CN116356703A - Construction method for main tower upper cross beam and tower crown of cable-stayed bridge - Google Patents

Abstract

The invention provides a construction method for the upper beam and tower crown of the main tower of a cable-stayed bridge, comprising: step S1, after the two middle tower columns are closed, continue pouring the main tower through a climbing form, and step S2, in the cavity of the closed area Pre-embed anchor bolts on the inner walls on both sides corresponding to the direction of the transverse bridge, fix the corbels through the anchor bolts, and set distribution beams along the bridge direction above the corbels. In step S3, set the outer mold corresponding to the upper beam through the climbing formwork system. The steel bars corresponding to the upper beam are bound internally, and the steel bars corresponding to the upper beam are connected to the steel bars corresponding to the tower column; step S4, the upper beam is poured through the horizontal layering method of concrete, so that the upper beam and the closing area are poured as a whole. The bottom formwork is set based on the closing area as the cavity of the upper main tower, and the outer formwork is set through the climbing formwork to realize the construction of the upper beam. During the construction process, the horizontal layered foundation is used for pouring to ensure the quality of concrete pouring.

Description

A construction method for the upper beam and tower crown of the main tower of a cable-stayed bridge

technical field

The invention belongs to the technical field of bridge construction, and in particular relates to a construction method for the upper beam and tower crown of a main tower of a cable-stayed bridge.

Background technique

Currently, cable-stayed bridges, suspension bridges, and other bridges with pylon structures generally adopt pylon shapes such as diamond-shaped, H-shaped, herringbone, A-shaped, inverted Y-shaped, etc. A-shaped pylons are commonly used in bridge design today. A form of bridge tower, generally including two independent tower columns, the two tower columns are closed above to form the upper beam and the cable tower, and the steel anchor beam is set in the cable tower to set the cable, the cable tower and the upper beam Construction quality directly determines the safety and service life of cable-stayed bridges.

Therefore, it is necessary to provide an improved technical solution for the above-mentioned deficiencies in the prior art.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies in the above-mentioned prior art and provide a safe, high-quality cable-stayed bridge construction method.

In order to achieve the above object, the present invention provides the following technical solutions:

A construction method for the upper beam and tower crown of a main tower of a cable-stayed bridge, comprising:

Step S1, after the two middle tower columns are closed, continue to pour the main tower through the climbing form until the pouring reaches the design elevation of the upper beam; wherein, the part of the main tower corresponding to the closing area is provided with an empty chamber;

Step S2, pre-embed anchor bolts on the inner walls of both sides corresponding to the transverse bridge direction in the cavity of the closing area, fix the corbels through the anchor bolts, and set a distribution beam along the bridge direction above the corbels, and the two load-bearing beams are respectively located in the distribution beams. At both ends of the beam, multiple I-beams are arranged between the two load-bearing beams, and the upper beam bottom form is supported by square wood above the I-beams;

Step S3, setting the outer form corresponding to the upper beam through the climbing formwork system, binding the steel bar corresponding to the upper beam inside the outer mold, and connecting the steel bar corresponding to the upper beam with the steel bar corresponding to the tower column;

In step S4, the upper beam is poured by using the method of horizontal layering through the concrete, so that the upper beam and the closing area are poured as a whole.

Preferably, the tower crown is a cone-like structure. During the casting process of the cable tower by the climbing formwork, the climbing formwork along the direction of the bridge can climb to the corresponding section of the tower crown, and the climbing formwork in the direction of the transverse bridge is one step below the climbing tower crown. Stop climbing after the section, and use the climbing formwork body in the direction of the bridge to carry out the construction of the tower crown formwork.

Preferably, the method also includes:

Step S5, after the upper beam is solidified to a preset strength, the bottom mold and the outer mold are removed, and after the removal is completed, the cable tower is poured section by section through the climbing formwork system;

The steel anchor beam construction is carried out synchronously during the pouring process of the cable tower section by section, so that the steel anchor beam and the cable tower are poured together.

