Bracket-free box girder bridge pier underpinning device

Abstract

The invention relates to a support-free box girder bridge pier underpinning device, which belongs to the technical field of bridge construction, is applied to a large longitudinal slope bridge, comprises an underpinning pier column poured under the large longitudinal slope bridge, and is characterized by comprising a box-type cross beam, a supporting cross beam, a support and a jacking assembly, the two cross beams stretch across the tops of the underpinning pier columns, the supports are fixedly installed on the top faces of the supporting cross beams so as to bear the large longitudinal slope bridge, and the jacking assemblies are detachably installed on the top faces of the box type cross beams and used for jacking the bottom face of the large longitudinal slope bridge so that the large longitudinal slope bridge can be underpinned to the supports from the existing supports. Pier column underpinning and temporary jacking supporting are combined, the erecting work of a temporary support is omitted, traffic on a middle broken bridge is not needed, the pier underpinning efficiency is greatly improved, the bridge and culvert pier column underpinning progress is accelerated, and the cost is saved.

Description

Technical Field

[0001] The invention belongs to the technical field of bridge construction, and in particular relates to a pier underpinning device for a bracket-free box girder bridge. Background Art

[0002] With the gradual construction of my country's expressway trunk network and urban road network, new urban roads often need to intersect with existing expressways or urban viaducts in three dimensions. New ramps need to pass under existing viaducts, or new ramps are set under viaducts. Due to the dense piers of viaducts, the layout of new ramps encounters obstacles from viaduct piers. When the line position of the new ramp is difficult to adjust to avoid the existing piers, or the adjustment will result in a significant cost, it is necessary to use pier replacement technology to transform the existing piers to meet the conditions for the layout of the new ramp.

[0003] Due to the increasing pressure on urban interchange traffic, the normal operation of existing bridge traffic must not be affected during the reconstruction of large longitudinal slope bridges. Therefore, it is necessary to propose key technologies for replacing pier columns and crossbeams without interrupting bridge traffic, which can not only ensure the structural safety of large longitudinal slope bridges, but also reasonably shorten the construction period.

[0004] The beam box is installed on the existing bridge piers through the existing supports. When replacing the existing bridge piers, the existing bridge piers and the existing supports need to be removed, and the beam box is installed on the bridge piers and supports of the replacement bridge;

[0005] At present, the main methods of bridge pier replacement include new portal frame replacement, which requires the erection of temporary supports to lift and evacuate the large longitudinal slope bridge before it can be carried out. There is also pile foundation replacement technology, which requires the construction of new replacement piles and box beams on both sides of the existing pile foundation to replace the existing pile foundation. This method requires traffic interruption and is relatively expensive. The above existing bridge pier replacement methods not only have a great impact on existing traffic, but also have a long construction period, waste project funds, and are not conducive to bridge pier reconstruction work.

[0006] Therefore, there is an urgent need for a bridge pier replacement device that can replace bridge piers without setting up a bracket and does not affect traffic. Summary of the invention

[0007] In order to solve the above problems existing in the prior art, the present invention provides a pier underpinning device for a box girder bridge without a support frame, which solves the problem that temporary supports need to be set up in the existing pier underpinning, affecting traffic and construction progress.

[0008] The purpose of the present invention can be achieved through the following technical solutions:

[0009] A pier underpinning device for a box girder bridge without a support frame is applied to a bridge with a large longitudinal slope, comprising a underpinning pier column cast directly below the bridge with a large longitudinal slope, comprising a box-type crossbeam, a supporting crossbeam, a bearing and a jacking assembly; both crossbeams span the top of the underpinning pier column, the bearing is fixedly installed on the top surface of the supporting crossbeam to bear the bridge with a large longitudinal slope, and the jacking assembly is detachably installed on the top surface of the box-type crossbeam to lift the bottom surface of the bridge with a large longitudinal slope so that the bridge with a large longitudinal slope can be underpinned from the existing bearing to the bearing.

[0010] Preferably, it also includes a beam bottom leveling assembly, which is installed at the bottom of the large longitudinal slope bridge, and the jacking assembly jacks the large longitudinal slope bridge through the beam bottom leveling assembly; the leveling assembly includes a leveling steel plate, a spiral adjuster and a fixing; the fixing is fixedly connected to the leveling steel plate and fixed to the large longitudinal slope bridge by bolts; the spiral adjuster is arranged on the jacking assembly and the leveling steel plate, and is used to adjust the height and angle of the leveling steel plate.

