Protection Structure for Immersed Prestressed Steel Tendons in the Warehouse Area and Pier Construction Method

Abstract

The present invention discloses a protective structure for submerged prestressed steel bundles in a reservoir area and a method for constructing bridge piers, including a bridge pier foundation section located in the reservoir area and a plurality of prestressed steel bundles at least partially embedded in the bridge pier foundation section, each prestressed steel bundle is sleeved with at least partially embedded in the bridge pier foundation section, and a cover plate is sealed on the top of each sleeve. The protective structure effectively protects the prestressed steel bundles immersed in water, ensuring that the prestressed steel bundles are still effective during the construction in the second year of low water level. The construction method is divided into two phases of low water level. During the first phase of low water level, a sleeve is set on the outside of the prestressed steel bundle to protect the prestressed steel bundle. During the second phase of low water level, the side portion of the sleeve is cut off. After the side portion is cut off, the sleeve can continue to serve as a rigid skeleton for the subsequent construction of the bridge tower.

Description

Technical Field

[0001] The present invention relates to the field of design and construction of prestressed steel tendons, and particularly to a protection structure for immersed prestressed steel tendons located in a reservoir area and a pier construction method. Background Art

[0002] For a general reservoir area, water storage starts from the normal low water level of 145.0 m on October 1st every year and reaches the normal high water level of 175 m by the end of October. This 175 m high water level is maintained for two months (during dry winter) to three months (during wet winter) from November, December, and January; due to power generation and downstream water supply needs, there will be a water level drop process. From January to May, the reservoir water level drops to the normal low water level of 145.0 m, and a new round of water storage starts in October, and so on in cycles. Therefore, the reservoir water level operates as follows:

[0003] From early June to the end of September, it operates at the low water level of 145 m; from early October to the end of October, it is the water storage period; from early November to the end of December (or the end of January), it operates at the high water level of 175 m; from early January to the end of May, it is the water level drop period. It can be seen that the reservoir area has a low water level of 145 m for only four months from early June to the end of September, and the water level quickly rises to the high water level of 175.0 m starting from October.

[0004] When constructing a pier in water, the higher the water level, the deeper the construction water depth, the more difficult the construction, the greater the construction risk, and the higher the construction cost. On the contrary, the lower the water level, the shallower the construction water depth, the simpler the construction, the smaller the construction risk, and the lower the construction cost. The piers of bridge projects built in the reservoir area are located in the water level fluctuation area of the reservoir, and their construction is directly affected by the rise and fall of the reservoir water level. Generally, in order to simplify construction, reduce construction risk, and save construction costs, the piers located in the reservoir area are selected to be constructed during the low water level period, that is, from June of each year to October of the following year. However, some pier foundation projects are particularly large and cannot be completed within the four months from June to October. In order to avoid construction during high water levels, some construction parties often carry out appropriate protection on the unfinished projects and choose to stop construction during the period from October to May of the following year when the water level is relatively high, and then resume construction during the low water level period from June to October of the following year. Some piers are arranged with a large number of prestressed steel tendons due to force requirements, and the prestressed steel tendons are relatively long. If the pier construction is not completed during the low water level period from June to October, the prestressed steel tendons arranged in the pier will be immersed in water from October to May of the following year without the protection of a concrete protective layer. In this way, the prestressed steel tendons will be immersed in water for half a year. After being severely corroded by water, the prestressed steel tendons will become unusable. In order to protect the effectiveness of the prestressed steel tendons, it is necessary to strictly protect the prestressed steel tendons arranged in the pier. Summary of the Invention

[0005] In view of the shortcomings of the prior art, one of the purposes of the present invention is to provide a protective structure for submerged prestressed steel strands in a reservoir area. The protective structure effectively protects the prestressed steel strands immersed in water, ensuring that the prestressed steel strands are still effective during construction during the low water level period in the second year.

