High-speed railway pier cap prefabricated installation and cast-in-place structure and construction method

Abstract

The invention provides a high-speed railway pier cap prefabricated installation and cast-in-place structure and a construction method, the high-speed railway pier cap prefabricated installation and cast-in-place structure comprises a first edge cover plate, a second edge cover plate and a plurality of middle cover plates which form a cover plate whole body, and the surface of the cover plate whole body is provided with a manhole; i-shaped steel is poured in the first edge cover plate, the second edge cover plate and the multiple middle cover plates, the I-shaped steel extends to the outer portion of the whole cover plate and is used for being in lap joint with the pier body, a cast-in-place mounting notch is formed in the top end of the hollow section of the pier body, and the cast-in-place mounting notch is matched with the I-shaped steel. According to the method, the concrete prefabricated cover plate is adopted to replace the in-pier support, the high-altitude operation risk during mounting and dismounting of the in-pier support is eliminated, and the safety of pier body construction is greatly improved; the construction period of each hollow pier can be shortened by 2 days; the cover plate is prefabricated by blocks and is convenient and fast to mount; the concrete pouring of the solid section has no mold explosion risk; costs of different processes are compared and researched, and a foundation is laid for application expansion.

Description

Technical Field

[0001] The present invention relates to the technical field of the capping of hollow piers, and specifically to a precast installation and cast-in-place structure and construction method for the pier cap of high-speed railways. Background Technique

[0002] In recent years, with the development of new bridge construction technologies, the thin-walled hollow pier technology has been increasingly widely used. Among them, the capping construction of hollow piers is a relatively difficult link in the construction of the lower part of the bridge. Most domestic capping constructions of hollow piers adopt full hall scaffolding inside the pier or the construction of installing bracket supports. When constructing with full hall scaffolding inside the pier, after the erection is completed, the support needs to be preloaded. After the construction is completed, materials can only be transported through a 0.8m×0.8m reserved hole at the pier top, and the construction period is relatively long; when constructing with bracket supports installed, steel plates are embedded at the lower part of the chamfer on the pier body, I-shaped steel bracket supports are welded, channels and square timbers are erected on them, and then formwork is laid. Compared with the full hall scaffolding construction method, it has obvious advantages, but this construction method also has the following three problems. First, installing brackets on the pier body changes the structural design of the pier, and its stress condition changes, and it is necessary to communicate with the design institute and draw additional drawings. Second, the amount of embedded materials is large and the welding construction amount is large, and the demolition difficulty of the entire system is also relatively large after the construction is completed. Third, when the brackets are demolished, the construction personnel work at high altitude, and the safety risk is extremely high.

[0003] In view of the above pain points, in order to completely eliminate the safety hazards existing in the installation and demolition of scaffolding and brackets inside the pier, to further consolidate the foundation of work safety and build a solid line of defense for work safety, a precast installation and cast-in-place structure and construction method for the pier cap of high-speed railways are proposed, using precast concrete covers to replace the traditional construction processes of scaffolding inside the pier or installing brackets, and reducing the high-altitude operation risk in the construction of hollow piers. Summary of the Invention

[0004] To achieve the above objectives, the present invention is realized through the following technical solutions: A precast installation and cast-in-place structure for the pier cap of high-speed railways includes a first edge cover, a second edge cover and a plurality of middle covers, forming an overall cover. An access hole is provided on the surface of the overall cover. I-shaped steel is poured inside the first edge cover, the second edge cover and the plurality of middle covers. The I-shaped steel extends outside the overall cover for lapping with the pier body. A cast-in-place installation notch is provided at the top of the hollow section of the pier body. The cast-in-place installation notch matches the I-shaped steel. Hoisting rings are provided at both ends of the surface of the I-shaped steel. The hoisting rings extend outside the cover for hoisting.

[0005] Preferably, the thickness of the overall cover is 20 cm, and the overall cover is poured with C30 concrete.

[0006] A precast installation and cast-in-place construction method for the pier cap of high-speed railways includes the following specific operation steps:

[0007] S1. Fabricate a fixed - mold for the cover plate according to the required dimensions of the high - speed railway pier cap by binding steel bars.

