CN116512417A - Industrial construction method and construction system for urban rail intersection thin-wall mixed-tensioning U-shaped beam - Google Patents

Abstract

The invention discloses an industrialized construction method and a construction system for urban rail intersection thin-wall mixed-tensioning U-shaped beams, wherein the construction of a U-shaped beam manufacturing pedestal and a beam storage tensioning pedestal is carried out in a field; the U-shaped beam steel bar cage is hung on a beam manufacturing pedestal through a hanging bracket; after the U-shaped beam reinforcement cage is in place, installing an embedded part, a U-shaped beam inner mold and a supporting system; optimizing the structure of the thin-wall mixed-tensioning U-shaped beam; pretensioned prestressing beam construction; casting beam body concrete; pretensioned prestressing bundles are put and cut; respectively hoisting two U-shaped beams to a beam storage tensioning pedestal by adopting a gantry crane; post-tensioning prestress beam construction; grouting and sealing the pore canal; and after the whole operation is finished, discharging quartz sand through a sand discharging hole of the steel sand box, so that the U-shaped beam is lowered onto a concrete base of the beam storage tensioning pedestal. The invention comprehensively and systematically solves the problems of large resource waste and low production efficiency in the prior art.

Description

Industrial construction method and construction system for urban rail intersection thin-wall mixed-tensioning U-shaped beam

Technical Field

The invention relates to the technical field of U-shaped beam production, in particular to an industrialized construction method and a construction system for urban rail intersection thin-wall mixed U-shaped beams.

Background

The prestressed concrete U-shaped beam has the technical characteristics of low building height, good noise reduction effect, high section space utilization rate, guaranteed driving safety, attractive appearance, good visual effect, low comprehensive manufacturing cost, easy maintenance of the whole structure and the like. However, the U-shaped beam is not applied in China at present, and the corresponding construction technology is not perfect.

The constant-section prefabricated U-shaped Liang Duowei pretensioned prestressed concrete structure is characterized in that prestressed steel bundles are stretched on a pedestal, concrete is poured, and prestress is built through adhesive force transmission. According to the structural design characteristics of the U-shaped beam, the constant-section U-shaped beam cannot meet the requirements of safe running of vehicles, cable bridge installation and attractive appearance in a small curve radius section, and the constant-section U-shaped beam is designed into a variable-section thin-wall mixed-open U-shaped beam. The variable cross-section thin-wall mixed-tensioned U-shaped beam is provided with prestress steel bundles except for the bottom plate area, and the bending prestress steel bundles are needed to be additionally arranged on the thin-wall areas on two sides. The technical characteristics of pretensioning prestressing construction are that the bending prestressing beam cannot be tensioned, and the post-tensioning construction is adopted after the concrete is poured and the strength required by the design is reached.

The two working areas of the Nanjing to sentence urban rail transit project DS6-TA02 are one-stop-one-interval, the adopted irregular complex appearance is a double-U-shaped variable cross section segmental beam, and the following problems can occur in the construction of the thin-wall mixed U-shaped beam:

1. the length of the U-shaped beam with the variable cross section between the adjacent cities is 26m, 28m, 30m and the like, and the cross section area of the prestress steel beam is 0.014 square meter by taking the U-shaped beam with the variable cross section of 5.21-5.41 as an example, the total number of the prestress steel beams is 102, the single prestress beams have different relaxation coefficients and different lengths, and the tension is time-consuming and labor-consuming, the overall tension stress is difficult to control and the like.

2. According to the established model simulation checking calculation, the post-tensioning prestress beam tensioning notch of the U-shaped beam is subjected to the largest stress, and concrete cracking is easy to occur.

3. The thin-wall mixed-tensioning U-shaped beam construction has 3 more working procedures than the standard section construction, and occupies long time for beam manufacturing pedestal and template, so that the engineering cost and the construction period are correspondingly increased.

Disclosure of Invention

The invention aims to: the invention aims to overcome the defects of the prior art, provides an industrialized construction method and a construction system for an urban rail cross-thin-wall mixed-tensioning U-shaped beam, solves the problems of difficult control of tensioning stress, easy structural damage, resource waste and the like in the production process of the thin-wall mixed-tensioning U-shaped beam, improves construction work efficiency and increases benefits.

The technical scheme is as follows: the invention relates to an industrialized construction method of an urban rail-to-thin wall mixed-tensioning U-shaped beam, which comprises the following steps:

s1, constructing a U-shaped beam manufacturing pedestal and a beam storage tensioning pedestal in a site, wherein the beam manufacturing pedestal supports 2U-shaped beams at one time, and a U-shaped beam bottom die, an outer die and a steam curing shed are synchronously installed during construction of the beam manufacturing pedestal;

s2, binding U-shaped beam steel bars on a U-shaped beam tire membrane frame and installing a prestress steel beam to obtain a U-shaped beam steel bar cage, and hanging the U-shaped beam steel bar cage onto a beam manufacturing pedestal by using a gantry crane through a hanging frame;

s3, installing an embedded part after the U-shaped beam reinforcement cage is in place, and positioning an inner die, an inner die support, an inner die moving system and an end die of the U-shaped beam;

