A method for reconstructing a bridge across a line

Abstract

The application discloses a method for reconstructing a cross-line bridge, which comprises the following steps: 1, determining a reconstruction scheme of the bridge; 2, constructing a main tower; 3, jacking up an original main beam; 4, tensioning a cable-stayed cable; 5, removing original bridge piers and temporary supports; and 6, newly building a road under the bridge. The application is aimed at the case that a main line of traffic is added under the bridge, and a main tower is newly built, so that the cable-stayed cable can be tensioned without affecting the main line of traffic. The support function of an original side span abutment is replaced by a cross beam and the cable-stayed cable, and the load is transmitted to the main tower by the cable-stayed cable. The original side span abutment is replaced by the temporary supports, and after the original side span abutment is removed, a road for vehicle passing can be newly built under the area, so that the resource consumption and the environmental burden caused by removing the whole bridge are avoided, and the economic and social benefits are remarkable, and the application has great popularization and application value.

Description

Technical Field

[0001] This invention belongs to the field of bridge construction technology, and specifically relates to a method for the renovation and utilization of an overpass. Background Technology

[0002] In order to improve the service level of highways, many expressways are facing the problems of reconstruction, expansion and upgrading of road grades, and the reconstruction and expansion of highway bridges is imminent.

[0003] For mainline widening or newly established interchanges, the reconstruction of overpasses becomes a key focus and challenge in expansion and reconstruction projects. Because the intermediate supports of continuous beam bridges are located in the positive bending zone, the prestressed steel reinforcement primarily counteracts the positive bending moment. When the intermediate piers are removed, the original supports become part of the mid-span area, and the load effect changes from positive to negative bending moment. Therefore, conventional reinforcement methods are insufficient to meet the load-bearing capacity requirements. Demolition and reconstruction are typically the primary approach, but this involves significant investment and social impact, severe environmental pollution, and does not meet the requirements of sustainable development. Furthermore, the construction period for demolition and reconstruction is long, significantly impacting mainline traffic and resulting in poor social and economic benefits. Therefore, there is an urgent need for a method for the reconstruction and utilization of overpasses that is rationally designed and can effectively solve the problem of mainline bridge traffic disruption caused by overpass construction. Summary of the Invention

[0004] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a method for the reconstruction and utilization of overpasses. This invention addresses the situation where a main traffic lane is added beneath the bridge. By constructing a new main tower, the cable-stayed bridge can be tensioned without affecting main traffic. A combination of crossbeams and cable-stayed bridges replaces the supporting function of the original side abutments, and the cable-stayed bridges transfer the load to the main tower. Demountable temporary supports are erected to easily replace the original side abutments that need to be demolished. After the original side abutments are demolished, a road for vehicle traffic can be built beneath the area, avoiding the resource consumption and environmental burden of demolishing the entire bridge. This results in significant economic and social benefits and has great potential for widespread application.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for the reconstruction and utilization of an overpass, characterized in that the method includes the following steps: Step 1: Determine the bridge reconstruction plan: Determine the length of the main beam extension section connecting to the original main beam and the length of the bridge deck extension section connecting to the original bridge deck in the new bridge, and determine the extension direction of the main beam extension section and the bridge deck extension section. Step 2, Main Tower Construction: Construct the main tower used for cable-stayed connection of the original main beam and the extended section of the main beam; wherein, the main tower includes a tower base, a foundation and a cable tower arranged sequentially from bottom to top; Step 3: Lift the original main beam: Step 301: Erect temporary supports: Erect temporary supports around the original side span abutment, with the top of the temporary supports and the bottom of the lifting section meeting the design gap value; wherein, the lifting section is the beam segment of the original main beam between the original mid-span pier and the original side span abutment. Step 302: Erect the lifting platform: Install multiple jacks on the top of the temporary support, and set temporary steel plate supports on the top of the jacks; wherein the top of the steel plate supports is in contact with the bottom of the lifting section; Step 303: Lift the original main beam: Determine the height of the lifting section according to the slope requirements of the bridge deck cross slope, and then use the jacks on the temporary support to lift the lifting section synchronously, so that the lifting section is removed from the original side span abutment and reaches the design height. Step 4: Tensioning the stay cables: Step 401, Crossbeam construction: A first crossbeam is installed on top of the original mid-span pier, and a second crossbeam is installed on top of the original side span abutment. Prestressed tendons are then installed on the first and second crossbeams. Step 402, Construction of the new bridge: First and second pile foundations are sequentially installed at the lower part of the original main beam extending towards the main beam extension section. Then, a first pile cap and a first pier are sequentially installed on top of the first pile foundations. A second pile cap is installed on top of the second pile foundations. A main beam extension section connected to the second crossbeam is then installed on top of the first pier and the second pile cap. Finally, a bridge deck extension section connected to the original bridge deck is installed on top of the main beam extension section. The distance between the first pile foundation and the tower foundation meets the width requirements of the new road under the bridge. Step 403: Tensioning the stay cables: A first cable and a second cable are installed on the tower; wherein the upper ends of the first cable and the second cable are both anchored into the upper end of the tower, the lower end of the first cable is anchored into the first crossbeam, and the lower end of the second cable is anchored into the second crossbeam. Then, the first and second cables are tensioned. After tensioning is completed, the first and second cables are anchored to complete the bridge reconstruction. Step 5: Remove the original bridge piers and temporary supports: After the reconstruction of the new bridge is completed, remove the original side span abutments and the temporary supports in sequence; Step 6: Construct a new road under the bridge: Construct the required traffic road between the main tower and the first pier to enable vehicle passage in the original side abutment area.