[0011] Preferably, it also includes a stabilizing component, which is installed between the jacking component and the large longitudinal slope bridge, and both ends of the stabilizing component are connected to the large longitudinal slope bridge; the stabilizing component includes a vertical steel frame and a horizontal steel frame; the vertical steel frame is vertically arranged at one end of the horizontal steel frame, the bottom of the horizontal steel frame is connected to the jacking component, and the vertical steel frame and the horizontal steel frame are connected to the large longitudinal slope bridge; the horizontal steel frame remains horizontal with the underpinning pier.

[0012] Preferably, it also includes a first adjusting mechanism and a second adjusting mechanism, wherein the first adjusting mechanism and the second adjusting mechanism are both installed on the underpinning pier, the first adjusting mechanism is connected to the vertical steel frame, and the second adjusting mechanism is connected to an end of the horizontal steel frame away from the vertical steel frame, and the first adjusting mechanism and the second adjusting mechanism are used to adjust the force applied to the stabilizing assembly at both ends of the large longitudinal slope bridge.

[0013] Preferably, the first adjusting mechanism includes a winding member, a pulley and a steel cable; the winding member is installed on the support pier, the pulley is located at the end of the large longitudinal slope bridge, and the steel cable is slidably connected to the pulley; the winding member is provided with a winding end and an unwinding end, and the ends of the steel cable are respectively fixed at the winding end and the unwinding end; the structures of the first adjusting mechanism and the second adjusting mechanism are consistent.

[0014] Preferably, the beam bottom leveling assembly is in close contact with the bottom of the large longitudinal slope bridge to form a lifting surface; the lifting assembly includes a plurality of jacks, and any of the jacks is in contact with the lifting surface.

[0015] Preferably, the lifting surface is aligned with the center line of the web of the large longitudinal slope bridge.

[0016] Preferably, the box-type crossbeam is composed of a steel crossbeam or a steel-concrete composite crossbeam.

[0017] The beneficial effects of the present invention are:

[0018] 1. First, set up the replacement piers and then install the box-type beam; place a jacking assembly on the top of the box-type beam, and after the jacking assembly lifts up the large longitudinal slope bridge, remove the existing bridge piers, and then install the supporting beam, place a bearing on the top of the supporting beam 4, lower the large longitudinal slope bridge, so that the large longitudinal slope bridge is supported on the bearing, and remove the jacking assembly after completing the pier underpinning work. This technical solution combines pier underpinning with temporary jacking support, eliminates the work of setting up temporary support, does not need to interrupt traffic on the bridge, greatly improves the efficiency of pier underpinning, speeds up the progress of bridge culvert pier underpinning, and saves costs.

[0019] 2. The stabilizing component is connected to the bridge body to effectively transfer the deadweight and lifting force of the large longitudinal slope bridge to the horizontal steel frame and the underpinning piers, preventing the risk of excessive tilting or collapse of the bridge during the lifting process; the vertical steel frame and the horizontal steel frame together form a stable support system, which improves the safety and reliability of the pier underpinning process and helps reduce the occurrence of structural deformation and stress concentration. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0021] Figure 1 It is a schematic diagram of the front view structure of the bridge pier support provided in one embodiment.

[0022] Figure 2 It is a schematic diagram of the side view structure of the bridge pier underpinning provided in one embodiment.

[0023] Figure 3 Schematic diagram of the connection structure of a box-type crossbeam provided in one embodiment.

[0024] Figure 4 The figure is a schematic diagram of the installation structure of the beam bottom leveling assembly provided in one embodiment.