[0006] Another object of the present invention is to provide a construction method for bridge piers located in a reservoir area. The construction method is divided into two phases of low water level construction. During the first phase of low water level, sleeves, cover plates and reinforcement structures are arranged on the outside of the prestressed steel bundles to protect the prestressed steel bundles. During the second phase of low water level, the reinforcement structure is dismantled and part of the side of the sleeve is cut off. After the side part is cut off, the sleeve can continue to serve as a rigid frame for the subsequent construction of the bridge tower (as a rigid frame for tying steel bars and formwork).

[0007] In order to solve the above technical problems, the present invention is implemented by the following technical solutions:

[0008] On the one hand, the present invention provides a protective structure for submerged prestressed steel bundles located in a reservoir area, including a pier foundation section located in the reservoir area and a plurality of prestressed steel bundles at least partially embedded in the pier foundation section, each of the prestressed steel bundles is sleeved with at least partially embedded in the pier foundation section, a cover plate is sealed on the top of each sleeve, and a reinforcement structure is fixed on each sleeve; the sleeve, cover plate and reinforcement structure form a stable protection system for the prestressed steel bundles.

[0009] Preferably, the top height of each sleeve needs to be higher than the highest water level in the reservoir area, so as to prevent water from seeping into the sleeve, and the height of the sleeve can also meet the subsequent construction requirements of the upper section of the bridge pier.

[0010] Preferably, the top height of the prestressed steel strand is located between the lowest water level and the highest water level in the reservoir area.

[0011] Preferably, the reinforcement structure includes a first I-beam column and a second I-beam column, one side flange of the first I-beam column extends into the sleeve along a slot provided in the length direction of the sleeve, a gap is left between the other side flange and the flange of another first I-beam column correspondingly installed on the adjacent sleeve, and the second I-beam column extends into the gap to clamp the flanges of the two first I-beam columns together. One side of the first I-beam column is clamped into the sleeve and fixedly connected thereto, and the other side is fastened and connected through the second I-beam column, forming a stable support system for the sleeve.

[0012] It is further preferred that the lengths of the first I-beam column, the second I-beam column and the sleeve are the same, so that the first I-beam column and the second I-beam column can better reinforce the sleeve.

[0013] Further preferably, at least a part of the lower segments of the first I-shaped steel column and the second I-shaped steel column are embedded in the pier foundation section. Embedding the lower segments of the first I-shaped steel column and the second I-shaped steel column in the pier foundation section can enhance the stability of the reinforcement structure and form an integral connection with the sleeve, resulting in stronger structural stability.

[0014] On the other hand, the present invention also provides a construction method for a pier located in a reservoir area, using the above-mentioned protective structure for prestressed steel bundles for construction. The construction method includes the following steps:

[0015] S1. During the first low water level period in the reservoir area, start the construction of the pier foundation section and simultaneously embed the lower segment of the prestressed steel bundle in the pier foundation section;

[0016] S2. After the construction of the pier foundation section is completed, sleeved the sleeve on the prestressed steel bundle exposed outside the pier foundation section, and simultaneously complete the arrangement of the reinforcement structure and the cover plate to form a protection system;

[0017] S3. During the second low water level period in the reservoir area, remove the reinforcement structure and use the sleeve as the stiffening skeleton for the subsequent construction of the upper part of the pier;

[0018] S4. After the reinforcement structure is removed, continue to pour and construct the upper part of the pier on the basis of the pier foundation section until the construction of the entire pier is completed.

[0019] Further preferably, the arrangement method of the reinforcement structure in step S2 is as follows: first, insert the first I-shaped steel column into the sleeve along the card slot of the sleeve, then connect the flanges of two adjacent first I-shaped steel columns through the second I-shaped steel column, and then weld and seal the connection between the first I-shaped steel column and the card slot, and finally embed the lower segments of the first I-shaped steel column and the second I-shaped steel column.

[0020] The removal method of the reinforcement structure in step S3 is as follows: partially or completely cut the sleeve, the first I-shaped steel column and the second I-shaped steel column along the preset cutting line as needed, and recycle the first I-shaped steel column and the second I-shaped steel column, so that at least part of the side wall of the sleeve is open.

