Post-tensioning prefabricated small box girder and construction method thereof

Abstract

The invention discloses a post-tensioning method prefabricated small box girder and a construction method thereof, and the post-tensioning method prefabricated small box girder comprises a bottom plate which extends along a first direction; the two web plates are connected to the two opposite sides of the bottom plate in the first direction respectively; the first pipeline is arranged in the bottom plate in the first direction, the second pipeline is arranged on the web plate in the direction forming a certain included angle with the first direction, the first end of the second pipeline is located at the end of the web plate in the first direction, and the second end of the second pipeline is located on the side, away from the web plate, of the bottom plate; the first prestressing tendon penetrates through the first pipeline, and the second prestressing tendon penetrates through the second pipeline. The post-tensioning method prefabricated small box girder is simple and convenient to construct and position, the pipeline grouting quality is easy to guarantee, the production efficiency is improved, and the prestress loss is reduced, so that the effective prestress of the structure is guaranteed, the structural safety and the service life of the girder body are facilitated, and meanwhile, the engineering cost is saved.

Description

Technical Field

[0001] The invention relates to the technical field of bridge construction, in particular to a post-tensioning prefabricated small box girder and a construction method thereof. Background Art

[0002] Prefabricated small box girders are widely used in highway bridges and urban bridges because they are prefabricated in factories, have reliable quality, short production and processing cycles, are easy to assemble at the construction site, have high safety, beautiful appearance, and strong durability.

[0003] In the traditional post-tensioned prefabricated small box beam, the prestressed steel strands set on the web of the box beam are a combination of straight sections and curved sections. It has the following shortcomings in construction: 1. The positioning of the prestressed pipe in the curved section is complex, and the construction accuracy is high; 2. Since the prestressed pipe is arranged in a concave curve, the inlet and outlet of the grouting are both located on the anchor pads at both ends, which are at the highest point of the pipe curve. Therefore, due to the flow of slurry, air masses will be trapped in the grouting pipe during the grouting process, which will cause the grouting to be not dense and affect the durability of the prestressing; 3. When the prestressed strands are tensioned, the steel strands in the curved section are easily stretched tightly against the pipe wall, and the friction generated by the contact with the pipe leads to serious loss of prestress, and the effective prestress of the structure is greatly reduced, which affects the performance of the beam structure. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a post-tensioned prefabricated small box girder, which is easy to construct and position, and the quality of pipeline grouting is easy to ensure, thereby improving production efficiency and reducing prestress loss, thereby ensuring effective prestress of the structure, which is beneficial to the structural safety and service life of the beam body, and saving engineering costs.

[0005] The present invention also aims to provide a construction method for the above-mentioned post-tensioned prefabricated small box girder.

[0006] According to an embodiment of the first aspect of the present invention, a post-tensioned prefabricated small box girder includes: a bottom plate, which extends along a first direction; two webs, which are respectively connected to two opposite sides of the bottom plate along the first direction; a first pipe and a second pipe, the first pipe is arranged in the bottom plate along the first direction, the second pipe is arranged in the web along a direction forming a certain angle with the first direction, and the first end is located at the end of the web along the first direction, and the second end is located on a side of the bottom plate away from the web; a first prestressed bundle and a second prestressed bundle, the first prestressed bundle is passed through the first pipe, and the second prestressed bundle is passed through the second pipe.

