted to the designated area using hoisting equipment to complete the dismantling of the closure section.

[0011] Further, in step S200, after the self-balancing system is installed in place, a pre-jacking force of 10t is applied to the closure section through the self-balancing system, and the steel plate in the support assembly is removed, so that a 2cm gap is left between the support assembly and the bottom of the main beam. In steps S500 to S800, after the self-balancing system is installed in place, a pre-jacking force equal to 90% of its own weight is applied to the corresponding beam segment through the self-balancing system, and the steel plate in the support assembly is removed, leaving a 2cm gap between the support assembly and the bottom of the corresponding beam segment.

[0012] Furthermore, the self-balancing system includes four load-sharing cylinders, a first hydraulic system, a second hydraulic system, a third hydraulic system, and a control system. The four load-sharing cylinders are respectively arranged between the four corners of the bottom of the beam segment and the top surface of the secondary longitudinal beam. Among them, the two load-sharing cylinders located on the front or rear side are connected in parallel and connected to the first hydraulic system. The other two load-sharing cylinders are independently connected to the second hydraulic system and the third hydraulic system, respectively. The first hydraulic system, the second hydraulic system, and the third hydraulic system are all connected to the control system and controlled by it.

[0013] Furthermore, the control system of the self-balancing system is configured to: calculate the equivalent dynamic stiffness under different excitation frequencies in real time based on the frequency response model of the equivalent dynamic stiffness of the hydraulic system, and adaptively adjust the support oil pressure according to the calculation results to compensate for the downward deflection and upward warping deformation of the beam. Meanwhile, based on the stress adaptive control convergence time prediction model, the stress adjustment convergence time is quantitatively predicted, and the construction process rhythm is optimized accordingly.

[0014] Furthermore, the cutting line between the closure segment and the main beam of the continuous beam bridge and the main beam of the cable-stayed bridge is set in an inverted V-shape along the longitudinal direction of the bridge. That is, the section of the box girder bottom plate corresponding to the cutting line is contracted inward by 40cm and extended obliquely upward along the contraction position. Except for the closure segment, the cutting lines of the other beam segments are all set in a direction perpendicular to the tangent direction of the main beam.

[0015] Furthermore, during the cutting operation of the closure section, steel wedges are driven into the cutting seam to prevent the cutting chain from jamming. If the cutting chain gets stuck or cannot be removed from the cutting seam, use a pneumatic hammer to break the concrete outside the prestressing tendons, then cut part of the prestressing tendons using an oxygen cutting method, and then continue the cutting operation. For any loose prestressing steel wires produced during the cutting process, use electric welding to weld them in place to prevent the prestressing steel wires from bouncing.

[0016] Furthermore, during the hoisting operation of the closure section, if the ends of the continuous beam main girder and the cable-stayed bridge main girder tilt upwards at the same time, the closure section is lifted by the self-balancing system. The maximum lifting force of the self-balancing system does not exceed the weight of the closure section itself. If it is still not possible to hoist smoothly after lifting, the steel wedges in the cutting joint are removed, and the cutting joint width is widened by cutting equipment. If the ends of the continuous beam and the cable-stayed bridge main beam deflect simultaneously, the beam segments at the ends of the continuous beam and the cable-stayed bridge main beam are lifted using a self-balancing system. The maximum lifting force of the self-balancing system shall not exceed the weight of the beam segment itself. If the beam cannot be lifted smoothly after lifting, the steel wedges in the cutting seam are removed, and the cutting seam width is widened using cutting equipment. If one side of the main beam of a continuous beam and the end of the main beam of a cable-stayed bridge deflects downwards and the other side deflects upwards, the deflected end of the beam is lifted using a self-balancing system. The maximum lifting force of the self-balancing system shall not exceed the weight of the beam itself. If the beam cannot be lifted smoothly after lifting, the closure section is lifted using the self-balancing system. If the above adjustment fails to lift the beam smoothly, cutting equipment is used to widen the cutting joint.

[0017] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects: 1. The present invention relates to a method for dismantling the main girder of a cable-stayed bridge based on stress self-adaptation using self-balancing hydraulic jacks. This method optimizes the traditional four-point statically indeterminate support system into a three-point statically determinate support system. By connecting two sets of hydraulic cylinders in parallel to form an isobaric support unit, the support force is equivalent to a stable three-point support structure. This mechanism avoids torsion, eccentric loading, and warping of the girder, and is unaffected by factors such as the shift of the box girder's center of gravity and differences in the flatness of the support surface. With the help of a closed-loop hydraulic system with an accumulator, it can automatically replenish or return oil according to the deformation of the girder, adaptively compensating for downward deflection and upward warping displacement. With the help of pressure sensors, it can achieve automatic pressure stabilization and overload protection, ensuring constant and controllable support force and strong long-term load stability. This improves the structural safety under complex dismantling conditions. By constructing an equivalent dynamic stiffness frequency response model of the hydraulic system and a stress adaptive control convergence time prediction model, the dynamic characteristics and control efficiency of the support system are accurately quantified, providing theoretical support for adaptive compensation and intelligent control, and further improving the stability and reliability of the support system.

[0018] 2. The present invention relates to a method for dismantling the main girder of a cable-stayed bridge based on stress self-adaptation using self-balancing hydraulic jacks. The method employs a cyclical construction process of "first closing the closure section, then standard beam sections, and releasing one cable stay after every two beam sections are dismantled." The main tower is dismantled in sections from top to bottom after multiple pairs of cable stays are released. Block 0 is hoisted in sections after the main tower is dismantled, gradually releasing the internal forces of the structure and avoiding abrupt changes and stress concentration. At the same time, the support components and self-balancing system can be reused. The process is highly standardized, and the construction rhythm is clear and controllable. This method ensures that the main girder and main tower maintain a stable alignment and are free from abnormal deformation during the system transition, while also enabling continuous flow operations, significantly improving dismantling efficiency and shortening the construction period.

