Back-pressure upside-down hanging supporting system for large-span cable-stayed bridge

Abstract

The invention relates to a reverse-pressure inverted-hanging supporting system for a large-span cable-stayed bridge beam, and belongs to the technical field of bridge construction, the reverse-pressure inverted-hanging supporting system comprises a bridge, the bridge comprises a side-span main beam and an approach bridge main beam which are arranged at intervals in the bridge direction, and an auxiliary pier located between the side-span main beam and the approach bridge main beam; and the back pressure base is fixedly arranged on the auxiliary pier, and the back pressure base is used for supporting the approach bridge main beam on the auxiliary pier and pressing the side span main beam on the auxiliary pier. Therefore, the dead weight of the approach bridge main beam, the dead weight of the auxiliary pier and the pile foundation of the auxiliary pier and the anti-drawing friction force of the pile foundation can be utilized to balance the unbalanced load of the side mid-span main beam, the stability and safety of the main tower structure are improved, the overall stress state of the bridge is improved, and the requirement of the auxiliary pier for the bearing capacity of a soil layer is reduced. The asymmetric load can be balanced by using fewer materials and a simpler and more convenient construction mode, the structural rigidity is improved, the stress of the bridge tower is optimized, and the aesthetic property of the bridge is improved.

Description

Technical Field

[0001] The present application relates to the technical field of bridge construction, and in particular to a counter-pressure inverted support system for a large-span cable-stayed bridge. Background Art

[0002] Cable-stayed bridges are a modern form of long-span bridges, which have been widely used around the world for their unique design and excellent performance. With the advancement of material science and construction technology, the span of cable-stayed bridges has gradually increased, developing towards super-long spans of kilometers.

[0003] However, due to the complexity of navigation conditions or topography, many bridges are usually designed with a large difference in length between the main span and the side span. This is extremely unfavorable to the stress and overall stability of the bridge tower structure, and it is often necessary to add counterweights to the side span main beam.

[0004] For example, in the related art, a space tower column cable-stayed bascule bridge with publication number CN101298753A discloses a cable-stayed bridge system structure, a space double cable plane, and the cables are centrally anchored at the upper end of the main tower. The main beam within the tail cable area of ​​the side span is provided with a weight to ensure the balance of the structure after horizontal rotation. The weight will increase the deadweight of the structure and the amount of materials used, resulting in complex construction and material waste, thereby increasing the difficulty of construction and the cost of the project. Summary of the invention

[0005] In response to the deficiencies or one of the deficiencies raised by the above-mentioned background technology, an embodiment of the present application provides a counter-pressure inverted support system for a large-span cable-stayed bridge, so as to improve the overall stiffness and stability of the large-span cable-stayed bridge and balance the asymmetric loads in the side and mid-span.

[0006] The embodiment of the present application provides a counter-pressure inverted support system for a long-span cable-stayed bridge, comprising:

[0007] A bridge, comprising a side span main beam and an approach bridge main beam arranged at intervals along the bridge direction, and an auxiliary pier located between the side span main beam and the approach bridge main beam;

[0008] A back-pressure base is fixedly arranged on the auxiliary pier, and is used to support the approach bridge main beam on the auxiliary pier, and to press the side span main beam down on the auxiliary pier to balance the unbalanced load of the side and middle span main beams.

[0009] In some embodiments, the counter-pressure base includes an L-shaped member and a cantilever member connected to each other, wherein the L-shaped member is fixed on the auxiliary pier and used to support the approach bridge main beam, and the cantilever member is used to press down the side span main beam.

[0010] In some embodiments, the counter-pressure base is a box-shaped steel member, the interior of the box-shaped steel member is filled with concrete, and the exterior of the box-shaped steel member is wrapped with a concrete layer.

[0011] In some embodiments, a first sensor for monitoring stress is disposed at one end of the cantilever member close to the L-shaped member, and a second sensor for monitoring pressure is disposed between the cantilever member and the main beam of the approach bridge.

[0012] In some embodiments, a positive pressure support is provided between the back-pressure base and the approach bridge main beam, and a back-pressure support is provided between the back-pressure base and the side span main beam, and the positive pressure support and the back-pressure support are subjected to pressure in opposite directions.