[0021] Even more preferably, the preset cutting line on the sleeve is located on the sleeve of the flange of the first I-shaped steel column facing away from the prestressed steel bundle. During the welding of the entire sleeve and the first I-shaped steel column and the cutting of the sleeve along the cutting line, since the flange of the first I-shaped steel column always acts as a baffle, the prestressed steel bundle is effectively protected from damage.

[0022] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0023] In the present invention, a sleeve is sleeved outside each prestressed steel strand. A cover plate is hermetically laid on the top of the sleeve, and a reinforcement structure is used to fix the sleeve. A protection system for the prestressed steel strand is formed among the sleeve, the cover plate and the reinforcement structure. In this way, during the more than half a year when the water level in the reservoir area is high, the prestressed steel strands in the lower part that have been constructed are well protected from being corroded by water. When the water level in the reservoir area drops to the low water level in the second year, the reinforcement structure is removed and part of the side of the sleeve is cut off, so that the sleeve can continue to serve as the stiffening skeleton for the upper part of the subsequent pier construction. In this way, not only the prestress in the lower part that has been constructed is well protected from damage, but also the sleeve for protecting the prestressed steel strand is fully utilized, saving the project cost to the greatest extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic structural view of the pier of the present invention during the construction in the first low water level period;

[0025] Figure 2 is a schematic cross-sectional structural view of the pier of the present invention during the construction in the first low water level period;

[0026] Figure 3 is Figure 2 an enlarged structural view of part A in

[0027] Figure 4 is a schematic structural view of the completed pier construction of the present invention.

[0028] Reference numerals: 1 - pier foundation section; 2 - construction section line of pier foundation section; 3 - upper part of pier; 4 - prestressed steel strand; 5 - sleeve; 6 - cover plate; 7 - reinforcement structure; 51 - clamping groove; 52 - cutting line; 71 - first I-shaped steel column; 72 - second I-shaped steel column; 73 - flange. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] In order to enable those skilled in the art to better understand the technical solution of the present invention, the preferred implementation scheme of the present invention will be described below in conjunction with specific embodiments. However, it should be understood that the drawings are only for illustrative purposes and cannot be construed as a limitation on this patent; in order to better illustrate this embodiment, some components in the drawings will be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted. The positional relationships described in the drawings are only for illustrative purposes and cannot be construed as a limitation on this patent.

[0030] The following combines the attached Figures 1 to 4 and the embodiments to further illustrate the present invention, but it is not used as a basis for limiting the present invention.

[0031] Since the amount of work below the high water level of 175.0m for some bridge piers is too large and cannot be completed during the low water level of 145.0m in a reservoir area, the prestressed steel bundle 4 of the lower section that has been constructed is already embedded in the pier foundation section 1 of the lower section that has been constructed, while the prestressed steel bundle 4 of the upper part of the pier upper section 3 that has not been constructed can only be immersed in water.

[0032] As Figures 1 to 3 shown, to avoid the prestressed steel bundle 4 exposed outside the pier foundation section 1 from being corroded and invalidated by soaking in water, this embodiment provides a protection structure for the immersed prestressed steel bundle 4 located in the reservoir area. The protection structure includes a sleeve 5, a cover plate 6, and a reinforcement structure 7. The sleeve 5 is correspondingly sleeved on the prestressed steel bundle 4, and a cover plate 6 is hermetically laid on the top of each sleeve 5, and a reinforcement structure is fixedly arranged on each sleeve 5; the sleeve 5, the cover plate 6, and the reinforcement structure 7 form a stable protection system for the prestressed steel bundle 4.

