Closure construction method for continuous rigid frame beam of lower-towing super large bridge
Technical Field
The invention belongs to the technical field of bridge construction, and particularly relates to a closure construction method for a continuous rigid frame beam of a lower-towed grand bridge.
Background
The bridge construction is generally carried out by adopting the steps of constructing a main bridge body towards a mid-span, constructing a main bridge body towards a side-span, finally constructing approach bridge bodies at two ends, and then carrying out mid-span folding and side-span folding. However, when the traditional bridge construction mode has the unidirectional construction of a main bridge, the bridge bodies at the two ends of the main bridge pier are unbalanced, a large amount of counter weights need to be manually carried out, and the counter weights are adjusted at any time along with the unidirectional construction of the main bridge body, so that the construction efficiency of the main bridge body is greatly reduced. Meanwhile, after the main bridge construction is finished, the approach bridge body is constructed again and the side span is folded, so that the height difference is large, the folded section beam body needs to be manually jacked, and the construction efficiency of side span folding is reduced. Therefore, the invention discloses a closure construction method for a continuous rigid frame beam of a lower-towed super large bridge, aiming at the problems of lower main bridge construction efficiency and lower side span closure efficiency in the traditional bridge construction.
Disclosure of Invention
The invention aims to provide a closure construction method for a continuous rigid frame beam of a lower-towed grand bridge, which can improve bridge construction, particularly improve the construction efficiency during side span closure.
The invention is realized by the following technical scheme:
a closure construction method for a continuous rigid frame beam of a lower-towed super-large bridge comprises the following steps:
a, constructing approach bridge continuous plate girders and boundary pier capping girders on two sides of a main bridge in advance before the construction of the main bridge, and reserving tensioning operation holes on the capping girders of the boundary piers and the approach bridge continuous plate girders;
b, pouring No. 0 beam section concrete at the top of the main pier, and mounting hanging baskets on two sides of the No. 0 beam section concrete;
c, synchronously, symmetrically moving forward hanging baskets on two sides, and symmetrically and circularly pouring subsequent cantilever beam sections to a mid-span and a side-span in a T-symmetric manner;
d, performing mid-span closure on the mid-span pouring mid-span closure section;
e, pouring the side span cantilever casting section in the unbalanced side span, installing a boundary pier bracket, and then pouring the side span cast-in-place section on the boundary pier bracket; and C, pouring a side span closure section at the side span cast-in-place section to close the side span and the approach bridge continuous plate girder, performing tensioning and anchor sealing through the tensioning operation hole reserved in the step A, and secondarily blocking the tensioning operation hole after tensioning and anchor sealing are completed.
The continuous plate girder approach is synchronously constructed at two ends of the main bridge in advance before the construction of the main bridge, and simultaneously, tensioning operation holes are reserved on the boundary pier capping beam and the continuous plate girder approach. And then constructing a No. 0 beam section on the main pier in advance, symmetrically installing hanging baskets on two sides of the No. 0 beam section, taking the cantilever end sliding to the No. 0 beam section as a foundation for pouring a next section of beam body, and circularly pouring the subsequent beam section according to the mode that the hanging baskets on the two sides synchronously, symmetrically move forwards and T symmetrically and circularly pour the subsequent cantilever beam section until one end is poured to the midspan and the other end is poured to the side span. And then carrying out mid-span closure, synchronously carrying out side-span closure at two ends of the main bridge after the mid-span closure is finished, after the side-span closure section is poured, arranging a tensioning steel beam hole on the side-span closure section corresponding to a reserved tensioning operation hole on the approach bridge continuous plate beam and the boundary pier cover beam, and penetrating the tensioning steel beam through the tensioning steel beam hole for tensioning and anchoring.
In order to better implement the present invention, further, the step D includes the following sub-steps:
d1, applying 180t of top thrust to two ends of the mid-span closure segment after the mid-span closure segment is poured, and ensuring that the mid-span relative displacement is about 8 cm;
d2, installing a stiff framework at the mid-span closure segment, binding steel bars by using a vertical mold, and then locking the stiff framework in a closure manner;
d3, carrying out weight pressing and counterweight on the mid-span closure segment, pouring and connecting the mid-span closure segment, and then carrying out reinforced concrete curing;
and D4, stretching the longitudinal prestressed steel beams in batches and anchoring and grouting after the concrete strength reaches the standard after concrete derivation.