[0007] According to the post-tensioning prefabricated small box beam of the present invention, the second pipe is arranged on the web along a direction that forms a certain angle with the first direction, and the first end of the second pipe is located at the end of the web along the first direction, and the second end is located on the side of the bottom plate away from the web, and the first prestressed bundle is arranged in the first pipe, and the second prestressed bundle is arranged in the second pipe. Compared with the curve arrangement of the prior art, the pipeline positioning is simpler, the construction accuracy requirement is lower, and the linear shape is easier to match the design coordinates, thereby improving production efficiency. The second pipe is arranged in a straight line. When the second prestressed bundle is tensioned, the second prestressed bundle is easily separated from the wall of the second pipe, reducing the contact friction between the second prestressed bundle and the inner wall of the second pipe, reducing the prestress loss, thereby ensuring the effective prestress of the structure, and being beneficial to the structural safety and service life of the beam body. In addition, during grouting, the slurry can flow from the first end to the second end, and the air mass will not be sandwiched in the grouting pipe during the grouting process, thereby ensuring the quality of the pipeline grouting and ensuring the durability of the prestress. At the same time, the pipeline arrangement method of the present application reduces the number of second prestressed bundles, saving engineering costs.

[0008] According to some embodiments of the present invention, along the first direction, the web is provided with at least one group of two symmetrical second pipes, and the second ends of the group of two symmetrical second pipes are respectively located on both sides of the center line of the web along the first direction.

[0009] According to some embodiments of the present invention, the distance from the intersection of the second end of the second prestressed bundle and the bottom plate to the center line of the web along the first direction is l1, and the length of the bottom plate along the first direction is l2, wherein (1 / 6)l2≤l1≤(3 / 10)l2.

[0010] According to some embodiments of the present invention, along the width direction of the web, there are at least two second pipes arranged at intervals.

[0011] According to some embodiments of the present invention, at least two of the second pipes are arranged in parallel.

[0012] According to some embodiments of the present invention, along the first direction, a distance between two adjacent second prestressed tendons is l3, (1 / 12)l2≤l3≤(1 / 10)l2.

[0013] According to some embodiments of the present invention, the angle between the second prestressed bundle and the first direction is α1, 5°≤α1≤20°.

[0014] According to some embodiments of the present invention, a protrusion is provided on a side of the bottom plate facing away from the web plate and at an intersection with the second end of the second pipe for anchoring the second prestressed bundle.

[0015] According to some embodiments of the present invention, there are multiple first pipes, and the multiple first pipes are arranged at intervals along the width direction of the bottom plate.

[0016] The construction method according to the second aspect of the present invention is applied to the post-tensioned prefabricated small box girder in the above embodiment, comprising the following steps: Step 1, inserting the first prestressed bundle and the second prestressed bundle into the first pipeline and the second pipeline respectively, anchoring both ends of the first prestressed bundle and the second prestressed bundle, and then tensioning the first prestressed bundle and the second prestressed bundle; Step 2: Grouting the first pipe and the second pipe.

[0017] According to the construction method of the embodiment of the present invention, the construction cost is saved by adopting the post-tensioning method in the above embodiment to prefabricate the small box beam.

[0018] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic elevation diagram of a prefabricated small box girder according to an embodiment of the present invention; Figure 2 yes Figure 1 Schematic diagram of the AA position in the middle; Figure 3 yes Figure 1 Schematic diagram of the middle BB; Figure 4 yes Figure 1 Schematic diagram at CC in the middle; Figure 5 yes Figure 1 Schematic diagram of DD in the figure.

[0020] Reference numerals: Prefabricated small box beam 100, Base plate 10, first pipe 11, first prestressed bundle 12, convex block 13, The web 20 , the second pipe 21 , the second prestressed bundle 22 , the top plate 30 , and the anchor assembly 40 . DETAILED DESCRIPTION

[0021] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0022] The disclosure below provides many different embodiments or examples to implement different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or letters in different examples. This repetition is for the purpose of simplicity and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific processes and examples of materials, but those of ordinary skill in the art can be aware of the applicability of other processes and / or the use of other materials.

[0023] The post-tensioned prefabricated small box girder 100 according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

[0024] Reference Figure 1-Figure 5 The post-tensioned prefabricated small box girder 100 according to the first embodiment of the present invention includes a bottom plate 10, two web plates 20, a first pipe 11 and a second pipe 21.

[0025] Reference Figure 1 The bottom plate 10 extends along a first direction. Exemplarily, the first direction may be a length direction of the bottom plate 10 .