[0033] Specifically, the sleeve 5 can be made of a steel pipe with a diameter larger than the outer diameter of the prestressed steel bundle 4, and the cover plate 6 is made of a steel plate and hermetically welded to the opening at the top of the sleeve 5; the reinforcement structure includes a first I-shaped steel column 71 and a second I-shaped steel column 72. One flange 73 of the first I-shaped steel column 71 extends into the sleeve 5 along the card slot 51 opened in the length direction of the sleeve 5, and there is a gap between the other flange 73 and the flange 73 of another first I-shaped steel column 71 correspondingly installed on the adjacent sleeve 5. The second I-shaped steel column 72 extends into this gap to clamp the flanges 73 of the two first I-shaped steel columns 71 together. At least part of the lower sections of the sleeve 5, the first I-shaped steel column 71, and the second I-shaped steel column 72 are embedded in the pier foundation section 1. The sizes of the first I-shaped steel column 71 and the second I-shaped steel column 72 can be selected according to the actual layout requirements of the prestressed steel bundle 4 on site.

[0034] The heights of the first I-shaped steel column 71, the second I-shaped steel column 72, and the sleeve 5 all need to be 1 - 2m higher than the highest water level of 175.0m in the reservoir area to prevent water in the reservoir area from entering the steel pipe and causing corrosion of the prestressed steel bundle 4. At the same time, a cover plate 6 is welded on the top of the sleeve 5 to prevent rainwater from entering the sleeve 5. In this way, a protection system for the prestressed steel bundle 4 is formed. After the water level in the reservoir area rises to the high water level of 175.0m, the prestressed steel bundle 4 can be well protected. The height of the sleeve 5 is higher than the highest water level in the reservoir area, so that the sleeve 5 can act as a stiffening skeleton for the subsequent construction of the pier upper section 3, eliminating the need to re-arrange the prestressed steel bundle 4, saving costs and shortening the construction period.

[0035] As Figure 4 shown, this embodiment also provides a bridge pier construction method based on the above protection structure, including the following steps:

[0036] S1. During the first low water level period in the reservoir area, start the construction of the pier foundation section 1 (the construction section line of the pier foundation section 1 is labeled 2 in the figure), and at the same time embed the lower section of the prestressed steel bundle 4 into the pier foundation section 1 so that the top height of the prestressed steel bundle 4 is located between the lowest and highest water levels in the reservoir area;

[0037] S2. After the construction of the pier foundation section 1 is completed, sleeved the sleeve 5 on the prestressed steel bundle 4 exposed outside the pier foundation section 1, and at the same time complete the arrangement of the reinforcement structure and the cover plate 6 to form a protection system;

[0038] Specifically, the arrangement method of the reinforcement structure is as follows: first, insert the first I-beam column 71 into the sleeve along the card slot 51 of the sleeve, then connect the flanges 73 of two adjacent first I-beam columns 71 by the second I-beam column 72, and then weld and seal the connection between the first I-beam column 71 and the card slot 51, and finally embed the lower sections of the first I-beam column 71 and the second I-beam column 72;

[0039] The removal method of the reinforcement structure is: according to needs, partially or completely cut the sleeve 5, the first I-beam column 71 and the second I-beam column 72 along the preset cutting line 52, recycle the first I-beam column 71 and the second I-beam column 72, so that at least part of the side wall of the sleeve 5 is open;

[0040] S3. During the second low water level period in the reservoir area, remove the reinforcement structure, remove the rust of the sleeve 5 and continue to act as the stiffening skeleton for the subsequent construction of the upper section 3 of the pier;

[0041] S4. After the reinforcement structure is removed, continue to pour and construct the upper section 3 of the pier on the basis of the pier foundation section 1 until the construction of the entire pier is completed.

[0042] Further, the preset cutting line 52 on the sleeve 5 is located on the sleeve 5 where the flange 73 of the first I-beam column 71 faces away from the prestressed steel bundle 4. During the welding of the entire sleeve 5 and the first I-beam column 71 and the cutting of the sleeve 5 along the cutting line 52, since the flange 73 of the first I-beam column 71 always acts as a baffle, the prestressed steel bundle 4 is effectively protected from damage.

[0043] Further, after the reinforcement structure is removed, it can be recycled and reused to save costs.