[0025] Figure sequence: 1. Bridge with large longitudinal slope; 21. Replacement of pier columns; 22. Existing piers; 3. Box beam; 4. Support beam; 5. Lifting assembly; 6. Beam bottom leveling assembly; 61. Leveling steel plate; 62. Screw adjuster; 63. Fixing piece; 7. Stabilizing assembly; 71. Vertical steel frame; 72. Horizontal steel frame; 81. First adjustment mechanism; 811. Winding piece; 812. Pulley; 813. Steel cable; 82. Second adjustment mechanism; 9. Support. DETAILED DESCRIPTION

[0026] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0027] like Figure 1-Figure 4 A pier replacement device for a box girder bridge without a support frame comprises a large longitudinal slope bridge 1, a replacement pier column 21, a box beam 3, a supporting beam 4 and a lifting assembly 5; the replacement pier column 21 is arranged at the bottom of the large longitudinal slope bridge 1, the box beam 3 spans the top of the replacement pier column 21, the supporting beam 4 is arranged on the box beam 3, and is used to install a bearing 9; the lifting assembly 5 is installed between the large longitudinal slope bridge 1 and the box beam 3, and is used to lift the large longitudinal slope bridge 1 and remove the existing bridge pier 22; the bearing 9 is located at the supporting The top of the beam 4, after being lifted by the jacking assembly 5, will support the large longitudinal slope bridge 1 to fall to the support 9; the box-type beam 3 is supported on the top of the replacement pier 21. It can be understood that the replacement pier 21 and the box-type beam 3 should be fixedly connected. The jacking assembly 5 is placed between the large longitudinal slope bridge 1 and the box-type beam 3. The jacking assembly 5 can lift the large longitudinal slope bridge 1 to dismantle the existing bridge piers 22, and after the supporting beam 4 and the support 9 are placed, the large longitudinal slope bridge 1 is lowered so that the large longitudinal slope bridge 1 is supported on the support 9.

[0028] The support-free box girder pier column underpinning device of this technical solution is implemented by first setting the underpinning pier column 21 and then installing the box beam 3, placing the jacking assembly 5 between the box beam 3 and the large longitudinal slope bridge 1, and then lifting the large longitudinal slope bridge 1 with the jacking assembly 5 to dismantle the existing bridge pier 22, and then installing the supporting beam 4 and the bearing 9. After the existing bridge pier 22 is replaced, the jacking assembly 5 can be removed, eliminating the work of setting up temporary supports, and directly using the box beam 3 to complete the system underpinning, thereby greatly improving the efficiency of bridge pier underpinning, accelerating the progress of bridge culvert pier underpinning, and saving costs.

[0029] In one embodiment, it also includes a bottom beam leveling assembly 6, which is installed at the bottom of the bridge with a large longitudinal slope 1, and the jacking assembly 5 jacks the bridge with a large longitudinal slope 1 through the bottom beam leveling assembly 6; the leveling assembly includes a leveling steel plate 61, a spiral adjuster 62 and a fixing member 63; the fixing member 63 is fixedly connected to the leveling steel plate 61 and fixed to the bridge with a large longitudinal slope by bolts; the spiral adjuster 62 is arranged on the jacking assembly 5 and the leveling steel plate 61, and is used to adjust the height and angle of the leveling steel plate 61; the leveling steel plate 61 is firmly connected to the bottom of the bridge with a large longitudinal slope through the fixing member 63 (such as angle steel, connecting plate, etc.), and is fixed by bolts to ensure that the leveling steel plate 61 can move with the bridge with a large longitudinal slope and is stable and reliable, and the spiral adjuster 62 is installed between the jacking assembly 5 and the leveling steel plate 61, and its function is to serve as a medium for height and angle adjustment. The spiral adjuster 62 has a rotatable screw and nut structure. By rotating the screw, the position of the nut on the screw can be controlled, thereby achieving fine adjustment of the height and tilt angle of the leveling steel plate 61. When it is necessary to lift the longitudinal slope bridge 1, the lifting assembly 5 (such as a hydraulic jack) starts to work, generating an upward lifting force, which first acts on the leveling steel plate 61. Since the leveling steel plate 61 is fixedly connected to the longitudinal slope bridge 1, the longitudinal slope bridge 1 will also rise accordingly; after the longitudinal slope bridge 1 is lifted to a sufficient height, the piers can be replaced or repaired. After completion, the longitudinal slope bridge 1 is smoothly lowered onto the underpinning pier 21 by reversely operating the lifting assembly 5 and the spiral adjuster 62, and the leveling steel plate 61 is adjusted again to ensure the stability and flatness of the longitudinal slope bridge 1 after restoration.