In order to better implement the present invention, further, the step E includes the following sub-steps:
e1, pouring the side span suspension casting section in the unbalanced side span, then tensioning the longitudinal prestressed steel cables in the span in batches and anchoring and grouting;
e2, synchronously installing hinged pier rear anchor cables at the side spans at the two sides;
e3, pre-burying profile steel in the boundary pier, erecting a bracket on the pre-buried profile steel, and pouring a side span cast-in-place section on the bracket;
and E4, removing the mid-span ballast weight balance weight and pouring the side-span closure section to carry out side-span closure, and completing the erection of the approach bridge hollow slab and balancing the weight of the interface pier.
In order to better realize the method, the side span suspension casting section is cast and then reinforced concrete is cured, and after the concrete strength reaches the standard, span longitudinal prestressed cables are tensioned in batches and anchored and grouted.
In order to better realize the method, further, after the side span closure segment is poured, reinforced concrete curing is carried out, after the concrete strength reaches the standard, span-middle longitudinal prestressed cables are tensioned in batches, and anchoring and grouting are carried out.
In order to better realize the invention, further, the longitudinal prestressed steel cables are tensioned according to a method of symmetrically tensioning in the transverse bridge direction and tensioning a long-strand longitudinal prestressed steel cable and then tensioning a short-strand longitudinal prestressed steel cable.
In order to better implement the invention, further, the whole weight of the midspan is borne by the cradle during the midspan folding.
Compared with the prior art, the invention has the following advantages and beneficial effects:
(1) before the main bridge construction, the construction of the boundary pier capping beam and the approach continuous plate beam at two ends of the main bridge is carried out in advance, meanwhile, tensioning operation holes are reserved in the boundary pier capping beam and the approach continuous plate beam for carrying out side span quick closure with a subsequent main bridge, and steel bundles pass through the reserved tensioning operation holes for carrying out tensioning and anchoring, so that the main bridge side span closure is not required to carry out the joining pier counterweight, and meanwhile, the subsequent counterweight dismantling process is omitted; meanwhile, the approach continuous plate girder and the boundary pier capping girder are constructed in advance and the side span closure is guided through the reserved tensioning operation hole, so that the problems of beam body height difference and unequal height top caps of the boundary piers, which are possibly caused when a main bridge is constructed firstly and then the approach bridge is constructed, are avoided, and the construction efficiency of the main bridge side span closure is greatly improved;
(2) according to the invention, the No. 0 beam section is constructed at the top of the main bridge pier, the hanging baskets are symmetrically arranged at two ends of the No. 0 beam section, the hanging baskets are used for weighing and carrying out T-symmetric pouring construction on subsequent beam bodies by means of the sliding of the hanging baskets, the balance of the beam bodies at two ends of the main bridge pier is effectively ensured, the construction speed of the main bridge is accelerated, and the construction efficiency of the main bridge is improved.
Drawings
FIG. 1 is a schematic view of the overall construction of the present invention;
FIG. 2 is a schematic construction diagram of No. 0 beam section and No. 1 beam section;
fig. 3 is a construction schematic diagram of a subsequent beam section.
Detailed Description
Example 1:
the closure construction method for the continuous rigid frame beam of the lower-towed super-large bridge in the embodiment is shown in fig. 1-3 and comprises the following steps:
a, constructing approach bridge continuous plate girders and boundary pier capping girders on two sides of a main bridge in advance before the construction of the main bridge, and reserving tensioning operation holes on the capping girders of the boundary piers and the approach bridge continuous plate girders;
b, pouring No. 0 beam section concrete at the top of the main pier, and mounting hanging baskets on two sides of the No. 0 beam section concrete;
c, synchronously, symmetrically moving forward hanging baskets on two sides, and symmetrically and circularly pouring subsequent cantilever beam sections to a mid-span and a side-span in a T-symmetric manner;
d, performing mid-span closure on the mid-span pouring mid-span closure section;
e, pouring the side span cantilever casting section in the unbalanced side span, installing a boundary pier bracket, and then pouring the side span cast-in-place section on the boundary pier bracket; and C, pouring a side span closure section at the side span cast-in-place section to close the side span and the approach bridge continuous plate girder, performing tensioning and anchor sealing through the tensioning operation hole reserved in the step A, and secondarily blocking the tensioning operation hole after tensioning and anchor sealing are completed.