s4: the method comprises the steps of optimizing the side wall structure of the thin-wall mixed-tensioned U-shaped beam, calculating the thickness of the side wall of the U-shaped beam according to the stress characteristics of the U-shaped beam with different spans, analyzing the stress of each part of the beam body, and reinforcing the area with the largest stress;

s5: the pretensioned prestress beam construction adopts a construction process of simultaneously tensioning two U-shaped beams, and the tensioning process flow is as follows: single end is initially adjusted to 15% sigma con, the whole is tensioned to 100% sigma con and kept under load for 3min sigma con anchoring, steam curing is adopted in construction, and the tensioning control stress is 0.7fpk+2 x At according to the actual temperature difference At between the steel bundle and the pedestal;

s6: pouring beam body concrete after the steel bar, the template and the prestress are checked and accepted;

s7: stretching and cutting the pretensioned prestressing beam, and stretching the pretensioned beam after the strength of the concrete reaches 85% and the elastic modulus reaches 90%;

s8, after the steel sand box is put into tension, two U-shaped beams are respectively hoisted to a beam storage tensioning pedestal by adopting a gantry crane, and at the moment, the beam storage tensioning pedestal is in a state of being jacked up by the steel sand box, and the steel sand box is stressed and continuous automatic spraying maintenance is carried out;

s9, post-tensioning prestressed bundle construction, wherein after the concrete strength reaches 95% of a design value, the elastic modulus reaches 100% of the design value and the age is not less than 7 days, the post-tensioning prestressed bundle construction is carried out, and two ends are synchronously tensioned, so that the tensioning process flow is as follows: 0 to 0.1 sigma con to 0.2 sigma con to tension control stress sigma con to hold the load for 5min anchoring;

s10, grouting a pore canal, sealing an anchor, performing pipeline vacuum auxiliary grouting within 48 hours after final pulling is completed, sealing a pretensioned sleeve by using epoxy mortar, and using C60 fine stone micro-expansion concrete for a rear Zhang Shufeng anchor;

s11, after the whole operation is completed, quartz sand is discharged through a sand unloading hole of the steel sand box, the U-shaped beam is lowered onto a concrete base of a beam storage tensioning pedestal, a stress point of the U-shaped beam is converted into a support position stress from an end part stress, and the U-shaped beam is transported to field erection after being stored for a specified time.

The technical scheme is further improved, the beam making pedestal in the step S1 comprises a pedestal foundation, reaction piers, tensioning beams, a dowel bar and a bottom die platform, wherein the bottom die platform is arranged at the top of the pedestal foundation, the tensioning beams are arranged at two sides of the bottom die platform, and the reaction piers are arranged at the outer sides of the tensioning beams; the reaction pier is internally connected with the pedestal foundation through pre-buried 600 multiplied by 300 multiplied by 20mm I-steel to form steel reinforced concrete, tensioning holes are reserved in the reaction pier, and 660 multiplied by 1360 multiplied by 20mm steel plates are arranged on two sides of each tensioning hole for reinforcement.

Further, the beam storage tensioning pedestal in the S1 comprises a concrete base and a steel sand box, wherein the steel sand box is arranged at the outer side corner of the concrete base and is connected with the concrete base through embedded bars; the steel sand box is internally provided with a base and quartz sand filled on the base, a top cover is supported above the quartz sand, and a sand unloading hole is formed in the middle of the steel sand box.

Further, in the step S4, according to the stress characteristics of the U-shaped beams with different spans, the side walls of the U-shaped beams are adopted to resist the centrifugal force generated by train operation, the thickness of the side walls is calculated by adopting a formula h= (FxSxVx 2)/127 g, wherein h is the thickness of the side walls, F is the tension control force, S is the span, V is the train operation speed, and g is the gravity acceleration; meanwhile, a designed checking model is established by adopting Midas civil, the stress on each part of the beam body is analyzed, a steel beam area with the largest stress is obtained, and the C12 screw-thread steel bars are used for manufacturing screw-thread steel bars and steel bar meshes for reinforcement.

Further, the S5 is to install anchor clamps on the fixed end of the pedestal one by one to anchor the prestress bundles, and the clamp piece is knocked by a sleeve of the propping clamping piece; installing connectors in the stretching end direction one by one and one by one, and screwing the two sleeves with a half-moon spanner and straightening the prestress beam; finally installing anchor clamps of the tensioning ends one by one; and 2 jacks of 30t are adopted for construction by tensioning, after all prestress bundles 2 are tensioned to 15% sigma con, the construction is carried out through 4 jacks of 600t, the counterforce pier is stressed at the moment, the stress sensor data are rechecked after the load is maintained for 3min by reinforcing reserved tensioning holes of the counterforce pier and embedding I-steel so as to meet the construction requirement, and if the prestress bundles are smaller than sigma con, the anchoring is carried out after the stress is controlled by the counterforce pier.

Further, the S7 sheet-releasing process: the two ends of the steel strand are synchronously put, the putting steps are 10% -10% -20%, the putting time interval of each step is 1 minute, after putting, the steel strand at the exposed part of the beam end is cut off by a manual abrasive wheel cutting machine, and the steel strand head outside the beam body is coated with an antirust material according to the design requirement.

