Method for replacing roadbed at bottom of existing expressway with simply supported beam

Abstract

The invention belongs to the technical field of existing expressway replacement construction, and relates to a method for replacing a bottom roadbed of an existing expressway with a simply supported beam, which comprises the following steps: S1, guiding an A-width passing vehicle to a B-width passing vehicle; s2, removing and cleaning a pavement structure layer of a section to be replaced in the construction width; s3, pre-machining the permanent steel casing according to engineering materials; s4, pile foundation drilling operation of the simply supported plate girder bridge is conducted on the replaced pavement of the existing expressway; s5, a permanent steel casing is put down to be connected with the pile foundation, a pile foundation reinforcement cage is placed, pile foundation concrete is poured, and a pier stud is formed; and S6, follow-up construction pouring of the simply supported plate girder bridge is conducted, and earth and stone excavation under the bridge is conducted synchronously till the permanent steel casing is completely exposed out of the earth and stone. The pile foundation and the pier column are integrally constructed, so that the process interval between the pile foundation and the pier column is omitted, the construction period is shortened, the risk of slope instability of the traffic width roadbed of the existing expressway is avoided, and the safety of traffic vehicles is further guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of replacement construction of existing expressways, and in particular to a method for replacing a bottom roadbed of an existing expressway with a simply supported beam. Background Art

[0002] With the continuous improvement of the expressway network, in order to achieve three-dimensional interconnection with existing expressways, new highway projects need to replace the existing expressway roadbed with bridges (mostly simply supported slab-girder bridges).

[0003] The common method of replacing the existing roadbed with a simply supported slab girder bridge is to demolish the existing road surface of the non-passing span, dig out the existing roadbed, and then construct the simply supported slab girder bridge. As most existing highways have integral roadbeds, unless the slope width of the existing roadbed in the passing span is insufficient, it is necessary to set up retaining walls, anchor spraying and other slope support and protection measures, otherwise it is very easy to cause the slope of the passing span to become unstable, posing a threat to the safety of passing vehicles. Taking slope support and protection measures has a long construction period and high cost, and has a long impact on the traffic of existing highways. Summary of the invention

[0004] The present invention aims at the shortcomings of the prior art of replacing the existing highway subgrade with a simply supported slab girder bridge, such as taking slope support protection measures, long construction period, high cost, and long impact on the traffic of the existing highway. A construction method for replacing the existing highway subgrade with a simply supported slab girder bridge is proposed.

[0005] The technical solution of the present invention is achieved by the following scheme: A method for replacing the existing highway bottom roadbed with a simply supported beam comprises the following steps: S1, vehicles passing through lane A are guided to pass through lane B; S2, demolish and clean the pavement structure layer of the section to be replaced in the construction area; S3, permanent steel casing pre-processing; S4, drilling work for pile foundation of simply supported slab girder bridge; S5, lower the permanent steel casing to connect with the pile foundation, place the pile foundation steel cage and pour the pile foundation concrete, and the pier column is formed; S6, subsequent construction and pouring of the simply supported slab girder bridge, and simultaneous excavation of earth and rock under the bridge until the permanent steel casing is fully exposed from the earth and rock; S7: When the A-span simply supported slab girder bridge is ready for traffic, guide vehicles on B-span to A-span; S8, construction of section B, repeating steps S2 to S6; S9, treat the outer surface of the permanent steel casing.

[0006] Through the above technical scheme, by lowering permanent steel casings into the pile foundation holes of the simply supported slab girder bridge, the construction of the simply supported slab girder bridge can be carried out without first excavating the existing roadbed, which effectively avoids the risk of instability of the roadbed slopes of the existing highway open to traffic, and the safety of passing vehicles is further guaranteed. The permanent steel casing is used to realize the integrated construction of pile foundation and pier, which eliminates the process interval between the two and shortens the construction period.

[0007] Preferably, the specific steps of step S5 include: S501, crane lifting of permanent steel casing; S502, use the steel casing lowering positioning auxiliary device to lower the permanent steel casing to ensure that the verticality, plane position and elevation of the permanent steel casing after final placement meet the relevant requirements of the standard; S503, after the permanent steel casing is in place, the permanent steel casing is suspended and fixed by using the steel casing lowering positioning auxiliary device, jack, temporary steel casing and hanging rod; S504, placing the pile foundation steel cage and pouring the pile foundation concrete until a pier is formed in the permanent steel casing; S505: After the pier is cast and formed, remove the steel casing lowering positioning auxiliary device, jack, temporary steel casing and suspension rods that suspend and fix the permanent steel casing. Preferably, in step S5, the permanent steel casing is sunk into the pile foundation by ≥50 cm.