[0008] S2. Install I - beams inside the fixed - mold, and ensure that the spacing of the I - beams does not affect the setting of the access hole.

[0009] S3. The cover plate is integrally cast with C30 concrete. During casting, use a plate vibrator to vibrate it densely. At the same time, make concrete test blocks to test the cube compressive strength of the concrete at 28 - day age and evaluate the quality of the concrete.

[0010] S4. Before pouring the concrete at the top of the hollow section of the pier shaft, reserve a cast - in - place installation notch for the cover plate, and then carry out the pouring.

[0011] S5. After removing the inner mold of the cast - in - place installation notch, roughen the concrete inside the cast - in - place installation notch. After roughening, hoist and install the precast cover plate in sections into the cast - in - place installation notch. The gap between the cover plate and the pier shaft and the entire cast - in - place installation notch are backfilled densely with the same - grade concrete as the pier shaft to prevent slurry leakage during the casting of the top - cap concrete.

[0012] Preferably, after the concrete strength at the chamfering part poured in S4 reaches 75% of the design strength, hoist and place the precast cover plate at the chamfering part on the pier shaft through the lifting ring.

[0013] Preferably, the spacing of the I - beams is consistent with the cast - in - place installation notch, and the width of the reserved cast - in - place installation notch shall not be greater than the designed spacing of the I - beams.

[0014] Preferably, in S3, after the cover plate is poured, it is covered and watered for curing in time.

[0015] The present invention provides a precast, installed and cast - in - place structure for a high - speed railway pier cap and a construction method, which has the following beneficial effects:

[0016] The present invention uses a concrete precast cover plate to replace the internal support of the pier, eliminating the risk of high - altitude operation for the installation and removal of the internal support of the pier, greatly improving the safety of pier - shaft construction; the construction period of each hollow pier can be shortened by 2 days; the cover plate is precast in sections, which is convenient and fast for installation; there is no risk of form explosion during the casting of the solid - section concrete; the costs of different processes are compared and studied, laying a foundation for expanding the application. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is the overall front layout diagram of Embodiment 1 in the present invention;

[0018] Figure 2 It is the overall side layout diagram of Embodiment 1 in the present invention;

[0019] Figure 3 It is the overall top - view diagram of the cover plate in Embodiment 1 in the present invention;

[0020] Figure 4 It is the overall split view of the cover plate in Embodiment 1 of the present invention;

[0021] Figure 5 It is the overall schematic diagram of the I-beam in Embodiment 1 of the present invention;

[0022] Figure 6 It is the overall front layout diagram in Embodiment 2 of the present invention;

[0023] Figure 7 It is the overall side layout diagram in Embodiment 2 of the present invention;

[0024] Figure 8 It is the overall top view of the cover plate in Embodiment 2 of the present invention;

[0025] Figure 9 It is the overall split view of the cover plate in Embodiment 2 of the present invention;

[0026] Figure 10 It is the overall schematic diagram of the I-beam in Embodiment 2 of the present invention.

[0027] Among them, 1, pier body; 2, cover plate; 21, first edge cover plate; 22, second edge cover plate; 23, middle cover plate; 24, access hole; 3, I-beam; 4, lifting ring; 5, cast-in-place installation notch. Specific embodiments

[0028] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0029] Taking the design of the hollow pier of Qingtian Special Bridge as an example, there are two types of designed pier heights for the hollow pier of Qingtian Special Bridge, which are 20m - 30m and 30m - 40m respectively. The concrete grade of the precast concrete cover plate is C35. The reserved notch is 15cm * 10cm, and the steel bar spacing at the reserved notch position is consistent with the design (15cm). The reserved notch is cast together with the pier top concrete during construction.