Further, the whole construction process adopts informatization control and is divided into three flows of information acquisition, data processing and information output;

the information acquisition includes: according to different seasons, the parameters of the concrete mixing proportion are adjusted, the performance indexes of raw materials are checked, and the method can be put into production to meet the design requirements; before construction, controlling stress according to the single prestress beam obtained by acquisition, adjusting and optimizing tension controlling stress according to the pedestal and prestress beam temperature obtained by measurement, and judging whether tensioning is in place or not according to actual stress fed back by a stress collector in the tensioning process; collecting the increase condition of curing temperature, humidity and strength, and carrying out the next working procedure after the strength is met; monitoring data acquisition is carried out on the U-shaped beam after forming;

the data processing includes: establishing a standard database according to the design content of the concrete mixing proportion, the performance index of raw materials and the design standard of the prestress beam control stress, formulating a control index, carrying out data comparison through information acquisition in the construction process, and after meeting the related requirements, determining that the construction requirements are met and entering the next working procedure; the standard database is adjusted by collecting the monitoring data of the U-shaped beam after forming;

the information output includes: and after the construction is completed, files are independently built for each U-shaped beam, the files comprise materials, construction and monitoring, two-dimension codes are manufactured according to the file contents and are posted at the striking positions of the U-shaped beams, and the files are linked to the file contents.

The construction system for realizing the urban rail intersection thin-wall mixed-tensioning U-shaped beam industrialized construction method comprises the following steps: the system comprises a beam manufacturing pedestal for preparing the thin-wall mixed-tensioning U-shaped beam, a U-shaped beam template system, a steam curing shed, intelligent tensioning equipment and a beam storage tensioning pedestal for storing the thin-wall mixed-tensioning U-shaped beam;

the beam making pedestal comprises a pedestal foundation, a counter-force pier, a tensioning beam, a dowel bar and a bottom die platform, wherein the dowel bar is arranged in the middle of the pedestal foundation, the bottom die platform is arranged above the pedestal foundation and used for supporting the U-shaped beam template system, the tensioning beam is respectively arranged on two sides of the bottom die platform, intelligent tensioning equipment is arranged at the tensioning beam, the counter-force pier is arranged on the outer side of the tensioning beam, the counter-force pier is connected with the pedestal foundation through pre-buried I-steel to form steel reinforced concrete, tensioning holes are reserved in the counter-force pier, steel plates are arranged on two sides of each tensioning hole for reinforcement, and jacks are arranged on the outer side of the counter-force pier;

the beam storage tensioning pedestal comprises a concrete base and a steel sand box, wherein the steel sand box is arranged at the outer side corner of the concrete base and is connected with the concrete base through embedded bars, a base and quartz sand filled on the base are arranged in the steel sand box, a top cover is supported above the quartz sand, and a sand unloading hole is formed in the middle of the steel sand box.

The beneficial effects are that: compared with the prior art, the invention has the advantages that: 1. the girder manufacturing pedestal is transformed, the structure of the original counter-force pier is optimized aiming at the large control stress of the pretensioned prestressing bundles, the original counter-force pier is connected with a foundation through the embedded I-steel to form a steel reinforced concrete structure, the shearing force generated by prestress tensioning is resisted by the simultaneous stress of the steel reinforced concrete, the bending moment brought by the tensioning force is resisted by the I-steel, the stress performance of the girder manufacturing pedestal is further improved, the arrangement sliding of the pedestal can be reduced by the embedded I-steel, the friction force of the girder manufacturing pedestal is increased, and the safety is enhanced; the counterforce pier is reserved the pre-buried bolt hole of entrance to a cave and is added assembled steel sheet, has further promoted the crack resistance who reserves the entrance to a cave, has avoided the phenomenon such as counterforce pier that produces because of local atress destroys to take place, but also reuse of assembled steel sheet simultaneously, effectively reduces construction cost, and the generalizability is strong. The hydraulic steel template and the supporting system used by the invention can be adjusted and recycled according to different structures, thereby reducing the waste of resources and improving the production efficiency. The beam making pedestal used in the invention can produce two beams at one time, thereby improving the production efficiency. The post-tensioned prestressing beam construction is carried out on the beam-storing tensioning pedestal, so that the occupied time for the beam-making pedestal and the template can be reduced, and the construction period and the cost are saved.

2. The new design stores roof beam stretch-draw pedestal, original storing roof beam pedestal only has the roof beam function of depositing, in order to reduce system roof beam pedestal occupation time, reform transform the back to storing the roof beam pedestal, have the stretch-draw effect concurrently, according to mechanical analysis, stretch-draw both ends atress is the weak area, the fulcrum must be at the port, it need simulate the roof beam body and erect the back operating mode to deposit the roof beam, the fulcrum is in roof beam body support position, through steel sand box and former storing roof beam pedestal combination application, can effectively combine stretch-draw and support, the local dispersion of stretch-draw stress can be resisted to the steel sand box, successfully accomplish the atress conversion, reach anticipated construction target.