[0030] In one embodiment, it also includes a stabilizing component 7, which is installed between the jacking component 5 and the long longitudinal slope bridge 1, and both ends of the stabilizing component 7 are connected to the long longitudinal slope bridge 1; the stabilizing component 7 includes a vertical steel frame 71 and a horizontal steel frame 72; the vertical steel frame 71 is vertically arranged at one end of the horizontal steel frame 72, and the bottom of the horizontal steel frame 72 is connected to the jacking component 5, and the vertical steel frame 71 and the horizontal steel frame 72 are connected to the long longitudinal slope bridge 1; the horizontal steel frame 72 is kept horizontal with the underpinning pier 21; first, the bottom of the horizontal steel frame 72 is firmly connected to the jacking component 5, and the vertical steel frame 71 is vertically arranged at one end of the horizontal steel frame 72; at the same time, the long longitudinal slope bridge of the vertical steel frame 71 and the horizontal steel frame 72 1 is connected and forms a right triangle with the large longitudinal slope bridge 1, wherein the inclined large longitudinal slope bridge 1 is the hypotenuse and the horizontal steel frame 72 is the horizontal right angle side. In this way, the uneven load on the underpinning surface of the large longitudinal slope bridge 1 during underpinning can be transferred to the end of the horizontal steel frame 72 with uniform force, so as to transmit force and disperse load; the main function of the horizontal steel frame 72 is to provide horizontal support. Since it is horizontal with the underpinning pier 21, when the large longitudinal slope bridge 1 is jacked up, the horizontal steel frame 72 can effectively prevent the large longitudinal slope bridge 1 from deflecting or shaking in the horizontal direction, thereby ensuring the smooth progress of the jacking process. The vertical steel frame 71 is responsible for enhancing the stability of the large longitudinal slope bridge 1 in the vertical direction. The stabilization component 7 is connected to the steep slope bridge 1 to effectively transfer the deadweight and lifting force of the steep slope bridge 1 to the horizontal steel frame 72 and the underpinning pier 21, thereby preventing the steep slope bridge 1 from excessively tilting or collapsing during the lifting process; the vertical steel frame 71 and the horizontal steel frame 72 together form a stable support system, thereby improving the safety and reliability of the pier underpinning process; the stabilization component 7 provides additional support for the steep slope bridge 1, thereby enhancing its overall stability during the lifting and pier replacement process, which helps to reduce the occurrence of structural deformation and stress concentration, thereby extending the service life of the bridge.

[0031] In one embodiment, it also includes a first adjustment mechanism 81 and a second adjustment mechanism 82, both of which are installed on the underpinning pier 21, the first adjustment mechanism 81 is connected to the vertical steel frame 71, and the second adjustment mechanism 82 is connected to the end of the horizontal steel frame 72 away from the vertical steel frame 71, and the first adjustment mechanism 81 and the second adjustment mechanism 82 are used to adjust the forces of the stabilizing component 7 at the left and right ends of the large longitudinal slope bridge 1; during the pier underpinning process, the large longitudinal slope bridge 1 may be subjected to a variety of complex forces, including deadweight and jacking force, especially when the large longitudinal slope bridge 1 is not parallel to the ground, resulting in During the lifting process, the lifting surfaces on the left and right ends of the gravity lifting point will be subjected to unbalanced forces, which will complicate the lifting situation. The first adjusting mechanism 81 and the second adjusting mechanism 82 are provided so that the stabilizing component 7 can more flexibly cope with these complex force conditions, and ensure the force balance and stability of the large longitudinal slope bridge 1. The first adjusting mechanism 81 is connected to the vertical steel frame 71, and is connected to the left side of the large longitudinal slope bridge 1. The second adjusting mechanism 82 is connected to the end of the horizontal steel frame 72 away from the vertical steel frame 71, and is connected to the right end of the large longitudinal slope bridge 1, and indirectly affects the force condition of the vertical steel frame 71 through the lever effect.

[0032] During the jacking process, the steep longitudinal slope bridge 1 is not only affected by its own gravity, but also by the jacking force generated by the jacking assembly 5 on the steep longitudinal slope bridge 1. Therefore, when using the first adjusting mechanism 81 and the second adjusting mechanism 82 to adjust the forces at both ends of the steep longitudinal slope bridge 1, it is necessary to consider the degree of inclination of the steep longitudinal slope bridge 1 and the jacking and supporting effect of the jacking assembly 5 on the steep longitudinal slope bridge 1 to avoid the jacking surface from losing control due to excessive inclination angle. In particular, when the object is tilted, its center of gravity will shift to one side. If the inclination angle is too large, the center of gravity may exceed the range of the supporting surface, causing the object to tip over and causing serious safety accidents.