[0008] Preferably, the specific pre-processing steps of step S3 include: S301, processing the permanent steel casing into the required length; S302, clean the debris and oil stains adhering to the permanent steel casing, and grind, remove rust and polish the inside and outside of the permanent steel casing; S303, spray a layer of water film on the outside of the permanent steel casing, cover the outside of the permanent steel casing with plastic sheeting, squeeze out the bubbles between the plastic sheeting and the steel casing, and ensure that the plastic sheeting and the permanent steel casing fit tightly.

[0009] Preferably, the specific construction steps of step S6 include: S601, construction of abutments and cap beams (including blocks and pad stones); S602, support installation and prefabricated slab beam hoisting; S603: Construction of the above-mentioned integral cast-in-place structure, bridge deck paving, anti-collision guardrail and other bridge deck systems and ancillary works; S604: excavate the earth and rock under the bridge until the permanent steel casing is completely exposed from the earth and rock; S605, paving of bridge deck asphalt surface layer and construction of bridge expansion joints.

[0010] Preferably, in step S604, after the casting and installation of the prefabricated slab beam is completed, the earthwork excavation under the bridge can be carried out simultaneously until the permanent steel casing is completely exposed from the earthwork.

[0011] Preferably, in step S604, the excavation boundary of earth and rock under the bridge is based on ensuring the stability of the roadbed slope of the passage width, and the earth and rock under the bridge is excavated using a front shovel excavator. As a preferred method, when excavating the earth and stone under the bridge, if the stone under the bridge is relatively complete and direct excavation is difficult, auxiliary equipment such as rock drills and breaker hammers are required for excavation; The earth and stone near the pier position are now excavated by manual labor combined with small machinery.

[0012] Preferably, in step S4, the diameter of the opening on the existing highway pavement is the diameter of the pile foundation of the simply supported slab beam bridge plus 20 cm, with an error of ≤1 cm.

[0013] Preferably, in step S9, after the steel casing is completely exposed from the earth and stone, the outer plastic sheet is peeled off, the outer surface is polished and coated with an anti-corrosion coating.

[0014] In summary, the present invention has the following beneficial effects: 1. The present invention lowers a permanent steel casing into the pile foundation hole of the simply supported slab girder bridge before constructing the simply supported slab girder bridge. There is no need to excavate the existing roadbed in advance, which effectively avoids the risk of instability of the roadbed slope of the existing highway open to traffic, and the safety of passing vehicles is further guaranteed. The permanent steel casing is used to realize the integrated construction of pile foundation and pier column, which saves the process interval between the two and shortens the construction period.

[0015] 2. After the casting of the prefabricated slab beam of the simply supported slab beam bridge is completed, the earthwork excavation under the bridge is carried out simultaneously, that is, the earthwork excavation operation can also be carried out normally during the process interval when the concrete strength of the simply supported slab beam bridge increases, which greatly shortens the time affecting the traffic on the existing highway.

[0016] 3. There is no need to set up retaining walls, anchor spraying and other slope support protection measures, which reduces construction costs and has a good support effect.

[0017] 4. The permanent steel casing is lowered and buried in the pile foundation for construction, so that the permanent steel casing can be directly used as the pier formwork and the outer side support of the pier, and cast and formed to realize the integrated construction of the pile foundation and the pier. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic plan view of vehicle passage after guidance of the present invention; Figure 2 It is a schematic plan view of the opening of an existing road surface according to the present invention; Figure 3It is a schematic elevation diagram of the permanent steel casing of the present invention after being lowered and positioned; Figure 4 It is a schematic diagram of the structural cross section of the simply supported plate girder bridge of the present invention after completion; Figure 5 It is a schematic diagram of the cross section of an existing expressway after the plate beam bridge is built according to the present invention; Figure 6 It is a schematic diagram of the three-dimensional structure of the permanent steel casing of the present invention; Figure 7 It is a construction flow chart of the present invention.

