Rapid cast-in-place process for T-shaped structure rotation prestressed concrete continuous box girder
By dividing the T-structure rotary prestressed concrete continuous box girder into multiple segments and synchronously constructing and prestressing tensioning, the problem of excessive construction period is solved, and the construction period is significantly shortened and construction costs are reduced.
Patent Information
- Application Number
- CN202510048603.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-13
- Publication Date
- 2025-03-21
AI Technical Summary
In the construction of T-structure rotary prestressed concrete continuous box beams, due to the prestressed tensioning of 10 days, the construction of the next section must wait for the previous section to be completed, resulting in serious idle work for personnel and mechanical work, which has delayed the construction period, especially when the railway "skylight time" is limited, the construction period is very limited.
A rapid cast-in-place process for T-structure rotary prestressed concrete continuous box beams is adopted. By dividing the box beams into multiple segments and retaining the post-casting strips between each segment, synchronous construction and prestressing tensioning between segments are achieved, and the construction period is shortened.
It effectively reduces the construction period, shortens the construction period by half, reduces construction costs, and reduces the impact on existing railway operations.
Smart Images
Figure CN119663753A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of bridge construction, and in particular to a rapid cast-in-place process for a T-structure swivel prestressed concrete continuous box girder. Background Art
[0002] In recent years, the construction of my country's transportation network has developed rapidly. In order to cross rivers or existing lines, bridge construction has increasingly adopted the form of rotation construction.
[0003] Refer to the attached Figure 1 . In the construction of T-structure rotating prestressed concrete continuous box girders, due to the 10-day concrete age requirement for prestressing, the construction of the latter section must be carried out after the tensioning of the previous section is completed, resulting in serious idleness of personnel and machinery, which prolongs the construction period. In particular, the construction of bridge rotation is restricted by the railway "window time". In order to minimize the impact of bridge rotation construction on railway operations, the construction period is very limited. Therefore, a cast-in-place construction process for prestressed concrete box girders with a short construction period and rapid construction is required. Summary of the invention
[0004] In order to overcome the deficiencies in the background technology, the present invention discloses a rapid cast-in-place process for a T-structure swivel prestressed concrete continuous box girder, the purpose of which is to shorten the construction period and quickly realize the cast-in-place construction of the prestressed concrete box girder.
[0005] In order to achieve the above-mentioned invention object, the present invention adopts the following technical scheme: A T-structure rotating prestressed concrete continuous box girder rapid casting process comprises the following steps: S1: Build the support and divide the box beam into 1 parts symmetrically with the middle support of the box beam as the center. # Segment, 2 # Segment, 3 # Segment, ..., N # Segment, then complete 1 # Erection and pouring of segmental formwork; S2: In 1 # Within the age of segmental concrete, complete 2 # The construction and pouring of the segmental formwork, including 1 # Segment and 2 # Keep a certain width of 1-2 between segments # Post-cast strip; S3:1 # After the segment concrete age is over, complete 1 # The longitudinal tensioning of the segmental prestressing is then completed simultaneously on both sides 1-2 # Pouring of post-cast strip; S4: In 1-2 #During the age of post-cast concrete, 3 # The construction and pouring of the segmental formwork, including # Segment and 3 # Keep a certain width of 2-3 between segments # Post-cast strip; S5: 1-2 # After the concrete age of the post-cast zone is over, complete 2 # The longitudinal tensioning of the segmental prestressing is then completed simultaneously on both sides 2-3 # Pouring of post-cast strip; S6: Repeat S4 and S5 until both sides are synchronized. # Longitudinal tensioning of segmental prestressing.
[0006] To further improve the technical solution, the width of the post-casting zone is 1-2m.
[0007] To further improve the technical solution, each segment was cast in two times, with the bottom plate and web plate cast in the first time and the top plate cast in the second time.
[0008] To further improve the technical solution, when the temperature is low at night, the post-casting strip is cast using the one-time casting method of C50 micro-expansive concrete.
[0009] To further improve the technical solution, before pouring the post-casting strip, the longitudinal steel bars at the post-casting strip should be overlapped according to the design drawings and relevant specifications, and the overlapped joints should be welded and reinforced. The single-sided welding length should not be less than 20d and the double-sided welding length should not be less than 10d.
[0010] To further improve the technical solution, before pouring the post-casting strip, check the connection status of the corrugated pipe joints one by one, and check whether the linear coordinates of the corrugated pipe meet the design requirements.