The main bridge comprises two main bridge piers, the pre-construction of the approach continuous plate girder is firstly carried out at two ends of the main bridge before the construction of the main bridge is carried out, the tensioning operation holes are reserved on the cover beam of the boundary pier and the approach continuous plate girder, then the approach continuous plate girder is tensioned and anchored and then is secondarily plugged, and the approach continuous plate girder can be completed before the construction of the main bridge.
And then respectively carrying out pier body capping construction on the tops of the two main piers, and installing a bracket embedded part and an embedded steel strand on the pier top. And (3) removing the hydraulic creeping formwork template on the pier body after the main pier is capped, and keeping the platform frame as an operating platform for installing the bracket of the pier top. The horizontal rods and the inclined rods of the bracket are assembled in advance on the bottom surface, are temporarily connected by using the steel cable to form an installation angle, and then the sling is sleeved on the horizontal rods, so that the bracket is integrally hoisted to the pier top of the main pier in a posture which is approximately the same as the installed posture for installation. And after the bracket is installed, continuously installing a bottom die leveling frame, a bottom template and a side template, after the bottom template and the side template of the bracket are installed, prepressing by adopting a preloading method, and cleaning the bin surface of the bracket after the prepressing is completed to prepare for construction of the No. 0 beam section.
And pouring No. 0 beam section concrete on the bracket to ensure that the strength of the concrete reaches more than 100% of the designed strength, tensioning after the age of the concrete is more than 10 days, and removing the formwork until the concrete reaches the designed strength. The hanging baskets are pre-assembled on the bottom surface and are hoisted to the pier top of the main pier, and a hanging basket loading test needs to be performed on the hanging baskets before installation, so that the rigidity and the strength of the hanging baskets are ensured. And (2) respectively installing hanging baskets on two sides of the No. 0 beam section at the pier top of the main pier, then sliding the hanging baskets to the cantilever end of the No. 0 beam section and determining the elevation of a vertical mold, then binding the No. 1 beam section steel bars by the vertical mold and finishing the laying of the prestressed pipeline, and preparing for the construction of the No. 1 beam section.
And synchronously and symmetrically pouring concrete of the No. 1 beam section on hanging baskets on two sides of the No. 0 beam section, and carrying out reinforced concrete curing, when the strength of the No. 1 beam section barrel reaches more than 90% of the design strength and the age reaches more than 7 days, carrying out tensioning on the longitudinal prestressed steel beam of the No. 1 beam section, carrying out anchoring and grouting after tensioning is finished, and then lagging and tensioning the vertical prestressed steel beam and carrying out anchoring and grouting to finish pouring of the No. 1 beam section. After the No. 1 beam section is poured, a bracket of the No. 0 beam section is detached, then a hanging basket is slid to a cantilever end of the No. 1 beam section, the elevation of a vertical mold is determined, the No. 2 beam section steel bars are bound by the vertical mold, then the No. 2 beam section is circularly constructed to the No. 22 beam section according to the step of constructing the No. 1 beam section, and the No. 22 beam section is a mid-span closure section. And after the construction of the No. 22 beam section is finished, installing a middle-span folding section stiff skeleton embedded part at the cantilever end of the No. 22 beam section.
Then mid-span closure can be carried out, and 180t of top thrust is applied to two ends of a mid-span closure section, so that the relative position of the mid-span is ensured to be less than or equal to 8 cm. And then installing a stiff skeleton of the closure segment in the mid-span closure segment embedded part storage, binding steel bars by using a vertical mold, and then locking the closure of the stiff skeleton of the closure segment. And after the closure section stiff skeleton is locked, replacing the hanging basket with a ballast hanging bracket, and then pouring midspan closure section concrete on the ballast hanging bracket and carrying out reinforced concrete curing. And after the strength of the concrete is more than or equal to 90% of the designed strength and the age is more than 7 days, tensioning the midspan longitudinal prestressed steel bundles in batches and anchoring and grouting. Each group of longitudinal prestressed steel bundles are tensioned according to the principle that a transverse bridge is symmetrically tensioned, a long bundle is tensioned firstly, and then a short bundle is tensioned, and then the span-middle vertical prestressed steel bundles are tensioned in a lagging mode.