[0006] The above-mentioned method for the renovation and utilization of an overpass is characterized in that: before step two, pile foundation construction is required, as follows: before construction, the site needs to be leveled, then the drilling position is located and the casing is installed, and then the concrete construction of the tower foundation is carried out inside the casing.

[0007] The above-mentioned method for renovating and utilizing an overpass bridge is characterized in that: in step two, there are two pylons, the two pylons have the same structural dimensions, and the two pylons are located on both sides of the original main beam; The specific construction steps of the main tower are as follows: construct multiple tower bases between the original mid-span pier and the original side-span abutment; construct the pier cap on the upper part of the multiple tower bases; then construct two cable towers on the upper part of the pier caps, so that the two cable towers are symmetrically arranged on both sides of the original main beam; and finally construct multiple connecting beams between the two cable towers.

[0008] The above-mentioned method for the reconstruction and utilization of an overpass is characterized in that: in step two, according to the formula... The height of the tower above the original main beam was determined; among which, This refers to the distance between the tower and the original mid-span pier. The angle between the tower and the first cable.

[0009] The above-mentioned method for renovating and utilizing an overpass is characterized in that: the bearing capacity of the second cable must meet the following requirements. The equivalent radius of the second cable cross section can be obtained as follows: ; The horizontal stresses of the stay cables on both sides of the tower are equal, that is... Therefore, the bearing capacity of the first cable is... Therefore, the equivalent radius of the first cable cross-section can be obtained as follows: ; Where N is the support reaction force of the original bridge at the top of the original side span abutment. The angle between the tower and the second cable. This refers to the stress in the first or second cable.

[0010] Compared with the prior art, the present invention has the following advantages: 1. This invention, by constructing detachable temporary supports, facilitates the replacement of the original side abutments that need to be demolished. This not only avoids damage to the original main beam and bridge deck structure but also reduces the impact of overpass construction on the main traffic flow located below the bridge, effectively solving the problem of the impact of overpass construction on the main traffic flow. At the same time, after the original side abutments are demolished, a new road for vehicle traffic can be built under the area, meeting the needs of road reconstruction and facilitating its widespread use.

[0011] 2. This invention addresses the situation where a main traffic artery is added beneath a bridge. Since the intermediate support of a continuous beam bridge is located in a positive bending zone, the prestressed steel reinforcement on the original main beam primarily counteracts the positive bending moment. When the intermediate pier is removed, the original support becomes the mid-span region, and the load effect changes from a positive bending moment to a negative bending moment. Therefore, conventional reinforcement methods are insufficient to meet the load-bearing capacity requirements. This invention, by constructing a new main tower, facilitates the tensioning of the stay cables without affecting main traffic flow, ensuring that the original structural stress pattern remains unchanged. This makes the overall stress on the beam more clearly defined. By using a combination of crossbeams and stay cables, the bending moment generated by tension is counteracted, allowing the main tower to primarily bear the pressure of the original main beam. Utilizing the high compressive strength of the main tower's concrete, the load-bearing capacity required for the new bridge is reduced, improving the applicability and economic efficiency of the main tower. The structure is reliable, stable, and performs well.