Preferably, the conical nut is pre-embedded on the top surface of the upper beam when the concrete is poured, and the steel anchor beam adjustment bracket is erected through the conical nut;

After the pouring of the upper beam is completed, the steel anchor beam adjustment bracket is installed on the embedded parts, and the steel anchor beam is lifted to the adjustment bracket for initial positioning;

Connect the cable conduit to the steel anchor beam through the flange, measure and double-check the position of the cable conduit, and after the steel anchor beam is accurately positioned, weld and fix it with the rigid frame of the tower column;

Bind the steel bars of the cable tower, and pour the steel anchor beams into a whole.

Preferably, before the installation of the first steel anchor beam, the tower column and the upper beam are monitored, and the installation position of the first steel anchor beam is determined so that the steel anchor beam overlaps the center line of the concrete section of the tower column along the centerline of the bridge, and according to the measurement results, take Steel backing plate for deviation correction.

Preferably, there are multiple steel anchor beams, and in the projection along the bridge direction, the multiple steel anchor beams are arranged in a pyramid shape.

Preferably, a manhole corresponding to the tower column or closing area is provided on the upper beam, and an inner mold corresponding to the manhole is provided during the pouring process of the upper beam.

Preferably, one layer of main reinforcement is arranged along the outer edge of the section of the tower column and the closing area and the outer edge of the inner chamber, and a manhole is provided between the tower column and the inner chamber of the closing area, and all steel bars passing through the manhole are cut off. The steel bar is closed at the cut-off point; after the upper beam is poured, the bottom form of the upper beam is removed through the manhole.

Preferably, before concrete pouring, the feeding points are evenly arranged according to the concrete flow radius, and the chutes and stringers are arranged. When the concrete enters the formwork, the free fall height of the concrete should not exceed 2m;

Concrete pouring shall be poured in layers, the thickness of each layer shall not be greater than 30cm, and continuous construction shall be ensured without interruption during construction;

When vibrating concrete, the vibrating rod should be inserted into the next layer to a certain depth. When vibrating, the insertion points should be moved evenly, in a row or in a staggered manner to avoid vibration leakage. The distance between the concrete vibrating rod and the formwork should be kept at 5-10cm.

Preferably, tower column monitoring is carried out during the construction process, and the monitoring positions include:

Arrange at least 4 settlement observation points for each tower cap to observe the settlement of the cap;

Two stress-strain and temperature test sections are arranged at the bottom of the lower tower column and the middle tower column to monitor the axial force of the tower; two stress-strain and temperature test sections are arranged on the cable tower to monitor the lateral force of the tower; A cross-section is arranged in the middle of the beam to monitor the force of the beam.

Beneficial effects: the bottom formwork is set on the basis of the closing area being the cavity of the upper main tower, and the outer formwork is set through the climbing formwork to realize the construction of the upper beam. During the construction process, the horizontal layered foundation is used for pouring to ensure that the concrete Pour quality. By pouring the upper beam integrated with the closing area, the stability of the main body is ensured, and at the same time, the overall quality of the main tower after the installation of the steel anchor beam is ensured to ensure the tension stability of the cable-stayed bridge.

Description of drawings

The accompanying drawings constituting a part of the present application are used to provide a further understanding of the present invention, and the schematic embodiments and descriptions of the present invention are used to explain the present invention, and do not constitute an improper limitation of the present invention. in:

Fig. 1 is the schematic diagram of main tower section division in the specific embodiment provided by the present invention;

Fig. 2 is the schematic diagram of closing area in the specific embodiment provided by the present invention;

Fig. 3 is the structural representation of tower crown climbing formwork construction in the specific embodiment provided by the present invention;

Fig. 4 is a schematic diagram of the distribution of steel anchor beams in a specific embodiment provided by the present invention.

In the figure: 1. tower base; 2. lower tower column; 3. lower beam; 4. middle tower column; 5. closing area; 6. upper beam; 7. cable tower; 8. tower crown; 9. manhole; 10. Climbing formwork; 11. Steel anchor beam; 12. Steel frame.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below, obviously, the described embodiments are only some of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present invention belong to the protection scope of the present invention.

In the description of the present invention, the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", " The orientations or positional relationships indicated by "top", "bottom", etc. are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and do not require that the present invention must be constructed and operated in a specific orientation, so they cannot be understood as Limitations on the Invention. The terms "connected" and "connected" used in the present invention should be understood in a broad sense, for example, it can be fixedly connected or detachably connected; it can be directly connected or indirectly connected through intermediate parts, for ordinary A skilled person can understand the specific meanings of the above terms according to specific situations.

