CN110700100A - Bailey beam bundle construction method for cast-in-situ platform of high-pier small-radius curve ramp bridge - Google Patents

Abstract

The invention belongs to the technical field of construction of constructional engineering, and discloses a Bailey beam bundle construction method for a cast-in-place platform of a high-pier small-radius curve ramp bridge, which is characterized by preparing before construction and arranging a support platform; measuring and positioning a bridge support system; constructing a steel pipe column and distribution and bracket support system; carrying out Bailey beam bundle platform construction; placing a transverse distribution beam on the Bailey beam, measuring a web plate side line on the transverse distribution beam, and marking; according to the cross section arrangement of the bowl buckle supports, the bowl buckle supports are erected from the web plate encryption position to two sides, and the adjacent arrangement distance of the cross section is changed when the bowl buckle supports exceed the web plate side line; the outer contour of the bowl buckle support, the web plate encrypted part and the non-encrypted section are arranged to form a saw-tooth shape; carrying out a simulated load test, pouring and carrying out permanent prestress construction on the bridge; and (6) dismantling the platform. The invention can effectively reduce the cost, ensure the safety of the temporary structure, has strong practicability and has good popularization and application values.

Description

Bailey beam bundle construction method for cast-in-situ platform of high-pier small-radius curve ramp bridge

Technical Field

The invention belongs to the technical field of construction engineering, and particularly relates to a Bailey beam bundle construction method for a cast-in-place platform of a high-pier small-radius curve ramp bridge.

Background

Currently, the closest prior art:

with the continuous and rapid advance of the infrastructure construction in China, the bridge engineering construction technology is different day by day. In the engineering construction of municipal bridges, rails and the like, the situations that the curve radius is small, the pier column height is high and obstacles need to be crossed are often seen, such as flyover ramps, bridges positioned on curved overhead and the like. The pier height usually reaches more than 10m during construction, and a crossing type cast-in-place platform is generally adopted. The support column in the crossing type cast-in-place platform is a steel pipe column in more structural forms at present, the upper crossing platform adopts 321 Bailey beam single layers, double layers and reinforced military beams or military beams with higher rigidity according to span and load, and CB200 Bailey bridges, D-shaped temporary beams and the like.

However, in actual construction, due to the fact that the modulus and the beam length of the Bailey beam change when the truss beam at the upper part of the small-radius curve bridge is arranged like the structural broken line of the Bailey beam, the projections of the position with larger web load and the position with smaller bottom plate and wing plate load on a plane often change in a curve mode, the Bailey beam is very difficult to arrange, the situation becomes extremely complex, meanwhile, the Bailey beam at the pier column position is influenced by the modulus, special-shaped Bailey beam rod pieces with various lengths need to be arranged, the cost is higher, and the construction operation difficulty is greatly increased.

In summary, the problems of the prior art are as follows: when a platform is built, the conventional high-pier curve small-radius beam body is complex in component installation, high in cost and construction operation difficulty due to the Bailey beam modulus and the beam length.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a Bailey beam bundle construction method for a cast-in-place platform of a high-pier small-radius curve ramp bridge.

The invention is realized in this way, a construction method for a Bailey beam bundle of a cast-in-place platform of a high-pier small-radius curve ramp bridge, which specifically comprises the following steps:

step one, preparation before construction: carrying out layout and calculation analysis on the bridge support system to determine a construction scheme;

step two, arranging a spanning type platform according to the economic span, analyzing the temporary support structure by using Midas civil, and arranging a support platform;

thirdly, performing measurement paying-off according to the support axis of the steel pipe column arrangement of the plan view, determining the installation position of the steel pipe column, and performing measurement positioning on the bridge support system;

step four, constructing a steel pipe column and distribution and bracket support system through continuous structure side pier steel pipe column support construction and continuous structure middle pier bracket construction;

step five, determining the number of the Bailey beams avoiding the pier stud position setting and the number of the horizontal connections increasing under the condition of the overall torsion effect of the Bailey beams under the condition of uneven load according to calculation and analysis, and performing Bailey beam bundle platform construction on the premise of maintaining the overall lateral torsion stability of the Bailey beam bundle main beam;

placing a transverse distribution beam on the Bailey beam, measuring a web side line on the transverse distribution beam, and marking; according to the cross section arrangement of the bowl buckle supports, the bowl buckle supports are erected from the web plate encryption position to two sides, and the adjacent arrangement distance of the cross section is changed when the bowl buckle supports exceed the web plate side line; the outer contour of the bowl buckle support, the web plate encrypted part and the non-encrypted section are arranged to form a saw-tooth shape;

step seven, carrying out a simulated load test, after the load reaches the standard, pouring from the place with the maximum cross center disturbance degree, and then pouring from the cross center to the pier column side; after the pouring is finished, adjusting the beam by adopting a single-beam tensioning jack one by one, and performing permanent prestress construction on the bridge, wherein the beam adjusting tension is 10% sigma k;

and step eight, adopting an integral dismantling method to dismantle the support platform.

Further, in step two, the support platform specifically includes:

a spanning type platform is arranged according to the economic span, the single-layer Bailey beam is poured to be 12-15 m in span, the spanning type support adopts a steel pipe column to support the Bailey beam, an I-steel transverse distribution beam is arranged on the Bailey beam, and a WDJ bowl buckle support is erected for slope adjustment; a transverse distribution square wood is arranged on the top of the WDJ bowl buckle support, a phi 48 multiplied by 3.5mm steel pipe is adopted above the square wood for longitudinal distribution or a steel plate is directly adopted, and a bamboo plywood is adopted on the square wood.

Further, in the fourth step, the continuous structure side pier steel pipe column supporting construction specifically includes:

during construction of the steel pipe column foundation, a loose structure is removed from the surface of the rock, after the bearing capacity of the foundation is achieved, a reinforced concrete buttress mode is adopted, a strip foundation is adopted for a buttress, and the top surface of the foundation is leveled; burying culvert pipes in individual areas such as river channels, firstly filling, constructing bored piles by adopting an impact hole-forming mode, burying embedded parts at the tops of the piles, arranging transverse distribution beams, and placing steel pipe buttresses on the distribution beams;

the steel pipe columns are connected in a flange connection mode, and the parallel connection between the steel pipe columns is connected by bolts with fixed sizes, so that the problems of large labor consumption and material loss caused by welding and repeated cutting are avoided; the sizes of the parallel connection parts are unified as much as possible according to the design support positions;

when the steel pipe column is installed, a crane is adopted for hoisting, and the parallel connection construction is completed when the steel pipe column is installed to the parallel connection position; the top surface of the steel pipe column is provided with a parallel connection, and the distance between the parallel connection and the top of the steel pipe column is controlled to be about 0.5 m; when the steel-pipe column installation is close to the pier column, be connected with the pier column, reduce slenderness ratio for increase the stability of steel-pipe column, improve bearing capacity.

