CN115821792A - Integral pushing construction method for large-tonnage multi-span high-gravity-center basket arch bridge - Google Patents

Abstract

The invention discloses an integral pushing construction method of a large-tonnage multi-span high-gravity center lifting basket arch bridge, which comprises the following steps of: s1, manufacturing a secondary assembly platform on the margin side of a field, uniformly and equidistantly arranging on-shore pushing temporary supports in a secondary assembly platform area, uniformly and equidistantly arranging in corresponding underwater areas the underwater pushing temporary supports, adopting a multi-point pushing mode, hoisting the front end section of a steel girder, and performing primary pushing; s2, hoisting the middle section of the steel main beam to a secondary assembling platform on a secondary assembling area, then installing an arch rib assembling support at the circular seam of the main and auxiliary arch sections on the steel main beam structure, and assembling an arch rib structure to form an integral structure and then performing secondary pushing; and S3, hoisting the rear end section of the steel girder to the secondary assembling platform by using a crawler crane in the secondary assembling area, performing third pushing, and then removing the temporary auxiliary facilities. The invention utilizes favorable landform conditions on the bank, adopts integral assembly on the bank and adopts a walking type large-tonnage integral pushing method with an arch. This scheme turns into a large amount of operations on water into land for the construction progress has reduced the safety risk of construction.

Description

Integral pushing construction method for large-tonnage multi-span high-gravity-center basket arch bridge

Technical Field

The invention relates to the field of bridge construction, in particular to an integral pushing construction method for a large-tonnage multi-span high-gravity-center basket arch bridge.

Background

With the continuous increase of national economy, the basket arch bridge has the advantages of beautiful shape, stable structure and higher frequency in urban construction.

The complex construction conditions in the urban environment have high requirements on space, construction period and ecological environment protection, the influence on the existing roads or rivers needs to be reduced as much as possible, the occupied positions of the roads and the field installation and construction time are reduced, and the pushing construction method can better meet the construction requirements of the urban environment. A floor steel pipe column support method is often adopted in the construction of a conventional large-span continuous beam, but the floor steel pipe column support method is greatly influenced by terrain conditions, the implementation environment and the application scene are often limited by working conditions, the construction cost is high, and the construction is complicated. And is limited by construction conditions such as inland river crossing, overlarge span, and incapability of entering a large-scale floating crane at a bridge position.

The conventional pushing construction method in the pushing construction is a beam arch separate installation method, namely, a beam is firstly pushed and installed, and then a support frame is erected on the beam to install arch ribs. Because the basket arch ribs are inwards inclined and greatly lose height, the basket tied arch bridge is a superposed beam, and the bridge floor cannot be hoisted by a crane standing, the method of firstly pushing the beam and then installing the arch ribs cannot be applied, and an integral pushing scheme with an arch is required.

Disclosure of Invention

The invention aims to solve the technical problem of providing an integral pushing construction method of a large-tonnage multi-span high-gravity-center basket arch bridge, which can accelerate the construction progress and reduce the construction safety risk, aiming at the defects of the prior art.

The technical scheme adopted by the invention is as follows: a large-tonnage multi-span high-gravity-center lifting basket arch bridge integral pushing construction method is characterized by comprising the following steps: the construction method of the basket arch bridge comprises the following steps:

s1, manufacturing a secondary assembly platform on the margin side of a field, uniformly and equidistantly arranging shore pushing temporary supports in a secondary assembly platform area, uniformly and equidistantly arranging underwater pushing temporary supports in a corresponding underwater area, and installing pushing equipment and pushing landing pad cushion blocks on the pushing supports in a multi-point pushing mode; then hoisting the front end segment of the steel girder and performing first pushing;

s2, hoisting the middle section of the steel girder to a secondary assembling platform on a secondary assembling area, positioning according to the simulated bridge coordinates, performing girth welding after positioning, mounting an arch rib assembling support at the girth of the main and auxiliary arch sections on the steel girder structure, assembling an arch rib structure, and performing secondary pushing after forming the integral structure;

and S3, hoisting the steel girder at the rear part of the bridge to a secondary assembly platform by using a crawler crane on the secondary assembly area, positioning according to the simulated bridge coordinates, performing girth welding after positioning, performing third pushing, and then removing the temporary auxiliary facilities.