[0011] To further improve the technical solution, stress monitoring points are set at the post-casting zone to meet the requirements of tension stress detection.
[0012] To further improve the technical solution, the longitudinal tensioning process is: construction preparation → initial stress → control tensioning stress under anchor → hold load for 5 minutes → anchoring → unloading.
[0013] To further improve the technical solution, dual control measures are adopted for longitudinal tensioning: the stress control of the steel bundle is taken as the goal, and the elongation of the steel bundle is used as the verification. The actual elongation of the steel bundle is compared with the theoretical elongation value, and the error should be within ±6%.
[0014] To further improve the technical solution, after the longitudinal tensioning is completed, the vacuum grouting process is used for timely grouting when the stress is relatively stable. The strength of the cement slurry is not less than 50MPa, the water-cement ratio is between 0.4 and 0.45, the water seepage rate is 2 to 3%, and the cement slurry is completely absorbed within 24 hours.
[0015] After implementing the above technical solution, the beneficial effects produced by the present invention are: 1. The construction of the next section can be carried out simultaneously with the construction of the previous section, effectively reducing the phenomenon of idle work of personnel and machinery. Compared with the existing continuous box girder cast-in-place construction process, this construction process can shorten the construction period by half and greatly reduce the construction cost.
[0016] 2. This construction technology is particularly suitable for the construction of rotating bridges and has little impact on existing railway operations. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Attached Figure 1 Shown is a schematic diagram of the segmented construction of an existing prestressed concrete continuous box girder.
[0018] Attached Figure 2 What is shown is the schematic diagram of the segmented construction of the prestressed concrete continuous box girder.
[0019] Attached Figure 3 Shown is a schematic diagram of the construction process in step S1.
[0020] Attached Figure 4 Shown is a schematic diagram of the construction process in step S2.
[0021] Attached Figure 5 Shown is a schematic diagram of the construction process in step S3.
[0022] Attached Figure 6 Shown is a schematic diagram of the construction process in step S4.
[0023] Attached Figure 7 and attached Figure 8 Shown is a schematic diagram of the construction process in step S5.
[0024] In the attached figure: 1, 1 # Segment; 2, 2 # Segment; 3, 3 # Segment; 4, 1-2 # Post-casting strip; 5, 2-3 # Post-cast joint; 6. Middle support point; 7. Steel bundle. DETAILED DESCRIPTION
[0025] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. It should be noted that in the description of the present invention, the terms "front", "rear", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, which are only for the convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. It should also be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the internal connection of two elements. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.
[0026] In this embodiment, a T-structure rotating prestressed concrete continuous box girder needs to be erected above the railway. The span of the rotating part of the box girder is 2×60m. The box girder adopts a single-box four-chamber section. The beam height at the middle support of the box girder is 6.2m, the beam height at the side support is 3m, and the bottom line of the beam changes according to a 1.8-order parabola. The top plate of the box girder is 26.78m wide, the cantilever length on both sides is 3m, the cantilever plate end is 20cm thick, the root is 60cm thick, the top plate is 28cm thick, the bottom plate is 28-58cm, and the web plate is 70-90cm thick; the bottom plate of the box girder is kept horizontal, the cross slope of the bridge deck is adjusted by the height of the box girder web plate, the middle web plate is kept vertical during construction, and the beam end and the cross beam are kept plumb.
[0027] In order to shorten the construction period and quickly realize the cast-in-place construction of prestressed concrete box girders, the present invention provides a T-structure swivel prestressed concrete continuous box girder rapid cast-in-place process, which comprises the following steps: S1: Build the support and divide the box beam into 1 parts symmetrically with the middle support of the box beam as the center. # Segment, 2 # Segment, 3 # Segment, ..., N # Segment, then complete 1 # Erection and pouring of segmental formwork.