3. The design method for optimizing the thin-wall post-tensioned U-shaped beam is characterized in that through design rechecking of different spans and radiuses, the centrifugal force, the speed of the vehicle and other related factors are comprehensively considered, and a design formula about the thickness of the side wall of the U-shaped beam is deduced, so that the design application of other similar projects can be effectively guided. The thin-wall mixed-tensioning U-shaped beam used is used for reinforcing the tensioning weak area, and the tensioning crack of the beam body can be prevented.

4. The optimized U-shaped beam mixed tension construction method uses a single beam-after-integral construction process, firstly simulates a structure to obtain control stress of a single steel beam, selects a jack meeting the condition to tension 15% of the control stress of the single steel beam, eliminates looseness, then selects a mode of integral tension by the jack meeting the condition to tension to 100% of the control stress, meets the design requirement, and can efficiently and safely finish the construction of the thin-wall mixed tension U-shaped beam by adopting a construction method of steam maintenance and post-tensioning of a beam storage pedestal to reduce the beam manufacturing time

5. The whole construction process adopts informatization control and is divided into three flows of information acquisition, data processing and information output, so that the control level of the construction process is comprehensively mastered, and the quality of the construction process is ensured. According to the invention, the construction parameters are continuously optimized through informatization management and control measures, the whole construction process of the U-shaped beam is monitored, the level of the whole beam is improved, and the waste of invalid resources can be effectively reduced.

Drawings

Fig. 1: a U-beam steel beam cross-sectional view;

fig. 2: a longitudinal section view of the U-shaped beam steel beam;

fig. 3: stretching a notch reinforcing steel bar reinforcement diagram;

fig. 4: a beam making pedestal, a template system and a curing shed integral diagram;

fig. 5: a longitudinal section view of the beam making pedestal;

fig. 6: a connection schematic diagram of the dowel bar and the bottom die platform;

fig. 7: a counterforce pier cross section drawing;

fig. 8: a counterforce pier longitudinal section view;

fig. 9: a structural schematic diagram of the beam storage tensioning pedestal for supporting the U-shaped beam;

fig. 10: a plane view of a beam storage tensioning platform;

fig. 11: a cross section view (initial state) of the beam storage tensioning platform;

fig. 12: a section view of the beam storage tensioning platform (after sand unloading of the steel sand box);

fig. 13: model diagram of U-shaped Liang Yansuan;

fig. 14: a mixed tension prestress beam arrangement model diagram;

fig. 15: pretensioned prestressing beam connection diagram;

fig. 16: monitoring a point location layout;

fig. 17: informationized control flow chart.

Wherein: 1. thin-wall post-tensioned U-shaped beam; 2. pretensioning a pretensioned beam; 3. post-tensioning the pre-stress beam; 4. screw-thread steel bar; 5. a beam manufacturing pedestal; 6. a beam storage tensioning pedestal; 7. a pedestal base; 8. a reaction pier; 9. stretching the cross beam; 10. a dowel bar; 11. a bottom die platform; 12. stretching the hole; 13. a steel plate; 14. i-steel; 15. high-strength twisted steel; 16. a connector; 17. an intelligent tensioning device; 18. 600t jack; 19. a U-beam template system; 20. steam curing shed; 21. monitoring the point positions; 22. a concrete base; 23. a steel sand box; 24. a top cover; 25. quartz sand; 26. sand discharging holes; 27. a base; 28. and (5) embedding reinforcing steel bars.

Detailed Description

The technical scheme of the invention is described in detail below through the drawings, but the protection scope of the invention is not limited to the embodiments.

Example 1: the industrial construction method for the urban rail cross-wall mixed-tensioning U-shaped beam provided by the invention is used for producing a U-shaped beam structure shown in figure 1, and the thin-wall mixed-tensioning U-shaped beam 1 is designed with a pretensioned prestressing beam 2 and a post-tensioned prestressing beam 3. Referring to fig. 2, the post-tensioned prestressing beam 3 is a bending prestressing beam, and the bending amplitude is large. The U-shaped beam template system adopts an all-steel structure and an integral design scheme, and the whole template is composed of a bottom die, an outer die, an inner die support, an inner die moving system and an end die, and additionally comprises accessories such as an outer die diagonal bracing, an inner die diagonal bracing, a horizontal bracing, an outer die pull rod, an inner die pull rod and an outer die pull rod.

The invention provides an industrialized construction method of an urban rail-to-thin wall mixed-tensioning U-shaped beam, which comprises the following steps:

s1, constructing a beam manufacturing pedestal and a beam storage tensioning pedestal: and (3) leveling the field, and performing beam making pedestal and beam storage tensioning pedestal construction after the soft foundation is treated. And synchronously installing the U-shaped beam bottom die, the outer die diagonal braces, the pull rods between the outer dies and the steam curing shed during construction of the beam manufacturing pedestal, as shown in figure 4.

Referring to fig. 5 and 6, the beam-making pedestal is composed of a pedestal foundation 7, a reaction pier 8, a tensioning beam 9, a dowel bar 10 and a bottom die platform 11. The counter-force piers 8 are used as members directly bearing the tensioning force, and the strength and the rigidity must meet the tensioning requirement. Referring to fig. 7 and 8, 660×1360×20mm steel plates 13 are arranged on two sides of a reserved tensioning hole 12 for reinforcement, and 600×300×20 i-steel 14 is embedded in the counterforce pier 8 and connected with a pedestal foundation 7 to form steel reinforced concrete, so that the shearing resistance of the counterforce pier is effectively enhanced, and the stress safety is ensured.