[0013] In some embodiments, the positive pressure bearing and the negative pressure bearing are any one of a pot-type rubber bearing, a plate-type rubber bearing, a spherical steel bearing, and a tension-compression bearing.

[0014] In some embodiments, the top surface of the side span main beam is flush with the top surface of the back pressure base, and a first corbel for pressing down the back pressure base is provided at one end of the side span main beam close to the approach bridge main beam.

[0015] In some embodiments, the top surface of the approach bridge main beam is flush with the top surface of the back pressure base, a second corbel is provided at one end of the approach bridge main beam close to the side span main beam, and a groove for extending the second corbel is provided on the back pressure base.

[0016] In some embodiments, the back-pressure base is extended along the transverse direction of the bridge and is located between the side span main beam and the approach bridge main beam, and both the side span main beam and the approach bridge main beam form expansion joints with the back-pressure base.

[0017] In some embodiments, the auxiliary pier includes a pier body fixedly connected to the back pressure base, and a pile foundation fixedly connected to the pier body, and the pile foundation is a friction pile foundation.

[0018] The beneficial effects of the technical solution provided by this application include:

[0019] An embodiment of the present application provides a counter-pressure inverted support system for a large-span cable-stayed bridge, wherein the bridge includes a side span main beam and an approach bridge main beam spaced apart along the direction of the bridge, and auxiliary piers located between the side span main beam and the approach bridge main beam; a counter-pressure base, which is fixedly arranged on the auxiliary piers, and is used to support the approach bridge main beam on the auxiliary piers, and to press the side span main beam down on the auxiliary piers.

[0020] Therefore, the self-weight of the main beam of the approach bridge, the self-weight of the auxiliary piers and their pile foundations, and the pull-out friction of the pile foundations can be used to balance the unbalanced load of the side and middle span main beams, improve the stability and safety of the main tower structure, improve the overall stress state of the bridge, and reduce the bearing capacity requirements of the auxiliary piers on the soil layer. Especially in the construction of asymmetric cable-stayed bridges with side and middle spans, it is possible to balance asymmetric loads, improve structural stiffness, optimize the stress on the bridge towers, improve the aesthetics of the bridge, adapt to complex terrain, and provide construction convenience with less materials and simpler construction methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 This is a structural schematic diagram of the counter-pressure inverted support system of an embodiment of the present application;

[0023] Figure 2 Schematic diagram of the structure of the back pressure base of the embodiment of the present application.

[0024] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0025] 1. Side span main beam; 11. First corbel; 2. Approach bridge main beam; 21. Second corbel; 3. Auxiliary pier; 31. Pier body; 32. Pile foundation; 4. Counter-pressure base; 41. L-shaped member; 42. Cantilever member; 5. Positive pressure support; 6. Counter-pressure support; 7. Stay cable; 8. Main tower; 9. Middle span main beam. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0027] In response to the deficiencies or one of the deficiencies raised by the above-mentioned background technology, an embodiment of the present application provides a counter-pressure inverted support system for a large-span cable-stayed bridge, so as to improve the overall stiffness and stability of the large-span cable-stayed bridge and balance the asymmetric loads in the side and mid-span.

[0028] See also Figure 1 and Figure 2As shown, the embodiment of the present application provides a counter-pressure inverted support system for a large-span cable-stayed bridge, comprising:

[0029] The bridge comprises a side span main beam 1 and an approach bridge main beam 2 arranged at intervals along the bridge direction, and an auxiliary pier 3 located between the side span main beam 1 and the approach bridge main beam 2;

[0030] The back-pressure base 4 is fixedly arranged on the auxiliary pier 3. The back-pressure base 4 is used to support the approach bridge main beam 2 on the auxiliary pier 3, and to press the side span main beam 1 down on the auxiliary pier 3 to balance the unbalanced load of the side and middle span main beams.