Further, in the fourth step, the pier bracket construction in the continuous structure specifically includes:

replacing the steel pipe column with a bracket supporting mode according to stress analysis except for opening the side pier; the bracket adopts a hoop and a prestressed pull rod mode to overcome horizontal tension, and the pin shaft resists a vertical shear mode:

(1) the embedded part adopts 32mm diameter finish rolling threads to resist the tension of the upper end of the bracket, the anchor ear and the concrete bear the tension together, and the shear force transmission of the outer bracket and the embedded part bracket is transmitted through a 100mm diameter pin shaft;

(2) the finish-rolled thread is anchored at the other end of the bridge pier, and the finish-rolled thread adopts a PSB 930-grade and standard matched prestressed anchor plate and nut;

(3) before and after installation of the phi 32 finish-rolled twisted steel, the phi 32 finish-rolled twisted steel needs to be protected to prevent the twisted steel from being damaged by electric welding, and the pre-limit tension of a single phi 32 finish-rolled twisted steel is 55 t; before the bracket is used, a single 25t pre-tightening force is applied to the finish rolling threads;

(4) the phi 100 steel bar needs to be quenched and tempered, the degree of finish is 6.3, and nondestructive inspection is needed after the completion; reserving phi 50 holes in phi 32 finish rolling twisted steel, reserving phi 102 holes in phi 100 steel bars, and keeping the hole depth at 600 mm;

(5) the phi 100 steel bar is made of 40Cr materials, the embedded part steel plate and the shear contact steel plate with the pin shaft steel plate are made of Q345B, and the other materials are Q235B materials;

(6) the groove weld joints are required to be completely melted, and the quality grade is two levels; drilling all holes by using a machine tool;

(7) the finish rolling screw thread needs to ensure vertical stress, so that bending and brittle fracture are avoided; the holes are accurately pre-buried, when the pin shaft bears shearing force, the finish-rolled threads are in a free tension state, and the shearing action is strictly forbidden;

(8) the steel bar processing length satisfies that there is 2cm clearance between spacing round pin axle and the bracket steel sheet for avoid the bracket when receiving the pulling force, take place the extrusion with spacing round pin axle contact.

Further, in the fifth step, the construction of the bailey beam bundle platform specifically comprises:

hoisting the Bailey beam in place by using a crane; hoisting is carried out according to groups;

when the Bailey beams are vertically arranged, the Bailey beams are arranged into an upper layer and a lower layer which are adjacent, and the staggered height influences the extension of the adjacent Bailey beams.

Further, in the seventh step, the simulated load test specifically includes:

(1) the pre-pressing loading of the bracket is carried out in three stages, and loads are sequentially applied to 60%, 80% and 100% of the pre-pressing load value of the segment unit (the maximum load working condition is used as a base after a coefficient of 1.2 times);

(2) when in pre-pressing loading, the transverse symmetrical loading is carried out along the midline;

(3) after each stage of loading is finished, monitoring the settlement amount of the support at intervals of 12h, and when the average value of settlement difference of the measurement points of the support for 2 continuous times is less than 2mm, continuously loading;

(4) after the settlement of each point is loaded to 120%, the unloading can be carried out once after the average value of the settlement of each point is less than 1mm or the average value of the settlement of each point is accumulated for 3 times continuously and is less than 5mm, and the unloading adopts symmetrical, balanced and synchronous unloading.

Further, in the eighth step, the integral disassembling method specifically includes:

according to calculation and analysis, reserving holes on the bridge at corresponding positions at lifting points required to be arranged under the dead weight load; the lowering hanger rod adopts 32mm finish rolling twisted steel, and the diameter of the reserved hole is not less than that of the connector;

when the integral dismantling method is used for dismantling the support platform, hoisting holes are formed in the top surface of a beam body which can bear the support platform after being tensioned, finish-rolled twisted steel bars are adopted, the crossing support platform such as a Bailey beam structure is hoisted, and the dead weight of the Bailey beam structure is converted into the beam body;

after the lower supporting steel pipe column is dismantled, the whole spanning type support platform is gradually lowered to the ground by using finish rolling twisted steel to be dismantled, so that the high-position spanning type low-position safe and quick dismantling is realized.

In summary, the advantages and positive effects of the invention are:

according to the invention, through the Bailey beam bundle main beam support similar to the concept of moving the formwork, the construction problems of complex component installation, large plane arrangement difficulty and the like caused by Bailey beam modulus and beam length when a high pier curve small-radius beam body is erected on a platform are solved; the method is well applied to engineering, provides a good demonstration for the construction design of the Bailey beam platform of the municipal engineering high pier small-radius curve ramp bridge, effectively reduces the cost, ensures the safety of a temporary structure, provides a reference for solving similar engineering construction, has strong practicability and has good popularization and application values.

The design of the crossing platform is optimized, the beam column arrangement thought is simple, the construction efficiency is improved, non-standard pole pieces are reduced, and the cost is reduced: according to the Bailey beam bundle platform construction method for the high-pier small-radius curve ramp bridge, the Bailey beam bundle main beam bearing mode is adopted, so that the construction problems that the installation of components is complex and the plane arrangement difficulty is high and the like caused by the Bailey beam modulus and the beam length when a platform is erected are solved, and the reduction of the construction efficiency caused by the influence of the beam length, the Bailey beam modulus and other factors and the need of accurate measurement and positioning during arrangement is avoided.

The slope-adjusting bowl-buckle support system has clear stress, realizes the arrangement of the bowl-buckle support system erected by curves according to a load arrangement diagram, and has good technical economy: the slope-adjusting bowl buckle support system is arranged in a zigzag manner, the bowl buckle support system is completely erected according to a load diagram curve, the work load of the bowl buckle support for dense erection is saved, the problem that a high-pier small-radius curve beam generally has a large longitudinal and transverse slope is solved, when the bowl buckle support system is adopted at the upper part of a spanning type Bailey beam platform for adjustment, the cross section arrangement of the bowl buckle support is also in a curve arrangement according to a wing plate, a web plate and a top bottom plate, and in order to ensure the stability of the support system, when all cross rods are connected and the arrangement requirement of vertical rods needs to be continuously changed according to the load arrangement form, the erection of the bowl buckle support is also difficult.

The invention is safe and reliable, and reduces the construction difficulty: high mound small radius curve roof beam stridees across formula bailey beam platform construction technology portion has only carried out the optimal design from interim support system and has started, sets up overall stability greatly increased behind the transverse connection between the bailey beam bundle girder, through simple optimal design, realizes practicing thrift the cost, and more important is that the structure is safer under same material consumption, reduces technical construction risk.

The invention has convenient construction, simple and applicable process and very practical guiding significance to the current situation of similar construction projects: the pier column in the middle of the continuous structure adopts a bracket mode except for the position of the side pier (considering avoiding the pier column bearing larger eccentric bending moment), so that the cost for treating the steel pipe column foundation is reduced, the cost is lower, and the work efficiency is improved. The pier stud position adopts prestressing force bracket, and bearing capacity improves, make full use of to drawing the principle. The invention is a conventional construction process, adopts the simplest method to solve the most practical problem, and has convenient construction and simple process.

