Bridge transition section step type pile plate structure and construction method

Abstract

The application relates to the technical field of road and bridge construction, and particularly provides a road and bridge transition section ladder-type pile plate structure and a construction method. The road and bridge transition section ladder-type pile plate structure is used for connecting an abutment and a roadbed, and comprises a transition pile foundation, a bearing plate and a transition block. A plurality of transition pile foundations are arranged on an extension line of the abutment in the direction of the roadbed, and a multi-span bearing plate is fixed on the plurality of transition pile foundations. The extension line of the abutment in the direction of the roadbed comprises N bearing plates arranged in sequence. The upper surface of the first bearing plate on the extension line of the abutment in the direction of the roadbed is flush with the lower bottom surface of a railway track plate. The structure enables the first bearing plate and the Nth bearing plate to evenly distribute the force borne to the roadbed filling body of the roadbed and the transition pile foundation, is beneficial to reducing the settlement of the road and bridge transition section, and the adjacent two bearing plates are connected through the transition block, which is beneficial to strengthening the uniform transition performance of the road and bridge transition section.

Description

Technical Field

[0001] This invention relates to the field of road and bridge construction technology, and more specifically, to a stepped pile-slab structure for road and bridge transition sections and its construction method. Background Technology

[0002] my country already possesses the world's largest and fastest high-speed railway network, requiring track structures with high smoothness. The transition section between the roadbed and bridges is a crucial component of high-speed railways and significantly impacts track smoothness. Differential settlement is a major controlling factor for the smoothness and comfort of train operation in the road-bridge transition section; excessive differential settlement in this section poses a threat to the operational safety of high-speed railways.

[0003] In existing technologies, an inverted trapezoidal transition section is usually used to connect with the bridge abutment, or a load-bearing plate structure and an inverted trapezoidal transition section are used together to connect with the bridge abutment. Both transition section forms have the problem of sudden stiffness changes due to the large differences between structural forms and materials. This will affect the safe operation and comfort of the train, and it is difficult to meet the requirements of higher train operating speeds. Summary of the Invention

[0004] The technical problem that this invention aims to solve is that the existing stepped pile-slab structure for road and bridge transition sections suffers from abrupt changes in stiffness and differential settlement due to significant differences in structural form and materials. This will affect the safe operation and comfort of trains.

[0005] To address the above problems, the present invention proposes the following technical solution: A stepped pile-slab structure for a bridge-road transition section is provided for connecting abutments and roadbeds. The stepped pile-slab structure for the bridge-road transition section includes transition piles, bearing plates, and transition blocks. Multiple transition piles are arranged on the extension line of the abutment toward the roadbed, and multiple spans of the bearing plate are fixed to the multiple transition piles. The bridge abutment extends along the roadbed direction, comprising N spans of the bearing slab arranged sequentially. The upper surface of the first span of the bearing slab on the extension line of the bridge abutment towards the roadbed direction is flush with the lower surface of the railway track slab; the upper surface of the second span of the bearing slab on the extension line of the bridge abutment towards the roadbed direction is flush with the lower surface of the foundation surface layer; the upper surface of the Nth span of the bearing slab on the extension line of the bridge abutment towards the roadbed direction is flush with the lower surface of the (N-1)th span of the bearing slab, and N≥2, and the lower surface of the Nth span of the bearing slab is flush with the lower surface of the roadbed fill. A stepped corner is formed at the connection between the Nth span bearing plate and the roadbed filling body, and at the connection between the Nth span bearing plate and the (N-1)th span bearing plate. A transition block is provided at each of the multiple stepped corners, and the two side walls of the transition block are respectively connected to the vertical and horizontal planes of the corresponding stepped corners.

[0006] The stepped pile-slab structure for road-bridge transition sections provided by this invention has, but is not limited to, the following beneficial effects compared to existing technologies: The railway track slab is installed on the first span bearing plate on the extension line of the abutment towards the roadbed. The upper surface of the Nth span bearing plate on the extension line of the abutment towards the roadbed is flush with the lower surface of the (N-1)th span bearing plate, and N≥2. The transition block is set on the upper surface of the Nth span bearing plate, and one side wall of the transition block is connected to the side wall of the (N-1)th span bearing plate. This structure allows the first span bearing plate and the Nth span bearing plate to evenly distribute the force they bear to the transition pile foundation, which helps to reduce the settlement of the road-bridge transition section. Furthermore, the connection between two adjacent bearing plates through the transition block helps to enhance the uniform transition of the stiffness of the overlying fill soil in the road-bridge transition section. The structure is relatively simple and the materials are relatively uniform, which can effectively avoid the problem of sudden stiffness changes due to large differences in structural form and materials, thereby improving the safe operation and comfort of trains and meeting the requirements of higher train operating speeds.