[0031] The counter-pressure inverted support system for a large-span cable-stayed bridge in the embodiment of the present application utilizes the self-weight of the approach bridge main beam 2, the auxiliary pier 3 and its pile foundation 32, and the pull-out friction of the pile foundation 32 to balance the unbalanced load of the side and middle span main beam, improve the stability and safety of the main tower 8 structure, improve the overall stress state of the bridge, and reduce the bearing capacity requirements of the auxiliary pier 3 on the soil layer. Especially in the construction of asymmetric cable-stayed bridges with side and middle spans, it is achieved to balance asymmetric loads with less materials and simpler construction methods, improve structural stiffness, optimize the stress on the bridge tower, improve the aesthetics of the bridge, adapt to complex terrain and provide construction convenience. Its main functions are as follows:

[0032] 1. It can balance the side span and mid-span loads. In a cable-stayed bridge, the main span is usually longer and the side span is shorter. If no balancing measures are taken, the load of the main span will cause the bridge tower to tilt toward the main span, resulting in uneven stress on the structure. The counter-pressure inverted support system transfers part of the main span load to the side span by setting a counter-pressure support 6 on the top of the auxiliary pier 3, thereby balancing the loads on both sides of the bridge tower and keeping the bridge tower vertical.

[0033] 2. It can improve the stress of the bridge tower. The bridge tower bears huge vertical and horizontal loads in the cable-stayed bridge. Especially when the side span and the main span are asymmetrical, the bending moment and shear force of the bridge tower will increase significantly. The counter-pressure inverted support system uses the self-weight of the approach bridge main beam 2, the auxiliary pier 3 and its pile foundation 32 through the counter-pressure support 6 to balance the tension of the side and middle span cable 7, reduce the bending moment and shear force of the bridge tower, optimize the stress state of the bridge tower, and reduce the design difficulty and material consumption of the bridge tower.

[0034] 3. It can optimize the stress on the bridge deck. The deck of a cable-stayed bridge will produce large bending moments and shear forces under load, especially when the side span and the main span are asymmetrical. The counter-pressure inverted support system improves the stress state of the bridge deck, reduces the bending moments and shear forces on the bridge deck, and improves the bearing capacity of the bridge deck by counter-pressure bearing 6.

[0035] 4. It can improve the structural rigidity. Cable-stayed bridges are prone to large deformation and vibration under dynamic loads such as wind loads and earthquake loads. The counter-pressure support 6 of the counter-pressure inverted support system will not have the risk of being emptied, and can effectively constrain the side span main beam 1, improve the overall rigidity of the bridge, reduce deformation and vibration, and enhance the wind resistance and earthquake resistance of the bridge.

[0036] Exemplarily, the anti-pressure inverted support system of the embodiment of the present application is composed of the main structure of the cable-stayed bridge, the auxiliary pier 3, and the anti-pressure base 4. Among them, the main structure of the cable-stayed bridge is composed of a bridge tower, a cable-stayed cable 7, a side span main beam 1, and a middle span main beam 9. The auxiliary pier 3 is located at the edge of the side span of the cable-stayed bridge to bear and transfer part of the load of the side span of the cable-stayed bridge.

[0037] The back pressure base 4 is placed above the auxiliary pier 3, and its structure is designed to be concave. The bottom of the back pressure base 4 is fixed to the auxiliary pier 3, and the upper inner surface of the concave is used to install the back pressure support 6. The upper surface of the side wall of the back pressure base 4 is dug out to make a platform for placing the positive pressure support 5 for supporting the main beam 2 of the approach bridge.

[0038] The back-pressure support 6 is hung upside down on the concave upper inner surface of the back-pressure base 4. The back-pressure support 6 is supported at the end of the side span main beam 1 of the cable-stayed bridge. The back-pressure support 6 mainly bears the unbalanced load of the side and middle span main beams 9 and transmits it to the back-pressure base 4. The bearing capacity of the back-pressure support 6 is determined according to the weight difference between the side span and the middle span and the load difference during the operation period.

[0039] It should be noted that the force transmission path of a general cable-stayed bridge is as follows: the main beam load is transmitted to the bridge tower through the inclined cables, and then transmitted to the pile foundation by the bridge tower. The remaining small part of the side span load is transmitted to the pile foundation through the side span auxiliary piers. The bridge tower and side pier supports provide longitudinal and lateral constraints.

[0040] However, due to the asymmetry of the side and middle span main beams of large-span cable-stayed bridges, the deadweight of the middle span main beams is much greater than that of the side span main beams. Therefore, the bridge towers will tilt and bend under the action of unbalanced loads, and generate upward pulling force on the side span main beams through the inclined cables.