[0012] 3. This invention achieves bridge reconstruction by relocating the original bridge piers and extending the bridge, allowing for the construction of new traffic roads in the original bridge abutment area. This avoids the large amount of construction waste caused by the complete demolition and reconstruction of the bridge, as well as the high economic costs required for building a new bridge. At the same time, it minimizes the impact on existing traffic lines, achieving good economic and social benefits and representing a trend towards high-quality development.

[0013] In summary, this invention addresses the situation where a main traffic artery is added beneath a bridge. By constructing a new main tower, cable-stayed bridge tensioning can be achieved without disrupting main traffic flow. A combination of crossbeams and cable-stayed bridge cables replaces the supporting function of the original side span abutments, and the cable-stayed bridge cables transfer the load to the main tower. Furthermore, the erection of detachable temporary supports facilitates the replacement of the original side span abutments that need to be demolished. After the original side span abutments are removed, a new road for vehicular traffic can be constructed beneath the area, avoiding the resource consumption and environmental burden associated with demolishing the entire bridge. This invention offers significant economic and social benefits and has great potential for widespread application.

[0014] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0015] Figure 1 This is a flowchart of the construction method of the present invention.

[0016] Figure 2 This is a schematic diagram of the original bridge structure of the present invention.

[0017] Figure 3 This is a schematic diagram of the structure of the present invention.

[0018] Figure 4 for Figure 3 Top view.

[0019] Figure 5 for Figure 3 AA sectional view.

[0020] Figure 6 for Figure 3 BB cross-sectional view.

[0021] Figure 7 This is a schematic diagram of the cable structure of the present invention.

[0022] Figure 8 for Figure 7 Top view.

[0023] Explanation of reference numerals in the attached figures: 1. Original main girder; 2. Original bridge deck; 3. Original mid-span abutment; 4. Original mid-span pier; 5. Original side-span abutment; 6. First pile foundation; 7. First pile cap; 8. First pier; 9. Second pile foundation; 10. Second pile cap; 11. First crossbeam; 12. Second crossbeam; 13. Main girder extension section; 14. Bridge deck extension section; 15. Tower foundation; 16. Abutment; 17. Cable tower; 18. First cable; 19. Second cable; 20. Upper anchorage; 21. Lower anchorage; 22. Connecting beam; 23. Temporary support; 24. Lifting section. Detailed Implementation

[0024] like Figures 1 to 8 As shown, a method for the renovation and utilization of an overpass according to the present invention includes the following steps: Step 1: Determine the bridge reconstruction plan: Determine the length of the main beam extension section 13 that connects to the original main beam 1 and the length of the bridge deck extension section 14 that connects to the original bridge deck 2 in the new bridge, and determine the extension direction of the main beam extension section 13 and the bridge deck extension section 14.

[0025] Based on the design calculations, the lengths of the main beam extension section 13 and the bridge deck extension section 14 are determined, which facilitates the subsequent determination of the positions of the first pile foundation 6 and the second pile foundation 9 used to support the main beam extension section 13.

[0026] Step 2, Main Tower Construction: Construct the main tower for cable-stayed connection of the original main beam 1 and the extended section 13 of the main beam; wherein, the main tower includes a tower base 15, a foundation 16 and a cable tower 17 arranged sequentially from bottom to top.

[0027] In this embodiment, before step two, pile foundation construction is required, as follows: before construction, the site needs to be leveled, then the drilling position is located and the casing is installed, and then the concrete construction of the tower base 15 is carried out inside the casing.

[0028] In actual construction, the casing can be made of steel or concrete and should be sturdy and leak-proof. When using a rotary drill, the inner diameter of the casing should be 20cm larger than the drill bit diameter, the top surface of the casing should be 2m above the construction water level, and preferably 0.3m above the construction ground. Its height should also meet the requirements of the mud level in the hole. The embedment depth of the casing should not be less than 2m. When the surface soil layer is soft, the length of the casing embedded in the dense soil layer should not be less than 0.5m. After the drilling depth of the bored pile reaches the design elevation, the hole depth and diameter should be checked. Only after meeting the specifications can the first hole cleaning be carried out. After the steel cage and guide pipe are hoisted and placed, the second hole cleaning should be carried out. After the second cleaning is completed and the thickness of the sediment at the bottom of the hole and the mud specific gravity and viscosity meet the requirements, concrete pile pouring should be carried out within half an hour.