The method is suitable for the construction of the large-pier small-radius curve beam with small curve radius, high pier column height (generally more than or equal to 10m) in municipal, rail, highway and other bridge engineering, or the construction of the layout engineering of the high-pier small-radius curve beam needing to cross the obstacle by adopting a crossing Bailey beam and a steel pipe column supporting platform.

Drawings

Fig. 1 is a flow chart of a Bailey beam bundle construction method of a cast-in-place platform of a high-pier small-radius curve ramp bridge provided by the embodiment of the invention.

Fig. 2 is a schematic diagram of a construction process provided in an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The technical scheme and the technical effect of the invention are explained in detail in the following with the accompanying drawings.

As shown in fig. 1, the construction method for the bailey beam bundle of the cast-in-place platform of the high-pier small-radius curve ramp bridge provided by the embodiment of the invention specifically comprises the following steps:

s101, preparation before construction: and carrying out layout and calculation analysis on the bridge support system to determine a construction scheme.

S102, arranging a spanning type platform according to the economic span, analyzing the temporary support structure by using Midas civil, and arranging a support platform.

S103, carrying out measurement paying-off according to the support axis of the steel pipe column arrangement in the plan view, determining the installation position of the steel pipe column, and carrying out measurement positioning on the bridge support system.

And S104, carrying out steel pipe column and distribution and bracket support system construction through continuous structure side pier steel pipe column support construction and continuous structure middle pier bracket construction.

And S105, determining the number of the Bailey beams avoiding the pier stud positions and the number of the horizontal connections under the condition of the overall torsion effect of the Bailey beams under the condition of uneven load according to calculation and analysis, and performing Bailey beam bundle platform construction on the premise of maintaining the overall lateral torsion stability of the Bailey beam bundle main beam.

S106, placing a transverse distribution beam on the Bailey beam, measuring a web edge line on the transverse distribution beam, and marking; according to the cross section arrangement of the bowl buckle supports, the bowl buckle supports are erected from the web plate encryption position to two sides, and the adjacent arrangement distance of the cross section is changed when the bowl buckle supports exceed the web plate side line; the outer contour of the bowl buckle support, the web plate encrypted part and the non-encrypted section are arranged to form a saw-tooth shape.

S107, carrying out a simulated load test, after the load reaches the standard, pouring from the place with the maximum cross center disturbance degree, and then pouring from the cross center to the pier column side; after the pouring is finished, adjusting the beam by adopting a single-beam tensioning jack one by one, and performing permanent prestress construction on the bridge, wherein the beam adjusting tension is 10% sigma k;

and S108, removing the support platform by adopting an integral removing method.

In step S102, the support platform arrangement provided in the embodiment of the present invention specifically includes:

a spanning type platform is arranged according to the economic span, the single-layer Bailey beam is poured to be 12-15 m in span, the spanning type support adopts a steel pipe column to support the Bailey beam, an I-steel transverse distribution beam is arranged on the Bailey beam, and a WDJ bowl buckle support is erected for slope adjustment; a transverse distribution square wood is arranged on the top of the WDJ bowl buckle support, a phi 48 multiplied by 3.5mm steel pipe is adopted above the square wood for longitudinal distribution or a steel plate is directly adopted, and a bamboo plywood is adopted on the square wood.

In step S104, the continuous structure side pier steel pipe column support construction provided by the embodiment of the present invention specifically includes:

during construction of the steel pipe column foundation, a loose structure is removed from the surface of the rock, after the bearing capacity of the foundation is achieved, a reinforced concrete buttress mode is adopted, a strip foundation is adopted for a buttress, and the top surface of the foundation is leveled; burying culvert pipes in individual areas such as river channels, filling, constructing bored piles by adopting an impact hole-forming mode, burying embedded parts at the tops of the piles, arranging transverse distribution beams, and placing steel pipe buttresses on the distribution beams.

The steel pipe columns are connected in a flange connection mode, and the parallel connection between the steel pipe columns is connected by bolts with fixed sizes, so that the problems of large labor consumption and material loss caused by welding and repeated cutting are avoided; the sizes between the parallel connection parts are unified as much as possible according to the design support positions.

When the steel pipe column is installed, a crane is adopted for hoisting, and the parallel connection construction is completed when the steel pipe column is installed to the parallel connection position; the top surface of the steel pipe column is provided with a parallel connection, and the distance between the parallel connection and the top of the steel pipe column is controlled to be about 0.5 m; when the steel-pipe column installation is close to the pier column, be connected with the pier column, reduce slenderness ratio for increase the stability of steel-pipe column, improve bearing capacity.

In step S104, the pier bracket construction in the continuous structure provided by the embodiment of the present invention specifically includes:

replacing the steel pipe column with a bracket supporting mode according to stress analysis except for opening the side pier; the bracket adopts a mode of adopting a hoop and a prestressed pull rod to overcome horizontal tension, and the pin shaft resists vertical shear force.

(1) The embedded part adopts 32mm diameter finish rolling screw thread to resist the pull force of the upper end of the bracket, the anchor ear and the concrete bear together, and the shear force transmission of the outer bracket and the embedded part bracket is transmitted through a 100mm diameter pin shaft.

(2) And the finish rolling thread is anchored at the other end of the bridge through a bridge pier, and the finish rolling thread adopts a PSB 930-grade and standard matched prestressed anchor plate and nut.

(3) Before and after installation of the phi 32 finish-rolled twisted steel, the phi 32 finish-rolled twisted steel needs to be protected to prevent the twisted steel from being damaged by electric welding, and the pre-limit tension of a single phi 32 finish-rolled twisted steel is 55 t; before the bracket is used, a single 25t pre-tightening force is required to be carried out on the finish rolling threads.

(4) The phi 100 steel bar needs to be quenched and tempered, the degree of finish is 6.3, and nondestructive inspection is needed after the completion; phi 50 holes are reserved in the phi 32 finish-rolled twisted steel, phi 102 holes are reserved in the phi 100 steel bar, and the hole depth is 600 mm.

(5) The phi 100 steel bar is made of 40Cr materials, the embedded part steel plate and the pin shaft steel plate are made of Q345B, and the other materials are Q235B materials.

(6) The groove weld joints are required to be completely melted, and the quality grade is two levels; and drilling all holes by using a machine tool.

(7) The finish rolling screw thread needs to ensure vertical stress, so that bending and brittle fracture are avoided; the holes are accurately embedded, and when the pin shaft bears shearing force, the finish-rolled threads are in a free tension state, and the shearing action is strictly forbidden.

(8) The steel bar processing length satisfies that there is 2cm clearance between spacing round pin axle and the bracket steel sheet for avoid the bracket when receiving the pulling force, take place the extrusion with spacing round pin axle contact.

In step S105, the bailey beam bundle platform construction provided by the embodiment of the present invention specifically includes:

hoisting the Bailey beam in place by using a crane; and hoisting according to groups.

When the Bailey beams are vertically arranged, the Bailey beams are arranged into an upper layer and a lower layer which are adjacent, and the staggered height influences the extension of the adjacent Bailey beams.

In step S107, the simulated load test provided in the embodiment of the present invention specifically includes:

(1) the pre-pressing loading of the support is carried out in three stages, and loads are sequentially applied to 60%, 80% and 100% of the pre-pressing load value of the segment unit (the maximum load working condition is used as a base after a coefficient of 1.2 times).