The present invention will be described in detail below with reference to the accompanying drawings and examples. It should be noted that, in the case of no conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

As shown in Figures 1-4, a construction method for the upper beam and tower crown of the main tower of a cable-stayed bridge includes: step S1, after the two middle tower columns 4 are closed, continue to pour the main tower through the climbing formwork 10 until pouring Up to the design elevation of the upper beam 6; wherein, the part of the main tower corresponding to the closure area 5 is provided with a cavity; step S2, pre-embed anchor bolts on the inner walls of both sides corresponding to the direction of the transverse bridge in each cavity, and fix the corbel through the anchor bolts , a distribution beam along the direction of the bridge is set above the corbel, two load-bearing beams are respectively located at both ends of the distribution beam, and a plurality of I-beams are arranged between the two load-bearing beams, and a square log is passed above the I-beam Carry out the support of the bottom formwork of the upper beam 6; the lateral dimension of the tower column is gradually reduced upwards, and the corbels are pre-embedded in the inner chamber of the tower column to erect the bracket construction. The support system on both sides of the beam is 15mm bamboo plywood + 10*10cm square wood + I10 I-shaped steel + I18 I-shaped steel + I45 I-shaped steel. In step S3, set the outer mold corresponding to the 6 positions of the upper beam through the climbing formwork 10 system. Bind the steel bar corresponding to the upper beam 6 inside the outer mold, and connect the steel bar corresponding to the upper beam 6 with the steel bar corresponding to the tower column; the bracket system in the middle part of the upper beam 6 is 15mm bamboo plywood + 10*10cm square wood + I10 I-beam + I22 I-beam + I45 I-beam, arrange corbels and climbing cone embedded parts in the poured section of the main tower as the fulcrum of the formwork construction support, step S4, pour the upper beam 6 through the horizontal layering method of concrete. By pouring the upper beam 6 integrated with the closing area 5, the stability of the main body is ensured, and at the same time, the overall quality of the main tower after the installation of the steel anchor beam 11 is ensured to ensure the tension stability of the cable-stayed bridge. Concrete pouring adopts the construction method of horizontal layering, and the slump of concrete entering the mold is controlled at 16-20cm. Concrete vibration uses plug-in vibrating rods, and the vibration time should not be too long to prevent the bellows from floating in some places due to vibration. The concrete pouring space is small. When pouring, the concrete pouring thickness should be relatively reduced, and the vibration should be in place to prevent grout leakage and vibration leakage. During the pouring process, set observation points on the bottom form to monitor the deflection of the bracket and formwork at any time, and pay close attention to the stress of the bracket and the formwork to ensure safe and smooth pouring; the closing area 5 includes: two symmetrically distributed A triangular or quasi-triangular chamber, and a section of pouring is carried out along the main tower trend above the triangular prism inner chamber, as an extension of the closing area 5, the extension has an inner cavity extending along the main tower trend The upper beam 6 is correspondingly arranged above the extension part; the hollow tower column and the closing area 5 can reduce the amount of concrete to the greatest extent while ensuring the strength of the cable-stayed bridge, reduce the construction volume, and speed up the construction efficiency. 6 is a solid structure except that the manhole 9 is set, which can increase the strength of the main body.

In another optional embodiment, when the middle tower column 4 is poured to the preset elevation of the closing area 5 by the method of climbing formwork 10, the climbing formwork 10 corresponding to the opposite sides of the two middle tower columns 4 is removed, and the climbing formwork 10 Splicing with the outer form in the closing area 5; installing the corbels on the exposed climbing cone anchor bolts after the climbing formwork 10 is removed. The tower crown 8 is a cone-like structure. During the casting process of the cable tower 7 by the climbing formwork 10, the climbing formwork 10 in the direction of the bridge can climb to the corresponding section of the tower crown 8, and the climbing formwork 10 in the direction of the bridge is climbing Stop climbing after a section below the tower crown 8, and use the 10 climbing formwork bodies in the direction of the bridge to carry out the construction of the tower crown 8 formwork. Bind steel bars in the tower crown 8 formwork, and complete the construction of the tower crown 8 by pouring, thereby completing all the construction of the main tower body. Partially use the dismantled climbing formwork 10 to restructure the frame body as the subsequent segment formwork operation platform; Turnover use, and then use mortar to smooth the holes left after the climbing cone is removed.