[0019] Explanation of the reference numerals in the drawings: 1. Frame A; 2. Frame B; 3. Permanent steel casing; 4. Water film; 5. Plastic sheeting; 6. Simply supported slab-girder bridge; 7. Existing highway pavement; 8. Pile foundation; 9. Temporary steel casing; 10. Top of pier; 11. Pile-column dividing line; 12. Pile bottom; 13. Hanger rod.

[0020] Picture A is a picture of the existing expressway under construction first; Picture B is a picture of the existing expressway under construction later. DETAILED DESCRIPTION

[0021] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described below with reference to the accompanying drawings and embodiments.

[0022] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the present invention is not limited to the specific embodiments of the following disclosure. The present invention is further described in detail below in conjunction with the accompanying drawings.

[0023] A method of replacing the existing highway bottom roadbed with a simply supported beam, such as Figure 1-Figure 7 As shown, the following steps are included: S1, vehicles passing through lane A are guided to pass through lane B; S2, demolish and clean the pavement structure layer of the section to be replaced in the construction area; S3, pre-processing of permanent steel casing according to engineering materials; S4, drilling of pile foundations for simply supported slab beam bridges on the existing highway pavement after replacement; S5, lower the permanent steel casing to connect with the pile foundation, place the pile foundation steel cage and pour the pile foundation concrete, and the pier column is formed; S6, subsequent construction and pouring of the simply supported slab girder bridge, and simultaneous excavation of earth and rock under the bridge until the permanent steel casing is fully exposed from the earth and rock; S7: When the A-span simply supported slab girder bridge is ready for traffic, guide vehicles on B-span to A-span; S8, construction of section B, repeating steps S2 to S6; S9, treat the outer surface of the permanent steel casing.

[0024] Compared with the demolition of the existing road surface of the non-passable section, the excavation of the existing roadbed and then the construction of the simply supported slab girder bridge, the pile foundation is drilled on the existing highway pavement and space is reserved for the lowering of the permanent steel casing. The permanent steel casing is used to realize the integrated construction of the pile foundation and piers, which provides good support for the simply supported slab girder bridge and perfectly avoids the risk of instability of the roadbed slope of the existing highway open section, and the safety of passing vehicles is further guaranteed.

[0025] In this construction, the permanent steel casing not only serves as a part of the pile foundation, but also serves as the formwork and outer support for the subsequent pouring of piers.

[0026] In step S1, before construction of section A, it is blocked and guided, and passing vehicles are guided to section B to prevent vehicles from affecting the construction.

[0027] In step S2, the pavement structure on the width to be constructed first (such as shoulders, driving lanes, curbs and semi-central dividing strips) is cleaned and removed to make it conform to the perforation plane.

[0028] The specific steps of step S5 include: S501, crane lifting of permanent steel casing; S502, use the steel casing lowering positioning auxiliary device to lower the permanent steel casing to ensure that the verticality, plane position and elevation of the permanent steel casing after final placement meet the relevant requirements of the standard; S503, after the permanent steel casing is in place, the permanent steel casing is suspended and fixed by using the steel casing lowering positioning auxiliary device, jack, temporary steel casing and hanging rod; S504, placing the pile foundation steel cage and pouring the pile foundation concrete until a pier is formed in the permanent steel casing; S505: After the pier is cast and formed, remove the steel casing lowering positioning auxiliary device, jack, temporary steel casing and suspension rods that suspend and fix the permanent steel casing.

[0029] In step S5, the permanent steel casing is sunk into the pile foundation by ≥50 cm.

[0030] The lowered permanent steel casing is used as the pier formwork and outer support of the pier for the subsequent casting of the pier. The pile foundation and the pier are constructed in one piece. The total length of the permanent steel casing is 50 cm longer than the total length of the pier. The part of the permanent steel casing that is longer than the total length of the pier is buried in the pile foundation and fixed with the subsequent casting of the pile foundation. It can provide stable support and protection for the pier during the entire construction process, enhancing the durability and seismic resistance of the structure.

[0031] When the pier is cast and reaches a certain strength, the auxiliary devices, jacks, temporary steel casing and hangers used to suspend and fix the permanent steel casing can be removed. At this time, the permanent steel casing has become part of the pier and provides it with outer support, improving the overall stability and bearing capacity of the structure.