[0029] The reinforcing cage can be fabricated in sections and extended during hoisting. The joint positions of the main reinforcement bars in the pile foundation reinforcing cage should meet the specifications. Effective positioning and lowering measures should be taken during the placement of the reinforcing cage to ensure accurate positioning and prevent impact on the borehole wall. After the reinforcing cage is in place, it should be reliably fixed to prevent it from floating during concrete pouring. The grouting height of the cast-in-place pile should be at least one meter higher than the designed pile top elevation. The grouting height should be based on ensuring the quality of the concrete at the pile top. Before constructing the pile cap, the pile head should be removed, but 10cm of concrete should be left inside the pile cap and pile cap to avoid damaging the pile body. The pile foundation concrete should be poured continuously without interruption. The filling coefficient of the concrete pouring should not be less than 1.0, and generally should not exceed 1.3.

[0030] In this embodiment, in step two, there are two cable towers 17, the two cable towers 17 have the same structural dimensions, and the two cable towers 17 are located on both sides of the original main beam 1.

[0031] The specific construction steps of the main tower are as follows: construct multiple tower bases 15 between the original mid-span pier 4 and the original side span abutment 5; construct the pier cap 16 on the upper part of the multiple tower bases 15; then construct two cable towers 17 on the upper part of the pier cap 16, and arrange the two cable towers 17 symmetrically on both sides of the original main beam 1; and then construct multiple connecting beams 22 between the two cable towers 17.

[0032] In actual construction, the main tower is a reinforced concrete structure. The pier 16 is located below the original main beam 1, and the length of the pier 16 is greater than the width of the original main beam 1. This allows the two cable towers 17 on the pier 16 to be located on both sides of the original main beam 1. The length direction of the pier 16 is the transverse direction of the bridge. At the same time, there are at least two connecting beams 22, which are located above and below the original main beam 1, respectively. This allows the upper and lower ends of the two cable towers 17 to be connected, forming a rectangular frame around the original main beam 1. This not only fixes the two cable towers 17 but also does not affect the construction of the original main beam 1 and the extension section 13 of the main beam.

[0033] Step 3: Lift the original main beam: like Figure 4 As shown, step 301, erecting temporary supports: erecting temporary supports 23 around the original side span abutment 5, with the top of the temporary supports 23 and the bottom of the lifting section 24 meeting the design gap value; wherein, the lifting section 24 is the beam segment of the original main beam 1 between the original mid-span pier 4 and the original side span abutment 5.

[0034] During actual construction, temporary support 23 is a steel pipe scaffolding structure. Considering the needs of the later permanent reinforcement and renovation plan for the bridge, the distance between the vertical centerline of temporary support 23 and the edge of the original side span abutment 5 is 2.25m, and the distance with the back wall is 3m. The center of the steel pipe scaffolding corresponds to the web plates on both sides of the lifting section 24 to prevent damage to the superstructure during the lifting process. When erecting temporary support 23, the verticality of the steel pipe flange end face must be checked and accepted with a level to ensure the verticality of the steel pipe installation. A steel pipe support working platform is erected around the steel pipe column to facilitate the construction personnel to tighten the flange bolts and weld the steel pipe connecting beams at different positions. At the same time, the weld between the flange and the steel pipe must be checked. The weld should be full. Two people should weld symmetrically during welding to avoid flange deformation, which would affect the installation. The bottom of the steel pipe and the embedded steel plate are fully welded. When welding the transverse connecting beam to the steel pipe column, it is installed from one side to the other.

[0035] In actual construction, the transverse connecting beams between steel supports are set according to the height of the steel pipe columns. The verticality of the steel supports must meet the relevant requirements of Article 8.6.1 of the "Highway Engineering Quality Inspection and Evaluation Standard, Volume 1, Civil Engineering" JTGF80-1-2017. According to the steel support structure verification of the steel pipe column lattice support, under the consideration of the most unfavorable load combination, the bearing capacity of the steel pipe lattice column, the bearing capacity of the transverse brace, the bearing capacity of the diagonal brace, and the bearing capacity of the foundation must all meet the specifications, and the overall structure must not experience linear buckling.