[0019] 3. The present invention relates to a method for dismantling the main girder of a cable-stayed bridge based on stress self-adaptation using self-balancing hydraulic jacks. The closure section employs an inverted V-shaped cutting line and steel wedges within the cut, effectively preventing wire saw jamming during cutting and cut obstruction during hoisting, ensuring continuous and smooth dismantling operations. Combined with a fixed pre-jacking force and a self-balancing support system, the alignment and stress state of the closure section can be precisely adjusted, adaptively compensating for upward or downward deformation of the main girders on both sides. Simultaneously, the use of diamond wire saws for static cutting results in low vibration and disturbance, enabling the closure section to be dismantled safely and controllably. This significantly reduces structural cracking, system imbalance, and construction safety risks, laying a stable stress foundation for subsequent segmented dismantling of the main girder.

[0020] 4. The cable-stayed bridge main beam dismantling method based on self-balancing hydraulic jack stress self-adaptation of the present invention can effectively constrain the beam displacement and vibration caused by the release of internal forces during the cutting of the closure section by setting up a self-balancing system under the closure section and adjacent beam sections and cooperating with vibration damping devices. This significantly improves the stability and safety of the main beam structure during dismantling and avoids beam cracking or instability caused by sudden stress changes. Attached Figure Description

[0021] Figure 1 This is a structural diagram of a cable-stayed bridge according to an embodiment of the present invention, which describes a method for dismantling the main girder of a cable-stayed bridge based on stress self-adaptation using self-balancing hydraulic jacks. Figure 2 This is a diagram showing the dismantling layout of the closure section of a cable-stayed bridge main beam dismantling method based on stress self-adaptation of self-balancing hydraulic jacks, according to an embodiment of the present invention. Figure 3 This is a layout diagram of the closure section after dismantling, based on a stress-adaptive self-balancing hydraulic jack according to an embodiment of the present invention. Figure 4 This is a schematic diagram of the dismantling of beam segments 31X# and 30X# based on stress self-adaptation using a self-balancing hydraulic jack, according to an embodiment of the present invention. Figure 5 This is a schematic diagram of the dismantling of beam segments 9X# and 8X# based on stress self-adaptation using a self-balancing hydraulic jack, according to an embodiment of the present invention. Figure 6 This is a structural diagram of a support assembly based on the stress self-adaptation of a self-balancing hydraulic jack, according to an embodiment of the present invention. Figure 7 This is a schematic diagram of a closure segment dividing line based on stress self-adaptation of a self-balancing hydraulic jack, according to an embodiment of the present invention. Figure 8 This is a schematic diagram of the load-equalizing cylinder connection in a self-balancing system based on stress adaptation of a self-balancing hydraulic jack, according to an embodiment of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0023] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0024] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0025] In this patent, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0026] Example 1 like Figure 1-8As shown, this embodiment of the invention provides a method for forming a spatial cable by first paralleling the two cables and then spatially pulling them together, including the following steps: S100: First, remove the bridge deck ancillary structures and bridge deck pavement layer, and erect scaffolds under the main beams of the cable-stayed bridge and the main beams of the continuous beam bridge. Support components are installed between the 6L# and 7L# beam segments of the main beams of the continuous beam bridge and the closure section, 28X# to 31X# beam segments of the main beams of the cable-stayed bridge and the scaffolds. Specifically, for cable-stayed bridges and continuous beam bridges, the construction joints formed during the in-situ casting of the main girder segments serve as natural dividing interfaces. These joints are used as cutting lines to divide the existing bridge into several independent segments. For cable-stayed bridges, the main girder is divided into segments 0X#, 1X# to 31X#, and the closure segment towards the mid-span, with the main tower as the reference point. For continuous beam bridges, the main girder is divided into segments 0L# and 1L# to 7L# towards the mid-span, with the stay cables divided into segments 1# to 15# towards both sides of the main tower. Using existing construction joints as cutting lines avoids densely packed prestressed tendon areas and critical stress sections within the box girder. Furthermore, dismantling is carried out segment by segment according to the original segment division method, ensuring that the stress transmission pattern is similar to the original design and construction state. This results in smooth release of internal forces, easy control of the structural alignment, and effectively reduces the risks of stress concentration, cracking, and instability during dismantling. The construction is highly safe and the process flow is smooth.

[0027] Furthermore, the bridge deck ancillary structures of the cable-stayed bridge include streetlights, guardrails, and expansion joints. The removal of the streetlights, guardrails, and expansion joints is carried out gradually from the top of the bridge piers to the mid-span, completing the unloading and removal of the bridge deck ancillary facilities.

[0028] Furthermore, the support components are located at the four corners of the bottom of the beam segment, and include steel supports, prefabricated unloading blocks, several steel plates, and rubber plates. The steel supports are located on the top of the secondary longitudinal beam at the top of the support, and the top of the steel supports is provided with prefabricated unloading blocks. The top of the prefabricated unloading blocks is provided with several steel plates, and a rubber plate is provided between the steel plates and the bottom of the main beam. The steel supports include steel pipes, and steel plates are welded to the top and bottom of the steel pipes. The prefabricated unloading blocks adopt existing technology, and their specific structure and working principle will not be described in this patent.

[0029] Specifically, during the construction preparation phase, the bridge deck ancillary structures and pavement layer are dismantled first to create conditions for subsequent main beam cutting, cable laying, and hoisting operations. The bridge deck ancillary structures include streetlights, guardrails, and expansion joints. During dismantling, the principle of symmetry, step-by-step, and progressing from the top of the pier to the middle of the span is followed. The ancillary facilities are unloaded symmetrically on each bridge, and the central median guardrail, streetlights, crash barriers, pedestrian railings, and expansion joints are dismantled in sequence to achieve the orderly unloading of the bridge deck ancillary facilities. The bridge deck pavement was removed by milling. First, the asphalt concrete pavement layer was milled, and the waste generated was collected and transported to a designated site for disposal. After milling, the bridge deck base was cleaned and leveled to ensure a clean interface for subsequent construction. After the removal of the bridge deck ancillary structures and pavement, a scaffold was erected under the main beams of the cable-stayed bridge and the continuous beam bridge. After the scaffold was erected and passed inspection, support components were installed between the scaffold and the bottom of beam segments 6L# and 7L# of the continuous beam bridge, as well as the bottom of the closure section and beam segments 28X# to 31X# of the cable-stayed bridge. The scaffold was actively lifted by jacks to ensure close contact between the scaffold and the bottom of the beam, ensuring uniform load-bearing, stability and reliability of the support system, providing a solid support foundation for the subsequent cable tensioning, self-balancing system installation and closure section cutting.