Referring to fig. 9, a beam storage tensioning pedestal 6 supports both sides of the bottom end of the thin-walled hybrid U-beam 1. Referring to fig. 10, the beam storage tensioning mount 6 is composed of a concrete base 22 and a steel box 23. Referring to fig. 11, a steel flask 23 is connected to a concrete base 22 through pre-buried bars 28, and the steel flask 23 is composed of a top cover 24, quartz sand 25, a sand discharge hole 26 and a base 27. When quartz sand is discharged through the sand discharging holes of the steel sand box, the U-shaped beam is lowered to the beam storage tensioning pedestal to obtain a concrete base, and the stress point of the U-shaped beam is converted into the stress of the support seat position from the stress of the end part, as shown in fig. 12.

S2, processing U-shaped beam steel bars: and U-shaped beam steel bar binding and prestress steel beam installation are carried out on the special U-shaped beam tire membrane frame, and the U-shaped beam steel bar cage is hung to the beam manufacturing pedestal 5 by using the gantry crane through the hanging frame.

S3, after the U-shaped beam reinforcement cage is in place, installing an embedded part, a U-shaped beam inner die, an inner die support, an inner die moving system, a pull rod between the inner die and the outer die, an end die and the like.

S4, optimizing the structure of the thin-wall mixed-tensioning U-shaped beam: according to the stress characteristics of the U-shaped beams with different spans, the side walls of the U-shaped beams are adopted to resist the centrifugal force generated by train operation. According to the model diagram of U-shape Liang Yansuan shown in FIG. 13, the sidewall thickness can be calculated as h= (FxSxVx 2)/127 g, where h = sidewall thickness, F is the tension control force, S is the span, V is the train running speed, and g is the gravitational acceleration. Referring to fig. 1, a thin-wall hybrid U-beam 1 is designed with a pretensioned prestressing beam 2 and a post-tensioned prestressing beam 3, and referring to fig. 2, the post-tensioned prestressing beam 3 is a bending prestressing beam with large bending amplitude. Referring to the mixed tensile prestress beam layout model diagram of fig. 14, for 102 prestress beams, a design checking model is built through Midas civil, stresses on all parts of a beam body are analyzed, the fact that the stress on a post-conclusion tensile prestress steel beam area is the largest is obtained, and in order to prevent damage of the area, a spiral rib and a steel bar net are manufactured by adopting a C12 threaded steel bar 4 to strengthen the area, referring to fig. 3.

S5, pretensioned prestressing beam construction; with reference to fig. 15, the pretensioned prestressing tendons 2 are connected to the high-strength twisted steel 15 by connectors 16 using a construction process of simultaneously tensioning two trusses. The tensioning process flow is as follows: single end is initially adjusted to 15% sigma con, the whole body is tensioned to 100% sigma con, and the load is maintained for 3min, and sigma con anchoring is achieved. And (3) carrying out construction by adopting steam curing, wherein the tension control stress is 0.7fpk+2 At according to the actual temperature difference At between the steel bundle and the pedestal.

Firstly, installing anchor clamps on the fixed end of a pedestal one by one to anchor the prestress beam 2, and knocking the clamping piece by using a sleeve of a special jacking clamping piece; then installing connectors 15 in the stretching end direction one by one and one by one, and screwing the two sleeves with a half-moon spanner and straightening the prestress beam 2; and finally installing anchor clamps at the tensioning ends one by one. The tensioning of the individual pieces is carried out by adopting 2 jacks of 30t, and the purpose of the tensioning is to eliminate the original loose state of the prestressed bundle 2, and the tensioning beam 9 is stressed at the moment. After all the prestress bundles 2 are tensioned to 15% sigma con, 4 jacks 18 are controlled to construct through the intelligent tensioning equipment 17, the counterforce pier 8 is stressed at the moment, and the construction requirements can be met through reinforcement of the reserved hole 12 of the counterforce pier 8 and embedding of the I-steel 13. After the load is held for 3min, the stress sensor data is rechecked, and the anchoring is carried out after no error (if the load is smaller than sigma con, the anchoring is carried out after the tension is carried out until the stress is controlled).

S6, pouring concrete and curing: and pouring the beam body concrete after the steel bars, the templates and the prestress are checked and accepted. The casting adopts a method of oblique segmentation and horizontal layering, and the web plates are symmetrically and continuously cast from one end to the other end. Except for the inserted vibrator, an attached vibrator is added at intervals of 2m at the lower parts of the outer mold and the inner mold, the thin wall is vibrated to be compact by Zhang Ouyu, and after pouring is completed, a beam body is maintained by moving the steam curing shed 16 to a beam making pedestal through a steel rail. Beam monitoring points 21 are arranged at both sides and mid-span of the beam as shown in fig. 16.