[0028] First, the foundation is treated. The support foundation is primed with a 50cm thick crushed stone cushion layer + 20cmC20 concrete. The foundation bearing capacity after the crushed stone replacement is not less than 120kPa. After the support is erected, the support is pre-stressed. The purpose of the support pre-stressing is to ensure the design line shape of the box girder and to avoid adverse effects on the box girder after foundation settlement. The pre-stressing method adopts pile loading pre-stressing. Before the pre-stressing construction, the load of the cast-in-place beam is calculated according to the design drawings, and then the support is pre-stressed with cement blocks with a weight of 1.1 times the total load. After the support pre-stressing is qualified, square wood or square steel is laid on the support, and the formwork is laid on it and the steel bars are tied. The specific steps are: install the bottom formwork → install the outer formwork → tie the bottom plate and web steel bars → install the corrugated pipe → install the inner formwork → install the end formwork → tie the top plate steel bars. After the template is laid and the steel bars are tied, 1 # Concrete pouring of sections.
[0029] Refer to the attached Figure 2 In this embodiment, the box beam is symmetrically divided into 1 # Segments 1 and 2 # Segments 2 and 3 # Segment 3.
[0030] Refer to the attached Figure 3 . 1 # Segment 1 is 30m long. It takes 7 days from laying the formwork, tying the steel bars to pouring the concrete. The pouring is carried out in two times. After the installation of the bottom web formwork and the tying of the steel bars, the bottom web is cast; after the installation of the top formwork and the tying of the steel bars, the top slab is cast. The pouring of the bottom web concrete should be carried out in a sloped layer along the cross section of the structure according to the height of the bottom plate and web of the box girder. The overall pouring sequence should be from 1 / 2 of each span to both ends in the longitudinal direction of the bridge, and from the center to the left and right sides in the transverse direction. The concrete should be poured in sections longitudinally and in layers horizontally.
[0031] S2: In 1 # Within the age of segment 1 concrete, complete 2 # The construction and pouring of the formwork for Section 2, including # Segments 1 and 2 # Keep a certain width of 1-2 between segments 2 # Post-cast strip 4.
[0032] Refer to the attached Figure 4 The concrete tensioning age control means that the prestressed steel strands can be tensioned only when the concrete strength reaches 95% of the design strength and the elastic modulus is not less than 95% of the 28-day elastic modulus of the concrete. # The age of the segmental concrete is 10 days. # The segment is the first to be poured, so it can be poured on the 18th day. # The segments are tensioned longitudinally.# The design length of each segment is 22m. # It takes 8 days from laying the formwork, tying the steel bars to pouring the concrete. During this free time, 2 # Erection and pouring of segmental formwork.
[0033] In build 2 # When using segment template, you need to # Segment and 2 # A certain width of post-casting strip is reserved between segments. # Segment and 2 # The post-casting strip between sections is 1-2 # Post-cast strip, 2 # Segment and 3 # The post-casting strip between sections is 2-3 # Post-cast strip. The width of the post-cast strip is generally 1-2m, which can provide construction workers with appropriate operating space for steel strand tensioning and grouting. In this embodiment, the width of the post-cast strip is 1.5m.
[0034] S3:1 # After the concrete age of segment 1 is over, complete 1 # The longitudinal tensioning of the prestressing of segment 1 is then completed simultaneously on both sides 1-2 # Pouring of post-cast strip 4.
[0035] Refer to the attached Figure 5 On the 18th day, insert the steel bundle 7 into the pre-buried corrugated pipe, and then # The segments are prestressed longitudinally. It is worth noting that the steel bundle 7 must be reserved with sufficient length to ensure the needs of longitudinal tensioning of the entire box girder. Longitudinal tensioning requires the use of special tensioning equipment and stress monitoring equipment to meet the prestressing design requirements of the box girder. Double control measures are taken during tensioning: the stress control of the steel bundle 7 is taken as the goal, and the elongation of the steel bundle 7 is used as a check. The actual elongation of the steel bundle is compared with the theoretical elongation value, and the error should be within ±6%. The tensioning process of the prestressed steel bundle is: construction preparation → initial stress (10% tensioning control stress) → tensioning stress control under the anchor → hold load for 5 minutes → anchoring → unloading. After the longitudinal prestressed steel bundle is tensioned, when the stress is relatively stable, the vacuum grouting process is used for timely grouting. The strength of the cement slurry is not less than 50MPa, the water-cement ratio is between 0.4 and 0.45, the water seepage rate is 2 to 3%, and the cement slurry is completely absorbed within 24 hours. After the tensioning is completed, the untensioned steel bundle 7 is inserted into 2 # The segments are embedded in the corrugated pipe.