[0041] The counter-pressure inverted support system provided in the present application cleverly utilizes the self-weight of the auxiliary pier 3 and the friction between its pile foundation 32 and the soil layer to provide downward force, which not only balances the load of the side and middle span main beams, but also saves the counterweight material of the side span main beam 1 and reduces the self-weight of the structure itself.

[0042] At the same time, the deadweight of the approach bridge main beam 2 applies pressure to the side span main beam 1 through the counter-pressure base 4. Under the premise of not affecting the safety of the bridge, the deadweight of the approach bridge main beam 2 can be further cleverly used to provide downward force to balance the load of the side and middle span main beam 9, which can reduce the requirements for the deadweight of the auxiliary pier 3 and the friction between its pile foundation 32 and the soil layer, save construction materials and shorten the construction period.

[0043] In some alternative embodiments: See Figure 1and Figure 2 As shown, an embodiment of the present application provides a counter-pressure inverted support system for a large-span cable-stayed bridge. The counter-pressure base 4 of the counter-pressure inverted support system for a large-span cable-stayed bridge includes an L-shaped member 41 and a cantilever member 42 that are interconnected. The L-shaped member 41 is fixed on the auxiliary pier 3 and is used to support the approach bridge main beam 2. The cantilever member 42 is used to press down the side span main beam 1.

[0044] The L-shaped member 41 and the cantilever member 42 of the embodiment of the present application are integrally arranged, and the L-shaped member 41 adds a docking surface with the auxiliary pier 3. To avoid the tensile warping of the back pressure base 4, the bottom surface of the L-shaped member 41 is fixed to the top of the auxiliary pier 3 by anti-pulling rivets, and the cantilever member 42 extends toward the side span main beam 1 and does not exceed the auxiliary pier 3, so as to facilitate the downward pressure of the approach bridge main beam 2. Exemplarily, the cantilever member 42 has a gradual cross-section, such as a fish belly shape, which can reduce stress concentration and improve bending stiffness.

[0045] In some alternative embodiments: See Figure 1 and Figure 2 As shown, an embodiment of the present application provides a counter-pressure inverted support system for a large-span cable-stayed bridge, wherein the counter-pressure base 4 of the counter-pressure inverted support system for a large-span cable-stayed bridge is a box-type steel member, the interior of the box-type steel member is filled with concrete, and the exterior of the box-type steel member is wrapped with a concrete layer.

[0046] The back-pressure base 4 of the embodiment of the present application is a box-type steel member. The cross-section of the box-type steel member is a rectangular or square hollow cross-section with good torsional resistance and can be suitable for complex stress conditions. The internal cavity of the box-type steel member is filled with high-strength concrete, and the surface is wrapped with a concrete layer formed by hardening of high-strength concrete, which can further improve the compression, bending and torsional resistance, so that the overall bearing capacity is significantly improved, which is suitable for complex stress scenarios with high loads and large spans in this application.

[0047] In some alternative embodiments: See Figure 1 and Figure 2 As shown, an embodiment of the present application provides a counter-pressure inverted support system for a large-span cable-stayed bridge, wherein a first sensor for monitoring stress is provided at one end of a cantilever member 42 close to an L-shaped member 41 of the counter-pressure inverted support system for a large-span cable-stayed bridge, and a second sensor for monitoring pressure is provided between the cantilever member 42 and the main beam 2 of the approach bridge.

[0048] Exemplarily, the cantilever member 42 of the embodiment of the present application is integrally arranged with the L-shaped member 41, and a first sensor (not shown in the figure) is installed on the cantilever member 42 near the root of the L-shaped member 41 (here is the area with maximum bending moment). The first sensor can be a fiber grating sensor, which is embedded in the cantilever member 42 to monitor stress, strain and temperature changes in real time.

[0049] A second sensor (not shown) is also installed between the cantilever member 42 and the main beam 2 of the approach bridge. The second sensor can be a piezoelectric sensor, such as a piezoelectric ceramic sensor or a piezoelectric film, to monitor the back pressure of the back pressure base 4 in real time. Finally, the data sent by the first sensor and the second sensor can be wirelessly transmitted to an external central monitoring system to achieve remote real-time monitoring and early warning.