After the mid-span closure is finished, the side-span closure construction at the two ends of the main bridge can be synchronously carried out. And (3) unbalanced cantilever end of the No. 22 beam section close to the side span is subjected to cantilever casting of the side span cantilever casting section concrete, and after the strength of the concrete is more than or equal to 90% of the design strength and the age is more than 7 days, longitudinal prestress steel beams in the span are tensioned in batches and grouting is anchored. And each longitudinal prestressed steel beam is tensioned according to the principle that the transverse bridge is symmetrically tensioned, a long beam is tensioned firstly and then a short beam is tensioned, and then the anchor cables behind the boundary piers at the two ends of the main bridge are synchronously installed. Then, a bracket is erected on the pre-embedded profile steel of the boundary pier, a side span cast-in-place section is poured on the bracket, the side span cast-in-place section is poured, and meanwhile, the balance weight is adjusted to ensure that the boundary pier is in an axis stressed state. And after the side span cast-in-place section is poured, changing the side span hanging basket into a hanging bracket, pouring a side span closure section on the hanging bracket to realize side span closure, performing tensioning anchor sealing through a tensioning operation hole reserved on the approach continuous plate girder, and secondarily blocking the tensioning operation hole after tensioning anchor sealing is finished. And after the strength of the concrete is more than or equal to 90% of the designed strength and the age is more than 7 days, tensioning the midspan longitudinal prestressed steel bundles in batches and anchoring and grouting. Each group of longitudinal prestressed steel bundles are tensioned according to the principle that a transverse bridge is symmetrically tensioned, a long bundle is tensioned firstly, and then a short bundle is tensioned, and then the span-middle vertical prestressed steel bundles are tensioned in a lagging mode. Then, erecting the bridge approach hollow slab and balancing the weight of the interface pier. And then the full-bridge hanging basket and the balance weight are removed to complete the full-bridge construction.
Example 2:
this embodiment is further optimized based on embodiment 1, and as shown in fig. 1, the step D includes the following sub-steps:
d1, applying 180t of top thrust to two ends of the mid-span closure segment after the mid-span closure segment is poured, and ensuring that the mid-span relative displacement is less than or equal to 8 cm;
d2, installing a stiff framework at the mid-span closure segment, binding steel bars by using a vertical mold, and then locking the stiff framework in a closure manner;
d3, carrying out weight pressing and counterweight on the mid-span closure segment, pouring and connecting the mid-span closure segment, and then carrying out reinforced concrete curing;
and D4, stretching the longitudinal prestressed steel beams in batches and anchoring and grouting after the concrete strength reaches the standard after concrete derivation.
Construction is carried out on two main piers to No. 22 beam sections according to the embodiment 1, then hanging baskets on the No. 22 beam sections are slid to the cantilever ends of the No. 22 beam sections to be used as closure section hangers, and meanwhile, water belt counterweight is hung on the cantilever ends of the No. 22 beam sections on the two main piers. And then installing a stiff framework at the cantilever end of the No. 22 beam section and binding a folding section steel bar. And applying a top thrust of 180t to two ends of the mid-span closure segment, ensuring that the mid-span relative displacement is less than or equal to 8cm, and simultaneously locking the stiff framework, the longitudinal steel bars and the template. And then pouring the mid-span closure segment, unloading the balance load with the same weight, performing tensioning anchoring and dismantling the hanging bracket after the mid-span closure segment is poured and the reinforced concrete is derived until the strength reaches the standard, and completing the mid-span closure.