[0030] Furthermore, the net distance between the bottom of the main beam of the cable-stayed bridge and the top of the secondary longitudinal beam of the support is not less than 50cm. By reserving an operating space of not less than 50cm between the bottom of the main beam and the top of the secondary longitudinal beam of the support, the smooth installation, relocation and turnover of equipment such as the self-balancing system and support components can be ensured. At the same time, it provides sufficient operating space for cutting construction, pipeline laying and on-site maintenance. This distance can effectively avoid interference between beam deformation and support structure during construction, improve the operational convenience of hydraulic jacking, alignment adjustment and other procedures, and enhance construction safety and work efficiency.

[0031] S200: Self-balancing systems are installed between the 7L# beam segment of the continuous beam bridge main girder, the closure segment of the cable-stayed bridge main girder, and the 31X# beam segment and the support. Simultaneously, vibration damping devices are installed between the closure segment and the top of the continuous beam bridge main girder. These vibration damping devices are spaced apart along the transverse direction of the bridge. The vibration damping devices utilize existing technology, and their specific structure and working principle are not detailed in this patent. By deploying self-balancing systems and vibration damping devices below the closure segment and adjacent beam segments, the displacement and vibration of the beam caused by the release of internal forces during the cutting process of the closure segment can be effectively constrained. This significantly improves the stability and safety of the main beam structure during demolition, preventing cracking or instability of the beam due to sudden stress changes.

[0032] Furthermore, the self-balancing system includes four load-equalizing cylinders, a first hydraulic system, a second hydraulic system, a third hydraulic system, and a control system. The four load-equalizing cylinders are respectively arranged between the four corners of the bottom of the beam segment and the top surface of the secondary longitudinal beam. The two load-equalizing cylinders located on the front or rear side are connected in parallel and connected to the first hydraulic system. The remaining two load-equalizing cylinders are independently connected to the second and third hydraulic systems, respectively. The first, second, and third hydraulic systems are all signal-connected to the control system and controlled by it. By connecting two load-equalizing cylinders on the same side in parallel to form an isobaric support unit, and cooperating with the other two independently controlled load-equalizing cylinders to form a three-point statically determinate support, it can automatically adapt to the influence of the box girder's center of gravity shift and the unevenness of the support surface, ensuring that the box girder is always stably supported in the same geometric plane. This completely eliminates the risk of beam torsion and warping caused by uneven force distribution at four points of static indeterminate stress. At the same time, the control system performs closed-loop adjustment of each hydraulic system to achieve precise control and adaptive compensation of the lifting force, significantly improving the stability and stress uniformity of the beam segment support and ensuring structural safety throughout the demolition process.

[0033] Specifically, the first, second, and third hydraulic systems have identical structures, each including an oil tank, a hydraulic pump station, an accumulator, a throttle orifice, and a proportional relief valve. The oil suction port of the hydraulic pump station is connected to the oil tank via an oil suction pipe to draw hydraulic oil from the tank. The oil outlet of the hydraulic pump station is connected to the main pressure oil circuit to provide power to the entire hydraulic system. A throttle orifice is connected in series in the oil circuit of the hydraulic cylinder's inlet to regulate the oil flow rate. The main pressure oil circuit is connected to the oil port of the accumulator, the oil inlet of the proportional relief valve, and the working oil port of the hydraulic cylinder. The oil outlet of the proportional relief valve is connected to the oil tank via a return oil pipe to achieve closed-loop regulation of system pressure and overload protection. The accumulator is connected in parallel to the main pressure oil circuit to absorb hydraulic shocks and pressure pulsations, compensate system flow in real time, and stabilize support pressure. The hydraulic cylinder, as an actuator, is connected to the main pressure oil circuit via a hydraulic pipeline and performs lifting and load-bearing actions under the drive of pressurized oil. The return oil from each circuit of the system and the overflow oil from the proportional relief valve all flow into the return oil pipeline and return to the oil tank, forming a closed-loop oil circuit.

[0034] Furthermore, a pressure sensor is installed on the top of the hydraulic cylinder. The pressure sensor, the first hydraulic system, the second hydraulic system, and the third hydraulic system are all connected to the control system signal. The pressure sensor can monitor the internal working pressure of the cylinder in real time. Under the coordinated action of the accumulator and the hydraulic system, the load-sharing cylinder can be automatically replenished with oil and its pressure stabilized in real time: when the beam deflects abnormally due to load changes, causing a decrease in pressure at the corresponding support point, the accumulator automatically replenishes oil to the load-sharing cylinder, pushing the piston rod to extend and automatically compensating for the beam's downward deformation; when the beam tilts upward, causing an increase in pressure in the corresponding cylinder, the oil automatically flows back to the accumulator under the action of pressure difference, and the piston rod retracts accordingly, adaptively compensating for the beam's upward deformation. At the same time, the hydraulic pump station can automatically compensate for the pressure loss of the accumulator, ensuring that the system always maintains the set working pressure. This structure enables continuous and precise control of the lifting force of the load-sharing cylinders, ensuring consistent pressure and balanced force distribution in the parallel support cylinders. Through dynamic oil replenishment and return from the accumulator, it can adaptively compensate for changes in beam shape such as deflection and tilting in real time, automatically balancing support reaction forces and buffering structural vibrations and load fluctuations during cutting and cable release, preventing damage to the beam from sudden pressure changes. The proportional relief valve can adjust the system's working pressure in real time, achieving soft start and smooth unloading, improving system response speed and control accuracy. The overall closed-loop oil circuit structure is compact, with low leakage and high efficiency. Combined with the automatic pressure compensation function, it ensures the self-balancing system remains stable and reliable under long-term loads and complex working conditions, truly achieving adaptive adjustment of the shape and self-balancing of forces, significantly improving the structural safety and construction stability throughout the entire bridge demolition process.