In an optional embodiment, the tower crown 8 is a hollow structure, the cable tower 7 is a hollow structure, and its internal chamber is connected to the tower crown 8 through a manhole, and an inspection hole is provided on the side of the tower crown 8, through which the Enter tower crown 8 and cable tower 7 in turn for maintenance.

Steel frames 12 distributed along the steel anchor beams are respectively embedded in the inner walls of the tower crown 8 or cable tower 7 chambers corresponding to the two ends of the steel anchor beams. It is located on both sides of the steel anchor beam and welded and fixed with the steel anchor beam. It is buried at the tower crown 8 and the cable tower 7 by pouring. Among them, the steel frame 12 is welded and lengthened, and each steel frame 12 corresponds to no less than two floors. For steel anchor beams, the joints of two adjacent steel frames 12 are not located at the same layer of steel anchor beams.

The lower edge of the steel anchor beam on the same floor is provided with a horizontal connecting frame for connecting the steel frames 12 in the horizontal direction to connect the steel frames 12 as a whole.

In another optional embodiment, in step S5, when the upper beam 6 is solidified to a preset strength, the bottom form and the outer form are removed, and after the removal is completed, the cable tower 7 is poured section by section through the climbing formwork 10 system; The steel anchor beam 11 is constructed simultaneously during the pouring process of the cable tower 7, so that the steel anchor beam 11 and the cable tower 7 are poured integrally, and the connection between the main towers of the steel anchor beam 11 is more stable through integral pouring. After the bridge is completed, when the shrinkage and creep are completed, the actual anchorage point elevation at the 7 ends of the cable-stayed cable tower and the elevation of the lower beam 3 are at the design theoretical position.

The steel anchor beam 11 is composed of a tension anchor beam and an anchor structure, which is used as a stay cable anchor structure, and is arranged in the cable tower 7, and mainly bears the balanced horizontal force of the stay cables. The bolted rigid connection is adopted between the anchor beam and the corbel. The steel anchor beam 11 is a box-shaped structure consisting of a web, a top plate, a bottom plate, an anchor backing plate, an anchor plate, a bearing plate, a stiffening plate under the anchor, and a vertical stiffening plate. Steel corbels are the supporting structure of steel anchor beams 11, and each steel anchor beam 11 is directly supported on a pair of steel corbel top plates. The steel corbel is composed of top plate, web plate, web stiffening plate, tower wall embedded steel plate, shear steel plate, shear nail and connecting steel plate connected with stiff frame.

的钢管作为托架的立柱，用2工25a作为分配梁；测量精确调整钢锚梁11位置，位置调整好后在支架上焊接限位板；上横梁6浇注完成后，在预埋件上安装钢锚梁11调节支架，起吊钢锚梁11至调节支架进行初定位；塔吊解钩，测量复核钢锚梁11位置，确保安装精度满足设计要求，将索导管通过法兰与钢锚梁11连接，测量复核索导管位置，钢锚梁11精确定位后，与塔柱劲性骨架焊接固定；进行索塔7钢筋绑扎，将钢锚梁11与一体浇注为一个整体。In another optional embodiment, the conical nut is pre-embedded on the top surface of the upper beam 6 when the concrete is poured, and the steel anchor beam 11 is set up to adjust the bracket through the conical nut; 4 about 3m long are installed on the pre-embedded parts, diameter

The steel pipe is used as the column of the bracket, and 2 workers 25a are used as the distribution beam; the position of the steel anchor beam 11 is accurately adjusted by measuring, and the position is adjusted, and the limit plate is welded on the bracket; after the upper beam 6 is poured, install it on the embedded part Steel anchor beam 11 adjusts the bracket, lifts the steel anchor beam 11 to the adjustment bracket for initial positioning; unhooks the tower crane, measures and double-checks the position of the steel anchor beam 11 to ensure that the installation accuracy meets the design requirements, and connects the cable guide to the steel anchor beam 11 through the flange , measure and double-check the position of the cable conduit, and after the steel anchor beam 11 is accurately positioned, it is welded and fixed with the rigid frame of the tower column; the cable tower 7 is bound with steel bars, and the steel anchor beam 11 is cast as a whole.