[0030] Embodiment 1:

[0031] As Figures 1 - 5As shown, a prefabricated installation and cast-in-place structure of a high-speed railway pier cap with a pier height of 20-30m comprises a first edge cover plate 21, a second edge cover plate 22 and a middle cover plate 23, forming a cover plate 2 as a whole, a manhole 24 is provided on the surface of the cover plate 2 as a whole, the manhole 24 is located between the second edge cover plate 22 and the middle cover plate 23, the insides of the first edge cover plate 21, the second edge cover plate 22 and the middle cover plate 23 are all cast with I-beams 3, the I-beams 3 extend to the outside of the cover plate 2 as a whole, for overlapping with the pier body 1, a cast-in-place installation groove 5 is provided at the top of the hollow section of the pier body 1, the cast-in-place installation groove 5 matches the I-beam 3, the overall thickness of the cover plate 2 is 20cm, the cover plate 2 is cast as a whole with C30 concrete, both ends of the surface of the I-beam 3 are provided with lifting rings 4, the lifting rings 4 extend to the outside of the cover plate 2 for lifting.

[0032] A high-speed railway pier cap prefabrication installation and cast-in-place construction method includes the following specific operation steps:

[0033] S1, according to the required size of the high-speed railway pier cap, steel bars are tied to produce a shaping mold for the cover plate 2;

[0034] S2, install the I-beam 3 inside the shaping mold, and ensure that the spacing of the I-beam 3 does not affect the setting of the entrance hole 24;

[0035] S3 and cover plate 2 are cast as a whole with C30 concrete. A flat vibrator is used to compact the concrete during casting. At the same time, concrete test blocks are made to test the cubic compressive strength of the concrete at 28 days of age and evaluate the quality of the concrete. After the casting of cover plate 2 in S3 is completed, it is promptly covered and watered for curing.

[0036] S4, before pouring concrete at the top of the hollow section of the pier body 1, reserve a cast-in-place installation notch 5 for the cover plate 2, and then pour. Figure 2 ) After the concrete strength reaches 75% of the design strength, the prefabricated cover plate 2 is hoisted through the lifting ring 4 and placed on the chamfer of the pier body 1. The spacing of the I-beams 3 is consistent with the cast-in-place installation grooves 5, and the width of the reserved cast-in-place installation grooves 5 shall not be greater than the designed spacing of the I-beams 3.

[0037] S5. After removing the inner mold of the cast-in-place installation slot 5, the concrete in the cast-in-place installation slot 5 is roughened to make the connection tighter. After roughening, the prefabricated cover plate 2 is hoisted in blocks and installed in the cast-in-place installation slot 5. The gap between the cover plate 2 and the pier body 1 and the cast-in-place installation slot 5 are all backfilled with concrete of the same grade as the pier body 1 to avoid leakage during the pouring of the top cap concrete.

[0038] Embodiment 2:

[0039] like Figures 6 - 10As shown in the figure, the precast installation and cast-in-place structure of the pier cap for high-speed railways with a pier height of 30 - 40m includes a first edge cover plate 21, a second edge cover plate 23, and two middle cover plates 22, forming the overall cover plate 2. An access hole 24 is provided on the surface of the overall cover plate 2. The access hole 24 is located on the middle cover plate 23 close to the second edge cover plate 22. I-beams 3 are poured inside the first edge cover plate 21, the second edge cover plate 22, and the two middle cover plates 23. The I-beams 3 extend outside the overall cover plate 2 for lapping with the pier body 1. A cast-in-place installation notch 5 is provided at the top of the hollow section of the pier body 1. The cast-in-place installation notch 5 matches the I-beams 3. The thickness of the overall cover plate 2 is 20 cm. The overall cover plate 2 is cast with C30 concrete. Hoisting rings 4 are provided at both ends of the surface of the I-beams 3. The hoisting rings 4 extend outside the cover plate 2 for hoisting.

[0040] A construction method for precast installation and cast-in-place of high-speed railway pier caps includes the following specific operation steps:

[0041] S1. According to the dimensions of the high-speed railway pier cap required, bind steel bars to make a sizing mold for the cover plate 2;

[0042] S2. Install the I-beams 3 inside the sizing mold and ensure that the spacing of the I-beams 3 does not affect the setting of the access hole 24;

[0043] S3. The overall cover plate 2 is cast with C30 concrete. During casting, a plate vibrator is used to vibrate it compactly. At the same time, concrete test blocks are made to test the cube compressive strength of the concrete at 28 days of age and evaluate the quality of the concrete. After the cover plate 2 is cast in S3, it is covered and watered for curing in time.