According to the technical scheme, the mode of controlling the stress change of the steel beam in the pushing process is as follows: and installing strain gauges at key control positions of connecting points of the steel girder structures, the supports and the arch ribs of each section before construction, testing the stress change of the steel girder during construction, and carrying out comparison analysis on the stress change of the steel girder and a simulation calculated value so as to control the stress change of the steel girder during the pushing process.

According to the technical scheme, a centralized control system is adopted for controlling the stress of the steel beam during construction, and the centralized control system comprises a real-time control system hardware module, a real-time control system software module, a real-time control network, a pump station electronic control unit and a sensor control unit.

According to the technical scheme, the linear control mode of the steel beam in the pushing process is as follows: according to the bridge forming line shape, the whole body is horizontally raised for a set distance during assembling, and the cushion blocks of the pushing landing cushion blocks are adjusted at the corresponding pushing temporary supports according to the line-shaped elevation change of the set distance in the pushing process; before the pushing starts, a vertical angle steel is welded on the outer side edges of the front end of the temporary cushion beam at the front end of each pushing temporary support and the rear end of the temporary cushion beam at the rear end, an operator controls deviation of the steel beam by taking the initial distance between the angle steel and a steel beam web plate as a reference, when the deviation of the steel beam exceeds a set distance, the pushing equipment synchronously jacks up the steel beam to be emptied with a shoveling and cushioning structure on the temporary cushion beam, the guiding equipment on each pushing temporary support needing to be adjusted retracts to one side of a guiding oil cylinder, and the guiding oil cylinder on the other side stretches to enable the deviation of the steel beam to transversely move to the initial position along with the sliding beam of the pushing equipment towards the retracting cylinder side.

According to the technical scheme, in the step S2, the arch rib assembling support comprises an arch rib temporary support and an A-bracing temporary support, the A-bracing is arranged on the steel girder bridge floor in a central symmetry mode, and the arch rib temporary support and the A-bracing temporary support are arranged at intervals and connected through connecting pieces.

According to the technical scheme, in the step S2, the arch rib structure is hoisted by using two crawler cranes from two ends to the middle in sequence, the matched connecting pieces installed in the trial assembly of the arch rib factory are used for quickly positioning, the distances between the suspender sections of the arch rib, the relative height difference of the suspender parts of the arch rib and the relative height difference of the end parts of the arch rib are detected, the code plates are fixed after the geometrical size is qualified, and then welding is carried out.

According to the technical scheme, in the step S3, a limit bracket is arranged at the pushing end, continuous pushing operation is stopped 1m before pushing is in place, inching operation is used, a set distance is set for forward pushing each time, observation is carried out, and the pushing in-place time is controlled.

According to the technical scheme, in the step S3, after the pushing is in place, the beam falling mode adopts integral beam falling, and the beam falling mode adopts a mode of extracting steel base plates one by one to protect; monitoring the height difference between the steel beam and each support in the beam falling process; and controlling the beam falling height in each round to be not more than 200mm, and circularly falling the beams in a symmetrical and alternate manner.

The beneficial effects obtained by the invention are as follows:

1. the invention aims to avoid disturbing rivers, can make the basket arch in sections, and adopts the on-shore integral assembly and walking type large-tonnage integral pushing method with the arch by utilizing favorable terrain conditions on the shore. This scheme turns into land with a large amount of operations on water, has reduced the influence to river ecological environment, and has accelerated the construction progress, has reduced the safe risk of construction.

2. The construction process of the invention adopts a staged multi-point pushing mode, which can avoid the configuration of large-scale pushing equipment, effectively control the deflection of the beam body during pushing, reduce the horizontal thrust to the pier during pushing to be very small and facilitate the adoption of a temporary pushing support with flexible structure.

3. The invention converts a large amount of overwater operation into land, selects a large crane to stand on the land for installation and construction, solves the problems that the floating crane cannot enter the field and the bridge floor cannot stand, reduces the safety risk of construction and accelerates the construction progress.

Drawings

Fig. 1 is a schematic layout view of a pushing temporary support provided in an embodiment of the present invention.

Fig. 2 is a schematic view of a state of hoisting a front end segment of a steel main beam in the construction process according to the embodiment of the invention.