(2) And when in pre-pressing loading, the transverse middle line is symmetrically loaded towards two sides.

(3) After each stage of loading is finished, the settlement amount of the support is monitored at intervals of 12h, and when the average value of settlement difference of the measurement points of the support for 2 times is less than 2mm, the support can be continuously loaded.

(4) After the settlement of each point is loaded to 120%, the unloading can be carried out once after the average value of the settlement of each point is less than 1mm or the average value of the settlement of each point is accumulated for 3 times continuously and is less than 5mm, and the unloading adopts symmetrical, balanced and synchronous unloading.

In step S108, the integral removal method provided in the embodiment of the present invention specifically includes:

according to calculation and analysis, reserving holes on the bridge at corresponding positions at lifting points required to be arranged under the dead weight load; the descending suspender adopts 32mm finish rolling twisted steel, and the diameter of the reserved hole is not less than the diameter of the connector.

When the integral dismantling method is used for dismantling the support platform, hoisting holes are formed in the top surface of a beam body which can bear the support platform after being tensioned, finish-rolled twisted steel bars are adopted, the crossing support platform such as a Bailey beam structure is hoisted, and the dead weight of the Bailey beam structure is converted into the beam body;

after the lower supporting steel pipe column is dismantled, the whole spanning type support platform is gradually lowered to the ground by using finish rolling twisted steel to be dismantled, so that the high-position spanning type low-position safe and quick dismantling is realized.

The technical solution and technical effects of the present invention are further described below with reference to specific embodiments.

Example 1:

1. background of the invention

The regional south east Yangtze section road and the subsidiary engineering of the Chongqing chemical industry park are located in the suburb long-life chemical industry park in Chongqing city. In the project, a K1+242.60 medium bridge has the mile pile number of K1+205.100, the design height of 268.734m, the design longitudinal slope of-2.00% and the full width of a bridge deck of 26.00m and is positioned on a curve, the upper structures of the medium bridge adopt post-tensioning prestressed concrete continuous box girders, the bridge abutment of the lower structure adopts a U-shaped bridge abutment and an open cut foundation, and the pile pier adopts a column pier and a pile foundation.

The mode that the steel pipe column supported the bailey beam and strideed across has been adopted during bridge superstructure construction, because curve radius is little, the bailey beam adopts the mode of broken line bailey beam bundle to arrange the position and avoids the pier stud, and the whole roof beam body is born the upper portion load by the girder that several groups of concentrated bailey beam bundles are constituteed, staggers a roof beam height on the adjacent pier stud difference. The lower steel pipe column is erected in a rectangular mode, and the Bailey beam support position mainly adopts a standard chord member reinforcing member to solve the problem that the Bailey beam is not supported on a node. The upper part adopts a bowl buckle support system to adjust the slope, and the bowl buckle supports are arranged in a zigzag manner, so that the problem of arrangement of the bowl buckle supports is solved.

The invention summarizes the defects in the current construction, forms a Bailey beam bundle platform construction method for a high-pier small-radius curve ramp bridge in municipal engineering, and solves the construction problems of complex component installation, large plane arrangement difficulty and the like caused by Bailey beam modulus and beam length when a platform is built by a high-pier curve small-radius beam body through Bailey beam bundle main beam support similar to the moving formwork concept.

The Bailey beam bundle platform construction method for the municipal engineering high-pier small-radius curve ramp bridge is well applied to engineering, provides a good demonstration for the construction design of the Bailey beam platform for the municipal engineering high-pier small-radius curve ramp bridge, effectively reduces the cost, ensures the safety of a temporary structure, provides a reference for solving similar engineering construction, and has strong practicability and good popularization and application values.

2. Characteristics of the method

2.1 striding over formula platform design optimization, the beam column is arranged the thinking simple, and the efficiency of construction improves, and non-sighting rod spare reduces, cost reduction: according to the Bailey beam bundle platform construction method for the high-pier small-radius curve ramp bridge, the Bailey beam bundle main beam bearing mode is adopted, so that the construction problems that the installation of components is complex and the plane arrangement difficulty is high and the like caused by the Bailey beam modulus and the beam length when a platform is erected are solved, and the reduction of the construction efficiency caused by the influence of the beam length, the Bailey beam modulus and other factors and the need of accurate measurement and positioning during arrangement is avoided.

2.2 the stress of the slope-adjusting bowl-buckle support system is clear, the bowl-buckle support system built by the curve is arranged according to the load arrangement diagram, and the technical economy is good: the slope-adjusting bowl buckle support system is arranged in a zigzag manner, the bowl buckle support system is completely erected according to a load diagram curve, the work load of the bowl buckle support for dense erection is saved, the problem that a high-pier small-radius curve beam generally has a large longitudinal and transverse slope is solved, when the bowl buckle support system is adopted at the upper part of a spanning type Bailey beam platform for adjustment, the cross section arrangement of the bowl buckle support is also in a curve arrangement according to a wing plate, a web plate and a top bottom plate, and in order to ensure the stability of the support system, when all cross rods are connected and the arrangement requirement of vertical rods needs to be continuously changed according to the load arrangement form, the erection of the bowl buckle support is also difficult.

2.3 safe and reliable reduces the construction degree of difficulty: high mound small radius curve roof beam stridees across formula bailey beam platform construction technology portion has only carried out the optimal design from interim support system and has started, sets up overall stability greatly increased behind the transverse connection between the bailey beam bundle girder, through simple optimal design, realizes practicing thrift the cost, and more important is that the structure is safer under same material consumption, reduces technical construction risk.

2.4 construction convenience, simple process is suitable for, has very realistic guiding significance to similar construction project current situation at present: the pier column in the middle of the continuous structure adopts a bracket mode except for the position of the side pier (considering avoiding the pier column bearing larger eccentric bending moment), so that the cost for treating the steel pipe column foundation is reduced, the cost is lower, and the work efficiency is improved. The pier stud position adopts prestressing force bracket, and bearing capacity improves, make full use of to drawing the principle. The construction technology of the invention is a conventional construction technology, the most practical problem is solved by adopting the simplest method, the construction is convenient, and the technology is simple.

3. Application scope

The method is suitable for the construction of the large-pier small-radius curve beam with small curve radius, high pier column height (generally more than or equal to 10m) in municipal, rail, highway and other bridge engineering, or the construction of the layout engineering of the high-pier small-radius curve beam needing to cross the obstacle by adopting a crossing Bailey beam and a steel pipe column supporting platform.

4. Principle of the process

When the Bailey beam crossing type cast-in-place platform of the high-pier curved ramp bridge is constructed, in order to avoid the difference caused by the lengths of the inner arc line and the outer arc line of the curved beam, nonstandard Bailey beams with various specifications need to be configured to meet the requirements of length and modulus. Pier stud position conflicts result in a span beam body to need the stub bar of multiple specification length to match. The arrangement position needs to be accurately measured and lofted, otherwise, the arrangement of the Bailey beam cannot be completed due to inaccurate position.