[0032] like Figure 4 and Figure 5 As shown, there are cap beams, slab beams and other structures on the piers until they are flush with the original highway pavement, and then the pavement structure is set and divided.

[0033] The specific pre-processing steps of step S3 include: S301, processing the permanent steel casing into the required length; S302, clean the debris and oil stains adhering to the permanent steel casing, and grind, remove rust and polish the inside and outside of the permanent steel casing; S303, spray a layer of water film on the outside of the permanent steel casing, cover the outside of the permanent steel casing with plastic sheeting, squeeze out the bubbles between the plastic sheeting and the steel casing, and ensure that the plastic sheeting and the permanent steel casing fit tightly.

[0034] Determine the required length of the permanent steel casing according to the design requirements of the engineering materials to ensure that it can meet the protection and support requirements after installation. Carefully grind the inside and outside of the permanent steel casing to remove rust and uneven parts on the surface, then perform rust removal to ensure that there is no rust residue on the surface of the steel casing. Finally, polish it to make the surface of the steel casing smoother and improve its durability. Plastic sheeting is attached to the surface of the permanent steel casing to form a protective layer to ensure that the permanent steel casing will not be corroded and damaged due to dirt accumulation when it is lowered into the borehole. The steel casing covered with plastic sheeting is easier to slide and position, reducing friction with the hole surface, reducing construction difficulty and time, and making it easier to insert the steel casing into the soil.

[0035] The specific construction steps of step S6 include: S601, construction of abutments and cap beams (including blocks and pad stones); S602, support installation and prefabricated slab beam hoisting; S603: Construction of the above-mentioned integral cast-in-place structure, bridge deck paving, anti-collision guardrail and other bridge deck systems and ancillary works; S604: excavate the earth and rock under the bridge until the permanent steel casing is completely exposed from the earth and rock; S605, paving of bridge deck asphalt surface layer and construction of bridge expansion joints.

[0036] In step S604, after the casting and installation of the precast slab beam is completed, the earthwork excavation under the bridge can be carried out synchronously until the permanent steel casing is completely exposed from the earthwork. Due to the existence of the outer support of the permanent steel casing, the earthwork excavation operation can also be carried out normally during the process interval of the concrete strength increase of the simply supported slab beam bridge, and the time affecting the existing highway traffic is greatly shortened.

[0037] In step S604, the excavation boundary of the earthwork under the bridge is based on ensuring the stability of the roadbed slope of the passage width. The earthwork under the bridge is excavated by a front shovel. When the earthwork under the bridge is excavated, if the stone under the bridge is relatively complete and direct excavation is difficult, auxiliary equipment such as a rock drill and a breaker are required for excavation; The earth and stone near the piers are now excavated manually with the help of small machines. The piers are important supporting structures of the bridge, and their stability and integrity are directly related to the safety of the bridge. In the excavation of earth and stone near the piers, the use of large machines may cause damage to the piers due to improper operation or complex geological conditions. The use of manual excavation with the help of small machines can more precisely control the excavation force and range, thereby effectively avoiding damage to the pier structure.

[0038] In step S4, the diameter of the opening in the existing highway pavement is the diameter of the pile foundation of the simply supported slab beam bridge plus 20 cm, with an error of ≤1 cm, to reserve space for the permanent steel casing that needs to be lowered later.

[0039] In step S9, after the steel casing is completely exposed from the earth and stone, the plastic sheet covering it is peeled off, the outer surface is polished and an anti-corrosion coating is applied.

[0040] Another polishing can further improve the smoothness of the permanent steel casing and increase the adhesion between the anti-corrosion coating and the steel casing. The anti-corrosion coating can isolate the steel casing from direct contact with the surrounding environment and prevent moisture, oxygen and other corrosive substances from corroding the steel casing. This not only extends the service life of the steel casing, but also reduces the cost of maintenance and replacement. In addition, the anti-corrosion coating can also improve the durability and stability of the steel casing, ensuring that it can remain in good working condition in harsh environments.