[0026] Reference Figure 2-Figure 5 The two webs 20 are respectively connected to two opposite sides of the bottom plate 10 along the first direction to form a chamber with an opening at the top with the bottom plate 10. Exemplarily, the two webs 20 are located on the same side of the bottom plate 10 and are inclined in a direction away from each other, that is, the distance between one end of the two webs 20 connected to the bottom plate 10 is smaller than the distance between the other ends of the two webs 20.

[0027] In some embodiments, reference Figure 2-Figure 5 The prefabricated small box girder also includes a top plate 30 , which is connected to the other ends of the two web plates 20 .

[0028] Reference Figure 1-Figure 5The first pipe 11 and the second pipe 21 are used to set the first prestressed bundle 12 and the second prestressed bundle 22. The first pipe 11 is arranged in the bottom plate 10 along the first direction, and the first prestressed bundle 12 can be arranged in the first pipe 11 to provide prestress for the bottom plate 10 structure. The second pipe 21 is arranged in the web 20 along a direction that forms a certain angle with the first direction, that is, the second pipe 21 is arranged in a straight line on the web 20. Compared with the curve setting of the prior art, the pipeline positioning is simpler, the construction accuracy requirement is lower, and the line shape is easier to match the design coordinates, thereby improving production efficiency. The second pipe 21 is set in a straight line. When the second prestressed bundle 22 is tensioned, the second prestressed bundle 22 is easily separated from the inner wall of the second pipe, reducing the contact friction between the second prestressed bundle 22 and the inner wall of the second pipe, reducing the prestress loss, thereby ensuring the effective prestress of the structure, and is beneficial to the structural safety and service life of the beam body. The first end of the second pipe 21 is located at the end of the web 20 along the first direction, and the second end is located on the side of the bottom plate 10 away from the web 20. In this way, during grouting, the slurry can flow from the first end to the second end, and air masses will not be trapped in the grouting pipe during the grouting process, thereby ensuring the quality of the pipe grouting and the durability of the prestress. At the same time, the number of second prestressed bundles 22 is reduced, saving engineering costs.

[0029] Therefore, refer to Figure 1-Figure 5 According to the post-tensioning prefabricated small box beam 100 of the present invention, the second pipe 21 is arranged on the web 20 along a direction that forms a certain angle with the first direction, and the first end of the second pipe 21 is located at the end of the web 20 along the first direction, and the second end is located on the side of the bottom plate 10 away from the web 20. Compared with the curve setting of the prior art, the pipe positioning is simpler, the construction accuracy requirement is lower, and the line shape is easier to match the design coordinates, thereby improving production efficiency. The second pipe 21 is set to be linear. When the second prestressed bundle 22 is tensioned, the second prestressed bundle 22 is easily separated from the inner wall of the second pipe, reducing the contact friction between the second prestressed bundle 22 and the inner wall of the second pipe, reducing the prestress loss, thereby ensuring the effective prestress of the structure, which is beneficial to the structural safety and service life of the beam body. In addition, during grouting, the slurry can flow from the first end to the second end, and the air mass will not be sandwiched in the grouting pipe during the grouting process, thereby ensuring the quality of the pipe grouting and ensuring the durability of the prestress. At the same time, the pipe setting method of the present application reduces the number of second prestressed bundles 22, saving engineering costs.

[0030] In some embodiments, the first end of the second pipe 21 is located at an end of the web 20 away from the bottom plate 10 .

[0031] It is understandable that the first prestressed bundle is arranged in the first pipeline, and can be arranged in the same direction as the first pipeline, or at a smaller angle to the first pipeline; preferably, the first prestressed bundle is arranged in the same direction as the first pipeline. The second prestressed bundle can be arranged in the same direction as the second pipeline, or at a smaller angle to the first pipeline; preferably, the second prestressed bundle is arranged in the same direction as the second pipeline.