[0036] During welding, the weld grade for steel supports, flanges, and stiffening ribs shall be Grade I, and the rest shall be Grade II. All butt joints shall be Grade I welds, which must be fully penetrated. Welding materials, methods, and process parameters shall be determined through welding procedure qualification. The mechanical properties of the weld shall be verified through experimental analysis to be no less than those of the base material. Automatic welding should be used as much as possible, whether in the factory or on the construction site. Manual arc welding may be used only for welds where automatic welding is difficult. The on-site welding temperature shall be designed to be 10–15 degrees Celsius. Adjustments shall be made when assembling welds at different temperatures. The impact of daily temperature differences on the welds should be fully considered when assembling welds on the site to ensure that the temperature is basically the same during welding. Welding should be avoided under direct sunlight.

[0037] This invention, by constructing detachable temporary supports, facilitates the replacement of the original side abutment 5 that needs to be demolished. This not only avoids damage to the structure of the original main beam 1 and the original bridge deck 2, but also reduces the impact of the overpass construction on the main traffic line located below the bridge, effectively solving the problem of the overpass construction affecting the main traffic line bridge. At the same time, it also facilitates the design of a new main traffic line at the site of the demolished original side abutment 5, meeting the needs of road reconstruction and facilitating its widespread use.

[0038] Step 302: Erect the lifting platform: Install multiple jacks on the top of the temporary support 23, and set temporary steel plate supports on the top of the jacks; wherein the top of the steel plate supports is attached to the bottom of the lifting section 24.

[0039] It should be noted that, in order to ensure that the beam is subjected to uniform force during jacking, steel plates are placed on the bottom of the jacks, and the plunger end of the jack rests on the web of the box girder of jacking section 24. The jacks must be placed stably. When the bottom of jacking section 24 has a large transverse slope, wedge-shaped rubber plates are set at the bottom of jacking section 24 to achieve leveling, so as to ensure that the jacks are in close contact with the bottom of the beam. In addition, all jacks and high-pressure oil pumps must be test-run before construction to ensure that no malfunctions occur during construction.

[0040] Step 303: Lifting the original main beam: Determine the height of the lifting section 24 according to the slope requirements of the bridge deck cross slope, and then use the jacks on the temporary support 23 to lift the lifting section 24 synchronously, so that the lifting section 24 is separated from the original side span bridge abutment 5 and reaches the design height, thereby realizing the overall lifting of the lifting section 24 of the original main beam 1.

[0041] In actual construction, before the jacking operation, the original records of the bridge design are consulted. The jacking capacity of the jacks is at least twice the jacking load weight, and the jacks located under the side beams need to be additionally increased. In this embodiment, two jacks are set at the top of each steel pipe column, that is, four jacks are set at the bottom of each jacking section 24.

[0042] In actual construction, in order to meet the requirements of multi-point synchronous control jacking, the jacks are of the same model and connected to the PLC controller for multi-point synchronous control jacking system. Each jacking height is 2mm, and the total jacking height is 35cm. Each jack must be managed by a dedicated person who uses a steel ruler to measure the jacking height at any time to ensure that the jacking height at each jack is basically consistent and the height error cannot exceed 1mm.

[0043] Before jacking, mark the height of each jack position with a marker pen for easy measurement during jacking. Use a total station to observe the longitudinal and transverse displacement of the bridge during jacking to guide construction. During jacking, install dial gauges and longitudinal displacement observation marks, and use both vertical displacement and jack hydraulic pressure gauge readings for dual control. Ensure the vertical displacement difference remains relatively consistent to accurately control the vertical and horizontal displacement of the beam during jacking, thus guiding construction. When the jacking force reaches 500kN, close monitoring and observation are required. Simultaneously, observe the top of the beam, bridge deck, and negative bending moment section 24 for cracks and deformation. If any abnormalities are found, report immediately, stop jacking operations, analyze the cause, and take appropriate remedial measures.

[0044] The superstructure is lifted to the designed position, above the new crossbeam. After the new abutment, the superstructure crossbeam and the bearing pad stones are modified and the construction is completed and the superstructure has reached its strength, the superstructure is lifted again, all the bridge bearings are replaced, and the jacks are lowered step by step to transfer the original load on the lifting platform to the new abutment and bearings.

[0045] Step 4: Tensioning the stay cables: Step 401, Crossbeam Construction: A first crossbeam 11 is installed on the top of the original mid-span pier 4, and a second crossbeam 12 is installed on the top of the original side span abutment 5. Crossbeam prestressing tendons are installed on the first crossbeam 11 and the second crossbeam 12.