And reserving a folding hanger reserved hole when the 22# section is poured, and removing beam surface sundries and other temporary loads before folding. During the construction of the mid-span closure section, two hanging basket bottom die front beams of the mid-span are used as supporting platforms, two front hanging belts at the front end of the bottom die are moved to two sides of a box girder, the two hanging belts in the middle are used for sealing the hanging belts through notches so as to be detached, the inner and outer guide beams of the hanging basket move forwards, the inner and outer side templates are dragged, the bottom die is properly lowered, the steel templates are adopted as bottom die panels of the closure section, and 7I 32I-shaped steels sharing the bridge direction are used as bearing longitudinal beams. The external construction platform outside the beam body directly utilizes the existing construction platform outside the hanging basket without independent installation.
After the mid-span closure hanger is in place, counterweights are arranged on the top of the 22# section beam on two sides of the large mileage and the small mileage. The weight of the counterweight is 1/2 of the weight of the closure segment. Adopt water tank water storage counter weight, every water tank uses 1 big discharge water pump discharge of 7.5kw, and standard discharge capacity 40m thin year. Welding a water tank framework by using reinforcing steel bars and angle steel in advance, laying a wood-rubber plate in the water tank, covering a layer of waterproof geotextile, carrying out capacity marking on one side by using battens, and carrying out capacity marking once every 20cm, wherein the length of the water tank is 3m, the width of the water tank is 4m, the height of the water tank is 2m, and the capacity of the water tank is 40 m; the bottom of each water tank is provided with a water drain valve with the diameter of 100mm, which is used as a standby drain hole in emergency and can be used as an auxiliary drain hole when the water pump drains insufficient. After the water tank is installed, the total packet length is reported, and the capacity is rechecked together by field supervision, so that the water is added for balancing after the balancing requirement is met.
And actually measuring the end position of the cantilever before locking the closure section steel support. The actual measurement and theoretical height difference of the cantilever ends, the relative height difference of the two cantilever ends and the transverse deviation of the axes of the cantilever end beam body meet the standard requirements, and the relative height difference of the two cantilever ends is less than 1cm and the axis deviation is less than 1cm when the two cantilever ends are closed. When the side span is closed, only the stiff framework is locked. When the midspan is closed, pushing needs to be carried out before the stiff framework is locked, and in the closing section pushing process, double control of displacement and pushing force is carried out, so that the horizontal displacement of the pier top is mainly controlled.
The pre-pushing is carried out before the locking and sealing welding of the mid-span stiff skeleton to eliminate the influence caused by the later shrinkage and creep of the concrete, the horizontal thrust is designed to be 180t, the horizontal displacement of the beam body is 8cm, the horizontal thrust and the horizontal displacement are controlled in a double way during construction, and the top thrust is applied according to the requirement of a monitoring unit.
Before pushing, one end of the stiff skeleton is welded with the embedded steel plate, and the other end of the stiff skeleton is welded after being pushed in place. And (3) accurately measuring the length of the closure segment before the stiff skeleton is installed, and carrying out blanking manufacture according to the principle that the length is slightly smaller than the actual size. The stiff skeleton is integrally hoisted to the position of the embedded part, and if a gap exists, a 3-10 mm steel plate is adopted for filling and welding firmly. And the locking time of the stiff skeleton is controlled to be the lowest temperature in the same day, the welding seam is full when the stiff skeleton is locked, and the welding length meets the requirement of a design drawing. The construction pushing is carried out by adopting 4 jacks simultaneously, the jacks are arranged according to design requirements, the jacks and the pressure gauge are required to be matched for calibration and use, and the calibration state is required to meet the standard requirement. The pushing process needs to be kept synchronous and carried out stably, and the elevation of the cantilever section, the axis change and the displacement condition of the main pier body are observed at the same time.
Welding of the stiff skeleton and the jack pushing temporary support is strictly carried out according to design requirements, a direct current arc welding process is used for welding, welding seams at the edge of the steel plate are welded at intervals and then are gradually supplemented, and the steel plate is prevented from deforming after one-time welding. The skeleton welding seam should be full and continuous, the thickness of the welding seam is consistent with that of the steel plate, the residual welding slag should be removed completely, and the quality of the welding seam is controlled according to the design and specification requirements.