In another optional embodiment, before the first steel anchor beam 11 is installed, the tower column and the upper beam 6 are monitored, the installation position of the first steel anchor beam 11 is determined through control analysis, and at the same time, the first steel anchor beam is calculated and determined. The pre-elevation value of beam 11 is installed so that the centerline of steel anchor beam 11 along the bridge direction overlaps with the centerline of the concrete section of the tower column, and steel backing plates are used to correct the deviation according to the measurement results. The ideal target geometric line shape of steel anchor beam 11 is determined by steel The center point of the section of the anchor beam 11 is given. The installation and positioning of the steel anchor beam 11 adopts the three-dimensional coordinate method of the TCA2003 total station, and the bottom surface elevation, top surface elevation, and flatness of the steel anchor beam 11 and steel corbels are measured by a precision level. Choose a time period when the temperature is low and constant, and there is no wind to measure the three-dimensional coordinates of the anchor point of the cable guide and the point of exit from the tower, calculate the deviation from the theoretical coordinates, and make fine adjustments with the adjusting device and the turnbuckle set on the four sides of the cable guide. After the adjustment is completed, re-test until the three-dimensional coordinate deviation of the anchor point and the tower exit point does not exceed 3mm. When the accuracy meets the requirements, the cable guide and the rigid frame are welded and fixed immediately.

Due to deviations in the inclination of the steel anchor beam 11 during manufacture and installation, the pre-deviation gradually accumulates and increases with the continuous heightening of the anchor beam, and the cumulative deviation of the installation of the anchor beam must be controlled. When the anchor beam is installed to a certain height, deflection correction must be carried out. Steel gaskets are used for deflection correction. That is, according to the batches of anchor beams and hoisting on site, a layer of deflection correction pads is set in each batch. to set. When the steel anchor beam 11 is manufactured, the height of the steel anchor beam 11 on the upper side of each spacer is correspondingly reduced, so that the thickness of the spacer is equal to that of the reduced steel anchor beam 11 height and the original design steel anchor beam 11 height.

Before a batch of anchor beams are installed and positioned, measure the actual inclination of the anchor beams, determine the adjustment value according to the measured value, cut the backing plate, and install it together with the next batch of steel anchor beams 11 .

In another optional embodiment, there are multiple steel anchor beams 11 , and the plurality of steel anchor beams 11 are arranged in a pyramid shape on the projection along the bridge direction.

There are 54 pairs of stay cables in each main tower, and 27 pairs of steel anchor beams 11 are arranged in total. The steel anchor beams 11 are placed horizontally, and each anchor beam anchors a pair of stay cables. The steel anchor beam 11 and the steel corbel are welded and formed respectively in the factory and then assembled for trial assembly, and the installation tool is temporarily reinforced to match the components. After the overall hoisting of the steel anchor beam 11 and the steel corbel is completed, the concrete of the tower column of the corresponding section shall be poured according to the construction progress. Temporary reinforcement matching components for tooling; after the tensioning of the stay cables of the whole bridge and the completion of the second phase of construction, tighten the high-strength bolts between the steel anchor beam 11 on the side of the main span and the steel corbel to completely lock the relative sliding between the anchor beam and the corbel .

In another optional embodiment, a manhole 9 corresponding to the pylon or closing area 5 is provided on the upper beam 6 , and an inner mold corresponding to the manhole 9 is provided during the pouring process of the upper beam 6 . After the upper beam 6 is poured, the bottom form of the upper beam 6 is removed through the manhole 9 .

A layer of main reinforcement is arranged along the outer edge of the tower column and the closing area 5 and the outer edge of the inner chamber, and a manhole 9 is provided between the tower column and the inner chamber of the closing area 5, and all steel bars passing through the manhole 9 are cut off. The truncated steel bars are closed at the truncation point; the wall thickness of the pylon 7, the upper beam 6, and the closing area 5 are gradually thickened within a certain range of the intersection, and the wall thickness is within 10 meters of the handover. The wall thickness of the tower column gradually changes from 1m to 2.2m. The middle tower column 4, the lower tower column 2, and the top of the tower are single-box single-chamber sections, and the stay cable anchorage area of the cable tower 7 is a single-box three-room section. The middle tower column 4 is provided with a 1.8m×1.0m manhole 9 on the inner side of the tower column at the bridge deck, through which the power pipeline passes. The 4-height of the middle tower column adopts a four-sided large chamfered single-box single-chamber cross-section, and the basic wall thickness is 1m.