[0046] In actual construction, the steel bars of the first crossbeam 11 and the second crossbeam 12 are first tied and prestressed ducts are pre-embedded. Then, concrete is poured separately. After the concrete strength meets the design requirements, the prestressed tendons of the crossbeams are installed and tensioned and anchored. The width and height of the first crossbeam 11 and the second crossbeam 12 are the same as the width and height of the original main beam 1, so that the original bridge deck 2 and the bridge deck extension section 14 can be flush.

[0047] like Figures 5 to 6 As shown, step 402, construction of the new bridge: First pile foundation 6 and second pile foundation 9 are sequentially installed at the lower part of the extension direction of the original main beam 1 towards the main beam extension section 13. Then, first pile cap 7 and first pier 8 are sequentially installed on the upper part of the first pile foundation 6, and second pile cap 10 is installed on the upper part of the second pile foundation 9. Then, the main beam extension section 13 connected to the second crossbeam 12 is installed on the upper part of the first pier 8 and the second pile cap 10. Then, the bridge deck extension section 14 connected to the original bridge deck 2 is installed on the upper part of the main beam extension section 13. The distance between the first pile foundation 6 and the tower base 15 meets the width requirements of the new road under the bridge.

[0048] In actual construction, the first pile foundation 6 is located between the original side span abutment 5 and the second pile foundation 9. By setting the first pile cap 7 and the first pier 8 on the top of the first pile foundation 6, it is easier to have a stronger bearing capacity and better bear the load transmitted by the main beam extension section 13. The second pile foundation 9 is located on the side span of the overall bridge after the renovation. By setting the second pile cap 10 directly on the top of the second pile foundation 9, the construction is simple and practical while meeting the bearing capacity requirements.

[0049] like Figures 7 to 8 As shown, step 403, tensioning the stay cables: A first cable 18 and a second cable 19 are installed on the tower 17. The upper ends of the first cable 18 and the second cable 19 are both anchored into the upper end of the tower 17, the lower end of the first cable 18 is anchored into the first crossbeam 11, and the lower end of the second cable 19 is anchored into the second crossbeam 12. Then, the first cable 18 and the second cable 19 are tensioned. After tensioning is completed, the first cable 18 and the second cable 19 are then anchored to complete the reconstruction of the bridge and form a new bridge structure system.

[0050] In this embodiment, in step two, according to the formula It was determined that the height of tower 17 was higher than that of the original main beam 1; among which, The distance between Tower 17 and the original mid-span pier 4. The angle between cable tower 17 and the first cable 18.

[0051] In this embodiment, the load-bearing capacity of the second cable 19 must meet the following requirements. The equivalent radius of the cross section of the second cable 19 can be obtained as follows: The horizontal stresses of the stay cables on both sides of Tower 17 are equal, that is... Therefore, the bearing capacity of the first cable 18 is... Therefore, the equivalent radius of the cross-section of the first cable 18 can be obtained as follows: Among them, the support reaction force N at the top of the original bridge abutment 5 can be obtained through the finite element analysis results of the original bridge. The angle between cable 17 and the second cable 19. The stress is for the first cable 18 or the second cable 19.

[0052] During actual construction, the horizontal components of the force borne by the first cable 18 and the second cable 19 on both sides of the main tower are equal. Therefore, the stress values ​​of the first cable 18 and the second cable 19 are equal. Since they are essentially equal, the same value is used in the calculation. Using the above formula, the equivalent radius of the cross section of the first cable 18 is obtained respectively. The equivalent radius of the cross section of the second cable 19 Its equivalent radius represents the corresponding cable force value, which makes it easier for technicians to flexibly select one or more steel strands to make the first cable 18 and the second cable 19 while meeting the cable force requirements.

[0053] During tensioning, an upper anchorage 20 is installed at the top of the tower 17, and the upper ends of the first cable 18 and the second cable 19 are fixed to both sides of the upper anchorage 20, respectively. Then, a lifting device is used to suspend the first cable 18 and the second cable 19 from the top of the tower 17 to the original bridge deck 2 and the bridge deck extension section 14, respectively. At the same time, lower anchorages 21 are installed inside the first crossbeam 11 and the second crossbeam 12, and the lower ends of the first cable 18 and the second cable 19 are fixed inside the lower anchorages 21, respectively. Then, the first cable 18 and the second cable 19 are tensioned to reach the design stress. During the tensioning process, it is necessary to closely monitor parameters such as the elongation and stress changes of the first cable 18 and the second cable 19 to ensure that the performance of the first cable 18 and the second cable 19 meets the design requirements. In addition, the cable force of the first cable 18 and the second cable 19 should be adjusted according to the construction process and design requirements of the cable-stayed bridge to ensure the stability and safety of the cable-stayed bridge.