[0033] Furthermore, the adjustment range of the first adjustment mechanism 81 and the second adjustment mechanism 82 is between 0.087G and 0.26G, where G is the deadweight of the longitudinal slope bridge 1; when the adjustment force of the second adjustment mechanism 82 is close to 0.26G, that is, the longitudinal slope bridge 1 at one end of the first adjustment mechanism 81 is higher and the angle between it and the jacking surface is close to 15°, the first adjustment mechanism 81 starts to apply force, and together with the second adjustment mechanism 82, the inclination state of the longitudinal slope bridge 1 is adjusted, and the force applied by the second adjustment mechanism 82 is smaller than the force of the first adjustment mechanism 81, so that under the action of the first adjustment mechanism 81, the angle difference between the higher end of the longitudinal slope bridge 1 and the jacking surface is gradually reduced to a stable control range, thereby slowing down the inclination of the longitudinal slope bridge 1;

[0034] Similarly, if the regulating force of the first regulating mechanism 81 is close to 0.087G, that is, the large longitudinal slope bridge 1 at one end of the first regulating mechanism 81 is lower and the angle between it and the jacking surface is close to -5°, the second regulating mechanism 82 starts to apply force, and together with the first regulating mechanism 81, regulates the inclination state of the large longitudinal slope bridge 1, and the force applied by the first regulating mechanism 81 is smaller than the force of the second regulating mechanism 82, so that the large longitudinal slope bridge 1 gradually returns to its original inclination state;

[0035] By setting a reasonable adjustment range for the large longitudinal slope bridge 1, it can be ensured that the bridge is evenly stressed during the adjustment process, and structural problems caused by excessive stress of the jacking component 5 on the large longitudinal slope bridge 1 can be avoided. The jacking component 5 and the large longitudinal slope bridge 1 always maintain a dynamic balance during the jacking and adjustment process and are controlled within a controllable range. This helps to ensure the smooth progress of the replacement, extend the service life of the bridge, and improve its overall stability.

[0036] Thereby, the force adjustment of the large longitudinal slope bridge 1 in the horizontal direction is realized. The first adjustment mechanism 81 and the second adjustment mechanism 82 cooperate with each other during the working process and act on the stabilizing component 7 and the large longitudinal slope bridge 1 together to adjust the inclined large longitudinal slope bridge 1, so that the force of the large longitudinal slope bridge 1 is simplified; through the action of the first adjustment mechanism 81 and the second adjustment mechanism 82, the comprehensive adjustment of the force at both ends of the large longitudinal slope bridge 1 can be realized to ensure the stability and safety of the bridge during the jacking and pier replacement process. By introducing two independent adjustment mechanisms, the force at both ends of the large longitudinal slope bridge 1 can be accurately adjusted respectively. This design improves the flexibility and accuracy of the adjustment and helps to achieve more refined construction control.

[0037] In one embodiment, the first adjusting mechanism 81 includes a winding member 811, a pulley 812 and a steel cable 813; the winding member 811 is installed on the replacement pier 21, the pulley 812 is located at the end of the large longitudinal slope bridge 1, and the steel cable 813 is slidably connected to the pulley 812; the winding member 811 is provided with a winding end and an unwinding end, and the ends of the steel cable 813 are respectively fixed at the winding end and the unwinding end; the first adjusting mechanism 81 and the second adjusting mechanism 82 have the same structure, and the winding member 811 is installed on the replacement pier 21, and has two functional ends of winding and unwinding. When the winding member 811 performs the winding action, the steel cable 813 is wound into the winding end, thereby generating a downward force on the end of the large longitudinal slope bridge 1, so as to maintain the balance of the two ends of the large longitudinal slope bridge 1; on the contrary, when the winding member 811 performs the unwinding action, the steel cable 813 is released from the unwinding end and tightened from the winding end, so as to adjust the force condition of the end of the large longitudinal slope bridge 1 to keep it in a balanced state at both ends. The wheel is installed at the end of the large longitudinal slope bridge 1 as a guide device for the steel cable 813; the design of the pulley 812 allows the steel cable 813 to slide smoothly, reducing friction and wear, while ensuring the smoothness of the adjustment process; the position of the pulley 812 also determines The direction and point of action of the tension of the steel cable 813 affect the adjustment effect of the vertical steel frame 71 or the horizontal steel frame 72. During the replacement of the piers, the force adjustment of the large longitudinal slope bridge 1 requires extremely high precision, and the traditional rigid connection or simple adjustment method can hardly replace the pulley 812 to meet this requirement. Since the first adjustment mechanism 81 and the second adjustment mechanism 82 have the same structure and can work independently, the two ends of the stabilizing component 7 are adjusted. By controlling the winding and unwinding actions of the two adjustment mechanisms, the comprehensive force adjustment of the large longitudinal slope bridge 1 in the horizontal and vertical directions can be achieved, ensuring the stability and safety of the bridge during the jacking and pier replacement process.