[0035] Furthermore, the control system, based on the equivalent dynamic stiffness frequency response model of the hydraulic system, adjusts the pressure and flow of each hydraulic system in real time to achieve adaptive compensation for the dynamic deformation of the beam. It also uses a stress adaptive control convergence time prediction model to estimate the total time it takes for the self-balancing system to adjust the beam stress to within a preset tolerance, thereby adjusting the construction schedule accordingly. The core control logic of the self-balancing system is based on the equivalent dynamic stiffness frequency response model of the hydraulic system. This model accurately describes the dynamic characteristics of the hydraulic support system under different external excitation frequencies, providing a theoretical basis for adaptive compensation. Its expression is as follows: ; Among them, K eq (ω) represents the equivalent dynamic stiffness (N / m) of the hydraulic system at angular frequency ω. It is a complex value, with its real part representing the stored (elastic) stiffness and its imaginary part representing the dissipative (damping) characteristics. K static Let ω be the static stiffness of the system (N / m). n The natural frequency (rad / s) of the hydraulic-mechanical coupling system is given by ν, χ are dimensionless dynamic correction coefficients representing the fluid inertia effect, viscous damping effect, and system-added mass effect, respectively, determined by the specific parameters of the self-balancing system, and j is the imaginary unit.eq (ω) is the equivalent frequency-dependent damping coefficient (N·s / m).

[0036] K static The static stiffness of the system (N / m) is determined by the compressibility of the oil, the flexibility of the pipeline, and the accumulator. Its calculation formula is: ; Among them, A i E represents the piston area of ​​each hydraulic cylinder. oil V is the effective bulk modulus of the oil (Pa). eff The effective oil volume of the system (m³) 3 ), β acc V is the polyvariance index of the accumulator gas. acc This represents the gas volume of the accumulator.

[0037] ω n The natural frequency (rad / s) of the hydraulic-mechanical coupling system is calculated as follows: ; Wherein, m eq L represents the equivalent mass of the beam segment (kg). eff The effective support length of the hydraulic cylinder is (m).

[0038] C eq (ω) is the equivalent frequency-dependent damping coefficient (N·s / m), calculated as follows: ; Among them, C viscous The hydraulic system viscosity damping coefficient (N·s / m) is determined by the oil viscosity and pipeline friction coefficient, ρ is the hydraulic oil density (kg / m³), Q0 is the rated flow rate of the hydraulic pump station (m³ / s), and C... d Let A be the flow coefficient of the throttling orifice. orifice Where ω is the cross-sectional area of ​​the throttling orifice (m²). c The cutoff frequency (rad / s) represents the damping characteristic.

[0039] In the bridge demolition construction of this embodiment, actions such as cutting, hoisting, and cable tensioning will introduce disturbances of a specific frequency ω. The control system calculates the equivalent dynamic stiffness K of the system under this disturbance in real time through the above model. eq (ω), based on which the pressure and flow of each hydraulic system are actively adjusted, so that K eq(ω) is always maintained within the optimal range, thereby adaptively compensating for the dynamic deformation of the beam and avoiding resonance. This is the core theoretical support for the "stress self-adaptation" of this self-balancing system. The application of this formula enables the system to accurately respond to dynamic load fluctuations during construction, solving the technical defects of traditional hydraulic supports that only consider static stiffness and cannot cope with dynamic disturbances, and significantly improving the stability and control accuracy of the support system.

[0040] Meanwhile, to achieve intelligent management of construction progress and accurately control the rhythm of each process, this embodiment adopts a stress adaptive control convergence time prediction model to predict the time required for the self-balancing system to adjust from the initial state to within the target stress tolerance. This provides a quantitative basis for adjusting the construction rhythm and optimizing resource allocation. Its expression is as follows: ; Where, τ converge τ is the estimated total convergence time (s) for the stress adaptive control system. min Let τ be the theoretical minimum convergence time (s) under ideal conditions, determined by the physical limits of the system; α be the initial error sensitivity coefficient; ‖Δσ‖ be the norm of the initial stress deviation vector (Pa); ε be the preset stress convergence accuracy (Pa); and τ be the initial error sensitivity coefficient. delay denoted as the average delay time (s) for a single control cycle, N is the estimated maximum number of control iterations required; β is the iterative learning efficiency factor (β>0), and k is the control iteration number index, which is dimensionless.

[0041] τ min The calculation formula is: ; Where, ω BW To control the system bandwidth, ζ sys ζ is the actual damping ratio of the system. opt The optimal damping ratio is approximately 0.707.

[0042] α is the initial error sensitivity coefficient, calculated as follows: ; Where w is the control gain, which is adjusted according to the construction accuracy requirements, and σ ref Let be the reference stress, and ‖Δσ‖ be the norm (Pa) of the initial stress deviation vector.

[0043] ‖Δσ‖ is the norm (Pa) of the initial stress deviation vector, calculated as follows: ; Where n is the number of stress monitoring points, σ i，0 For the initial stress, σ i,target The target stress is...

[0044] In this embodiment, the convergence time prediction model is mainly applied to key processes such as closure segment cutting and beam segment demolition: the model predicts τ converge If the estimated time is long, the next cutting or cable laying process will be automatically delayed to ensure that the stress in the beam is fully adjusted to a safe range; by analyzing τ delay The system's structure can identify time bottlenecks in sensors, controllers, or actuators, enabling targeted optimization and improved construction efficiency. Simultaneously, by combining historical construction data, it can estimate the probability distribution of convergence time, achieving dynamic and quantitative assessment of construction risks. This solves the problems of traditional construction, such as the inability to quantitatively predict stress adjustment time and the tendency for disorganized process connections, providing strong support for intelligent management of construction progress.

[0045] Furthermore, to further enhance construction safety, the system also includes a monitoring unit, a data transmission unit, an early warning unit, and a human-machine interaction unit. The monitoring unit connects to the control system via the data transmission unit, and the control system connects to the human-machine interaction unit wirelessly. Together, they achieve real-time monitoring, data acquisition, anomaly early warning, and closed-loop control throughout the entire construction process. The monitoring unit includes a beam monitoring unit, a hydraulic system monitoring unit, and an environmental monitoring unit. Each monitoring unit is wirelessly connected to the data transmission module, which transmits the collected real-time data to the control system. The early warning module is integrated into the control system and the human-machine interaction unit, providing dual early warning. The beam monitoring unit includes multiple stress-strain monitoring points arranged along each segment of the beam. Each monitoring point is equipped with a high-precision strain gauge and a stress sensor for real-time monitoring. The system collects stress data of the beam itself in real time; simultaneously, displacement sensors and vibration sensors are installed on the top and sides of the beam segment to monitor the vertical and lateral displacement and angular deformation of the beam in real time, and to collect the vibration frequency parameters of the beam synchronously. All monitoring data collected by the above beam monitoring sensors are transmitted to the control system in real time, providing basic data support for beam stress regulation; the hydraulic system monitoring unit includes flow sensors and pressure sensors installed in the pipelines of the first, second, and third hydraulic systems, respectively, and a displacement sensor is added to the top of the load-sharing cylinder to monitor the working pressure, oil flow, and cylinder piston rod extension and retraction of each hydraulic system in real time, and to collect the pressure and oil temperature data of the accumulator synchronously. At the same time, it monitors abnormal conditions such as leakage and pressure changes in the hydraulic system, providing real-time data support for the pressure and flow regulation of the control system. The environmental monitoring unit includes deploying environmental monitoring terminals in the construction area to collect environmental parameters such as ambient temperature, humidity, wind speed, and rainfall in real time. At the same time, high-definition cameras and tension sensors are installed at the cable tensioning points and the cutting points of the closure section to monitor the cable tensioning speed, cable force changes, and sudden stress changes in the beam during the cutting process, so as to realize the visualization and digital monitoring of the construction conditions.