S7, pretensioned prestressing beam tensioning and cutting: and after the strength of the concrete reaches 85% and the elastic modulus reaches 90%, the prestressed beam is stretched. The two ends are synchronously stretched, the stretching steps are 10% -10% -20%, and the stretching time interval of each step is 1 minute. After the steel strand is put, the exposed part of the beam end is cut off (symmetrically cut from two sides to the middle and from top to bottom) by a manual abrasive wheel cutter, and the steel strand head outside the beam body is coated with an antirust material according to the design requirement.

S8, beam moving: after the steel sand box is placed and tensioned, two U-shaped beams are respectively hoisted to the beam storage tensioning pedestal by adopting a gantry crane, and at the moment, the beam storage tensioning pedestal is in a state of being lifted up by the steel sand box, and the steel sand box is stressed and automatic spraying maintenance is continued.

S9, post-tensioning prestress beam construction: and after the strength of the concrete reaches 95% of the design value and the elastic modulus reaches 100% of the design value and the age is not less than 7 days, carrying out post-tensioning prestress beam construction, and synchronously tensioning the two ends. The tensioning process flow is as follows: 0- & gt 0.1 sigma con- & gt 0.2 sigma con- & gt tensioning control stress sigma con (containing anchor friction loss) & gt holding load for 5min anchoring.

S10, grouting and sealing an anchor hole: after the final drawing is completed, pipeline vacuum auxiliary grouting is carried out within 48 hours, epoxy mortar is adopted for end sealing of the pretensioned sleeve, and C60 fine stone micro-expansion concrete is adopted for the rear Zhang Shufeng anchor.

S11, after the whole operation is completed, quartz sand is discharged through a sand discharging hole of the steel sand box, the U-shaped beam is lowered onto a beam storage tensioning pedestal to obtain a concrete base, a stress point of the U-shaped beam is converted into a support position stress from an end stress, as shown in fig. 16, and the U-shaped beam is transported to field erection after being stored for a certain time.

The method comprehensively and systematically solves the problems of large resource waste and low production efficiency in the prior art by the beam making pedestal, the hydraulic template system, the steel bar processing jig frame and the steel bar hanging frame, and forms a set of urban rail intersection thin-wall mixed-tensioning U-shaped beam industrialized production method.

Example 2: the whole construction process adopts informatization control, and as shown in fig. 17, the method comprises three flows of information acquisition, data processing and information output. In the aspect of information acquisition, firstly, parameters of the mixing proportion are adjusted according to different seasons, the performance index of raw materials is checked, and the method can be put into production to meet the design requirement. And secondly, acquiring actual temperature difference between the steel bundles and the pedestal and actual control stress data of the single steel bundle before construction, adjusting and optimizing tension control stress, and judging whether the tension is in place or not according to the feedback of the actual stress of the stress acquisition device in the tensioning process. Thirdly, collecting the growth conditions of curing temperature, humidity and strength, and carrying out the next procedure after the strength is met. And fourthly, monitoring data acquisition is carried out on the U-shaped beam after forming, and main factors of difference generated by analyzing the monitoring data are analyzed. The four-aspect information is collected and summarized and then processed, firstly, the production information of the U-shaped beam can be comprehensively known in real time, secondly, the tensioning and maintenance levels of the U-shaped beam are improved through information optimization construction process control, and thirdly, basic data are reserved for erection, test running and operation of the subsequent U-shaped beam. By informatization control, the control of the tensile stress can be checked, the quality of concrete is improved, and the process interval time is reduced.

And (3) data processing: and (3) establishing a standard database according to the design content of the concrete mixing proportion, the test data of the raw materials and the design standard of the prestress beam control stress, and formulating a control index. And data comparison is carried out through information acquisition in the construction process, and after relevant requirements are met, the construction requirements can be considered to be met, and the next procedure is carried out. And the standard database is further adjusted by collecting the formed U-shaped beam monitoring data, so that the forming quality of the U-shaped beam is ensured.

And (3) information output: each U-shaped beam independently establishes files after construction is completed, and comprises three contents of materials, construction and monitoring, so that the whole process quality can be traced. According to the file content, each U-shaped beam is made to be two-dimensional codes and is posted at the striking position of the U-shaped beam, the two-dimensional codes are linked to the file content, and relevant information is known in time.

Example 3: the invention also provides a construction system for realizing the industrialized construction method of the urban rail intersection thin-wall mixed-tensioning U-shaped beam, which comprises the following steps: the system comprises a beam manufacturing pedestal for preparing the thin-wall mixed-tensioning U-shaped beam, a U-shaped beam template system, a steam curing shed, intelligent tensioning equipment and a beam storage tensioning pedestal for storing the thin-wall mixed-tensioning U-shaped beam;

the beam manufacturing pedestal comprises a pedestal foundation, counter-force piers, tensioning beams, a dowel bar and a bottom die platform, wherein the dowel bar is arranged in the middle of the pedestal foundation, the bottom die platform is arranged above the pedestal foundation and used for supporting a U-shaped beam template system, the tensioning beams are respectively arranged on two sides of the bottom die platform, intelligent tensioning equipment is arranged at the tensioning beams, the counter-force piers are arranged on the outer sides of the tensioning beams, the counter-force piers are connected with the pedestal foundation through pre-buried I-steel to form steel reinforced concrete, tensioning holes are reserved in the counter-force piers, steel plates are arranged on two sides of each tensioning hole for reinforcement, and jacks are arranged on the outer sides of the counter-force piers;

the beam storage tensioning pedestal comprises a concrete base and a steel sand box, wherein the steel sand box is arranged at the outer side corner of the concrete base, the steel sand box is connected with the concrete base through embedded bars, a base and quartz sand filled on the base are arranged in the steel sand box, a top cover is supported above the quartz sand, and a sand unloading hole is formed in the middle of the steel sand box.