[0038] In one embodiment, the beam bottom leveling assembly 6 is in close contact with the bottom of the long longitudinal slope bridge 1 to form a lifting surface; the lifting assembly 5 includes a plurality of jacks, and the jacks are in contact with the lifting surface; the beam bottom leveling assembly 6 is in close contact with the bottom of the long longitudinal slope bridge 1 to form a stable lifting surface, so that the lifting force can be evenly and effectively transmitted to the long longitudinal slope bridge 1, thereby ensuring the stability and safety of the lifting process; at the same time, the lifting assembly 5 is composed of a plurality of jacks, and the plurality of jacks are evenly distributed on the lifting surface, and the precise lifting of the long longitudinal slope bridge 1 is achieved through synchronous control; the design of the beam bottom leveling assembly 6 and the lifting assembly 5 ensures The uniform transmission of the jacking force and the stable support of the bridge 1 with a large longitudinal slope are achieved, thereby greatly reducing the construction risk; the beam bottom leveling component 6 first ensures a close fit with the bottom of the bridge 1 with a large longitudinal slope, and the jacking surface is made to reach a preset flatness and support strength through the beam bottom leveling component 6, so that during the jacking process, the bridge 1 with a large longitudinal slope can be evenly stressed to avoid damage caused by local stress concentration. Multiple jacks are used as jacking power sources and are installed at different positions of the jacking surface. When the jacks are started, upward jacking forces are generated, and these jacking forces are transmitted to the bridge 1 with a large longitudinal slope through the jacking surface, thereby realizing the lifting of the bridge 1 with a large longitudinal slope.

[0039] In one embodiment, the jacking surface is aligned with the center line of the web of the large longitudinal slope bridge 1; the alignment of the horizontal jacking surface with the center line of the bridge web is one of the key factors to ensure the safety and stability of the jacking process, which can reduce the safety hazards caused by unbalanced jacking force and protect the safety of construction personnel and bridge structures; during the bridge jacking process, the large longitudinal slope bridge 1 is often required to perform precise height and posture adjustments; the alignment of the jacking surface with the center line of the bridge web, that is, the line of action of the jacking force is consistent with the main load-bearing structure (web) of the bridge, helps to reduce the torque or lateral force caused by the deviation of the jacking force, and ensures that the bridge maintains a stable posture during the jacking process. The close fit between the horizontal jacking surface and the large longitudinal slope bridge 1 enables the jacking force to be efficiently transmitted to the large longitudinal slope bridge 1.