[0007] Preferably, the stepped pile-slab structure of the road-bridge transition section further includes geotextile, and geotextile is laid on the upper surface of each of the bearing plates except for the first span bearing plate.

[0008] Preferably, the stepped pile-slab structure of the road-bridge transition section further includes a subgrade surface layer and a filler layer. A railway track slab is laid on the geotextile of the first span bearing slab, a subgrade surface layer is laid on the geotextile of the second span bearing slab, and filler is laid on the geotextile of the third span bearing slab and subsequent bearing slabs.

[0009] Preferably, the surface layer of the subgrade is cast from graded crushed stone mixed with 5% cement.

[0010] This invention also provides a construction method for a stepped pile-slab structure in a road-bridge transition section, used for constructing the stepped pile-slab structure in a road-bridge transition section as described above. The method includes the following steps: S1. First determine the position of the Nth span bearing plate, then determine the N-1th span bearing plate, the N-2th span bearing plate, and so on until the position of the 1st span bearing plate; S2. Determine the mileage of the abutment, construct the abutment pile foundation and the abutment, and backfill and compact the abutment foundation pit using graded crushed stone or C25 concrete; S3. Excavate steps, use the excavated material from the road cut as fill material for the bridge backfill area construction, the roadbed outside the bearing plate structure section is filled with fill material, and compacted in layers to the bottom surface of the Nth span bearing plate; S4. Mark the location of the transition pile foundation, and then carry out the construction of the transition pile foundation, as well as the construction from the Nth span bearing plate to the (N-1)th span bearing plate; S5. The transition block is set at the step angle formed by the Nth span bearing plate and the roadbed fill, and at the step angle formed by the Nth span bearing plate and the (N-1)th span bearing plate, and the two side walls of the transition block are respectively connected to the vertical and horizontal planes of the corresponding step angles; S6. Level the load-bearing plate from the first span to the Nth span using M35 concrete mortar, and then lay the geotextile. S7. Using the bearing plate structure constructed in step S4 as the boundary, fill the road cut excavation as fill material on the side near the bridge abutment, with a compaction degree of not less than 95%. In the transition section near the roadbed, fill qualified materials to the top of the bearing plate structure constructed in S4 according to the structural type and requirements of the roadbed in the section. S8. Repeat the construction of multiple transition piles and the (N-1)th span bearing plate in the order of steps S4 to S7 until the construction of the first span bearing plate; S9. After the first span bearing plate structure is completed, the graded crushed stone of the subgrade surface is filled simultaneously with the subgrade of the section. The subgrade surface layer contains 5% cement within the length of the transition section, the compaction degree is not less than 97%, and the length of the transition section is not less than 20m.

[0011] Preferably, in step S3, a small mechanical compactor is used to compact the area adjacent to the bridge abutment, ensuring that the main structure of the bridge abutment is not damaged, and the compaction degree is not less than 95%.

[0012] Preferably, in step S4, the diameter of the transition pile foundation is 1.0m, and it is cast with reinforced concrete of grade not lower than C35.

[0013] Preferably, the depth of the transition pile foundation into the weakly weathered bedrock is determined based on bearing capacity calculations and shall not be less than 2m.

[0014] Preferably, in steps S4 and S8, the width of the Nth span bearing plate extends 0.5m beyond the stress influence line of the railway track slab; the length of the 1st span bearing plate is 5.6m and is aligned with the joint of the track slab; the thickness of the 1st span bearing plate is 1m to 1.5m. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall structure of the stepped pile-slab structure for the transition section of a road and bridge according to an embodiment of the present invention.

[0016] Explanation of reference numerals in the attached figures: 1. Transition pile foundation, 21. First span bearing plate, 22. Second span bearing plate, 23. Third span bearing plate, 3. Transition block, 4. Roadbed fill, 5. Subgrade surface layer, 6. Bridge abutment, 60. Bridge abutment pit, 7. Geotextile. Detailed Implementation

[0017] The embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate this application, but should not be used to limit the scope of this application.