[0046] The control system analyzes the real-time data collected by each monitoring unit in real time. Combining the calculation results of the equivalent dynamic stiffness frequency response formula of the hydraulic system and the convergence time prediction formula of stress adaptive control, it determines whether the beam stress, hydraulic system conditions, and construction environment are within a safe range. When the monitoring data exceeds the preset threshold, the early warning module immediately issues an audible and visual warning. At the same time, the control system automatically adjusts the pressure and flow of the hydraulic system or suspends the construction process until the monitoring data returns to a safe range. This forms a closed-loop intelligent management and control system of "monitoring-analysis-early warning-control", which further improves the safety and intelligence level of bridge demolition construction, ensures that the formula calculations are accurately matched with the actual construction conditions, and guarantees the stability and controllability of the entire construction process.

[0047] S300: Multiple rounds of graded tensioning were implemented for stay cables #14 and #15, gradually releasing the cable force until complete unloading. Subsequently, the anchorage connections between stay cables #14 and #15 and the main beams of the continuous beam bridge and cable-stayed bridge were released. The use of multiple rounds of graded tensioning can avoid sudden unloading of cable force, which could cause abrupt changes in the stress and excessive vibration of the main beam and main tower, ensuring a smooth transition of structural stress during cable removal. Synchronous and symmetrical tensioning can ensure balanced stress on both sides of the bridge, effectively control tower deflection, main beam alignment and stress changes, and significantly improve the safety and controllability of the cable removal process.

[0048] S400: Using specialized cutting equipment, the closure section is cut according to the preset cutting line, and then the closure section is lifted and moved as a whole by hoisting equipment to complete the dismantling of the closure section; Furthermore, step S400 specifically includes the following steps: S410: Use specialized cutting equipment to perform cutting operations along the pre-set cutting line between the closure section and the 7L# beam segment of the main beam of the continuous beam bridge; S420: After the above cutting is completed, the vibration damping device is then removed; S430: Continue to use special cutting equipment to carry out cutting operations along the preset cutting line between the closure section and the 31X# beam segment of the cable-stayed bridge main beam; S440: After all cutting operations are completed, the closure section is hoisted to the designated area using hoisting equipment to complete the dismantling of the closure section.

[0049] By adopting a segmented and step-by-step cutting method, excessive stress release during a single cut can be avoided, effectively reducing the impact and vibration on the main beam structure during the cutting of the closure section. The sequence of cutting the continuous beam side first, then removing the vibration damping device, and finally cutting the cable-stayed bridge side can smoothly release the constraint internal force of the closure section, ensuring the structural alignment and stress safety. The overall lifting and moving can ensure the complete removal of the closure section in one go, improving demolition efficiency and construction safety, and reducing disturbance to the surrounding structure.

[0050] S500: Support components are installed between the 26X# to 27X# beam segments of the cable-stayed bridge main girder and the support structure. The 13# stay cable is tensioned in stages until the cable force is completely unloaded. Then, the anchorage connection between the 13# stay cable and the main girder of the cable-stayed bridge is released. The self-balancing system under the 7L# beam segment of the continuous beam main girder is removed and installed between the 30X# beam segment and the support structure. The 31X# and 30X# beam segments are cut sequentially along the preset cutting line using cutting equipment. After cutting, the two beam segments are lifted off the support structure using hoisting equipment. By pre-installing support components and tensioning the stay cables in stages, the internal forces of the structure can be released smoothly, avoiding sudden changes in the stress and alignment of the main girder. The self-balancing system can be reused, which can ensure the support stiffness and stability during beam segment cutting, improve equipment utilization, and reduce construction costs. The method of segmented cutting and overall lifting and moving ensures smooth construction process and can effectively reduce disturbance to adjacent beam segments and the support system, improving the safety and efficiency of demolition construction.

[0051] S600: Move the support components located at the bottom of beam segments 31X# and 30X# to the bottom of beam segments 24X# and 25X#. Implement graded tensioning of cable 12# until the cable force is completely unloaded. Then, remove the anchorage connection between cable 12# and the main beam of the cable-stayed bridge. Move the self-balancing system at the bottom of beam segments 31X# and 30X# to the bottom of beam segments 28X# and 29X#. Use cutting equipment to cut beam segments 28X# and 29X# sequentially along the preset cutting line. After cutting, use hoisting equipment to lift the two beam segments away from the support. By reusing support components and self-balancing systems, the utilization rate of construction equipment can be greatly improved, the amount of repeated erection work can be reduced, and the construction cost can be lowered, while ensuring the support stiffness and stress stability of the beam segments. The staged and symmetrical release of the cable tension can smoothly transition the structural stress, avoiding sudden stress changes, abnormal alignment, and tower deflection exceeding limits in the main beam. The segmented cutting and segment-by-segment lifting method has a tight connection between the work processes, which can effectively control construction disturbance and ensure the overall structural safety and construction efficiency during the demolition process.

[0052] S700: Repeat the construction procedure of step S500 above, and cyclically advance the beam segment demolition operation until the demolition of beam segment 6X# and beam segment 7X# is completed; First, the closure section is demolished. Then, after every two beam sections are demolished, a stay cable is laid, and the demolition work is carried out section by section in this cyclical manner.