The Bailey beam bundle platform construction method for the municipal engineering high-pier small-radius curve ramp bridge arranges Bailey beam girders in a bundle to form a girder bearing mode similar to that of a movable formwork and a bridge girder erection machine. The degree of difficulty reduces when the workman operates, arrange near the pier stud can, can set up the prestressing force bracket in pier stud position and bear, reduced the basic processing expense greatly. When the Bailey beam is not supported at the node position, the chord is reinforced by adopting a standard reinforcing piece, so that the Bailey beam is very convenient.

The bowl buckle support of the curved beam body is arranged according to a load schematic diagram, and the preparation rule arrangement of positions needing to be arranged in an encrypted manner such as webs is realized on the premise that the bowl buckle support is integrally connected through continuous adjustment of the distance between the transverse position rods.

5. Construction process flow and operation key points

5.1 construction Process

The construction process flow is shown in figure 2.

5.2 operating points

5.2.1 preparation of construction

(1) And collecting bridge design information, knowing the geological condition of the position of the pier stud of the bridge, and carrying out layout and computational analysis on the bridge support system. And organizing a construction technician to be familiar with a construction drawing and technical specifications and well carry out technical bottom-crossing work before starting work.

(2) The construction process should be communicated with a design institute, and simultaneously, the construction process should ask for supervision, opinions of owners and units, organize a workshop and preliminarily determine the construction process.

(3) And respectively calculating to determine a special construction scheme after the erection of the support system is finished through calculation analysis, and finishing the approval process.

(4) And (5) compiling the stress and displacement monitoring of the bridge pier of the beam body and completing the approval process.

(5) Preparing the beam concrete mix proportion trial and the raw material inspection.

(6) Relevant site water and electricity facing arrangement is well made so as to facilitate site construction.

5.2.2 scaffold platform construction design

5.2.2.1 construction design of bracket system: and the cast-in-place beam pouring scheme is determined by arranging a spanning type platform according to the economic span. The single-layer Bailey beam is generally poured, the span is distributed at 12-15 m, the span type support can also be a steel pipe column to support the Bailey beam, meanwhile, in order to adjust the slope, I-steel transverse distribution beams can be arranged on the Bailey beam, and then a WDJ bowl buckle support is erected. A transverse distribution square wood is arranged on the top of the WDJ bowl buckle support, a phi 48 multiplied by 3.5mm steel pipe is adopted above the square wood for longitudinal distribution or a steel plate is directly adopted, and a bamboo plywood is adopted on the square wood. Special attention is paid to design:

(1) when the Bailey beam bundle system bears the design and calculation of upper load, the height of the beam body of general municipal engineering is low (1.8m/2.4m), and the beam body generally needs to be poured for 2 times, and during calculation and analysis, the influence of the second pouring of concrete on the stress of the first pouring of concrete and the bracket is considered according to the specification, and whether the first pouring of concrete cracks or not is evaluated (all the beam bodies need to be poured for several times). The load is typically applied in one application (although the first pour is less loaded).

(2) Because the plane position of the web plate of the curved beam body is changed continuously, the load borne by the Bailey beam at different positions is not seriously uneven, and the Bailey beam bundle needs to adopt a transverse distribution beam to restrain lateral torsion so as to ensure the lateral rigidity of the Bailey beam bundle.

5.2.2.2 computational analysis: the temporary structures can be analyzed using Midas civil mainly for temporary scaffold structures,

and calculating and analyzing according to the technical specifications of the safety of the bowl-buckled scaffold for the JGJ166-2016 building construction and the technical specifications of the temporary supporting structure for the JGJ300-2013 building construction.

5.2.2.3 validation measures: the construction process adopts a 'double control' principle, and under the control of calculation and analysis, the deformation observation of the bracket system is enhanced during construction, and the comparison and verification with the calculation and analysis are carried out.

5.2.3 bridge support system measurement positioning

The support system is in curve special-shaped arrangement, the support system is complex, and measurement and positioning work must be done before construction. The construction, measurement and positioning of the Bailey beam steel pipe column are carried out, firstly, measurement and paying-off are carried out according to the support axis arranged on the steel pipe column in a plan view, and the installation position of the steel pipe column is determined. The axis of the distribution beam on the steel pipe column is generally supported at the position of the vertical rod of the Bailey beam.

5.2.4 construction of steel pipe column and distribution and bracket support system:

5.2.4.1 continuous structure side pier steel pipe column support construction

When the steel pipe column foundation is constructed, the loose structure is removed from the surface of the rock, after the bearing capacity of the foundation is achieved, a reinforced concrete buttress mode is adopted, the buttress adopts a strip foundation, and the top surface of the foundation is leveled. Burying culvert pipes in individual areas such as river channels, filling, constructing bored piles by adopting an impact hole-forming mode, burying embedded parts at the tops of the piles, arranging transverse distribution beams, and placing steel pipe buttresses on the distribution beams. Under general conditions, the bearing capacity of the temporary structure single pile in the municipal engineering construction process is small, and the single pile foundation and the bearing platform can be adopted for bearing.

Adopt flange joint mode between the steel-pipe column, the parallel connection between the steel-pipe column can adopt fixed dimension's bolted connection, avoids adopting the welding and cutting repeatedly, leads to a large amount of artifical consumptions and material loss. The size between the parallel connection can be unified as much as possible according to the design support position.

When the steel pipe column is installed, a crane is generally adopted for hoisting, and parallel connection construction is started to be completed when the steel pipe column is installed to a parallel connection position, so that the stability of installing the steel pipe column is ensured. The top surface of the steel pipe column is connected with the distribution beam without welding, so that the bending moment of the distribution beam is prevented from being transmitted to the steel pipe column, the steel pipe column is made into a bending component, and the due bearing capacity is not fully exerted. The top surface of the steel pipe column is provided with a parallel connection, and the distance between the parallel connection and the top surface of the steel pipe column is controlled to be about 0.5 m. When the steel pipe column is installed to be close to the pier column, the steel pipe column should be connected with the pier column as far as possible, and reducing the slenderness ratio is the most effective measure, so that the stability of the steel pipe column can be improved, and the bearing capacity is improved.

5.2.4.1 continuous structure middle pier bracket construction

In order to reduce the steel pipe column foundation treatment construction, a bracket supporting mode can be adopted to replace the steel pipe column according to the stress analysis except for the side pier. The bracket adopts a mode of adopting a hoop and a prestressed pull rod to overcome horizontal tension, and the pin shaft resists vertical shear force.

(1) The embedded part adopts 32mm diameter finish rolling threads to resist the tension of the upper end of the bracket, the anchor ear and the concrete bear the tension together, and the shear force transmission of the outer bracket and the embedded part support is transmitted through a 100mm diameter pin shaft.

(2) And the finish rolling thread is anchored at the other end of the bridge through a bridge pier, and the finish rolling thread adopts a PSB 930-grade and standard matched prestressed anchor plate and nut.