[0018] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0019] It should be noted that in the XYZ coordinate system provided in this article, the positive direction of the X-axis represents the right, and the negative direction of the X-axis represents the left; the positive direction of the Y-axis represents the front, and the negative direction of the Y-axis represents the back; the positive direction of the Z-axis represents the top, and the negative direction of the Z-axis represents the bottom. The meanings of the Z-axis, X-axis, and Y-axis are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0020] See Figure 1 The present invention provides a stepped pile-slab structure for a bridge transition section, used to connect the bridge abutment 6 and the roadbed. The stepped pile-slab structure for the bridge transition section includes a transition pile 1, a bearing plate and a transition block 3. A plurality of the transition piles 1 are arranged on the extension line of the bridge abutment 6 toward the roadbed, and the bearing plate is fixed on the plurality of transition piles 1.

[0021] The bridge abutment 6 extends along the roadbed direction, including N spans of the bearing plates arranged sequentially. The upper surface of the first span bearing plate 21 on the extension line of the bridge abutment 6 towards the roadbed direction is flush with the lower bottom surface of the railway track slab. The upper surface of the second span bearing plate 22 on the extension line of the bridge abutment 6 towards the roadbed direction is flush with the lower bottom surface of the foundation surface. The upper surface of the Nth span bearing plate on the extension line of the bridge abutment 6 towards the roadbed direction is flush with the lower bottom surface of the (N-1)th span bearing plate, and N≥2. The lower bottom surface of the Nth span bearing plate is flush with the lower bottom surface of the roadbed fill 4.

[0022] Step angles are formed at the connection between the Nth span bearing plate and the roadbed filling body 4, and at the connection between the Nth span bearing plate and the (N-1)th span bearing plate. Transition blocks 3 are respectively provided at multiple step angles, and the two side walls of the transition blocks 3 are respectively connected to the vertical and horizontal planes of the corresponding step angles.

[0023] Specifically, the cross-section of the transition block 3 is a right-angled triangle or a right-angled trapezoid. One side wall of the bottom edge of the transition block 3 is fixed to the upper surface of the Nth span bearing plate. One side wall of the right-angled edge of the transition block 3 is connected to the side wall of the (N-1)th span bearing plate facing the Nth span bearing plate.

[0024] The transition block 3 is made of precast concrete, and the concrete grade is the same as that of the bearing plate.

[0025] In this embodiment, the railway track slab is installed on the first span bearing plate 21 on the extension line of the bridge abutment 6 towards the roadbed. The upper surface of the Nth span bearing plate on the extension line of the bridge abutment 6 towards the roadbed is flush with the lower surface of the (N-1)th span bearing plate, and N≥2. The transition block 3 is set on the upper surface of the Nth span bearing plate, and one side wall of the transition block 3 is connected to the side wall of the (N-1)th span bearing plate. This structure allows the first span bearing plate 21 and the Nth span bearing plate to distribute the force evenly to the transition pile foundation 1, which helps to reduce the settlement of the road-bridge transition section. Furthermore, the connection between two adjacent bearing plates through the transition block 3 helps to enhance the uniform transition of the stiffness of the overlying fill soil in the road-bridge transition section. The structure is relatively simple and the materials are relatively uniform, which can effectively avoid the problem of sudden stiffness changes due to large differences in structural form and materials, thereby improving the safe operation and comfort of trains and meeting the requirements of higher train operating speeds.

[0026] Preferably, the stepped pile-slab structure of the road-bridge transition section further includes geotextile 7, and geotextile 7 is laid on the upper surface of each of the bearing plates except for the first span bearing plate 21.

[0027] In this embodiment, the geotextile 7 is used to enhance the overall connection strength of the road-bridge transition section.

[0028] Preferably, the stepped pile-slab structure of the road-bridge transition section further includes a subgrade surface layer 5 and a filler layer. A railway track slab is laid on the geotextile 7 of the first span bearing plate 21, the subgrade surface layer 5 is laid on the geotextile 7 of the second span bearing plate 22, and a filler layer is laid on the geotextile 7 of the third span bearing plate and subsequent bearing plates.

[0029] Preferably, the subgrade surface layer 5 is cast from graded crushed stone mixed with 5% cement.

[0030] In this embodiment, the filling layer and the subgrade surface layer 5 are used to level the surface of the railway subgrade and also help to reduce settlement.

[0031] In this embodiment, the structure is beneficial to enhance the uniform transition performance of the stepped pile-slab structure in the road-bridge transition section and reduce the differential settlement of the road-bridge transition section.