[0053] Using a standardized cyclical process for segmental dismantling of beams ensures a clear and controllable construction flow, strong operational consistency, and facilitates on-site organization and safety management. Each segment follows the logic of "support forward movement → graded tensioning of stay cables → rotation and positioning of self-balancing system → segmental cutting → overall lifting and moving," which continuously ensures stable structural stress and controllable alignment, avoiding stress concentration or instability caused by improper dismantling sequence. At the same time, cyclical construction can significantly improve overall dismantling efficiency, shorten the construction period, and reduce the risks of the entire construction process.

[0054] S800: Install support components between beam segments 0X# and 1X# and the support frame. Move the self-balancing system located at the bottom of beam segments 6X# and 7X# to the bottom of beam segments 4X# and 5X#. Use cutting equipment to cut beam segments 4X# and 5X# sequentially along the preset cutting line. Repeat the aforementioned demolition process until beam segments 1X# and 2X# are demolished. Use cutting equipment to longitudinally cut beam segment 0# into multiple blocks. Use hoisting equipment to lift the multiple blocks off the support frame to complete the overall demolition work.

[0055] By continuously reusing the supporting components and self-balancing system, the equipment utilization rate is further improved, and the material input and construction period are reduced. For the small-mileage beam segments near the pier top, the graded and segmented dismantling process is still adopted to ensure that the structural stress always transitions smoothly and avoids stress concentration at the ends. The longitudinal segmenting and hoisting of the 0X# beam segment can reduce the weight of a single hoisting piece, adapt to the on-site hoisting equipment capacity, improve hoisting safety and construction flexibility, and ensure that the overall dismantling construction is completed safely, orderly and efficiently.

[0056] Furthermore, in step S200, after the self-balancing system is installed in place, a pre-jacking force of 10t is applied to the closure section through the self-balancing system, and the steel plate in the support assembly is removed, so that a 2cm gap is left between the support assembly and the bottom of the main beam, and the self-balancing system independently bears the load of the corresponding beam segment. In steps S500 to S800, after the self-balancing system is installed in place, a pre-jacking force equal to 90% of its own weight is applied to the corresponding beam segment through the self-balancing system, and the steel plate in the support assembly is removed, leaving a 2cm gap between the support assembly and the bottom of the corresponding beam segment, so that the self-balancing system can support the force alone.

[0057] By applying a fixed pre-jacking force to the closure section and a pre-jacking force proportional to the self-weight of the standard beam section, the self-weight of part of the beam section can be offset in advance, and the initial stress system can be established smoothly. The 2cm gap can avoid uneven load distribution caused by the joint force of the support components and the self-balancing system, and ensure that the support stiffness and displacement of the beam section are completely controlled by the self-balancing system, so as to realize the adaptive adjustment of internal forces. This method can effectively reduce the sudden stress change and linear fluctuation of the beam body during cutting and cable laying, and significantly improve the structural stability and safety of the entire construction process.

[0058] Furthermore, the cutting line between the closure segment and the main beam of the continuous beam bridge and the main beam of the cable-stayed bridge is set in an inverted V-shape along the longitudinal direction of the bridge. That is, the section of the box girder bottom plate corresponding to the cutting line is contracted inward by 40cm and extended obliquely upward along the contraction position. Except for the closure segment, the cutting lines of the other beam segments are all set in a direction perpendicular to the tangent direction of the main beam.

[0059] Specifically, by designing the cutting line of the closure section as an inverted V-shape, jamming caused by displacement of the cantilever end and shrinkage of the cut can be effectively avoided during the hoisting of the closure section, reducing hoisting resistance and facilitating the smooth removal of the closure section. Simultaneously, the inclined cutting surface reduces the probability of the cut squeezing the wire saw during the cutting process, lowering the risk of chain jamming and improving the smoothness of the cutting operation. The remaining beam segments are cut vertically perpendicular to the tangent line of the main beam, resulting in a neat cutting path and convenient construction. This ensures straight cuts and even stress release, simplifying the cutting process and facilitating the subsequent segmented hoisting of beam segments, thereby improving the overall safety and efficiency of the demolition work.

[0060] Furthermore, during the cutting operation of the closure section, steel wedges are driven into the cutting seam in real time to keep the cutting seam open and prevent the cutting chain from getting stuck due to the narrowing of the cut due to the release of internal forces in the beam. If the cutting chain gets stuck or cannot be removed from the cutting seam, use a pneumatic hammer to break the concrete outside the prestressing tendons, then cut part of the prestressing tendons using an oxygen cutting method, and then continue the cutting operation. For any loose prestressing steel wires produced during the cutting process, use electric welding to weld them in place to prevent the prestressing steel wires from bouncing.

[0061] By placing steel wedges inside the cut, the saw chain can be effectively prevented from being pinched when the cut closes, ensuring a continuous and smooth cutting process and improving construction reliability. Using a pneumatic pick in conjunction with oxygen cutting to deal with chain jamming can quickly resume construction without damaging the main structure, reducing construction interruption time. Welding loose prestressed steel wires can eliminate the safety hazards of prestressed tendons rebounding and injuring people or damaging equipment, significantly improving the safety and controllability of cutting operations.

[0062] Furthermore, during the hoisting operation of the closure section, if the ends of the continuous beam main girder and the cable-stayed bridge main girder tilt upwards at the same time, the closure section is lifted by the self-balancing system. The maximum lifting force of the self-balancing system does not exceed the weight of the closure section itself. If it is still not possible to hoist smoothly after lifting, the steel wedges in the cutting seam are removed, and the cutting seam width is widened by cutting equipment to eliminate the cutting obstruction. If the ends of the continuous beam and the cable-stayed bridge main beam deflect simultaneously, the beam segments at the ends of the continuous beam and the cable-stayed bridge main beam are lifted using a self-balancing system. The maximum lifting force of the self-balancing system shall not exceed the weight of the beam segment itself. If the beam cannot be lifted smoothly after lifting, the steel wedges in the cutting seam are removed, and the cutting seam width is widened using cutting equipment. If one side of the main beam of a continuous beam and the end of the main beam of a cable-stayed bridge deflects downwards and the other side deflects upwards, the deflected end of the beam is lifted using a self-balancing system. The maximum lifting force of the self-balancing system shall not exceed the weight of the beam itself. If the beam cannot be lifted smoothly after lifting, the closure section is lifted using the self-balancing system. If the above adjustment fails to lift the beam smoothly, cutting equipment is used to widen the cutting joint.