[0050] Specifically, in some embodiments, the first sensor adopts a fiber Bragg grating sensor. There are three fiber Bragg grating sensors, which are arranged along the length direction of the cantilever member 42, at the upper surface, lower surface and neutral axis position of the root of the cantilever member 42 (the connection between the cantilever member 42 and the L-shaped member 41), to monitor the strain distribution of the tension, compression and neutral layer respectively. The fiber Bragg grating sensor is fixed to the surface of the cantilever member 42 by spot welding or epoxy resin, and covered with a stainless steel sheath to prevent construction damage.

[0051] A fiber Bragg grating demodulator (such as MOI SM130) is used to scan the reflection wavelength changes of the fiber Bragg grating sensor in real time. Multiple fiber Bragg grating sensors are connected in series through a fiber optic splitter. The fiber optic signal is transmitted to the data acquisition station on the bridge tower or abutment through the pre-buried optical cable on the bridge deck. The data is uploaded to the cloud platform in real time for real-time monitoring and abnormal warning.

[0052] By real-time monitoring of the strain distribution at the root of the cantilever, it is determined whether the cantilever member 42 is overloaded or has local buckling. For example, by setting an early warning threshold, when the strain exceeds 80% of the design value, an alarm is triggered to prompt inspection of structural damage. Fatigue damage can also be evaluated through the strain time history curve to predict the remaining life.

[0053] Specifically, in some embodiments, the second sensor uses a piezoelectric film, the back-pressure support 6 between the cantilever member 42 and the main beam 2 of the approach bridge uses a spherical support, and the piezoelectric film is arranged between the upper support plate of the spherical support and the sliding plate (here is the dynamic pressure fluctuation area). The piezoelectric film is cut into strips that match the sliding surface, bonded to the surface of the sliding plate with conductive glue, and covered with a protective layer (such as a polyimide film) to prevent mechanical wear.

[0054] The charge signal output by PVDF is converted into a voltage signal through a charge amplifier, and then input into the data acquisition card after amplification. The dynamic sampling frequency is set to ≥1kHz to capture the transient fluctuation of contact pressure. The high-frequency noise is eliminated through a low-pass filter to extract the effective pressure signal. The data can be recorded synchronously with the above-mentioned fiber Bragg grating sensor to correlate and analyze the load and strain response.

[0055] By real-time monitoring of the pressure distribution on the sliding interface, it is possible to determine whether the bearing is overloaded or partially empty. If the pressure peak exceeds the design value or is unevenly distributed, it indicates that the bearing lubrication has failed or the installation is deviated. At the same time, the dynamic response of the bearing under live load can be analyzed in combination with vehicle load data to optimize bridge operation management.

[0056] It should be noted that the fiber Bragg grating sensor can monitor bending and shear strain in real time and prevent structural damage by being precisely arranged at the root of the cantilever member 42. The piezoelectric film is installed on the bearing sliding interface to dynamically capture contact pressure fluctuations and optimize maintenance strategies. The combination of the two data provides full life cycle health monitoring for cable-stayed bridges. The synergy of the two can achieve a transition from "passive maintenance" to "active warning", significantly improving safety and durability.

[0057] In some alternative embodiments: See Figure 1 and Figure 2 As shown, an embodiment of the present application provides a counter-pressure inverted support system for a large-span cable-stayed bridge, wherein a positive-pressure support 5 is arranged between a counter-pressure base 4 and the approach bridge main beam 2 of the counter-pressure inverted support system for a large-span cable-stayed bridge, and a counter-pressure support 6 is arranged between the counter-pressure base 4 and the side span main beam 1, and the pressure directions of the positive-pressure support 5 and the counter-pressure support 6 are opposite.

[0058] A positive pressure support 5 is installed between the second bracket 21 of the approach bridge main beam 2 of the embodiment of the present application and the L-shaped member 41 of the back pressure base 4. The positive pressure support 5 is used to withstand the vertical pressure generated by the approach bridge main beam 2 under the action of the dead load and live load, and at the same time adapt to the horizontal displacement of the approach bridge main beam 2 (such as temperature deformation, displacement caused by live load, etc.). The support stability of the approach bridge main beam 2 can be improved.