[0032] This invention also provides a construction method for a stepped pile-slab structure in a road-bridge transition section, used for constructing the stepped pile-slab structure in a road-bridge transition section as described above. The method includes the following steps: S1. First determine the position of the Nth span bearing plate, then determine the N-1th span bearing plate, the N-2th span bearing plate, and so on until the position of the 1st span bearing plate 21; S2. Determine the mileage of the abutment 6, construct the pile foundation of the abutment 6 and the abutment 6, and backfill and compact the abutment foundation pit 60 with graded crushed stone or C25 concrete. S3. Excavate steps, use the excavated material from the road cut as fill material for the bridge backfill area construction, the roadbed outside the bearing plate structure section is filled with fill material, and compacted in layers to the bottom surface of the Nth span bearing plate; S4. Mark the location of the transition pile foundation 1, and then carry out the construction of the transition pile foundation 1, as well as the construction from the Nth span bearing plate to the (N-1)th span bearing plate; S5. The transition block 3 is set at the step angle formed by the Nth span bearing plate and the roadbed fill body 4, and at the step angle formed by the Nth span bearing plate and the (N-1)th span bearing plate. The two side walls of the transition block 3 are respectively connected to the vertical and horizontal planes of the corresponding step angles. S6. Level the load-bearing plate from the first span 21 to the Nth span using M35 concrete mortar, and then lay the geotextile 7. S7. Using the bearing plate structure constructed in step S4 as the boundary, fill the road cut excavation as fill material on the side near the bridge abutment, with a compaction degree of not less than 95%. In the transition section near the roadbed, fill qualified materials to the top of the bearing plate structure constructed in S4 according to the structural type and requirements of the roadbed in the section. S8. Repeat the construction of multiple transition pile foundations 1 and the (N-1)th span bearing plate in the order of steps S4 to S7 until the construction of the first span bearing plate; S9. After the first span of the bearing slab structure is completed, the surface layer of the subgrade is filled with grade 5 crushed stone simultaneously with the subgrade of the section. Among them, the surface layer of the subgrade within the length of the transition section is mixed with 5% cement, the compaction degree is not less than 97%, and the length of the transition section is not less than 20m.

[0033] Preferably, in step S3, a small mechanical compactor is used to compact the area adjacent to the bridge abutment 6, without damaging the main structure of the bridge abutment 6, and the compaction degree is not less than 95%.

[0034] Preferably, in step S4, the diameter of the transition pile foundation 1 is 1.0m, and it is cast with reinforced concrete of grade not lower than C35.

[0035] Preferably, the depth of the transition pile foundation 1 into the weakly weathered bedrock layer is determined based on bearing capacity calculations and shall not be less than 2m.

[0036] Preferably, in steps S4 and S8, the width of the Nth span bearing plate extends 0.5m beyond the stress influence line of the railway track slab; the length of the first span bearing plate 21 is 5.6m and it is aligned with the joint of the track slab; the thickness of the first span bearing plate 21 is 1m to 1.5m.

[0037] In this embodiment, the coordination of the transition pile foundation 1, the bearing plate, the transition block 3, the geotextile 7, the filler layer, and the subgrade surface layer 5 improves the uniform transition performance of the stepped pile-slab structure in the road-bridge transition section, reduces differential settlement, and minimizes its impact on the smoothness of the road-bridge transition section. This method can effectively solve the problem of differential settlement in the road-bridge transition section of high-speed railways or highways, ensure the safe operation of high-speed railway trains and highway vehicles, and is convenient and feasible to construct, with broad application prospects.

Claims

1. A stepped pile-slab structure for a road-bridge transition section, used to connect the bridge abutment (6) and the roadbed, characterized in that, The stepped pile-slab structure of the road-bridge transition section includes transition pile foundations (1), bearing plates and transition blocks (3). Multiple transition pile foundations (1) are set on the extension line of the bridge abutment (6) towards the roadbed, and multiple spans of the bearing plates are fixed on multiple transition pile foundations (1). The bridge abutment (6) extends along the roadbed direction and includes N spans of the bearing plates arranged sequentially. The upper surface of the first span bearing plate (21) on the extension line of the bridge abutment (6) towards the roadbed direction is flush with the lower bottom surface of the railway track slab. The upper surface of the second span bearing plate (22) on the extension line of the bridge abutment (6) towards the roadbed direction is flush with the lower bottom surface of the foundation surface. The upper surface of the Nth span bearing plate on the extension line of the bridge abutment (6) towards the roadbed direction is flush with the lower bottom surface of the (N-1)th span bearing plate, and N≥2. The lower bottom surface of the Nth span bearing plate is flush with the lower bottom surface of the roadbed fill (4). At the connection between the Nth span bearing plate and the roadbed filling body (4) and at the connection between the Nth span bearing plate and the N-1th span bearing plate, step angles are formed. Transition blocks (3) are respectively provided at multiple step angles, and the two side walls of the transition blocks (3) are respectively connected to the vertical and horizontal planes of the corresponding step angles.