[0036] Longitudinal tensioning and grouting can be completed on the same day, and 0-1 on both sides can be completed simultaneously on the 19th day. #Pouring of post-cast strips. Before pouring, the longitudinal reinforcement at the post-cast strips needs to be overlapped. The longitudinal reinforcement should be overlapped according to the design drawings and relevant specifications, and the overlap should be welded and reinforced. The single-sided welding length should not be less than 20d and the double-sided welding length should not be less than 10d. Before pouring, the connection of the corrugated pipe joints should be checked one by one, and the linear coordinates of the corrugated pipe should be checked to see if they meet the design requirements. The pouring process adopts the one-time pouring and molding method of C50 micro-expansion concrete. The pouring can be selected during the night when the temperature is lower. When pouring, pay attention to the synchronous and symmetrical pouring of both sides of the T structure to avoid concrete cracking.
[0037] S4: In 1-2 # During the period of 4 years of concrete pouring, 3 # The construction and pouring of the formwork for Section 3, including # Segments 2 and 3 # Keep a certain width of 2-3 between segments 3 # Post-cast strip 5.
[0038] Refer to the attached Figure 6 1-2 # The age of the post-cast concrete is 5 days, so it can only be repaired on the 25th day. # The segments are tensioned longitudinally. # The design length of each segment is 23m. # It takes 9 days from laying the formwork, tying the steel bars to pouring the concrete. During this free time, 3 # The construction and pouring of the segmental formwork. # When using segment template, you need to # Segment and 3 # A 1.5m post-cast joint is retained between sections.
[0039] S5: 1-2 # After the concrete age of post-cast zone 4 is over, complete 2 # The longitudinal tensioning of the prestressing of segment 2 is then completed simultaneously on both sides 2-3 # Pouring of post-cast strip 5.
[0040] Refer to the attached Figure 7 . Day 25, 2 # Segment and 1-2 # The age of the post-cast strip has ended, and the 2 # The longitudinal tensioning of the segment prestressing is then completed simultaneously on both sides 2-3 # Pouring of the post-cast strip.
[0041] S6: 2-3 # After the concrete age of the post-cast zone is over, the 3 # Longitudinal tensioning of segmental prestressing.
[0042] Refer to the attached Figure 8 . Wait 2-3 # After the 5-day age of the post-cast concrete, the 3 # Longitudinal tensioning and grouting of segmental prestressing.
[0043] 3 # After longitudinal tensioning and grouting, the segment forms a prestressed rotating box girder, and then the box girder rotation process is implemented: remove the support and temporary sand box (after the tensioning and grouting of the beam body are completed) → remove the temporary lock → clean up the construction site → weigh → counterweight → trial rotation → formal rotation.
[0044] Refer to the attached Figure 1 In the existing prestressed concrete continuous box girder cast-in-place process, 1 # Section 1 requires 7 days of construction, and then it will take until the 18th day to complete the construction of Section 1. # The segment is longitudinally tensioned; 2 # Section 2 requires 8 days of construction, and then it will take until the 37th day to complete Section 2. # The segment is longitudinally tensioned; 3 # Section 3 requires 9 days of construction, and then it will take until the 57th day to complete the construction of Section 3. # The segments are longitudinally tensioned.
[0045] Compared with the existing technology, this cast-in-place technology can make the construction of the next section proceed at the same time as the previous section, effectively reducing the phenomenon of idle workers and machinery. More importantly, the construction period of this cast-in-place technology only takes 31 days, which saves nearly half of the construction period compared with the existing technology.
[0046] It is worth noting that in this embodiment, the box beam is only symmetrically divided into three segments. For more segments, steps S4 and S5 can be repeated until the Nth segment is synchronously completed. # Longitudinal tensioning of segmental prestressing. For example, to divide the box girder into five segments symmetrically, in addition to the same S1-S5 steps, there are the following steps: S6: In 2-3 # During the age of post-cast concrete, 4 # The construction and pouring of the segmental formwork, including 3 # Segment and 4 # Keep a certain width of 3-4 between segments # Post-cast strip.
[0047] S7: 2-3 # After the concrete age of the post-cast zone is over, complete 3 # The longitudinal tensioning of the segmental prestressing is then completed simultaneously on both sides 3-4 # Pouring of the post-cast strip.
[0048] S8: At 3-4# During the age of post-cast concrete, 5 # The construction and pouring of the segmental formwork, including # Segment and 5 # Keep a certain width of 4-5 between segments # Post-cast strip.