Fig. 3 and 4 are structural diagrams of a guide beam according to an embodiment of the present invention.

Fig. 5 is a schematic structural construction state diagram of a guide beam provided in an embodiment of the present invention.

Fig. 6 and 7 are schematic layout views of an arch rib assembling support according to an embodiment of the present invention.

FIGS. 8-9 are schematic views illustrating a second stage pushing state provided by an embodiment of the present invention.

Fig. 10 is a schematic diagram of a third stage pushing state provided in the embodiment of the present invention.

Fig. 11 is a schematic structural diagram of an overall basket arch bridge provided in the embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined or explained in subsequent figures.

In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings or orientations or positional relationships that the products of the application usually place when in use, and are used only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the devices or elements being referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present application. Furthermore, the terms "first," "second," "third," and the like are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance.

Furthermore, the terms "horizontal", "vertical", "overhang" and the like do not imply that the components are required to be absolutely horizontal or overhang, but may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.

In the description of the present application, it is further noted that, unless expressly stated or limited otherwise, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art.

In this application, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may comprise direct contact of the first and second features, or may comprise contact of the first and second features not directly but through another feature in between. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

The characteristics and performance of the integral pushing construction method of the large-tonnage multi-span high-gravity-center basket arch bridge are further described in detail in the following by combining the embodiment.

The embodiment provides a large-tonnage multi-span high-gravity-center lifting basket arch bridge integral pushing construction method, wherein the lifting basket arch bridge adopts (35 +40+220+40+35 + 370) m lifting basket tied arch bridge, and comprises an arch rib structure and a steel main beam structure, the arch rib structure is longitudinally provided with two arch ribs, each arch rib is divided into a main arch rib and an auxiliary arch rib, the main arch span is 220m, the auxiliary arch span is 300m, the main arch rib span ratio is 1/4.0, the rise height is 55m, the arch center belongs to a high gravity center, and the elevation projection of an arch axis is a parabola. The arch rib transversely inclines inwards, and the inclination angle is 12.5 degrees. A cross brace is arranged between the two transverse main arches. The arch rib at the arch top is close to each other, the arch top cross brace adopts a plate type structure of a flat box, and two sides of the arch top cross brace are arc-shaped. And web members are arranged between the main arch rib and the auxiliary arch rib, and two ends of the two arch ribs are respectively connected with the steel main beam through the arch beam joint section. The steel main beam structure consists of two side tie beams, a middle combined bridge deck and a cross beam, wherein the bridge deck is of a reinforced concrete structure, and the height of the tie beam is 4.0m. The total 29 pairs of full-bridge suspenders, suspender interval 7m, suspender adopt parallel steel wire sling. The full-bridge supporting body is a five-span continuous supporting system, and the arched beams are fixedly connected. The load of the main beam in the suspender area is transferred to the arch rib through the suspender, and finally the load is transferred to the support through the arch foot; the non-boom area load is transferred to the support via the main beam. The pier adopts a column pier, and the foundation adopts a bearing platform and a pile foundation.

The manufacturing method of the basket arch bridge segment comprises the following steps:

s1, dividing the arch rib structure and the steel main beam structure into a plurality of sections in a factory for manufacturing;

s2, pre-assembling steel arch rib segments: a plurality of segments are continuously pre-assembled on the gantry pier, the assembly adopts a side lying method, a jig frame is used as an outer cover, the vertical face of each block unit is in position in a linear mode, and a reinforcing facility is used for ensuring precision and safety. Adopt half vice rib (the whole try on dress of main and vice rib web member) whole line type try on dress method, every half rib adopts a continuous wheel bridge to try on dress, 4 half ribs in full-bridge, and the full-bridge is totally 8 rounds, and the steel rib segment is assembled the process flow who adopts in advance:

preparing a gantry pier jig frame → lofting each datum point → positioning the upper tire of the segment → adding safety support and temporary measures → discharging the tire after the measurement and acceptance are qualified.

And S3, pre-assembling a steel girder structure, continuously pre-assembling multiple beams on a total assembly jig frame, wherein the assembly adopts a 'orthographic assembly method', the jig frame is used as an outer tire, the vertical surfaces of the block units are in place in a linear mode, and reinforcing facilities are used for ensuring the precision and the safety.