2. The stepped pile-slab structure for the transition section of a road and bridge according to claim 1, characterized in that, It also includes geotextile (7), the upper surface of each of the bearing plates from the first span bearing plate (21) to the Nth span bearing plate is covered with the geotextile (7), it also includes a subgrade surface layer (5) and a filler layer, a railway track slab is laid on the geotextile (7) of the first span bearing plate (21), the subgrade surface layer (5) is laid on the geotextile (7) of the second span bearing plate (22), and a filler layer is laid on the geotextile (7) of the third span bearing plate and the subsequent bearing plates.

3. The stepped pile-slab structure for the transition section of a road and bridge according to claim 2, characterized in that, The surface layer (5) of the base bed is poured with graded crushed stone mixed with 5% cement.

4. A construction method for a stepped pile-slab structure in a road-bridge transition section, characterized in that, For constructing the stepped pile-slab structure of the road-bridge transition section as described in any one of claims 2-3, the method includes the following steps: S1. First determine the position of the Nth span bearing plate, then determine the position of the (N-1)th span bearing plate, the (N-2)th span bearing plate and so on until the position of the 1st span bearing plate (21); S2. Determine the mileage of the abutment (6), construct the abutment (6) pile foundation and the abutment (6), and backfill and compact the abutment foundation pit (60) with graded crushed stone or C25 concrete; S3. Excavate steps, use the excavated material from the road cut as fill material for the bridge backfill area construction, the roadbed outside the bearing plate structure section is filled with fill material, and compacted in layers to the bottom surface of the Nth span bearing plate; S4. Mark the location of the transition pile foundation (1), and then carry out the construction of the transition pile foundation (1), as well as the construction from the Nth span bearing plate to the N-1th span bearing plate; S5. The transition block (3) is set at the step angle formed by the Nth span bearing plate and the roadbed filling body (4), and at the step angle formed by the Nth span bearing plate and the N-1th span bearing plate. The two side walls of the transition block (3) are respectively connected to the vertical and horizontal planes of the corresponding step angles. S6. Level the load-bearing plate from the first span (21) to the Nth span using M35 concrete mortar, and then lay the geotextile (7). S7. Using the bearing plate structure constructed in step S4 as the boundary, fill the road cut excavation as fill material on the side near the bridge abutment, with a compaction degree of not less than 95%. In the transition section near the roadbed, fill qualified materials to the top of the bearing plate structure constructed in S4 according to the structural type and requirements of the roadbed in the section. S8. Repeat the construction of multiple transition piles (1) and the N-1th span bearing plate in the order of steps S4 to S7 until the construction of the 1st span bearing plate; S9. After the first span bearing plate (21) structure is completed, the subgrade surface layer (5) graded crushed stone is filled simultaneously with the subgrade of the section. The subgrade surface layer (5) within the length of the transition section is mixed with 5% cement, the compaction degree is not less than 97%, and the length of the transition section is not less than 20m.

5. The construction method of the stepped pile-slab structure for the transition section of a road and bridge according to claim 4, characterized in that, In step S3, small mechanical compaction is used to compact the bridge abutment (6) in a manner that does not damage the main structure of the bridge abutment (6), and the compaction degree is not less than 95%.

6. The construction method of the stepped pile-slab structure for the transition section of a road and bridge according to claim 4, characterized in that, In step S4, the diameter of the transition pile foundation (1) is not less than 1.0m, and it is cast with reinforced concrete of grade not lower than C35.

7. The construction method of the stepped pile-slab structure for the transition section of a road and bridge according to claim 4, characterized in that, In step S4, the depth of the transition pile foundation (1) into the weakly weathered bedrock layer is determined according to the bearing capacity calculation and shall not be less than 2m.

8. The construction method of the stepped pile-slab structure for the transition section of a road and bridge according to claim 4, characterized in that, In steps S4 and S8, the width of the Nth span bearing plate extends 0.5m beyond the stress influence line of the railway track slab; the length of the first span bearing plate (21) is 5.6m and is aligned with the plate seam of the track slab; the thickness of the first span bearing plate (21) is 1m to 1.5m.

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