[0041] The above description is only a preferred embodiment of the present invention and does not limit the present invention in other forms. Any technician familiar with the profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes for application in other fields. However, any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for replacing the existing highway bottom roadbed with a simply supported beam, characterized in that: The steps include: S1, vehicles passing through lane A are guided to pass through lane B; S2, demolish and clean the pavement structure layer of the section to be replaced in the construction area; S3, pre-processing of permanent steel casing according to engineering materials; S4, drilling of pile foundations for simply supported slab beam bridges on the existing highway pavement after replacement; S5, lower the permanent steel casing to connect with the pile foundation, place the pile foundation steel cage and pour the pile foundation concrete, and the pier column is formed; S6, subsequent construction and pouring of the simply supported slab girder bridge, and simultaneous excavation of earth and rock under the bridge until the permanent steel casing is fully exposed from the earth and rock; S7: When the A-span simply supported slab girder bridge is ready for traffic, guide vehicles on B-span to A-span; S8, construction of section B, repeating steps S2 to S6; S9, treat the outer surface of the permanent steel casing.

2. The method for replacing the existing highway bottom roadbed with a simply supported beam according to claim 1, characterized in that: The specific steps of step S5 include: S501, crane lifting of permanent steel casing; S502, use the steel casing lowering positioning auxiliary device to lower the permanent steel casing to ensure that the verticality, plane position and elevation of the permanent steel casing after final placement meet the relevant requirements of the standard; S503, after the permanent steel casing is in place, the permanent steel casing is suspended and fixed by using the steel casing lowering positioning auxiliary device, jack, temporary steel casing and hanging rod; S504, placing the pile foundation steel cage and pouring the pile foundation concrete until a pier is formed in the permanent steel casing; S505: After the pier is cast and formed, remove the steel casing lowering positioning auxiliary device, jack, temporary steel casing and suspension rods that suspend and fix the permanent steel casing.

3. The method for replacing the existing highway bottom roadbed with a simply supported beam according to claim 2, characterized in that: In step S5, the permanent steel casing is sunk into the pile foundation by ≥50 cm.

4. The method for replacing the existing highway bottom roadbed with a simply supported beam according to claim 1, characterized in that: The specific pre-processing steps of step S3 include: S301, processing the permanent steel casing into the required length; S302, clean the debris and oil stains adhering to the permanent steel casing, and grind, remove rust and polish the inside and outside of the permanent steel casing; S303, spray a layer of water film on the outside of the permanent steel casing, cover the outside of the permanent steel casing with plastic sheeting, squeeze out the bubbles between the plastic sheeting and the steel casing, and ensure that the plastic sheeting and the permanent steel casing fit tightly.

5. The method for replacing the existing highway bottom roadbed with a simply supported beam according to claim 1, characterized in that: The specific construction steps of step S6 include: S601, construction of abutments and cap beams (including blocks and pad stones); S602, support installation and prefabricated slab beam hoisting; S603: Construction of the above-mentioned integral cast-in-place structure, bridge deck paving, anti-collision guardrail and other bridge deck systems and ancillary works; S604: excavate the earth and rock under the bridge until the permanent steel casing is completely exposed from the earth and rock; S605, paving of bridge deck asphalt surface layer and construction of bridge expansion joints.

6. The method for replacing the existing highway bottom roadbed with a simply supported beam according to claim 5, characterized in that: In step S604, after the casting and installation of the prefabricated slab beam is completed, the earth and stone excavation under the bridge can be carried out synchronously until the permanent steel casing is completely exposed from the earth and stone.

7. The method for replacing the existing highway bottom roadbed with a simply supported beam according to claim 6, characterized in that: In step S604, the excavation boundary of the earth and rock under the bridge is based on ensuring the stability of the roadbed slope of the passage width, and the earth and rock under the bridge is excavated using a front shovel excavator.

8. The method for replacing the existing highway bottom roadbed with a simply supported beam according to claim 7, characterized in that: When excavating the earth and stone under the bridge, if the stone under the bridge is relatively complete and direct excavation is difficult, auxiliary equipment such as rock drills and breaker hammers are required for excavation; The earth and stone near the pier position are now excavated by manual labor combined with small machinery.

9. The method for replacing the existing highway bottom roadbed with a simply supported beam according to claim 1, characterized in that: In step S4, the diameter of the opening in the existing highway pavement is the diameter of the pile foundation of the simply supported slab beam bridge plus 20 cm, with an error of ≤1 cm.

10. The method for replacing the existing highway bottom roadbed with a simply supported beam according to claim 1, characterized in that: In step S9, after the steel casing is completely exposed from the earth and stone, the plastic sheet covering it is peeled off, the outer surface is polished and coated with an anti-corrosion coating.

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