[0032] It should be noted that the first prestressed bundle and the second prestressed bundle are formed by binding a plurality of prestressed members, and the prestressed members can be prestressed steel bars, for example. When the prefabricated small box beam is processed by the post-tensioning method, it is necessary to lay pipelines and pass the prestressed bundles through the pipelines, and the number of pipelines is limited based on the cost and available space, so a prestressed bundle is set in each pipeline.

[0033] In some embodiments of the present invention, reference Figure 2 Along the first direction, the web 20 is provided with at least one group of two symmetrical second pipes 21, and the second ends of the group of two symmetrical second pipes 21 are respectively located on both sides of the center line of the web 20 along the first direction.

[0034] By arranging at least one set of two symmetrical second pipes 21 along the first direction, prestress can be provided at both ends of the beam body. The second ends of the two second pipes 21 are respectively located on both sides of the center line of the web 20 along the first direction, which is convenient for arrangement, prevents the two prestress pipes from crossing, and keeps the prestress on both sides of the center line of the beam body along the first direction balanced.

[0035] It can be understood that since a group of two prestressed pipes are symmetrically arranged, that is, the distances between the second ends of the two prestressed pipes and the center line of the web 20 along the first direction are the same, and the inclination angles of the two prestressed pipes are the same.

[0036] In some embodiments of the present invention, reference Figure 1 (The first pipe 11 and the second pipe 21 are not shown in the figure), the distance from the intersection of the second end of the second prestressed bundle 22 and the bottom plate 10 to the center line of the web 20 along the first direction is l1, and the length of the bottom plate 10 along the first direction is l2, where (1 / 6)l2≤l1≤(3 / 10)l2.

[0037] By setting the distance l1 from the intersection of the second end of the second prestressed bundle 22 with the bottom plate 10 to the center line of the web 20 along the first direction to (1 / 6)l2≤l1≤(3 / 10)l2, the performance of the beam is ensured and the construction and setting are convenient.

[0038] Specifically, l1 can be (1 / 6)l2, (1 / 5)l2, (1 / 4)l2, (7 / 30)l2, (4 / 15)l2, (3 / 10)l2, etc.

[0039] In some embodiments of the present invention, reference Figure 2 Along the width direction of the web 20, there are at least two second pipes 22 arranged at intervals.

[0040] By arranging at least two second pipes 21 at intervals along the width direction of the web 20 , the prestressing force of the beam body can be increased, thereby ensuring the performance of the beam body structure.

[0041] Specifically, two, three, four, seven, etc. second pipes 21 may be arranged at intervals along the width direction of the web 20. When there are three or more second pipes 21, the three or more second pipes 21 may be arranged at random intervals or evenly at the same intervals. Preferably, the three or more second pipes 21 are evenly arranged at the same intervals.

[0042] Along the width direction of the web 20, the angles between the plurality of second pipes 21 and the first direction may be the same or different. When the angles between the plurality of second pipes 21 and the first direction are different, in order to avoid the plurality of second pipes 21 from crossing, the angle between the second pipe 21 farther from the bottom plate 10 and the first direction should be smaller than the angle between the second pipe 21 closer to the bottom plate 10 and the first direction, and the difference between the two may be 3° to 5°.

[0043] In some embodiments of the present invention, at least two second pipes 21 are arranged in parallel.

[0044] Arranging at least two second pipelines 21 in parallel facilitates the arrangement and construction, reduces the construction difficulty, and improves the construction efficiency.

[0045] It is understandable that there may be two or more second pipes 21. When there are two second pipes 21, the two second pipes 21 are arranged in parallel. When there are more than two second pipes 21, the more than two second pipes 21 may be arranged in parallel, or two, three, etc. second pipes 21 may be arranged in parallel, and the angle between the remaining second pipes 21 and the first direction may be greater or less than the angle between the aforementioned two, three, etc. second pipes 21 and the first direction. The difference may be 3° to 5°.