In another optional embodiment, before the concrete is poured, the feeding points are evenly arranged according to the concrete flow radius, and the chute and stringer are arranged. When the concrete enters the formwork, the free fall height of the concrete should be controlled not to exceed 2m; When the length is not more than 3.5 meters, the pull screw adopts the standard length-to-length pull method. The PVC sleeve is passed between the templates on both sides, and the pull screw is passed through the sleeve. When pouring a solid section with a thickness greater than 3.5 meters, use a 6-meter-long tension screw to weld with the self-provided Φ25 steel bar (or transverse main bar), the welding length is greater than 200mm, and fix it on the steel back corrugated with a female connecting pad. Concrete pouring is poured in layers, and the thickness of each layer is not more than 30cm. During the construction, continuous construction should be ensured without interruption; when the concrete is vibrated, the vibrating rod should be inserted into the next layer to a certain depth. Move in a staggered manner to avoid vibration leakage, and the distance between the mixing vibrator and the formwork should be kept at 5-10cm. After the pouring is completed, two methods of watering and curing agent curing are used for concrete curing, that is, curing agent is used for curing when the temperature is lower than 5°C, and watering is used for curing when the temperature is higher than 5°C.

In another optional embodiment, tower column monitoring is carried out during the construction process, and the monitoring positions include: at least 4 settlement observation points are arranged on each tower column cap to observe the settlement of the cap; Two stress-strain and temperature test sections are arranged at each of the four roots of the tower column to monitor the axial force of the tower; two stress-strain and temperature test sections are arranged on the cable tower 7 to monitor the lateral force of the tower; the lower beam 3 and the upper beam 6 A section is arranged in the middle of the span to monitor the force of the beam. Ensure that after the main tower is capped, the structural stress state meets the requirements of the design and relevant specifications. Take reasonable control measures to ensure the stability and safety during the construction of the main tower, especially during the construction of the middle tower column 4, to ensure that the outer side of the tower column does not suffer from tensile cracks. After the bridge is completed, when the shrinkage and creep are completed, the actual anchorage point elevation at the 7 ends of the cable-stayed cable tower and the elevation of the lower beam 3 are at the design theoretical position. During the construction of the main tower, the elevation of the anchorage point of the stay cable at the tower end and the elevation of the top of the padded rock of the 3 top supports of the lower beam should be considered.

After reviewing the whole construction process of the whole bridge and calculating the construction stage, combined with the relevant information fed back by the construction unit and the manufacturing unit, the pre-lift amount of the tower column is determined. The factors considered in determining the amount of prelift mainly include: foundation settlement, foundation elastic compression, tower column self-weight elastic compression, deformation caused by concrete shrinkage and creep, and compression under the action of bridge cable forces. It can be understood that, the above description is only exemplary, and this embodiment of the present application does not limit it.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are within the scope of the pending rights of the present invention. within the scope of protection.

Claims (10)

1. A construction method for an upper cross beam and a crown of a main tower of a cable-stayed bridge is characterized by comprising the following steps:

step S1, after two middle tower columns are closed, continuing to perform main tower casting through a climbing die until the main tower is cast to the designed elevation of the upper cross beam; wherein, the part of the main tower corresponding to the folding area is provided with an empty chamber;

s2, embedding anchor bolts in the inner walls of two sides of a closed region cavity corresponding to the transverse bridge direction, fixing brackets through the anchor bolts, arranging a distribution beam along the bridge direction above the brackets, respectively arranging two bearing beams at two ends of the distribution beam, arranging a plurality of I-steel between the two bearing beams, and supporting an upper cross beam bottom die above the I-steel through square timber;

step S3, arranging an outer mold corresponding to the upper beam through a climbing mold system, binding steel bars corresponding to the upper beam in the outer mold, and connecting the steel bars corresponding to the upper beam with the steel bars corresponding to the tower columns;

and S4, pouring the upper cross beam through concrete by adopting a horizontal layering method, so that the upper cross beam and the folding area are poured into a whole.