The pre-splicing process flow of the steel girder segments comprises the following steps: the method comprises the following steps of tire building and frame placing → main longitudinal beam positioning → small longitudinal beam positioning → stepped propelling, and assembling and welding section by section.

S4, due to the fact that the overall dimension of the arched beam combination section is too large, transportation is inconvenient, and the arched beam combination section and the corresponding cross beam are segmented to form a unit element and then are transported to the site to be assembled and welded;

the construction method for operating the lifting basket arch bridge to the site by adopting integral pushing after the sectional type manufacturing of the lifting basket arch bridge comprises the following steps:

s1, a first stage of basket vault pushing construction:

1.1 as shown in fig. 1, a secondary splicing platform, a girder storage area, a steel girder splicing jig frame and an arch rib splicing jig frame are manufactured on the spacious side of the site, a steel girder splicing support 100 is erected at the circumferential joint of a girder segment, meanwhile, shore pushing temporary supports 110 are uniformly and equidistantly arranged in the splicing platform area, underwater pushing temporary supports 120 are uniformly and equidistantly arranged in the corresponding underwater area, and pushing equipment and pushing landing pad blocks are installed on each pushing support (also identical to a pier).

In the embodiment, the steel beam pushing adopts walking type pushing equipment, and the existing walking type pushing equipment in the market is selected and used in the project. The pushing equipment is responsible for vertical jacking and longitudinal pushing of the steel beam and has a transverse limiting function during pushing construction. The pushing equipment has certain vertical adjusting capacity (not less than 200 mm) and horizontal deviation rectifying capacity (not less than 50 mm). The walking type pushing equipment mainly comprises a sliding surface structure, an upper sliding structure, a lower supporting structure, a supporting oil cylinder, a transverse adjusting oil cylinder, a pushing oil cylinder and the like, and is combined and sequentially moved through hydraulic driving of a computer control box so as to meet construction requirements.

In the construction process, a mathematical formula of a dynamic principle of multipoint dispersion pushing is applied: when Σ Fi > Σ (Fi ± ai) Ni, the beam can be pushed.

In the formula: fi is the jacking force of the jacking power device at the ith pier; ni — fulcrum instantaneous (maximum) fulcrum reaction at the ith pier; fi-the corresponding coefficient of friction of the fulcrum device at the ith pier; ai is the longitudinal slope rate of the pier, "+" is the upward slope top pushing, and "-" is the downward slope top pushing; note: here the pier comprises a temporary pier, a main tower or abutment, an auxiliary pier.

The multi-point pushing mode is adopted, the walking pushing equipment is arranged on each pier, the concentrated pushing force is dispersed to each pier, large pushing equipment can be avoided being configured, the deflection of a beam body during pushing can be effectively controlled, the horizontal pushing force to the piers during pushing can be reduced to be small, and temporary piers with structurally flexible piers are convenient to adopt.

1.2 as shown in fig. 2, hoisting the front end segment 130 of the steel girder to a secondary assembly platform by using a crawler crane in a secondary assembly area, positioning according to the simulated bridge formation coordinates, performing girth welding after positioning, and installing an arched girder joint section 140 by using a bracket method through matching with the convex arched rib connection system of the steel girder.

1.3 as shown in fig. 3-5, a guide beam 150 is installed, and the guide beam is arranged at the front end of the front end section of the steel main beam, so as to reduce the maximum cantilever length of the front end section of the steel main beam, thereby reducing the internal force of the front end of the main beam in the pushing construction process and playing a role in guiding. The guide beam consists of two main beams and a transverse connecting system, the two main beams of the guide beam are of variable cross-section steel box structures and are in bolted connection with the two main longitudinal beams, and the left and right guide beams are connected by a steel pipe connecting system.