[0063] By employing a graded and controllable jacking adjustment strategy for three typical deformation conditions—upward tilting, downward deflection, and unilateral deviation—the alignment of the main beam end can be precisely corrected, effectively eliminating hoisting obstacles such as cut-out compression and jamming. Strictly limiting the jacking force to not exceed the beam segment's self-weight can prevent secondary stress or damage to the structure caused by excessive jacking force. Combined with auxiliary measures to widen the cutting seam, the success rate of hoisting the closure segment and construction safety can be significantly improved, ensuring continuous and efficient dismantling procedures.

[0064] Furthermore, the existing bridge was dismantled using a diamond wire saw cutting process. Diamond wire sawing uses a diamond wire as the cutting component. Driven by a motor, the diamond wire circulates at high speed around the surface to be cut, achieving the separation of reinforced concrete components through a grinding action. Because single-crystal diamond is used as the abrasive material, it can efficiently and stably cut hard structures such as stone and high-strength reinforced concrete. The drive unit uses a variable frequency motor, ensuring smooth and reliable operation, and can be remotely controlled. The entire cutting process is simple, safe, and controllable, with low vibration and noise, enabling the beam separation and cutting to be completed with almost no disturbance to the surrounding structure.

[0065] Before dismantling beam segments 1X and 2X, support components were pre-installed at the bottom of beam segment 0X to form a stable bottom support system, ensuring the structural stability of the main beam near the main tower. The main tower dismantling process was delayed after the cable stays were tensioned and dismantled. The main tower dismantling was then initiated after all eight pairs of cable stays were tensioned and dismantled, proceeding segment by segment from top to bottom. The hoisting of the main tower segments was not carried out simultaneously with the hoisting of the cable stays. After the entire main tower above the main beam was dismantled, diamond wire saws were used to longitudinally cut beam segment 0X into several segmented pieces. These segments were then hoisted away from the site sequentially using hoisting equipment, ultimately completing the overall dismantling of the entire bridge. Setting up support components for beam segment 0X# in advance effectively constrains the displacement of beam segments near the pier top, preventing stress concentration and abrupt changes in alignment at the ends caused by the release of the upper stay cables and the segmental dismantling of the main beam. This ensures reliable support throughout the dismantling process. Delaying the dismantling of the main tower after the release of the eight pairs of stay cables allows for the gradual release of the constraint forces between the main beam and the main tower, avoiding system imbalance caused by the coordinated stress of the main tower, stay cables, and main beam, and significantly reducing structural safety risks during dismantling. Dismantling the main tower segment by segment from top to bottom reduces the volume of each dismantling operation, lowers the hoisting load and the risks of high-altitude work, and makes the construction process safer and more controllable. Using longitudinal segmented cutting and hoisting for beam segment 0X# reduces the weight of each hoisting segment, adapts to the performance of on-site lifting equipment, and avoids excessive impact on the pier top during overall dismantling, thus achieving an orderly, stable, and efficient dismantling process for the entire bridge.

[0066] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for dismantling the main girder of a cable-stayed bridge based on stress self-adaptation using self-balancing hydraulic jacks, characterized in that, include S100: First, remove the bridge deck ancillary structures and bridge deck pavement layer, and erect scaffolds under the main beams of the cable-stayed bridge and the main beams of the continuous beam bridge. Support components are installed between the 6L# and 7L# beam segments of the main beams of the continuous beam bridge and the closure section, 28X# to 31X# beam segments of the main beams of the cable-stayed bridge and the scaffolds. S200: Self-balancing systems are installed between the 7L# beam segment of the main beam of the continuous beam bridge, the closure segment of the main beam of the cable-stayed bridge, and the 31X# beam segment and the support. At the same time, vibration damping devices are installed between the closure segment and the top of the main beam of the continuous beam bridge. S300: Implement multiple rounds of graded tension release for cables #14 and #15, gradually releasing cable force until complete unloading, and then disconnect the anchorage connection between cables #14 and #15 and the main beam of the continuous beam bridge and the main beam of the cable-stayed bridge; S400: Using specialized cutting equipment, the closure section is cut according to the preset cutting line, and then the closure section is lifted and moved as a whole by hoisting equipment to complete the dismantling of the closure section; S500: Install support components between the 26X# to 27X# beam segments of the main girder of the cable-stayed bridge and the support frame. Perform graded tensioning of the 13# cable-stayed cable until the cable force is completely unloaded. Then, release the anchorage connection between the 13# cable-stayed cable and the main girder of the cable-stayed bridge. Remove the self-balancing system under the 7L# beam segment of the continuous beam main girder and install it between the 30X# beam segment and the support frame. Use cutting equipment to cut the 31X# and 30X# beam segments sequentially along the preset cutting line. After cutting, use hoisting equipment to lift the two beam segments away from the support frame. S600: Move the support components located at the bottom of beam segments 31X# and 30X# to the bottom of beam segments 24X# and 25X#. Implement graded tensioning of cable 12# until the cable force is completely unloaded. Then, remove the anchorage connection between cable 12# and the main beam of the cable-stayed bridge. Move the self-balancing system at the bottom of beam segments 31X# and 30X# to the bottom of beam segments 28X# and 29X#. Use cutting equipment to cut beam segments 28X# and 29X# sequentially along the preset cutting line. After cutting, use hoisting equipment to lift the two beam segments away from the support. S700: Repeat the construction procedure of step S500 above, and cyclically advance the beam segment demolition operation until the demolition of beam segment 6X# and beam segment 7X# is completed; S800: Install support components between beam segments 0X# and 1X# and the support frame. Move the self-balancing system located at the bottom of beam segments 6X# and 7X# to the bottom of beam segments 4X# and 5X#. Use cutting equipment to cut beam segments 4X# and 5X# sequentially along the preset cutting line. Repeat the aforementioned demolition process until beam segments 1X# and 2X# are demolished. Use cutting equipment to longitudinally cut beam segment 0# into multiple blocks. Use hoisting equipment to lift the multiple blocks off the support frame to complete the overall demolition work.