[0059] At the same time, a back-pressure support 6 is installed between the cantilever member 42 of the back-pressure base 4 and the first corbel 11 of the side span main beam 1. The back-pressure support 6 is used to bear the upward pull force and can always be in a compressed state. It can adapt to the complex stress state of the side span main beam 1 under the action of alternating tension and compression loads, ensuring that the bridge can work normally under various working conditions.

[0060] In some alternative embodiments: See Figure 1 and Figure 2 As shown, an embodiment of the present application provides a counter-pressure inverted support system for a large-span cable-stayed bridge, wherein the positive pressure bearing 5 and the counter-pressure bearing 6 of the counter-pressure inverted support system for a large-span cable-stayed bridge are any one of a pot-type rubber bearing, a plate-type rubber bearing, a spherical steel bearing, and a tension-compression bearing.

[0061] The positive pressure bearing 5 of the embodiment of the present application adopts a basin-type rubber bearing, which is composed of a steel basin, a rubber pad and an upper bearing plate. The rubber pad provides elastic deformation capability, and the steel basin limits lateral displacement. It has a strong bearing capacity (up to thousands of tons) and is suitable for supporting the main beam of a large-span cable-stayed bridge. It has good vertical stiffness and horizontal displacement adaptability. It has high durability and low maintenance cost. It can be used to withstand the vertical pressure generated by the dead load and live load of the main beam 2 of the approach bridge, while allowing a certain horizontal displacement (such as temperature deformation).

[0062] Furthermore, a polytetrafluoroethylene (PTFE) sliding layer can be added between the rubber pad and the upper bearing plate to reduce the friction coefficient (μ≤0.03) and improve the horizontal displacement capacity. Alternatively, a lead core or high damping rubber can be set in the steel basin to enhance the energy dissipation capacity of the bearing and adapt to earthquake loads.

[0063] The counter-pressure bearing 6 of the embodiment of the present application adopts a spherical steel bearing, which is composed of an upper bearing plate, a spherical sliding pair and a lower bearing plate. The spherical sliding pair allows multi-directional rotation and displacement. It can adapt to complex stress states (such as tension and compression alternating loads). It is flexible to rotate and can effectively release the local bending moment of the main beam. It has good durability and is suitable for bearing dynamic loads for a long time. It can be used to withstand the upward pull force (negative reaction force) that may be generated by the side span main beam 1, while adapting to the rotation and horizontal displacement of the side span main beam 1.

[0064] Furthermore, a shape memory alloy SMA or a spring device can be embedded in the spherical sliding pair so that the support automatically resets after unloading, reducing residual deformation and achieving a self-resetting function; or a rigid block can be added to the top of the support to fix the connection to the back pressure base 4 to limit excessive displacement under extreme wind loads.

[0065] In some alternative embodiments: See Figure 1 and Figure 2 As shown, an embodiment of the present application provides a counter-pressure inverted support system for a large-span cable-stayed bridge, wherein the top surface of the side span main beam 1 of the counter-pressure inverted support system for a large-span cable-stayed bridge is flush with the top surface of the counter-pressure base 4, and a first corbel 11 for pressing down the counter-pressure base 4 is provided at one end of the side span main beam 1 close to the approach bridge main beam 2.

[0066] The counter-pressure base 4 of the embodiment of the present application balances the unbalanced load of the side and middle span main beams by pressing down the first corbel 11 of the side span main beam 1. The setting of the first corbel 11 allows the top surface of the side span main beam 1 to be flush with the top surface of the counter-pressure base 4, which simplifies the construction method and improves the aesthetics of the bridge.

[0067] In some alternative embodiments: See Figure 1 and Figure 2As shown, an embodiment of the present application provides a counter-pressure inverted support system for a large-span cable-stayed bridge, wherein the top surface of the approach bridge main beam 2 of the counter-pressure inverted support system for a large-span cable-stayed bridge is flush with the top surface of the counter-pressure base 4, a second corbel 21 is provided at one end of the approach bridge main beam 2 close to the side span main beam 1, and a groove for extending the second corbel 21 is provided on the counter-pressure base 4.