[0054] It should be noted that during the tensioning process, it is necessary to monitor the cable force, stress, strain, alignment, temperature, and main tower deviation. Construction monitoring should be carried out in the early morning when the temperature is relatively stable. The cable force test uses a strain gauge to capture the cable's natural frequency. When the measured cable force error exceeds 2, the cable force should be adjusted until the requirements are met. After the cable force adjustment is completed, the stress, strain, alignment, temperature, and main tower deviation should be measured immediately. Tensioning and cable adjustment are carried out in stages in this way.

[0055] In actual construction, the steps for sealing the anchors are as follows: First, clean the concrete surface with a wire brush and blower to remove debris and loose stones; then, apply primer to the cleaned concrete surface to seal the pores and prevent corrosion of the anchors or structure; next, install the anchor bolts and nuts according to the dimensions and positions shown in the design drawings, and tighten the nuts with a wrench, ensuring the tightening force meets the requirements of the product manual; finally, apply sealant to the contact surfaces of the anchor bolts and nuts to prevent the intrusion of water and harmful gases.

[0056] Step 5: Remove the original bridge piers and temporary supports: After the new bridge is connected, remove the original side span abutment 5 and the temporary support 23 in sequence, clean up the site and dispose of all waste.

[0057] During actual construction, the position of the cutting line on the bridge pier is first determined using surveying instruments such as a rangefinder or total station, and the position of the cutting line is marked. Then, a drilling rig is used to drill holes on the cutting line, and the reinforcing bars are inserted into the drill holes and fixed in the bridge pier with concrete. Then, a cutting machine is used to cut the bridge pier along the cutting line. During the cutting process, the stability of the bridge pier must be ensured to prevent the bridge pier from collapsing. At the same time, a crane or other appropriate equipment is used to remove the cut part. After the cutting is completed, the site is cleaned up and all waste is disposed of.

[0058] Step 6: Construct a new road under the bridge: Construct the required traffic road between the main tower and the first pier 8 to enable vehicle passage in the area of ​​the original side abutment 5.

[0059] During actual construction, the original traffic road was constructed on the side of the original bridge abutment 3 away from the main tower. By demolishing the original side abutment 5 and constructing the main tower and the first pile foundation 6 on both sides of the original side abutment 5, it is convenient to construct a traffic road between the main tower and the first pile foundation 6. The reconstruction of the traffic road under the bridge can be met with a smaller bridge reconstruction project, which is highly practical.

[0060] This invention achieves bridge reconstruction by relocating the original bridge piers and extending the bridge, allowing for the construction of new roads in the original bridge abutment area. This avoids the large amount of construction waste caused by the complete demolition and reconstruction of the bridge, as well as the high economic costs required for building a new bridge. At the same time, it minimizes the impact on traffic, achieving good economic and social benefits and representing a trend towards high-quality development.

[0061] This invention addresses the situation where a main traffic artery is added beneath a bridge. Since the intermediate support of a continuous beam bridge is located in a positive bending zone, the prestressed steel reinforcement on the original main beam 1 primarily counteracts the positive bending moment. When the intermediate pier is removed, the original support becomes the mid-span region, and the load effect changes from a positive bending moment to a negative bending moment. Therefore, conventional reinforcement methods are insufficient to meet the load-bearing capacity requirements. This invention, by constructing a new main tower, facilitates cable tensioning without affecting main traffic flow, ensuring that the original structural stress pattern remains unchanged. This makes the overall stress on the beam more clearly defined. By using a combination of crossbeams and inclined cables, the bending moment generated by tension is counteracted, allowing the main tower to primarily bear the pressure of the original main beam 1. Utilizing the high compressive strength of the main tower's concrete, the load-bearing capacity required for the new bridge is reduced, improving the main tower's applicability and economic efficiency. The structure is reliable, stable, and performs well.