1.4 installation strain gauge

Before construction, strain gauges are arranged at key control positions such as connection points of front end sections of steel girders and supports and arch ribs and midspan (circular seams of the steel girders and the arch rib sections), stress changes of the steel girders are tested during construction and are compared and analyzed with a simulation calculated value to control the stress changes of the steel girders during the pushing process. During construction, a centralized control system is adopted, and comprises a real-time control system hardware module, a real-time control system software module, a real-time control network, a pump station Electronic Control Unit (ECU) and a Sensor Control Unit (SCU), wherein the pushing construction synchronism is strictly controlled in the construction process; the set of control system is provided with a sub-controller on each bridge pier, the sub-controller is mainly used for collecting feedback data of a sensor and receiving instructions of a main controller to drive a hydraulic electromagnetic valve, and the sub-controller is connected with 1 set of main controllers through a CAN bus; the main controller realizes the centralized control of the whole system, including: control of jacking and pushing devices, calculation processing of pressure data and displacement data and alarming of various faults.

1.5, as shown in fig. 6, performing the first pushing: the specific pushing process comprises the following steps: firstly, a steel beam is jacked, a jacking jack controls an oil cylinder to reach a set piston stroke through a control system, and a jacking device and the steel beam are jacked up to be away from a pad beam by a distance (controlled to be about 2 cm). Then the steel beam moves forward, the jacking oil cylinder is synchronously controlled by the control system, the shifter is pushed to drive the steel beam to move forward to a set piston stroke position, and the steel beam moves forward. And then the steel beam descends to the pad beam, and after the steel beam moves to the displacement set by the system for force system conversion, the jacking jack piston retracts to return, so that the steel beam falls on the pad beam, and the force system conversion is carried out. Finally, returning the horizontal jack retracting cylinder to the original return stroke state of the horizontal jack retracting cylinder to finish one stroke pushing, taking the five steps of motions as a cycle, and repeating the cycle to realize the pushing translation positioning of the steel beam.

In the steel beam pushing construction process, the linear control of the steel beam is very important and needs to be closely observed. The linear control mode is as follows:

1) According to the line shape of the formed bridge, the whole body is horizontally raised by a set distance (considering the height of a main pier support and the influence of a main pier cushion beam) during assembling, and the cushion block of the cushion block is adjusted at the corresponding temporary support pier (temporary pushing support) according to the line elevation change of every 2m during the pushing process, so that the line shape of the steel beam is consistent with the line shape of the formed bridge.

2) Before the pushing starts, a vertical angle steel with the height of 3 meters is welded on the outer edges of the front end of the temporary pad beam at the front end of each temporary pier (a pushing temporary support) and the rear end of the temporary pad beam at the rear end, an operator controls the deviation of the steel beam by taking the initial distance of the angle steel on a web plate of the steel beam as a reference, when the deviation of the steel beam exceeds 50mm, the pushing equipment synchronously jacks up the steel beam to be separated from a copy pad structure on the temporary pad beam, the deviation of each pier pushing equipment needing to be adjusted is guided to a single-side retracting cylinder of an oil cylinder, and the other side of the guiding oil cylinder extends to enable the deviation of the steel beam to return to the initial position of the transverse moving towards the retracting cylinder side of the guiding oil cylinder along with the sliding beam of the pushing equipment. The transverse linear control of the steel beam is mainly controlled through a transverse adjusting oil cylinder, and the vertical linear control is mainly completed through a vertical jack in the pushing equipment.

3) In the pushing process, a measuring department tracks the control axis of the reflective sheet at the web of the measured steel beam in the whole process, the measuring result reports the pushing of the main control room, and the adjusting condition is verified by the measuring department after the deviation of the main control room is adjusted.

The measures for preventing the midline deviation comprise:

a. ensuring synchronous pushing: before each pushing, the performance of a central control system and pushing equipment at each pier position should be carefully checked, and double control is carried out through pushing displacement and pushing force in the pushing process, so that the pushing displacement is taken as the main part, and the coordination and unification of forward displacement of the left side and the right side of the steel beam are ensured.

b. And (3) monitoring measures: and central line deviation monitoring points are arranged at the top surfaces of the front end and the tail end of the steel beam, and continuous observation is carried out in the pushing process. After the steel beam is hung to the splicing platform, a red paint pen is used as a mileage marking line at a position 1m (outer side) away from the center line of the slide way on the bottom surface of the steel beam, the distance between the marking lines is 1m, scales are drawn out by the paint pen on the outer side of the slide way at the same time, the scales are accurate to centimeter, and therefore an operator beside each slide way can visually observe whether the footage on the two sides is synchronous or not in the pushing process.

c. Limiting measures are as follows: the steel beam is limited by various guide devices during pushing, which is the most direct and effective means for preventing the steel beam from transversely deviating, and 4 transverse adjusting oil cylinders are arranged in the pushing equipment, so that the position of a segment can be transversely adjusted, and the deviation in the pushing process can be corrected at any time.