[0068] The back-pressure base 4 of the embodiment of the present application achieves stable support for the main beam 2 of the approach bridge by supporting the first corbel 11 of the approach bridge main beam 2, so that the top surface of the approach bridge main beam 2 can be flush with the top surface of the back-pressure base 4. The construction method is simple and the aesthetics of the bridge is improved.

[0069] In some alternative embodiments: See Figure 1 and Figure 2 As shown, an embodiment of the present application provides a counter-pressure inverted support system for a large-span cable-stayed bridge, wherein a counter-pressure base 4 of the counter-pressure inverted support system for a large-span cable-stayed bridge is extended along the transverse direction of the bridge and is located between the side span main beam 1 and the approach bridge main beam 2, and both the side span main beam 1 and the approach bridge main beam 2 form expansion joints with the counter-pressure base 4.

[0070] The expansion joints formed between the side span main beam 1 and the back pressure base 4, and between the back pressure base 4 and the approach bridge main beam 2 in the embodiment of the present application can adapt to the deformation of the side span main beam 1 and the approach bridge main beam 2 caused by temperature changes, concrete shrinkage and live loads, thereby ensuring the safety of the bridge structure.

[0071] In some alternative embodiments: See Figure 1 and Figure 2 As shown, an embodiment of the present application provides a counter-pressure inverted support system for a large-span cable-stayed bridge. The auxiliary pier 3 of the counter-pressure inverted support system for a large-span cable-stayed bridge includes a pier body 31 fixedly connected to a counter-pressure base 4, and a pile foundation 32 fixedly connected to the pier body 31, and the pile foundation 32 is a friction type pile foundation.

[0072] The unbalanced load on the side and mid-span main beam of the embodiment of the present application is relatively large. In order to prevent the counter-pressure base 4 from being tensilely warped, tensile-resistant steel nails are added to the bottom surface of the counter-pressure base 4 and the top of the auxiliary pier 3 to strengthen the connection and improve the tensile resistance of the base.

[0073] In addition, in order to improve the tensile strength of the counter-pressure inverted support system, the pile foundation 32 of the auxiliary pier 3 is configured as a friction pile foundation in the embodiment of the present application, and the tensile strength is provided by the friction between the pile foundation 32 and the surrounding soil layer.

[0074] For example, the self-weight of the middle span main beam 9 is defined as G Z , the self-weight of the side span main beam 1 is G B , the deadweight of auxiliary pier 3 G F , the pull-out friction force of the pile foundation 32 of the auxiliary pier 3 is FF , the force on the back pressure support 6 is F, and the maximum back pressure it can provide is F max , k is the safety factor. Based on the basic principle of structural mechanics force balance;

[0075] F=G Z -G B

[0076] The design of the back pressure support 6 of the back pressure inverted support system should meet the following requirements:

[0077] F max ≥k(G Z -G B )

[0078] When G F ≥k(G Z -G B ), F F Just design according to the normal bridge pile foundation bearing capacity;

[0079] When G F <k(G Z -G B ), F F The tensile strength should be considered. While meeting the normal bridge pile foundation bearing capacity design, G F +F F ≥k(G Z -G B ).

[0080] Among them, the pile foundation pull-out friction force F F It is determined according to the pull-out coefficient λ of the friction pile foundation. The pull-out coefficient λ of the friction pile foundation is the ratio of the pull-out bearing capacity of the pile foundation to the friction resistance of the compressive side, reflecting the difference between the pile-soil interface under tension and compression. The value is usually in the range of 0.5-0.8. According to the "Highway Bridge and Culvert Foundation and Foundation Design Code" JTG 3363-2019, the pull-out bearing capacity formula of a single pile is:

[0081] T d =Σλ i q sik μ i l i

[0082] T d is the design value of the pull-out bearing capacity of a single pile; i is the pull-out coefficient of the i-th layer of soil; q sik is the standard value of the compressive lateral friction resistance of the i-th layer of soil; μ i is the circumference of the pile; l i is the pile length of the i-th soil layer.

[0083] Generally, the λ of precast piles in sandy soil can be taken as 0.6; the λ of cast-in-place piles in clay can be taken as 0.75.