2. The method for dismantling the main girder of a cable-stayed bridge based on stress self-adaptation using a self-balancing hydraulic jack, as described in claim 1, is characterized in that... The bridge deck ancillary structures of the cable-stayed bridge include streetlights, guardrails, and expansion joints. The removal of the streetlights, guardrails, and expansion joints is carried out gradually from the top of the bridge piers to the mid-span, completing the unloading and removal of the bridge deck ancillary facilities.

3. The method for dismantling the main girder of a cable-stayed bridge based on stress self-adaptation using a self-balancing hydraulic jack, as described in claim 1, is characterized in that... The support components are located at the four corners of the bottom of the beam segment. They include steel supports, prefabricated unloading blocks, several steel plates, and rubber plates. The steel supports are located on the top of the secondary longitudinal beam at the top of the support. The top of the steel supports is equipped with prefabricated unloading blocks, and the top of the prefabricated unloading blocks is equipped with several steel plates. A rubber plate is provided between the steel plates and the bottom of the main beam. The steel supports also include steel pipes, and steel plates are welded to the top and bottom of the steel pipes.

4. The method for dismantling the main girder of a cable-stayed bridge based on stress self-adaptation using a self-balancing hydraulic jack, as described in claim 1, is characterized in that... Step S400 specifically includes the following steps: S410: Use specialized cutting equipment to perform cutting operations along the pre-set cutting line between the closure section and the 7L# beam segment of the main beam of the continuous beam bridge; S420: After the above cutting is completed, the vibration damping device is then removed; S430: Continue to use special cutting equipment to carry out cutting operations along the preset cutting line between the closure section and the 31X# beam segment of the cable-stayed bridge main beam; S440: After all cutting operations are completed, the closure section is hoisted to the designated area using hoisting equipment to complete the dismantling of the closure section.

5. The method for dismantling the main girder of a cable-stayed bridge based on stress self-adaptation using a self-balancing hydraulic jack, as described in claim 1, is characterized in that... In step S200, after the self-balancing system is installed in place, a pre-jacking force of 10t is applied to the closure section through the self-balancing system, and the steel plate in the support assembly is removed, so that a 2cm gap is left between the support assembly and the bottom of the main beam. In steps S500 to S800, after the self-balancing system is installed in place, a pre-jacking force equal to 90% of its own weight is applied to the corresponding beam segment through the self-balancing system, and the steel plate in the support assembly is removed, leaving a 2cm gap between the support assembly and the bottom of the corresponding beam segment.

6. The method for dismantling the main girder of a cable-stayed bridge based on stress self-adaptation using a self-balancing hydraulic jack, as described in claim 5, is characterized in that... The self-balancing system includes four load-sharing cylinders, a first hydraulic system, a second hydraulic system, a third hydraulic system, and a control system. The four load-sharing cylinders are respectively arranged between the four corners of the bottom of the beam segment and the top surface of the secondary longitudinal beam. The two load-sharing cylinders located on the front or rear side are connected in parallel and connected to the first hydraulic system. The other two load-sharing cylinders are independently connected to the second and third hydraulic systems, respectively. The first, second, and third hydraulic systems are all connected to the control system and controlled by it.

7. The method for dismantling the main girder of a cable-stayed bridge based on stress self-adaptation using a self-balancing hydraulic jack, as described in claim 6, is characterized in that... The control system of the self-balancing system is configured to: calculate the equivalent dynamic stiffness under different excitation frequencies in real time based on the frequency response model of the equivalent dynamic stiffness of the hydraulic system, and adaptively adjust the support oil pressure according to the calculation results to compensate for the downward deflection and upward deformation of the beam. Meanwhile, based on the stress adaptive control convergence time prediction model, the stress adjustment convergence time is quantitatively predicted, and the construction process rhythm is optimized accordingly.

8. The method for dismantling the main girder of a cable-stayed bridge based on stress self-adaptation using a self-balancing hydraulic jack according to claim 1, characterized in that, The cutting line between the closure segment and the main beam of the continuous beam bridge and the main beam of the cable-stayed bridge is set in an inverted V-shape along the longitudinal direction of the bridge. That is, the section of the box girder bottom plate corresponding to the cutting line is contracted inward by 40cm and extended obliquely upward along the contraction position. Except for the closure segment, the cutting lines of the other beam segments are set in a direction perpendicular to the tangent direction of the main beam.

9. The method for dismantling the main girder of a cable-stayed bridge based on stress self-adaptation using a self-balancing hydraulic jack, as described in claim 1, is characterized in that... During the cutting operation of the closure section, steel wedges are driven into the cutting seam to prevent the cutting chain from jamming. If the cutting chain gets stuck or cannot be removed from the cutting seam, use a pneumatic hammer to break the concrete outside the prestressing tendons, then cut part of the prestressing tendons using an oxygen cutting method, and then continue the cutting operation. For any loose prestressing steel wires produced during the cutting process, use electric welding to weld them in place to prevent the prestressing steel wires from bouncing.

10. The method for dismantling the main girder of a cable-stayed bridge based on stress self-adaptation using a self-balancing hydraulic jack, as described in claim 1, is characterized in that... When hoisting the closure section, if the ends of the continuous beam and the cable-stayed bridge beam tilt upwards at the same time, the closure section is lifted by the self-balancing system. The maximum lifting force of the self-balancing system shall not exceed the weight of the closure section itself. If it is still not possible to hoist it smoothly after lifting, the steel wedges in the cutting joint are removed and the cutting joint width is widened by cutting equipment. If the ends of the continuous beam and the cable-stayed bridge main beam deflect simultaneously, the beam segments at the ends of the continuous beam and the cable-stayed bridge main beam are lifted using a self-balancing system. The maximum lifting force of the self-balancing system shall not exceed the weight of the beam segment itself. If the beam cannot be lifted smoothly after lifting, the steel wedges in the cutting seam are removed, and the cutting seam width is widened using cutting equipment. If one side of the main beam of a continuous beam and the end of the main beam of a cable-stayed bridge deflects downwards and the other side deflects upwards, the deflected end of the beam is lifted using a self-balancing system. The maximum lifting force of the self-balancing system shall not exceed the weight of the beam itself. If the beam cannot be lifted smoothly after lifting, the closure section is lifted using the self-balancing system. If the above adjustment fails to lift the beam smoothly, cutting equipment is used to widen the cutting joint.

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