[0040] In one embodiment, the box-type cross beam 3 is composed of a steel cross beam or a steel-concrete composite cross beam; with the continuous increase in traffic volume and the increasing weight of vehicle loads, higher requirements are placed on the bearing capacity of the bridge. The box-type cross beam 3 has a larger cross-sectional area and a reasonable cross-sectional shape, which can effectively improve the overall stiffness and stability of the bridge; at the same time, the use of steel or steel-concrete composite materials can also reduce the deadweight of the bridge and reduce the requirements for the bearing capacity of the foundation, thereby optimizing the bridge structure design. The box-type cross beam 3 is made of steel or steel-concrete composite materials, has a higher bearing capacity and stiffness, and can meet the requirements of modern traffic on bridge performance. The steel cross beam is characterized by its high strength, high toughness and good weldability, and can withstand larger bending moments and shear forces; in the box structure, the steel is processed into a beam with a certain cross-sectional shape, and an overall force system is formed through reasonable arrangement and connection. When the bridge is subjected to external loads, the steel beam can effectively disperse and transfer the load to the piers or other supporting structures; in summary, the box beam 3 is composed of a steel beam or a steel-concrete composite beam, and plays an important role in the bridge structure. Its working principle is based on the mechanical properties of the material and the rationality of the structural design, and is necessary to improve the bridge's bearing capacity, optimize the bridge structure design, and adapt to complex construction environments. At the same time, this design method can also produce beneficial effects such as improving bridge safety, extending service life, and promoting sustainable development.

[0041] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A pier underpinning device for a box girder bridge without a support frame, applied to a bridge with a large longitudinal slope, including a underpinning pier cast directly below the bridge with a large longitudinal slope, characterized in that: It includes a box-type crossbeam, a supporting crossbeam, a bearing and a jacking assembly; both crossbeams span the top of the underpinning pier, the bearing is fixedly installed on the top surface of the supporting crossbeam to bear the large longitudinal slope bridge, and the jacking assembly is detachably installed on the top surface of the box-type crossbeam to jack up the bottom surface of the large longitudinal slope bridge so that the large longitudinal slope bridge is underpinned from the existing bearing to the bearing.

2. The support-free box girder bridge pier underpinning device according to claim 1 is characterized in that: It also includes a beam bottom leveling assembly, which is installed at the bottom of the large longitudinal slope bridge, and the jacking assembly jacks the large longitudinal slope bridge through the beam bottom leveling assembly; the leveling assembly includes a leveling steel plate, a spiral adjuster and a fixing part; the fixing part is fixedly connected to the leveling steel plate and fixed to the large longitudinal slope bridge by bolts; the spiral adjuster is arranged on the jacking assembly and the leveling steel plate, and is used to adjust the height and angle of the leveling steel plate.

3. The support-free box girder bridge pier underpinning device according to claim 1 is characterized in that: It also includes a stabilizing component, which is installed between the jacking component and the large longitudinal slope bridge, and both ends of the stabilizing component are connected to the large longitudinal slope bridge; the stabilizing component includes a vertical steel frame and a horizontal steel frame; the vertical steel frame is vertically arranged at one end of the horizontal steel frame, the bottom of the horizontal steel frame is connected to the jacking component, and the vertical steel frame and the horizontal steel frame are connected to the large longitudinal slope bridge; the horizontal steel frame remains horizontal with the underpinning pier.

4. The support-free box girder bridge pier underpinning device according to claim 3 is characterized in that: It also includes a first adjusting mechanism and a second adjusting mechanism, both of which are installed on the underpinning pier, the first adjusting mechanism is connected to the vertical steel frame, and the second adjusting mechanism is connected to an end of the horizontal steel frame away from the vertical steel frame, and the first adjusting mechanism and the second adjusting mechanism are used to adjust the force of the stabilizing assembly at both ends of the large longitudinal slope bridge.

5. The support-free box girder bridge pier underpinning device according to claim 4 is characterized in that: The first adjusting mechanism includes a winding piece, a pulley and a steel cable; the winding piece is installed on the supporting pier, the pulley is located at the end of the large longitudinal slope bridge, and the steel cable is slidably connected to the pulley; the winding piece is provided with a winding end and an unwinding end, and the ends of the steel cable are respectively fixed on the winding end and the unwinding end; the structures of the first adjusting mechanism and the second adjusting mechanism are consistent.

6. The support-free box girder bridge pier underpinning device according to claim 2, characterized in that: The beam bottom leveling assembly is in close contact with the bottom of the large longitudinal slope bridge to form a lifting surface; the lifting assembly includes a plurality of jacks, and any of the jacks is in contact with the lifting surface.

7. The support-free box girder bridge pier underpinning device according to claim 6 is characterized in that: The jacking surface is aligned with the center line of the web of the large longitudinal slope bridge.

8. The support-free box girder bridge pier underpinning device according to claim 1, characterized in that: The box-type cross beam is composed of a steel cross beam or a steel-concrete composite cross beam.

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