As described above, although the present invention has been shown and described with reference to certain preferred embodiments, it is not to be construed as limiting the invention itself. Various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (8)

1. An industrialized construction method for urban rail intersection thin-wall mixed-tensioning U-shaped beams is characterized by comprising the following steps:

s1, constructing a U-shaped beam manufacturing pedestal and a beam storage tensioning pedestal in a site, wherein the beam manufacturing pedestal supports 2U-shaped beams at one time, and a U-shaped beam bottom die, an outer die and a steam curing shed are synchronously installed during construction of the beam manufacturing pedestal;

s2, binding U-shaped beam steel bars on a U-shaped beam tire membrane frame and installing a prestress steel beam to obtain a U-shaped beam steel bar cage, and hanging the U-shaped beam steel bar cage onto a beam manufacturing pedestal by using a gantry crane through a hanging frame;

s3, installing an embedded part after the U-shaped beam reinforcement cage is in place, and positioning an inner die, an inner die support, an inner die moving system and an end die of the U-shaped beam;

s4: the method comprises the steps of optimizing the side wall structure of the thin-wall mixed-tensioned U-shaped beam, calculating the thickness of the side wall of the U-shaped beam according to the stress characteristics of the U-shaped beam with different spans, analyzing the stress of each part of the beam body, and reinforcing the area with the largest stress;

s5: the pretensioned prestress beam construction adopts a construction process of simultaneously tensioning two U-shaped beams, and the tensioning process flow is as follows: single end is initially adjusted to 15% sigma con, the whole is tensioned to 100% sigma con and kept under load for 3min sigma con anchoring, steam curing is adopted in construction, and the tensioning control stress is 0.7fpk+2 x At according to the actual temperature difference At between the steel bundle and the pedestal;

s6: pouring beam body concrete after the steel bar, the template and the prestress are checked and accepted;

s7: stretching and cutting the pretensioned prestressing beam, and stretching the pretensioned beam after the strength of the concrete reaches 85% and the elastic modulus reaches 90%;

s8, after the steel sand box is put into tension, two U-shaped beams are respectively hoisted to a beam storage tensioning pedestal by adopting a gantry crane, and at the moment, the beam storage tensioning pedestal is in a state of being jacked up by the steel sand box, and the steel sand box is stressed and continuous automatic spraying maintenance is carried out;

s9, post-tensioning prestressed bundle construction, wherein after the concrete strength reaches 95% of a design value, the elastic modulus reaches 100% of the design value and the age is not less than 7 days, the post-tensioning prestressed bundle construction is carried out, and two ends are synchronously tensioned, so that the tensioning process flow is as follows: 0 to 0.1 sigma con to 0.2 sigma con to tension control stress sigma con to hold the load for 5min anchoring;

s10, grouting a pore canal, sealing an anchor, performing pipeline vacuum auxiliary grouting within 48 hours after final pulling is completed, sealing a pretensioned sleeve by using epoxy mortar, and using C60 fine stone micro-expansion concrete for a rear Zhang Shufeng anchor;

s11, after the whole operation is completed, quartz sand is discharged through a sand unloading hole of the steel sand box, the U-shaped beam is lowered onto a concrete base of a beam storage tensioning pedestal, a stress point of the U-shaped beam is converted into a support position stress from an end part stress, and the U-shaped beam is transported to field erection after being stored for a specified time.

2. The urban rail transit thin-wall mixed-tensioning U-shaped beam industrialized construction method according to claim 1, which is characterized in that: the beam making pedestal in the step S1 comprises a pedestal foundation, reaction piers, tensioning beams, a dowel bar and a bottom die platform, wherein the bottom die platform is arranged at the top of the pedestal foundation, the tensioning beams are arranged at two sides of the bottom die platform, and the reaction piers are arranged at the outer sides of the tensioning beams; the reaction pier is internally connected with the pedestal foundation through pre-buried 600 multiplied by 300 multiplied by 20mm I-steel to form steel reinforced concrete, tensioning holes are reserved in the reaction pier, and 660 multiplied by 1360 multiplied by 20mm steel plates are arranged on two sides of each tensioning hole for reinforcement.

3. The urban rail transit thin-wall mixed-tensioning U-shaped beam industrialized construction method according to claim 1, which is characterized in that: the beam storage tensioning pedestal in the S1 comprises a concrete base and a steel sand box, wherein the steel sand box is arranged at the outer side corner of the concrete base and is connected with the concrete base through embedded bars; the steel sand box is internally provided with a base and quartz sand filled on the base, a top cover is supported above the quartz sand, and a sand unloading hole is formed in the middle of the steel sand box.