2. The construction method of the main tower top beam and the tower crown of the cable-stayed bridge according to claim 1, wherein the tower crown is of a conical-like structure, the climbing formwork along the bridge direction can climb to the section corresponding to the tower crown in the process of cable tower pouring by the climbing formwork, the climbing formwork along the bridge direction stops climbing after climbing the section below the tower crown, and the construction of the tower crown template is performed by using the climbing formwork along the bridge direction.

3. The cable-stayed bridge main tower upper beam and tower crown construction method according to claim 1, wherein the method further comprises:

s5, dismantling the bottom die and the outer die when the upper cross beam is solidified to be of preset strength, and carrying out cable tower pouring section by section through a climbing die system after dismantling;

and synchronously carrying out steel anchor beam construction in the process of casting the cable towers section by section, so that the steel anchor beam and the cable towers are integrally cast.

4. The construction method of the main tower upper beam and the tower crown of the cable-stayed bridge according to claim 3, wherein a conical nut is pre-buried on the top surface of the upper beam when the concrete of the upper beam is poured, and a steel anchor beam adjusting bracket is erected through the conical nut;

after the upper beam is poured, installing a steel anchor beam adjusting bracket on the embedded part, and hoisting the steel anchor beam to the adjusting bracket for initial positioning;

connecting a cable guide pipe with a steel anchor beam through a flange, measuring the position of a rechecking cable guide pipe, and welding and fixing the steel anchor beam with a tower column stiffness framework after the steel anchor beam is accurately positioned;

and binding reinforcing steel bars of the cable tower, and casting the steel anchor beam and the integrated steel anchor beam into a whole.

5. The method for constructing the top beam and the crown of the main tower of the cable-stayed bridge according to claim 4, wherein before the first section of steel anchor beam is installed, the tower column and the top beam are monitored, the installation position of the first section of steel anchor beam is determined, the center line of the steel anchor beam along the bridge overlaps with the center line of the concrete section of the tower column, and a steel backing plate is adopted for correcting the deviation according to the measurement result.

6. A method for constructing a main tower top beam and a tower crown of a cable-stayed bridge according to claim 3, wherein a plurality of steel anchor beams are arranged in a pyramid shape on the forward projection.

7. The method for constructing the top beam and the crown of the main tower of the cable-stayed bridge according to claim 1, wherein the top beam is provided with manholes corresponding to the tower columns or the folding areas, and the top beam is provided with an inner mold corresponding to the manholes in the casting process.

8. The construction method of the main tower top beam and the tower crown of the cable-stayed bridge according to claim 2, wherein the tower column and the closure zone are respectively provided with 1 layer of main reinforcement along the outer edge of the section and the outer edge of the inner chamber, a manhole is arranged between the tower column and the inner chamber of the closure zone, all reinforcement passing through the manhole is cut off, and the cut-off reinforcement is closed at the cut-off position; and after the upper beam is poured, the bottom die of the upper beam is removed through the manhole.

9. The construction method of the main tower upper cross beam and the tower crown of the cable-stayed bridge according to claim 1, wherein before concrete pouring, blanking points are uniformly arranged according to the flowing radius of the concrete, a chute and a string barrel are arranged, and when the concrete enters a template, the free falling height of the concrete is controlled to be not more than 2m;

the concrete pouring is carried out in a layered mode, the thickness of each layer is not more than 30cm, and continuous construction is ensured not to be interrupted in construction;

when the concrete is vibrated, the vibrating rod should be inserted into the next layer to a certain depth, and the inserting points are uniformly moved in rows or in a staggered manner during the vibration so as to avoid vibration leakage, and the distance between the mixing vibrating rod and the template is preferably kept at 5-10 cm.

10. The method for constructing the main tower top beam and the tower crown of the cable-stayed bridge according to claim 1, wherein the monitoring of the tower column is performed in the construction process, and the monitoring position comprises:

at least 4 settlement observation points are arranged on each tower column bearing platform, and bearing platform settlement observation is carried out;

2 stress strain and temperature test sections are respectively arranged at the roots of the lower tower column and the middle tower column, and the axial stress condition of the tower is monitored; 2 stress strain and temperature test sections are distributed on the cable tower, and the transverse stress condition of the tower is monitored; and the middle of the lower beam and the upper beam is respectively provided with 1 section, and the stress condition of the beams is monitored.

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