(3) And a feasible measure is taken on site, so that the precision requirement of the preformed hole of the phi 100 steel bar is ensured, and the error is +/-2 mm. Before and after installation of the phi 32 finish-rolled twisted steel, the twisted steel needs to be protected to prevent being damaged by electric welding, appearance quality inspection needs to be carried out before the twisted steel is used reversely, and if the twisted steel is damaged by electric welding, the twisted steel is forbidden to be used strictly. The pre-limit tension of a single phi 32 finish-rolled threaded steel bar is 55 t. Before the bracket is used, a single 25t pre-tightening force is required to be carried out on the finish rolling threads.

(4) The phi 100 steel bar needs to be quenched and tempered, the degree of finish is 6.3, and nondestructive inspection is needed after the completion. Phi 50 holes are reserved in the phi 32 finish-rolled twisted steel, phi 102 holes are reserved in the phi 100 steel bar, and the hole depth is 600 mm.

(5) The phi 100 steel bar is made of 40Cr materials, the embedded part steel plate and the pin shaft steel plate are made of Q345B, and the other materials are Q235B materials.

(6) Except for the indication, the welding seams in the figure are fillet welding seams, the welding height hf is 10mm, and the appearance quality grade is three grades. The groove weld joints are required to be melted through, and the quality grade is two grades.

(7) All holes in the figure must be drilled by a machine tool, and oxygen acetylene cutting is strictly forbidden.

(8) The structure in the drawing is complex, the processability is poor, the welding sequence is noticed during actual processing, and the quality of each welding line is strictly ensured.

(9) The finish rolling screw thread must guarantee the vertical stress, avoid appearing buckling brittle failure. Holes must be pre-buried accurately, and when the pin shaft bears shearing force, the finish-rolled threads are in a free tension state, and the shearing action is forbidden.

(10) The steel bar processing length should satisfy that there is 2cm clearance between spacing round pin axle and the bracket steel sheet, avoids the bracket when receiving the pulling force, takes place the extrusion with spacing round pin axle contact.

5.2.5 Bailey beam bundle platform construction:

according to calculation and analysis, the number of Bailey beams arranged at the positions avoiding pier studs and the number of horizontal connections increased under the condition of uneven load (the positions of web plates are constantly changed, and conventional arrangement still exists) by the Bailey beam integral torsion effect are determined by the Bailey beam platform, so that the integral lateral torsion stability of the Bailey beam main beam is maintained.

When the Bailey beam bundle is constructed, a crane is adopted to hoist the Bailey beam in place. The general hoisting is carried out according to the group hoisting (such as 2 pieces and 1 group), and the lateral stability during the hoisting is mainly considered, and the placing lateral becomes flexible and unstable.

When the bailey beam is vertically arranged, in order to not consider that the bailey beam needs to be matched with the modulus at the longitudinal position, the bailey beam can be arranged into an upper layer and a lower layer which are adjacent, and the staggered height can be influenced after the extension of the adjacent bailey beam is avoided.

5.2.6 construction of the bowl buckle support system:

after the steel pipe column is positioned, the Bailey beams are placed according to the cross section arrangement. And placing a transverse distribution beam on the Bailey beam, measuring the edge line of the web plate on the transverse distribution beam, and marking.

Before the bowl buckle support system is constructed, a transverse distribution beam is placed on the Bailey beam, a web side line is measured on the transverse distribution beam, after marks are made, bowl buckle supports are erected from a web plate encryption position to two sides according to the cross section arrangement of the bowl buckle supports, and the adjacent arrangement distance of the cross section is changed when the bowl buckle supports exceed the web side line. Because the web side line is a curve, the outer contour of the bowl buckle bracket, the web encryption part and the non-encryption section are arranged to form a saw-tooth shape.

5.2.7 simulation load test

Before pouring, overload prepressing is carried out according to the standard requirement to detect the bearing capacity of the bracket template system, and the overload prepressing also follows the loading sequence from midspan to two piers. And a monitoring measure is made, so that the construction monitoring is enhanced, the elastic deformation of the structure is monitored, and the inelastic deformation is eliminated.

5.2.7.1 test conditions: and after the platform is installed, the platform can be checked and accepted according to the steel structure engineering construction specification GB50755-2012 and the design scheme. The simulation load test process refers to the specification of steel pipe full-hall support preloading technical specification JGJT 194-containing 2009 for graded loading.

5.2.7.2 load value: during loading, loading is carried out according to the maximum load working condition (drawing a load sketch) obtained by calculation according to the working condition, and the prepressing weight is 120% of the maximum calculated working condition load. The loading can be performed by precast concrete blocks or sand bags and the like.

5.2.7.3 simulation load flow:

(1) the pre-pressing loading of the support is carried out in three stages, and loads are sequentially applied to 60%, 80% and 100% of the pre-pressing load value of the segment unit (the maximum load working condition is used as a base after a coefficient of 1.2 times).

(2) And when in pre-pressing loading, the transverse middle line is symmetrically loaded towards two sides.

(3) After each stage of loading is finished, the settlement amount of the support is monitored at intervals of 12h, and when the average value of settlement difference of the measurement points of the support for 2 times is less than 2mm, the support can be continuously loaded.

(4) After the settlement of each point is loaded to 120%, the unloading can be carried out once after the average value of the settlement of each point is less than 1mm or the average value of the settlement of each point is accumulated for 3 times continuously and is less than 5mm, and the unloading adopts symmetrical, balanced and synchronous unloading.

5.2.7.4 test point arrangement:

the arrangement of the bracket deformation observation points conforms to the following regulations:

(1) when the span of the structure does not exceed 40m, arranging an observation section every 1/4 spans along the longitudinal direction of the structure; when the structure span is larger than 40m, the distance between the longitudinally adjacent observation sections is not larger than 10 m;

(2) at least 5 observation points on each observation section are symmetrically arranged;

(3) each group of observation points is arranged on the corresponding positions of the top of the bracket and the bottom of the bracket.

5.2.7.5 record and result application: the pre-pressing aims at eliminating uneven compactness of foundation treatment of the support structure and uneven settlement (inelastic deformation) of the support structure in the use process caused by connection gaps of all members, mastering the elastic deformation of each hole in the use process of the full support, and providing a formwork erecting basis for the support members due to the deflection change.

And the elevation of the vertical mold is a superposition result of the actually measured elastic deformation value and the upward arching value. And comprehensively measuring each measuring point before prepressing, recording the absolute elevation h1 (multiple points to be measured), standing and observing after each stage of prepressing, finishing prepressing to correspond to the absolute elevation h2 of each point, and measuring the elevation h3 of each point after detaching and unloading to serve as a basis for calculating the elastic deformation value.

Inelastic deformation value △ t1 ═ h1-h3

Elastic deformation value △ t2 ═ h1-h2- △ t1

The deformation measurement obtains the deformation to set the pre-camber according to a quadratic parabola shape.

The pre-pressing observation record table can be carried out according to the attached table of Steel pipe full-hall bracket pre-pressing technical regulation (JG/T194-2009).

During construction, attention must be paid to control the occurrence of an overload condition. If the prepressing sand bag rains in the prepressing process, the wet weight is increased.