[0046] In some embodiments of the present invention, reference Figure 1 , along the first direction, the distance between two adjacent second prestressed tendons 22 is l3, (1 / 12)l2≤l3≤(1 / 10)l2.

[0047] The interval l3 between two adjacent second prestressed tendons 22 along the first direction is set to a range of (1 / 12)l2≤l3≤(1 / 10)l2, thereby ensuring the prestress required by the beam structure and saving costs.

[0048] Specifically, l3 can be (1 / 12)l2, (11 / 120)l2, (1 / 11)l 2、 (1 / 10)l2 etc.

[0049] In some embodiments of the present invention, reference Figure 1 , the included angle between the second prestressed strand 22 and the first direction is α1, 10°≤α1≤20°.

[0050] By setting the included angle α1 between the second prestressed tendon 22 and the first direction to 10°-20°, the prestress of the beam body is ensured while the arrangement of the second prestressed tendons 22 is reduced, thus saving the construction cost.

[0051] Specifically, the angle α1 between the second prestressed strand 22 and the first direction may be 10°, 12°, 15°, 18°, 20°, etc.

[0052] In some embodiments of the present invention, reference Figure 1 A protrusion 13 is provided at the intersection of the bottom plate 10 on the side facing away from the web plate 20 and the second end of the second pipe 21 for anchoring the second prestressed bundle 22 .

[0053] By arranging the protrusion 13 on the side of the bottom plate 10 away from the web 20 , the second prestressed bundle 22 can be anchored to the protrusion 13 after passing through the second pipe 21 and passing out of the bottom plate 10 .

[0054] It can be understood that the bump 13 can be a concrete bump 13 .

[0055] In some embodiments, when there are multiple second pipes 21, the protrusions 13 can be multiple and correspond one to one with the second pipes 21. Of course, two or more second pipes 21 can correspond to one protrusion 13.

[0056] In some embodiments of the present invention, reference Figure 2-Figure 5 There are multiple first pipes 11, and the multiple first pipes 11 are arranged at intervals along the width direction of the bottom plate 10.

[0057] By arranging a plurality of first pipes 11 at intervals along the width direction of the bottom plate 10 , the prestressing requirement of the beam body on the bottom plate 10 is met.

[0058] Specifically, the number of the first pipes 11 can be two, three, five, etc.

[0059] The plurality of first pipelines 11 may be arranged in parallel; or their extended lines may be arranged at a certain angle but not intersecting; preferably, the plurality of first pipelines 11 are arranged in parallel.

[0060] When there are three or more first pipes 11, the distance between two adjacent first pipes 11 along the direction perpendicular to the first direction is the same. Of course, in other embodiments, the distance between two adjacent first pipes 11 may also be different.

[0061] The construction method according to the second aspect of the present invention is applied to the post-tensioned prefabricated small box girder 100 in the above embodiment, and comprises the following steps: Step 1, inserting the first prestressed bundle 12 and the second prestressed bundle 22 into the first pipe 11 and the second pipe 21 respectively, anchoring both ends of the first prestressed bundle 12 and the second prestressed bundle 22, and then tensioning the first prestressed bundle 12 and the second prestressed bundle 22; A first prestressing bundle 12 is inserted into each first pipe 11 , and a second prestressing bundle 22 is inserted into each second pipe 21 .

[0062] Both ends of the first prestressed bundle 12 can be anchored to a pedestal or the like through an anchoring assembly 40. One end of the second prestressed bundle 22 located at the web 20 can be anchored to a pedestal or the like through an anchoring assembly 40, and the other end can be anchored to a protrusion 13 or the like.

[0063] The tensioning of the first prestressed tendon 12 and the second prestressed tendon 22 may be performed by a jack or the like.

[0064] Step 2: Grouting the first pipeline 11 and the second pipeline 21.