[0044] Based on the description and drawings of the present invention, those skilled in the art can easily manufacture or use a protection structure for an immersed prestressed steel bundle in a reservoir area and a construction method for a pier according to the present invention, and can achieve the positive effects recorded in the present invention.

[0045] Unless otherwise specified, in the present invention, if there are terms such as "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial direction", "radial direction", "circumferential direction", etc., the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms used to describe the orientation or positional relationship in the present invention are only for illustrative purposes and should not be construed as a limitation of this patent. For those of ordinary skill in the art, the specific meanings of the above terms can be understood in combination with the drawings and according to specific circumstances. In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features.

[0046] Unless otherwise clearly defined and limited, in the present invention, if there are terms such as "arranged", "connected" and "coupled", they 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 directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0047] The above are only the preferred embodiments of the present invention and do not impose any formal limitations on the present invention. Any simple modifications and equivalent changes made to the above embodiments based on the technical essence of the present invention all fall within the protection scope of the present invention.

Claims

1. A protective structure of submerged prestressed steel strands located in the reservoir area, comprising a pier foundation section located in the reservoir area and a plurality of prestressed steel strands at least partially embedded in the pier foundation section, Features: Each of the prestressed steel strands is covered with a sleeve, at least a portion of which is embedded in the foundation section of the pier, and a cover plate is sealed on the top of each sleeve; the top height of each sleeve must be higher than the highest water level in the reservoir area; A reinforcement structure is fixedly arranged on each of the sleeves, and the reinforcement structure includes a first I-beam column and a second I-beam column, a flange on one side of the first I-beam column extends into the sleeve along a slot provided in the length direction of the sleeve, a gap is left between the flange on the other side and a flange of another first I-beam column correspondingly installed on the adjacent sleeve, and the second I-beam column extends into the gap to clamp the flanges of the two first I-beam columns together; The construction method of the protective structure comprises the following steps: S1. During the first low water level period in the reservoir area, the construction of the pier foundation section begins, and the lower section of the prestressed steel strand is embedded in the pier foundation section at the same time; S2. After the construction of the pier foundation section is completed, the sleeve is placed on the prestressed steel strands exposed outside the pier foundation section, and the reinforcement structure and cover plate are arranged at the same time to form a protection system; S3. During the second low water level period in the reservoir area, the reinforcement structure is removed and the sleeve is used as the rigid skeleton of the upper section of the subsequent bridge pier construction; S4. After the reinforcement structure is removed, the upper section of the pier is poured on the basis of the pier foundation section until the construction of the entire pier is completed; The arrangement method of the reinforcement structure in step S2 is: firstly insert the first I-beam steel column into the sleeve along the slot of the sleeve, then clamp the flanges of two adjacent first I-beam steel columns together through the second I-beam steel column, then weld and seal the connection between the first I-beam steel column and the slot, and finally pre-embed the lower sections of the first I-beam steel column and the second I-beam steel column; The method for dismantling the reinforcement structure in step S3 is: partially or completely cut off the sleeve, the first I-beam column and the second I-beam column along a preset cutting line as needed, recover the first I-beam column and the second I-beam column, so that at least part of the side wall of the sleeve is open.

2. The protective structure of the submerged prestressed steel strands in the reservoir area according to claim 1, Features: The top height of each sleeve must be 1 to 2 meters higher than the highest water level in the reservoir area.

3. The protective structure of the submerged prestressed steel strands in the reservoir area according to claim 1, Features: The top height of the prestressed steel strand is located between the lowest water level and the highest water level in the reservoir area.

4. The protective structure of the submerged prestressed steel strands in the reservoir area according to claim 1, Features: The first I-beam column, the second I-beam column and the sleeve have the same length.

5. The protective structure of the submerged prestressed steel strands in the reservoir area according to claim 1, Features: At least a portion of the lower sections of the first I-beam column and the second I-beam column are embedded in the pier foundation section.

6. The protective structure of the submerged prestressed steel strands in the reservoir area according to claim 1, Features: The preset cutting line on the sleeve is located on the sleeve where the flange of the first I-beam column is away from the prestressed steel strand.

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