5.2.8 construction and casting

During construction, construction is carried out according to relevant technical specifications strictly, the bowl buckle support is inspected and accepted according to the specifications, and a cross brace, a floor sweeping rod and the like are made to enhance the integrity of the support system. Because the compression component is mainly stability control, the connection between the steel pipe columns must be made, and the steel pipe columns are connected with the pier columns according to the construction design, so that the out-of-plane stability constraint is increased.

When pouring is carried out, pouring is carried out from the place with the largest midspan disturbance degree, and then pouring is carried out from midspan symmetry to the pier stud side. The concrete construction organization is strengthened, the influence of later poured concrete on the first poured concrete caused by overlong pouring time is avoided, and the delayed coagulation of the later poured concrete is fully considered when the mix proportion of the concrete is designed. During pouring, special attention should be paid to setting up a maintenance test block under the same condition, and indexes such as strength, elastic modulus and the like of the concrete in the same period are tested.

Considering that the integrity and the shearing resistance of the web wood mold are poorer than those of a steel mold, the outer side mold and the bottom of the web are suggested to adopt the integral steel mold. The prestress construction of the reinforcing steel bars is carried out according to the construction organization design, and the prestress construction is not different from the conventional construction. Should the bellows installation quality carry out strict inspection before concrete placement, whether the inspection bellows has the damaged condition, whether spatial position sets up correctly, whether the ground tackle installation is correct. The contact of sharp objects such as iron parts and the like and the corrugated pipe is avoided in construction, and the pipeline is protected. During concrete pouring construction, the vibrating rod is prevented from contacting the corrugated pipe as far as possible, and meanwhile, the corrugated pipe at the web plate or the sawtooth plate is prevented from directly contacting the positioning reinforcing steel bars, so that the corrugated pipe is carefully constructed and carefully protected.

When pouring concrete, special attention should be paid to the implementation of measures for ensuring the concrete compactness of the reinforcing steel bar dense area at the anchoring position. When pouring, the concrete is prevented from directly impacting the pipeline and the positioning steel bars, and the pipeline is prevented from shifting.

After concrete pouring, the pipeline is flushed by high-pressure water in time, the drain hole is opened, slurry leakage liquid and other impurities possibly existing in the pipeline are flushed clean, and the pipeline is blown dry by high-pressure air.

The accuracy of the embedded position of the embedded part is comprehensively checked before the beam body is poured, the embedded elevation and the plane position are mainly well controlled, and whether the embedded part is fixed stably or not is carefully checked. When concrete is poured, the feed opening is required to avoid impact deflection on the embedded sensor.

Because the stress of the position of the embedded part is concentrated, special attention should be paid to ensure the compactness of the concrete during pouring. Special attention is paid to guarantee the construction performance of the concrete, the concrete has good fluidity, and the compactness of the concrete in a reinforcing steel bar dense area is guaranteed.

5.2.9 construction of permanent prestress of bridge:

after the concrete pouring is finished, the permanent prestress tensioning construction can be carried out after the design tensioning condition is reached.

Before the permanent prestress formal tensioning, a single-beam tensioning jack is adopted to adjust the beam one by one, and the beam adjusting tension is 10 percent sigma k. And (3) referring to a municipal engineering acceptance standard requirement prestress formal tensioning program: 0 → initial tension tonnage (10% sigma k) → 100% sigma k tension tonnage → holding the load for 5 minutes for anchoring, and other projects are executed according to corresponding design and acceptance standard requirements.

5.2.10 integral removal of the support platform

And after the beam construction is finished, adopting an integral dismantling method after the beam body tensioning grouting meets the design requirements. According to calculation and analysis, the lifting points are required to be arranged under the dead weight load, and holes are reserved on the bridge at the corresponding positions. The descending suspender adopts 32mm finish rolling twisted steel, and the diameter of the reserved hole is not less than the diameter of the connector.

When the integral dismantling method is used for dismantling the support platform, hoisting holes are formed in the top surface of a beam body which can bear the support platform after being tensioned, finish-rolled twisted steel bars are adopted, the crossing support platform such as a Bailey beam structure is hoisted, and the dead weight of the Bailey beam structure is converted into the beam body. After the lower supporting steel pipe column is dismantled, the whole spanning type support platform is gradually lowered to the ground by using finish rolling twisted steel to be dismantled, so that the high-position spanning type low-position safe and quick dismantling is realized.

In order to ensure that the hoisting loads of a plurality of hoisting points are basically consistent as much as possible, and the finish rolling threads are in a vertical state as much as possible and are not bent due to inconsistent hoisting of the hoisting points, the height difference of the hoisting points is controlled within 2cm, and the unbalanced condition is considered in calculation and analysis.

And the lowering is determined by adopting a jack according to the calculated single-point load, and the jack is selected according to 2 times of the hoisting load. When the lifting jack is lowered, the lower locking nut is rotated upwards to contract the jack cylinder and the lifting jack is lowered by the height of the stroke of the cylinder.

A hoisting state;

after the height of the oil cylinder is lowered, the lower nut is locked on the bridge floor, the stress is converted into the lower nut, and the Bailey beam is lowered for the second stage.

And at the moment, rotating the upper nut by one stroke height of the oil cylinder, extending the oil cylinder out, converting the stress to the upper nut, rotating the lower nut by one height of the oil cylinder, and lowering the Bailey beam to a third stage.

And (4) continuously lowering the Bailey beam according to the 1-3 stage circulation of lowering the oil cylinder.

Since the finish-rolled rebar is generally 9m long, the lowering of the rebar to a height greater than 9m cannot be continued. At the moment, the connected finish rolling twisted steel is required to be placed and installed well in the reserved conversion hole beside the hoisting hole, the lower nut is locked at the bridge floor at the anchoring position of the original jack, the jack is moved to the conversion hole, and the platform is continuously placed. And the process is circulated until the platform is lowered to the ground. The dismantling of the bracket system generally follows the principle of 'dismantling after first supporting and then dismantling after first supporting', and a special safe construction scheme is required to be compiled to ensure the construction safety.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims (7)

1. A Bailey beam bundle construction method for a cast-in-place platform of a high-pier small-radius curve ramp bridge is characterized by comprising the following steps of:

step one, arranging a bridge support system, calculating and analyzing to determine a construction scheme;

step two, arranging a spanning type platform according to the economic span, analyzing the temporary support structure by using Midas civil, and arranging a support platform;

thirdly, performing measurement paying-off according to the support axis of the steel pipe column arrangement of the plan view, determining the installation position of the steel pipe column, and performing measurement positioning on the bridge support system;

step four, constructing a steel pipe column and distribution and bracket support system through continuous structure side pier steel pipe column support construction and continuous structure middle pier bracket construction;

step five, calculating and analyzing, namely determining the number of the Bailey beams avoiding the pier stud position and the number of the horizontal connections increased under the condition of the overall torsion effect of the Bailey beams under the condition of uneven load, and constructing the Bailey beam bundle platform on the premise of maintaining the overall lateral torsion stability of the Bailey beam bundle main beam;

placing a transverse distribution beam on the Bailey beam, measuring a web side line on the transverse distribution beam, and marking; according to the cross section arrangement of the bowl buckle supports, the bowl buckle supports are erected from the web plate encryption position to two sides, and the adjacent arrangement distance of the cross section is changed when the bowl buckle supports exceed the web plate side line; the outer contour of the bowl buckle support, the web plate encrypted part and the non-encrypted section are arranged to form a saw-tooth shape;

step seven, carrying out a simulated load test, after the load reaches the standard, pouring from the place with the maximum cross center disturbance degree, and then pouring from the cross center to the pier column side; after the pouring is finished, adjusting the beam by adopting a single-beam tensioning jack one by one, and performing permanent prestress construction on the bridge, wherein the beam adjusting tension is 10% sigma k;

and step eight, adopting an integral dismantling method to dismantle the support platform.