[0062] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for the renovation and utilization of an overpass, characterized in that, The method includes the following steps: Step 1: Determine the bridge reconstruction plan: Determine the length of the main beam extension section (13) connected to the original main beam (1) and the length of the bridge deck extension section (14) connected to the original bridge deck (2) in the new bridge, and determine the extension direction of the main beam extension section (13) and the bridge deck extension section (14); Step 2, Main Tower Construction: Construct the main tower for cable-stayed connection of the original main beam (1) and the extended section (13) of the main beam; wherein the main tower includes a tower base (15), a pile cap (16) and a cable tower (17) arranged sequentially from bottom to top. Step 3: Lift the original main beam: Step 301: Erect temporary supports: Erect temporary supports (23) around the original side span abutment (5), and the top of the temporary supports (23) and the bottom of the lifting section (24) meet the design gap value; wherein, the lifting section (24) is the beam segment of the original main beam (1) between the original mid-span pier (4) and the original side span abutment (5); Step 302: Erect the lifting platform: Install multiple jacks on the top of the temporary support (23) and set temporary steel plate supports on the top of the jacks; wherein the top of the steel plate supports is attached to the bottom of the lifting section (24); Step 303, Lifting the original main beam: Determine the height of the lifting section (24) according to the slope requirements of the bridge deck cross slope, and then use the jacks on the temporary support (23) to lift the lifting section (24) simultaneously, so that the lifting section (24) is separated from the original side span bridge abutment (5) and reaches the design height; Step 4: Tensioning the stay cables: Step 401, construction of crossbeams: A first crossbeam (11) is set on the top of the original mid-span pier (4), a second crossbeam (12) is set on the top of the original side span abutment (5), and crossbeam prestressing tendons are installed on the first crossbeam (11) and the second crossbeam (12); Step 402, Construction of the new bridge: First pile foundation (6) and second pile foundation (9) are set in sequence at the lower part of the extension direction of the original main beam (1) towards the main beam extension section (13). Then, first pile cap (7) and first pier (8) are set in sequence on the upper part of the first pile foundation (6). Second pile cap (10) is set on the upper part of the second pile foundation (9). Then, main beam extension section (13) connected to the second crossbeam (12) is set on the upper part of the first pier (8) and the second pile cap (10). Then, bridge deck extension section (14) connected to the original bridge deck (2) is set on the upper part of the main beam extension section (13). The distance between the first pile foundation (6) and the tower base (15) meets the width requirements of the new bridge road. Step 403: Tensioning the stay cables: A first cable (18) and a second cable (19) are installed on the tower (17); wherein the upper ends of the first cable (18) and the second cable (19) are both anchored into the upper end of the tower (17), the lower end of the first cable (18) is anchored into the first crossbeam (11), and the lower end of the second cable (19) is anchored into the second crossbeam (12); Then the first cable (18) and the second cable (19) are tensioned. After the tensioning is completed, the first cable (18) and the second cable (19) are anchored to complete the reconstruction of the bridge. Step 5: Remove the original bridge piers and temporary supports: After the reconstruction of the new bridge is completed, remove the original side span abutment (5) and the temporary supports (23) in sequence. Step 6: Construct a new road under the bridge: Construct the required traffic road between the main tower and the first pier (8) to enable vehicle passage in the area of ​​the original side bridge abutment (5); In step two, there are two cable towers (17), the two cable towers (17) have the same structural dimensions, and the two cable towers (17) are located on both sides of the original main beam (1); The specific construction steps of the main tower are as follows: construct multiple tower bases (15) between the original mid-span pier (4) and the original side span abutment (5), construct the pier cap (16) on the upper part of the multiple tower bases (15), then construct two cable towers (17) on the upper part of the pier cap (16), and arrange the two cable towers (17) symmetrically on both sides of the original main beam (1), and then construct multiple connecting beams (22) between the two cable towers (17). In step two, according to the formula The height of the tower (17) above the original main beam (1) was determined; among which, The distance between the tower (17) and the original mid-span pier (4) is... The angle between the tower (17) and the first cable (18); The bearing capacity of the second cable (19) must meet the following requirements. The equivalent radius of the cross section of the second cable (19) can be obtained as follows: ; The horizontal stresses of the stay cables on both sides of the tower (17) are equal, that is Therefore, the bearing capacity of the first cable (18) is: Therefore, the equivalent radius of the cross-section of the first cable (18) can be obtained as follows: ; Where N is the support reaction force of the original bridge at the top of the original side span abutment (5), The angle between the tower (17) and the second cable (19) is... The stress is for the first cable (18) or the second cable (19).

2. A method for renovating and utilizing an overpass according to claim 1, characterized in that: Before step two, pile foundation construction is required, as follows: before construction, the site needs to be leveled, then the drilling position is located and the casing is installed, and then the concrete construction of the tower foundation (15) is carried out inside the casing.

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