Pushing force is applied through the temporary framework by pushing, one end of the temporary framework is welded and fixed, the other end of the temporary framework is used as a pushing back by arranging a bracket on the beam top, when the pushing force meets the design requirement, the temporary framework and the bracket arranged on the pushing are disassembled after the rigid framework of the closure is locked, the mid-span closure of the grand bridge is dragged down according to the site construction progress in 10 months and at night, the design closure temperature is 10-14 degrees, the actual temperature is 10-14 degrees, and the specific pushing force and displacement are finally determined by a linear monitoring unit according to the day temperature of the closure. The jack should be designed symmetrically and symmetrically in the horizontal direction and should be synchronously opened.
Before pushing, oil meter readings corresponding to stress of each stage are calculated in advance according to an oil top calibration data table, meanwhile, technicians are arranged to carry out displacement measurement at the closure opening, and four stages of loading are carried out according to the sequence of 0%, 25%, 50%, 75% and 100% when the top thrust is applied. And comparing the displacement control data with the displacement control data required by design after each loading is finished, and making a relevant record.
Other parts of this embodiment are the same as embodiment 1, and thus are not described again.
Example 3:
this embodiment is further optimized based on the foregoing embodiment 1 or 2, and as shown in fig. 1, the step E includes the following sub-steps:
e1, pouring the side span suspension casting section in the unbalanced side span, then tensioning the longitudinal prestressed steel cables in the span in batches and anchoring and grouting;
e2, synchronously installing hinged pier rear anchor cables at the side spans at the two sides;
e3, pre-burying profile steel in the boundary pier, erecting a bracket on the pre-buried profile steel, and pouring a side span cast-in-place section on the bracket;
and E4, removing the mid-span ballast weight balance weight and pouring the side-span closure section to carry out side-span closure, and completing the erection of the approach bridge hollow slab and balancing the weight of the interface pier.
After the mid-span closure construction is finished, synchronously performing side-span closure construction at two ends of the main bridge, sliding a hanging basket on a No. 22 beam section close to the side span towards the cantilever end to serve as a hanging bracket, then pouring the side-span suspension casting section in an unbalanced manner, performing concrete maintenance after the pouring of the side-span suspension casting section is finished, and tensioning the mid-span longitudinal prestressed steel cable for anchoring. And (5) after the construction of the side span suspension casting section is finished, tensioning and grouting, and cleaning construction machines and materials on the top surface of the beam. The hanging basket of the side span suspension casting section is kept in place, the inner guide beam and the outer guide beam move forwards to drag the inner side template and the outer side template, the bottom template is fixed through the side span side hanging basket hanging strip and a side span cast-in-place section bracket, the hanging basket bottom template front hanging strip moves to two sides of the beam width by utilizing a hanging basket self bottom template system, the inner side template and the outer side template of the hanging basket are adopted in the closing section, the inner sliding beam and the outer sliding beam slide out and are anchored on the cast-in-place section, and the inner side template and the outer side template slide out in place along with.
Synchronously installing rear anchor cables of the hinged piers at the side spans at two sides, embedding profile steel in the boundary piers, erecting a bracket on the embedded profile steel, pouring a side-span cast-in-place section on the bracket, performing concrete maintenance after the side-span cast-in-place section is poured, and tensioning a mid-span longitudinal prestressed steel cable for anchoring. And then installing a stiff framework on the cantilever end of the side span cast-in-place section, binding a closure section steel bar, and pouring the side span closure section to realize side span closure.
The side span closure is measured before the stiff skeleton is not pushed to be locked, the actual measurement and theoretical height difference of the cantilever ends, the relative height difference of the two cantilever ends and the transverse deviation of the axes of the cantilever end beam body are determined to meet the standard requirements, and the relative height difference of the two cantilever ends is required to be less than 1cm and the axis deviation is required to be less than 1cm when the closure is carried out. One end of the stiff skeleton is welded with the embedded steel plate, and if a gap exists at the other end of the stiff skeleton, the stiff skeleton is plugged by a 3-10 mm steel plate and is firmly welded. And the locking time of the stiff skeleton is controlled to be the lowest temperature in the same day, the welding seam is full when the stiff skeleton is locked, and the welding length meets the requirement of a design drawing.
The rest of this embodiment is the same as embodiment 1 or 2, and therefore, the description thereof is omitted.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and all simple modifications and equivalent variations of the above embodiments according to the technical spirit of the present invention are included in the scope of the present invention.