2. The construction method for the Bailey beam bundle of the cast-in-place platform of the high-pier small-radius curve ramp bridge, according to claim 1, is characterized in that in the second step, the support platform arrangement specifically comprises: a spanning type platform is arranged according to the economic span, the single-layer Bailey beam is poured to form a span of 12-15 m, the steel pipe column is adopted by a spanning type support to support the Bailey beam, and an I-steel transverse distribution beam is arranged on the Bailey beam; then, erecting a WDJ bowl buckle support for slope adjustment; a transverse distribution square wood is arranged on the top of the WDJ bowl buckle support, a phi 48 multiplied by 3.5mm steel pipe is adopted above the square wood for longitudinal distribution or a steel plate is directly adopted, and a bamboo plywood is adopted on the square wood.

3. The construction method of the Bailey beam bundle of the cast-in-place platform of the high-pier small-radius curve ramp bridge, according to claim 1, is characterized in that in the fourth step, the support construction of the steel pipe column of the side pier with the continuous structure specifically comprises the following steps:

during construction of the steel pipe column foundation, a loose structure is removed from the surface of the rock, after the bearing capacity of the foundation is achieved, a reinforced concrete buttress mode is adopted, a strip foundation is adopted for a buttress, and the top surface of the foundation is leveled; burying culvert pipes in individual areas such as river channels, firstly filling, constructing bored piles by adopting an impact hole-forming mode, burying embedded parts at the tops of the piles, arranging transverse distribution beams, and placing steel pipe buttresses on the distribution beams;

the steel pipe columns are connected by flanges, and the parallel connection between the steel pipe columns is realized by bolts with fixed size;

when the steel pipe column is installed, a crane is adopted for hoisting, and the parallel connection construction is completed when the steel pipe column is installed to the parallel connection position; the top surface of the steel pipe column is provided with a parallel connection, and the distance between the parallel connection and the top of the steel pipe column is controlled to be 0.5 m; when the steel pipe column is installed close to the pier column, the steel pipe column is connected with the pier column.

4. The construction method of the Bailey beam bundle of the cast-in-place platform of the high-pier small-radius curve ramp bridge according to claim 1, wherein in the fourth step, the construction of the pier bracket in the continuous structure specifically comprises the following steps:

replacing the steel pipe column with a bracket supporting mode according to stress analysis except for opening the side pier; the bracket adopts a hoop and a prestressed pull rod mode to overcome horizontal tension, and the pin shaft resists a vertical shear mode:

(1) the embedded part adopts 32mm diameter finish rolling threads to resist the tension of the upper end of the bracket, the anchor ear and the concrete bear the tension together, and the shear force transmission of the outer bracket and the embedded part bracket is transmitted through a 100mm diameter pin shaft;

(2) the finish-rolled thread is anchored at the other end of the bridge pier, and the finish-rolled thread adopts a PSB 930-grade and standard matched prestressed anchor plate and nut;

(3) before and after installation of the phi 32 finish-rolled twisted steel, the phi 32 finish-rolled twisted steel needs to be protected to prevent the twisted steel from being damaged by electric welding, and the pre-limit tension of a single phi 32 finish-rolled twisted steel is 55 t; before the bracket is used, a single 25t pre-tightening force is applied to the finish rolling threads;

(4) the phi 100 steel bar needs to be quenched and tempered, the degree of finish is 6.3, and nondestructive inspection is needed after the completion; reserving phi 50 holes in phi 32 finish rolling twisted steel, reserving phi 102 holes in phi 100 steel bars, and keeping the hole depth at 600 mm;

(5) the phi 100 steel bar is made of 40Cr materials, the embedded part steel plate and the shear contact steel plate with the pin shaft steel plate are made of Q345B, and the other materials are Q235B materials;

(6) the groove weld joints are required to be completely melted, and the quality grade is two levels; drilling all holes by using a machine tool;

(7) the finish rolling thread is vertically stressed; when the pin shaft bears shearing force, the finish rolling thread is in a free tension state;

(8) the steel bar processing length meets the requirement that the spacing pin shaft has a 2cm gap with the bracket steel plate, and the steel bar contacts with the spacing pin shaft to be extruded.

5. The construction method of the Bailey beam bundle of the cast-in-place platform of the high-pier small-radius curve ramp bridge, according to claim 1, is characterized in that in the fifth step, the construction of the Bailey beam bundle platform specifically comprises the following steps:

hoisting the Bailey beam in place by using a crane; hoisting is carried out according to groups;

when the Bailey beams are vertically arranged, the Bailey beams are arranged into an upper layer and a lower layer which are adjacent.

6. The construction method for the Bailey beam bundle of the cast-in-place platform of the high-pier small-radius curve ramp bridge, according to claim 1, is characterized in that in the seventh step, the simulated load test specifically comprises the following steps:

(1) the support preloading is carried out in three stages, and loads are sequentially applied to 60%, 80% and 100% of the preloading value of the segment unit;

(2) when in pre-pressing loading, the transverse symmetrical loading is carried out along the midline;

(3) after each stage of loading is finished, monitoring the settlement amount of the support at intervals of 12 hours, and when the average value of settlement difference of the measurement points of the support for 2 continuous times is less than 2 mm;

(4) after the settlement of each point is loaded to 120%, the unloading is carried out once after the settlement average value of each point is less than 1mm or the settlement average value of each point is accumulated for 3 times continuously and less than 5mm, and the unloading adopts symmetrical, balanced and synchronous unloading.

7. The construction method for the Bailey beam bundle of the cast-in-place platform of the high-pier small-radius curve ramp bridge, according to claim 1, wherein in the eighth step, the integral removing method specifically comprises the following steps:

according to calculation and analysis, reserving holes on the bridge at corresponding positions at lifting points required to be arranged under the dead weight load; the lowering hanger rod adopts 32mm finish rolling twisted steel, and the diameter of the reserved hole is not less than that of the connector;

when the integral dismantling method is used for dismantling the support platform, hoisting holes are formed in the top surface of a beam body which can bear the support platform after being tensioned, finish-rolled twisted steel bars are adopted, the crossing support platform such as a Bailey beam structure is hoisted, and the dead weight of the Bailey beam structure is converted into the beam body;

after the lower supporting steel pipe column is dismantled, the whole spanning type support platform is gradually lowered to the ground by using finish rolling twisted steel to be dismantled, and high-position spanning type low-position safe and quick dismantling is realized.

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