S2, pushing construction of the basket vault in a second stage:

2.1 hoisting the middle section of the steel girder to a secondary assembly platform by using a crawler crane on a secondary assembly area after the first pushing, positioning according to the simulated bridge forming coordinate, and performing girth welding after the positioning. As shown in fig. 7, then, arch rib assembling brackets are installed on the steel main beam, and the arch rib assembling brackets are divided into two types: one is that a main bridge is used for pushing a steel pipe A support 200 which is used as an arch rib temporary support in the arch rib assembling stage, and the A supports 200 are arranged in 6 groups along the longitudinal bridge direction and welded on a main beam; the other type is a floor lattice column support 210, 5 groups of supports are arranged along the longitudinal bridge direction, four groups of supports close to two side spans adopt concrete to enlarge foundations, the middle group adopts a steel pipe pile foundation, and the top of a lattice column is provided with a section steel distribution beam. In order to enhance the overall stability of the assembled support, the A support and the lattice column support are connected in pairs, wherein the middle-span tubular pile lattice column support is connected with the two groups of A supports.

2.2 according to from both ends to middle order, hoist and mount the arch rib with two track cranes, through the mating fitting quick location of installation when arch rib mill tries to assemble, detect the jib interval between the arch rib section, the relative difference in height of arch rib jib department, the relative difference in height of arch rib tip, the sign indicating number is fixed after the geometrical dimension is qualified, carry out the welding again, retest geometrical dimension after the welding seam is qualified.

2.3 to reduce the pushing weight, after the ribs are welded into a whole, the rib assembling bracket 200 is removed, as shown in fig. 8 and 9. The A-brace 210 is retained to ensure the overall stability of the main bridge arch 220 during the pushing process. And (5) pushing for the second time, and ensuring the center line of the steel beam to be within an allowable range through the limiting and deviation rectifying functions of the deviation rectifying oil cylinder.

S3, a third stage of basket vault pushing construction:

3.1 hoisting the rear steel girder of the bridge to a secondary assembly platform by using a crawler crane on a secondary assembly area after the second pushing, positioning according to the simulated bridge forming coordinate, and performing girth welding after the positioning.

3.2 carrying out third pushing: as shown in fig. 10, a limit bracket is arranged at the pushing end head to serve as a basis and a limit measure for pushing in place; and stopping continuous pushing operation 1m before pushing is in place, using inching operation, pushing forwards for 20cm each time, and observing. The pushing in-place time is controlled, and the segment displacement caused by temperature difference is prevented.

3.3 after the pushing is in place, the beam falling mode adopts integral beam falling, and because the weight is heavy, measurement work needs to be done before the beam falling, and the beam falling is in place successfully as soon as possible; the beam falling is subjected to emergency protection in a mode of extracting steel base plates one by one; monitoring the height difference between the steel beam and each support in the beam falling process; controlling the beam falling height of 200mm in each round, and circularly falling beams in symmetrical rotation; and (4) dismantling the A support, installing and tensioning the suspender and the tie bar, and dismantling the temporary auxiliary facility.

The embodiments described above are some, but not all embodiments of the present application. The detailed description of the embodiments of the present application is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

Claims (8)

1. A large-tonnage multi-span high-gravity-center lifting basket arch bridge integral pushing construction method is characterized by comprising the following steps: the construction method of the basket arch bridge comprises the following steps:

s1, manufacturing a secondary assembly platform on the margin side of a field, uniformly and equidistantly arranging shore pushing temporary supports in a secondary assembly platform area, uniformly and equidistantly arranging underwater pushing temporary supports in a corresponding underwater area, and installing pushing equipment and pushing landing pad cushion blocks on the pushing supports in a multi-point pushing mode; then hoisting the front end segment of the steel girder and performing first pushing;

s2, hoisting the middle section of the steel girder to a secondary assembling platform on a secondary assembling area, positioning according to the simulated bridge coordinates, performing girth welding after positioning, mounting an arch rib assembling support at the girth of the main and auxiliary arch sections on the steel girder structure, assembling an arch rib structure, and performing secondary pushing after forming the integral structure;

and S3, hoisting the rear end section of the steel girder to a secondary assembly platform by using a crawler crane on the secondary assembly area, positioning according to the simulated bridge coordinates, performing girth welding after positioning, performing third pushing, and then removing the temporary auxiliary facilities.