[0084] That is, when the auxiliary pier 3 is located in an area with poor soil, its foundation bearing capacity is insufficient to bear the load transmitted by the bridge structure. At this time, the upward pulling force generated by the unbalanced load of the side and middle span main beam 9 can offset part of the force transmitted to the soil by the superstructure, the auxiliary pier 3 and its pile foundation 32, thereby reducing the bearing capacity requirement of the auxiliary pier 3 foundation, being economical and beautiful, and greatly improving the construction convenience.

[0085] In the description of the present application, it should be noted that the terms "upper", "lower", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0086] It should be noted that, in this application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0087] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A counter-pressure inverted support system for a long-span cable-stayed bridge, characterized in that: include: A bridge, comprising a side span main beam (1) and an approach bridge main beam (2) arranged at intervals along the longitudinal direction of the bridge, and an auxiliary pier (3) located between the side span main beam (1) and the approach bridge main beam (2); A back-pressure base (4), the back-pressure base (4) is fixedly arranged on the auxiliary pier (3), and the back-pressure base (4) is used to support the approach bridge main beam (2) on the auxiliary pier (3), and to press the side span main beam (1) down on the auxiliary pier (3) to balance the unbalanced load of the side and middle span main beams.

2. The anti-pressure inverted support system for a long-span cable-stayed bridge according to claim 1, characterized in that: The counter-pressure base (4) comprises an L-shaped member (41) and a cantilever member (42) which are connected to each other, wherein the L-shaped member (41) is fixed on the auxiliary pier (3) and is used to support the approach bridge main beam (2), and the cantilever member (42) is used to press down the side span main beam (1).

3. The counter-pressure inverted support system for a long-span cable-stayed bridge according to claim 1 or 2, characterized in that: The counter-pressure base (4) is a box-shaped steel component, the interior of the box-shaped steel component is filled with concrete, and the exterior of the box-shaped steel component is wrapped with a concrete layer.

4. The anti-pressure inverted support system for a long-span cable-stayed bridge according to claim 2, characterized in that: A first sensor for monitoring stress is arranged at one end of the cantilever member (42) close to the L-shaped member (41), and a second sensor for monitoring pressure is arranged between the cantilever member (42) and the approach bridge main beam (2).

5. The anti-pressure inverted support system for a long-span cable-stayed bridge according to claim 1, characterized in that: A positive pressure support (5) is arranged between the counter-pressure base (4) and the approach bridge main beam (2), and a counter-pressure support (6) is arranged between the counter-pressure base (4) and the side span main beam (1), and the positive pressure support (5) and the counter-pressure support (6) are subjected to pressure in opposite directions.

6. The counter-pressure inverted support system for a long-span cable-stayed bridge according to claim 5, characterized in that: The positive pressure bearing (5) and the negative pressure bearing (6) are any one of a pot-type rubber bearing, a plate-type rubber bearing, a spherical steel bearing, and a tension-compression bearing.

7. The counter-pressure inverted support system for a long-span cable-stayed bridge according to claim 1, characterized in that: The top surface of the side span main beam (1) is flush with the top surface of the back pressure base (4), and a first bracket (11) for pressing down the back pressure base (4) is provided at one end of the side span main beam (1) close to the approach bridge main beam (2).

8. The counter-pressure inverted support system for a long-span cable-stayed bridge according to claim 1, characterized in that: The top surface of the approach bridge main beam (2) is flush with the top surface of the back pressure base (4); a second corbel (21) is provided at one end of the approach bridge main beam (2) close to the side span main beam (1); and a groove for extending the second corbel (21) is provided on the back pressure base (4).

9. The counter-pressure inverted support system for a long-span cable-stayed bridge according to claim 1, characterized in that: The back-pressure base (4) is extended in the transverse direction of the bridge and is located between the side span main beam (1) and the approach bridge main beam (2); the side span main beam (1) and the approach bridge main beam (2) both form expansion joints with the back-pressure base (4).

10. The counter-pressure inverted support system for a long-span cable-stayed bridge according to claim 1, characterized in that: The auxiliary pier (3) comprises a pier body (31) fixedly connected to the back pressure base (4), and a pile foundation (32) fixedly connected to the pier body (31), wherein the pile foundation (32) is a friction type pile foundation.

Images