[0065] Since prestressed steel bars are more susceptible to corrosion under high prestress (about 6 times that under normal conditions), grouting the first pipe 11 and the second pipe 21 can protect the first prestressed tendons 12 and the second prestressed tendons 22 from corrosion, thereby ensuring the durability of the structure. At the same time, after grouting, the first prestressed tendons 12 and the second prestressed tendons 22 are integrated with the surrounding concrete through mortar, thereby increasing the reliability of anchoring, and improving the crack resistance and bearing capacity of the structure. The cement slurry poured into the hole not only wraps the first prestressed tendons 12 and the second prestressed tendons 22, but also contacts the hole wall, bonding the prestressed tendons and the hole wall together to work together.

[0066] According to the construction method of the embodiment of the present invention, the construction cost is saved by adopting the post-tensioning method to prefabricate the small box beam 100 in the above embodiment.

[0067] In some embodiments, before step 1, the opening of the first pipe 11 and the opening of the second pipe 21 are sealed, and concrete is poured on the bottom plate 10 and the web 20. After the concrete strength reaches more than 70% of the design strength, the opening of the first pipe 11 and the opening of the second pipe 21 are opened.

[0068] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0069] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like 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, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0070] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or means that the first feature is lower in level than the second feature.

[0071] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0072] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A post-tensioned prefabricated small box girder, characterized in that: include: a bottom plate extending along a first direction; Two webs, the two webs are respectively connected to two opposite sides of the bottom plate along the first direction; A first pipe and a second pipe, wherein the first pipe is arranged in the bottom plate along the first direction, and the second pipe is arranged in the web along a direction forming a certain angle with the first direction, and the first end of the second pipe is located at the end of the web along the first direction, and the second end is located at a side of the bottom plate away from the web; A first prestressed bundle and a second prestressed bundle, wherein the first prestressed bundle is passed through the first pipeline, and the second prestressed bundle is passed through the second pipeline.

2. The post-tensioned prefabricated small box girder according to claim 1, characterized in that: Along the first direction, the web is provided with at least one group of two symmetrical second pipes, and the second ends of the group of two symmetrical second pipes are respectively located on both sides of the center line of the web along the first direction.

3. The post-tensioned prefabricated small box girder according to claim 2 is characterized in that: The distance from the intersection of the second end of the second prestressed bundle and the bottom plate to the center line of the web along the first direction is l1, and the length of the bottom plate along the first direction is l2, wherein (1 / 6)l2≤l1≤(3 / 10)l2.

4. The post-tensioned prefabricated small box girder according to claim 2, characterized in that: Along the width direction of the web, at least two second pipes are arranged at intervals.

5. The post-tensioned prefabricated small box girder according to claim 4, characterized in that: At least two of the second pipelines are arranged in parallel.

6. The post-tensioned prefabricated small box girder according to claim 4, characterized in that: Along the first direction, the distance between two adjacent second prestressed tendons is l3, (1 / 12)l2≤l3≤(1 / 10)l2.

7. The post-tensioned prefabricated small box girder according to any one of claims 1 to 6, characterized in that: An included angle between the second prestressed tendon and the first direction is α1, 5°≤α1≤20°.

8. The post-tensioned prefabricated small box girder according to any one of claims 1 to 6, characterized in that: A protrusion is provided on one side of the bottom plate away from the web plate and at the intersection with the second end of the second pipe, for anchoring the second prestressed bundle.

9. The post-tensioned prefabricated small box girder according to any one of claims 1 to 6, characterized in that: There are a plurality of the first pipes, and the plurality of the first pipes are arranged at intervals along the width direction of the bottom plate.

10. A construction method, applied to the post-tensioned prefabricated small box girder according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1, inserting the first prestressed bundle and the second prestressed bundle into the first pipeline and the second pipeline respectively, anchoring both ends of the first prestressed bundle and the second prestressed bundle, and then tensioning the first prestressed bundle and the second prestressed bundle; Step 2: Grouting the first pipe and the second pipe.

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