2. The integral pushing construction method of the large-tonnage multi-span high-gravity-center basket arch bridge according to claim 1, characterized in that: the method for controlling the stress change of the steel beam in the pushing process comprises the following steps: and installing strain gauges at key control positions at the connecting points of the steel girder structures, the supports and the arch ribs of each section before construction, testing the stress change of the steel girder during construction, and comparing and analyzing the stress change of the steel girder with a simulation calculated value to control the stress change of the steel girder during the pushing process.

3. The integral pushing construction method for the large-tonnage multi-span high-gravity center lifting basket arch bridge as recited in claim 2, wherein the method comprises the following steps: a centralized control system is adopted for controlling the stress of the steel beam during construction, and comprises a real-time control system hardware module, a real-time control system software module, a real-time control network, a pump station electronic control unit and a sensor control unit.

4. The integral pushing construction method of the large-tonnage multi-span high-gravity-center basket arch bridge according to claim 1 or 2, characterized in that: the linear control mode of the steel beam in the pushing process is as follows: according to the bridge forming line shape, the whole body is horizontally raised for a set distance during assembling, and the cushion blocks of the pushing landing cushion blocks are adjusted at the corresponding pushing temporary supports according to the line-shaped elevation change of the set distance in the pushing process; before the pushing starts, a vertical angle steel is welded at the front end of each temporary pushing support front end pad beam and the outer edge of the rear end of each rear end temporary pushing support rear end pad beam, an operator controls the deviation of the steel beam by taking the initial distance between the angle steel and a steel beam web plate as a reference, when the deviation of the steel beam exceeds a set distance, the pushing equipment synchronously jacks up the steel beam to be disengaged from a lifting pad structure on the temporary pushing support, the pushing equipment on each temporary pushing support needing to be adjusted is guided to a single-side retracting cylinder of the oil cylinder, and the guiding oil cylinder on the other side is extended to enable the deviation of the steel beam to be transversely moved to the initial position along with the sliding beam of the pushing equipment to the retracting cylinder side of the guiding oil cylinder.

5. The integral pushing construction method of the large-tonnage multi-span high-gravity-center basket arch bridge according to claim 1 or 2, characterized in that: in the step S2, the arch rib assembling support comprises an arch rib temporary support and an A-bracing temporary support, the A-bracing is arranged on the steel girder bridge floor in a central symmetry mode, and the arch rib temporary support and the A-bracing temporary support are arranged at intervals and are connected through connecting pieces.

6. The integral pushing construction method of the large-tonnage multi-span high-gravity-center basket arch bridge according to claim 5, characterized in that: in the step S2, hoisting the arch rib structure by using two crawler cranes in sequence from two ends to the middle, quickly positioning by using a matched connecting piece installed during trial assembly of an arch rib factory, and detecting the distance between the suspender of the arch rib sections, the relative height difference of the suspender of the arch rib and the relative height difference of the end part of the arch rib; after the geometric dimension is qualified, the code plate is fixed and then welding is carried out.

7. The integral pushing construction method of the large-tonnage multi-span high-gravity-center basket arch bridge according to claim 1 or 2, characterized in that: and step S3, arranging a limiting bracket at the pushing end, stopping continuous pushing operation at a position 1m before pushing is in place, using inching operation, setting a distance for forward pushing each time, observing and controlling the pushing in-place time.

8. The integral pushing construction method of the large-tonnage multi-span high-gravity-center basket arch bridge according to claim 7, characterized in that: in the step S3, after the pushing is in place, the beam falling mode adopts integral beam falling, and the beam falling mode adopts a mode of extracting steel base plates one by one to protect; monitoring the height difference between the steel beam and each support in the beam falling process; and controlling the beam falling height in each round to be not more than 200mm, and circularly falling the beams in a symmetrical and alternate manner.

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