4. The urban rail transit thin-wall mixed-tensioning U-shaped beam industrialized construction method according to claim 1, which is characterized in that: according to the stress characteristics of U-shaped beams with different spans, the U-shaped beam side walls are adopted to resist centrifugal force generated by train operation, the thickness of the side walls is calculated by adopting a formula h= (FxSxV2)/127 g, wherein h is the thickness of the side walls, F is tensioning control force, S is the span, V is train operation speed, and g is gravity acceleration; meanwhile, a designed checking model is established by adopting Midas civil, the stress on each part of the beam body is analyzed, a steel beam area with the largest stress is obtained, and the C12 screw-thread steel bars are used for manufacturing screw-thread steel bars and steel bar meshes for reinforcement.

5. The urban rail transit thin-wall mixed-tensioning U-shaped beam industrialized construction method according to claim 1, which is characterized in that: s5, firstly, installing anchor clamps on the fixed end of the pedestal one by one to anchor the prestress beam, and knocking the clamping piece by using a sleeve of the pushing clamping piece; installing connectors in the stretching end direction one by one and one by one, and screwing the two sleeves with a half-moon spanner and straightening the prestress beam; finally installing anchor clamps of the tensioning ends one by one; and 2 jacks of 30t are adopted for construction by tensioning, after all prestress bundles 2 are tensioned to 15% sigma con, the construction is carried out through 4 jacks of 600t, the counterforce pier is stressed at the moment, the stress sensor data are rechecked after the load is maintained for 3min by reinforcing reserved tensioning holes of the counterforce pier and embedding I-steel so as to meet the construction requirement, and if the prestress bundles are smaller than sigma con, the anchoring is carried out after the stress is controlled by the counterforce pier.

6. The urban rail transit thin-wall mixed-tensioning U-shaped beam industrialized construction method according to claim 1, which is characterized in that: the S7 sheet releasing process comprises the following steps: the two ends of the steel strand are synchronously put, the putting steps are 10% -10% -20%, the putting time interval of each step is 1 minute, after putting, the steel strand at the exposed part of the beam end is cut off by a manual abrasive wheel cutting machine, and the steel strand head outside the beam body is coated with an antirust material according to the design requirement.

7. The urban rail transit thin-wall mixed-tensioning U-shaped beam industrialized construction method according to claim 1, which is characterized in that: the whole construction process adopts informatization control and is divided into three flows of information acquisition, data processing and information output;

the information acquisition includes: according to different seasons, the parameters of the concrete mixing proportion are adjusted, the performance indexes of raw materials are checked, and the method can be put into production to meet the design requirements; before construction, controlling stress according to the single prestress beam obtained by acquisition, adjusting and optimizing tension controlling stress according to the pedestal and prestress beam temperature obtained by measurement, and judging whether tensioning is in place or not according to actual stress fed back by a stress collector in the tensioning process; collecting the increase condition of curing temperature, humidity and strength, and carrying out the next working procedure after the strength is met; monitoring data acquisition is carried out on the U-shaped beam after forming;

the data processing includes: establishing a standard database according to the design content of the concrete mixing proportion, the performance index of raw materials and the design standard of the prestress beam control stress, formulating a control index, carrying out data comparison through information acquisition in the construction process, and after meeting the related requirements, determining that the construction requirements are met and entering the next working procedure; the standard database is adjusted by collecting the monitoring data of the U-shaped beam after forming;

the information output includes: and after the construction is completed, files are independently built for each U-shaped beam, the files comprise materials, construction and monitoring, two-dimension codes are manufactured according to the file contents and are posted at the striking positions of the U-shaped beams, and the files are linked to the file contents.

8. The construction system for realizing the urban rail intersection thin-wall mixed-tensioning U-shaped beam industrialized construction method is characterized by comprising the following steps: the system comprises a beam manufacturing pedestal for preparing the thin-wall mixed-tensioning U-shaped beam, a U-shaped beam template system, a steam curing shed, intelligent tensioning equipment and a beam storage tensioning pedestal for storing the thin-wall mixed-tensioning U-shaped beam;

the beam making pedestal comprises a pedestal foundation, a counter-force pier, a tensioning beam, a dowel bar and a bottom die platform, wherein the dowel bar is arranged in the middle of the pedestal foundation, the bottom die platform is arranged above the pedestal foundation and used for supporting the U-shaped beam template system, the tensioning beam is respectively arranged on two sides of the bottom die platform, intelligent tensioning equipment is arranged at the tensioning beam, the counter-force pier is arranged on the outer side of the tensioning beam, the counter-force pier is connected with the pedestal foundation through pre-buried I-steel to form steel reinforced concrete, tensioning holes are reserved in the counter-force pier, steel plates are arranged on two sides of each tensioning hole for reinforcement, and jacks are arranged on the outer side of the counter-force pier;

the beam storage tensioning pedestal comprises a concrete base and a steel sand box, wherein the steel sand box is arranged at the outer side corner of the concrete base and is connected with the concrete base through embedded bars, a base and quartz sand filled on the base are arranged in the steel sand box, a top cover is supported above the quartz sand, and a sand unloading hole is formed in the middle of the steel sand box.