[0049] S9: 3-4 # After the concrete age of the post-cast zone is over, complete 4 # The longitudinal tensioning of the segmental prestressing is then completed simultaneously on both sides 4-5 # Pouring of the post-cast strip.
[0050] S10: 4-5 # After the concrete age of the post-cast zone is over, 5 # Longitudinal tensioning of segmental prestressing.
[0051] From the above, it can be seen that the more segments the cast-in-place process is divided into, the more construction time it saves.
[0052] Although the embodiments of the present invention have been shown and described, it is understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention, and the protection scope of the present invention is defined by the attached claims and their equivalents.
Claims
1. A T-structured rotating prestressed concrete continuous box girder rapid casting process, characterized by: The following steps are involved: S1: Build the support and divide the box beam into 1 parts symmetrically with the middle support of the box beam as the center. # Segment, 2 # Segment, 3 # Segment, ..., N # Segment, then complete 1 # Erection and pouring of segmental formwork; S2: In 1 # Within the age of segmental concrete, complete 2 # The construction and pouring of the segmental formwork, including 1 # Segment and 2 # Keep a certain width of 1-2 between segments # Post-cast strip; S3:1 # After the segment concrete age is over, complete 1 # The longitudinal tensioning of the segmental prestressing is then completed simultaneously on both sides 1-2 # Pouring of post-cast strip; S4: In 1-2 # During the age of post-cast concrete, 3 # The construction and pouring of the segmental formwork, including # Segment and 3 # Keep a certain width of 2-3 between segments # Post-cast strip; S5: 1-2 # After the concrete age of the post-cast zone is over, complete 2 # The longitudinal tensioning of the segmental prestressing is then completed simultaneously on both sides 2-3 # Pouring of post-cast strip; S6: Repeat S4 and S5 until both sides are synchronized. # Longitudinal tensioning of segmental prestressing.
2. A T-shaped rotating prestressed concrete continuous box girder rapid casting process as claimed in claim 1, characterized in that: The width of the post-pouring strip is 1-2m.
3. A T-shaped rotating prestressed concrete continuous box girder rapid casting process as claimed in claim 1, characterized in that: Each section is cast in two times, the first time is to complete the casting of the bottom plate and the web plate, and the second time is to complete the casting of the top plate.
4. A T-shaped rotating prestressed concrete continuous box girder rapid casting process as claimed in claim 1, characterized in that: When the temperature is low at night, the post-casting joint is poured using the one-time pouring method of C50 micro-expansive concrete.
5. A T-shaped rotating prestressed concrete continuous box girder rapid casting process as claimed in claim 1, characterized in that: Before pouring the post-cast strip, the longitudinal steel bars at the post-cast strip should be overlapped according to the design drawings and relevant specifications, and the overlapped joints should be reinforced by welding. The single-sided welding length should not be less than 20d and the double-sided welding length should not be less than 10d.
6. A T-shaped rotating prestressed concrete continuous box girder rapid casting process as claimed in claim 1, characterized in that: Before pouring the post-casting strip, check the connection of the corrugated pipe joints one by one, and check whether the linear coordinates of the corrugated pipe meet the design requirements.
7. A T-shaped rotating prestressed concrete continuous box girder rapid casting process as claimed in claim 1, characterized in that: Stress monitoring points are set at the post-casting zone to meet the requirements of tensile stress detection.
8. The rapid cast-in-place process for a T-shaped rotating prestressed concrete continuous box girder according to claim 1 is characterized by: The longitudinal tensioning process is: construction preparation → initial stress → control tensioning stress under anchor → hold load for 5 minutes → anchoring → unloading.
9. A T-shaped rotating prestressed concrete continuous box girder rapid casting process as claimed in claim 1, characterized in that: Longitudinal tensioning adopts dual control measures: the stress control of the steel bundle is the goal, and the elongation of the steel bundle is used as a check. The actual elongation of the steel bundle is compared with the theoretical elongation value, and the error should be within ±6%.
10. The rapid cast-in-place process for a T-shaped rotating prestressed concrete continuous box girder according to claim 1, characterized in that: After the longitudinal tensioning is completed, vacuum grouting technology is used to timely grouting when the stress is relatively stable. The strength of cement slurry is not less than 50MPa, the water-cement ratio is between 0.4 and 0.45, the water seepage rate is 2 to 3%, and the cement slurry is completely absorbed within 24 hours.