[0044] S4. Before pouring the concrete at the top of the hollow section of the pier body 1, reserve the cast-in-place installation notch 5 for the cover plate 2 and then pour. After the concrete strength at the chamfer (such as Figure 7 ) reaches 75% of the design strength in S4, the precast cover plate 2 is hoisted and placed at the chamfer on the pier body 1 through the hoisting rings 4. The spacing of the I-beams 3 is consistent with the cast-in-place installation notch 5, and the width of the reserved cast-in-place installation notch 5 shall not be greater than the spacing of the designed I-beams 3.

[0045] S5. After removing the inner mold of the cast-in-place installation notch 5, roughen the concrete inside the cast-in-place installation notch 5 to make the connection more compact. After roughening, hoist and install the precast cover plate 2 in sections into the cast-in-place installation notch 5. The gaps between the cover plate 2 and the pier body 1 and the entire cast-in-place installation notch 5 are backfilled and compacted with the same grade of concrete as the pier body. Avoid slurry leakage during the casting of the top cap concrete.

[0046] In summary, the structure and method of the present invention innovatively apply precast concrete cover plates to replace the in-pier support operation, completely eliminating the risk of high-altitude operation for installing and dismantling supports inside the pier, accelerating the construction progress of bridge hollow piers, saving construction costs. There are a total of 116 bridge hollow piers in Section 7 of the Yunnan-Guizhou section of the Yukun High-Speed Railway, and all of them are constructed using this process. As of now, 103 hollow piers have been constructed. Through the comparative analysis of economic benefits with the traditional process, each pier construction can save approximately 2,400 yuan in costs, and the cumulative value of cost savings is approximately 247,200 yuan.

[0047] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-speed railway pier cap prefabrication installation and cast-in-place structure, characterized by: It includes a first edge cover plate, a second edge cover plate and multiple middle cover plates to form a cover plate as a whole. An entry hole is opened on the surface of the cover plate as a whole. The first edge cover plate, the second edge cover plate and multiple middle cover plates are all cast with I-beams inside. The I-beams extend to the outside of the cover plate as a whole and are used to overlap with the pier body. The top of the hollow section of the pier body is provided with a cast-in-place installation groove, which matches the I-beam. Both ends of the surface of the I-beam are provided with lifting rings, which extend to the outside of the cover plate for lifting.

2. The high-speed railway pier cap prefabrication and cast-in-place structure according to claim 2 is characterized by: The overall thickness of the cover plate is 20 cm, and the cover plate is cast entirely with C30 concrete.

3. A method for prefabrication and cast-in-place construction of high-speed railway pier caps, characterized in that: The specific steps are as follows: S1. Tie steel bars and make cover plate shaping mold according to the required size of high-speed railway pier cap; S2. Install I-beams inside the finalizing mold and ensure that the spacing of the I-beams does not affect the setting of the entrance hole; S3. The cover plate is cast with C30 concrete as a whole. A flat plate vibrator is used to compact it during casting. At the same time, concrete test blocks are made to test the cubic compressive strength of concrete at 28 days of age and evaluate the quality of concrete. S4. Before pouring concrete at the top of the hollow section of the pier, reserve a cast-in-place installation notch for the cover plate and then pour; S5. After removing the inner form of the cast-in-place installation slot, roughen the concrete in the cast-in-place installation slot. After roughening, hoist the prefabricated cover plate in blocks and install it in the cast-in-place installation slot. The gap between the cover plate and the pier body and the cast-in-place installation slot are all backfilled and compacted with concrete of the same grade as the pier body.

4. The method for prefabrication and cast-in-place construction of high-speed railway pier caps according to claim 3 is characterized by: After the concrete strength of the chamfer poured in S4 reaches 75% of the design strength, the prefabricated cover plate is hoisted through the lifting ring and placed on the chamfer of the pier body.

5. The method for prefabrication and cast-in-place construction of high-speed railway pier caps according to claim 3 is characterized by: The I-beam spacing is consistent with the cast-in-place installation slot, and the reserved cast-in-place installation slot width shall not be greater than the designed I-beam spacing.

6. The method for prefabrication and cast-in-place construction of high-speed railway pier caps according to claim 3 is characterized by: In S3, after the cover plate is poured, it is promptly covered and watered for curing.

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