Method and structure for combined construction of embankment under existing railway roadbed

Abstract

The application provides a method for combined construction when a dike underpasses a railway roadbed, which comprises the following steps: firstly, constructing a roadbed overhead system, overhead existing railway roadbed sections in a flood discharge range, removing the existing railway roadbed in the flood discharge range, and casting a continuous rigid frame; secondly, constructing a cross bridge head at the intersection of the dike planning axis and the existing railway roadbed axis to form the main body of the dike underpassing the railway section; thirdly, constructing structural dikes at both ends of the cross bridge head and backfilling the dikes; and finally, removing the roadbed overhead system; in the construction process, pile foundations are arranged for all structures to reduce the deformation influence of the additional load of the new project on the existing railway. The application effectively solves the technical problems of the space limitation of the dike underpassing the railway roadbed, the structural space shortage, the high requirement for the settlement deformation control, and the difficulty in railway operation and construction in the new river regulation project, and meets the use requirement of the new project under the premise of ensuring the safe operation of the existing railway.

Description

Technical Field

[0001] The present invention belongs to the technical field of water conservancy projects, and in particular relates to a method and structure for jointly building an embankment under an existing railway subgrade when the embankment is restricted. Background Art

[0002] Levee projects refer to water-retaining structures built along rivers, canals, lakes, coasts, or at the edges of floodways, diversion areas, and reclaimed areas. River regulation projects are currently increasing, with earth-filled levees widely used as the primary flood control structures. However, when new levees encounter existing railway subgrades, horizontal intersections hinder the smooth closure of the levees. The traditional method of dismantling and restoring them after filling is almost impossible, especially for busy main lines during operation. Therefore, the key issue for these projects is how to successfully construct and pass under the existing railway without affecting its long-term operational safety.

[0003] When the embankment is restricted from passing under the existing railway subgrade, the following problems mainly exist: 1. When the embankment top elevation is higher than the railway shoulder, there is a risk of subgrade flooding; 2. The fill embankment cannot be closed, and the railway subgrade filling material cannot meet the anti-seepage requirements; 3. The high fill height and large additional load can cause the surface settlement caused by the new embankment to often reach tens of centimeters, which is far greater than the control value required for railway smoothness; 4. After the river embankment is built, the existing hydrological conditions are changed, and the railway subgrade is located in the flood-prone area, resulting in water blocking. Swirls are formed locally at the cross-section changes, aggravating surface scouring; 5. The water level difference between the dry season and the flood season is large. The horizontal load caused by the head change cannot be ignored on the safety of railway operation; 6. Railway operation cannot be interrupted during the construction period. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for the joint construction of an embankment under an existing railway subgrade when the embankment is restricted, which can at least solve some of the defects existing in the prior art.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for constructing an embankment under an existing railway subgrade when the embankment is restricted, comprising the following steps:

[0007] 1) Construct a roadbed overhead system to overhead the existing railway roadbed section within the flood discharge range, and then remove the existing railway roadbed within the flood discharge range;

[0008] 2) Construct several first pile foundations below the roadbed overhead system, and cast the lower foundation of the continuous rigid frame on the first pile foundations;

[0009] 3) Construct several second pile foundations at the planned embankment axis and build a cross bridge head at the intersection of the planned embankment axis and the existing railway subgrade axis. The cross bridge head is located below the subgrade overhead system and supported on the second pile foundations. Then, a continuous rigid frame superstructure is constructed.

[0010] 4) Construct structural embankments at both ends of the embankment corresponding to the cross bridge head, and backfill the earth-filled embankment, with the cross-section of the structural embankment and the earth-filled embankment connected smoothly;

[0011] 5) Dismantle the roadbed overhead system.

[0012] Furthermore, the elevated roadbed system includes an elevated bridge deck and a number of elevated piles supported at the bottom of the elevated bridge deck. The elevated bridge deck fully covers the existing railway roadbed section within the flood discharge range, and both ends of the elevated bridge deck extend to the existing railway roadbed outside the flood discharge range.

[0013] Furthermore, the cross bridge head includes a cross-shaped base plate and a baffle portion and a support portion arranged on the base plate. The baffle portion is relatively arranged on both sides of the horizontal section of the cross-shaped base plate. There are two support portions, which are arranged on the vertical section of the cross-shaped base plate and are respectively located on the outside of the two baffle portions. The two support portions are respectively connected with the continuous rigid frame and the existing railway subgrade outside the flood discharge range.

[0014] Furthermore, in step 3), an anti-seepage wall is constructed at the planned foundation of the embankment. The anti-seepage wall is located directly below the cross bridge head and extends along the planned axis of the embankment to the bottom of the structural embankment.

[0015] Furthermore, the structural embankment adopts a structural form in which the width gradually expands from the cross bridge head to the fill embankment.

[0016] Furthermore, the step 4) also includes constructing a retaining wall at the end of the structural embankment, wherein the retaining wall is arranged in a direction perpendicular to the planned axis of the embankment, and a third pile foundation is provided at the bottom of the retaining wall.

[0017] Furthermore, the step 4) also includes constructing barbed walls at the junctions between the two ends of the structural embankment and the fill embankment, wherein the barbed walls are arranged along the planned axis of the embankment.

[0018] Furthermore, the step 4) also includes backfilling lightweight concrete inside the structural embankment to form an underpass inspection channel connecting the upper surface of the fill embankment and the cross bridge head.

[0019] Furthermore, the step 4) also includes constructing a bridge head cone slope at the cross intersection of the cross bridge head.

[0020] In addition, the present invention also provides a combined structure for the embankment to be constructed under the existing railway subgrade when the embankment is restricted, which is constructed using the above method.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The method provided by the present invention for building an embankment under an existing railway subgrade when the space is limited effectively solves the technical difficulties of limited structural space, high requirements for settlement and deformation control, and difficulty in railway operation and construction when the space is limited for the embankment project under the railway subgrade in the newly built river channel regulation project. It meets the use needs of the newly built project while ensuring the safety of the existing railway operation.

[0023] (2) In the method provided by the present invention for jointly constructing an embankment under an existing railway subgrade when the embankment is restricted, pile foundations are provided for all structures to reduce the deformation effect of the additional load of the new construction on the existing railway. At the same time, anti-seepage walls and thorn walls are provided at the bottom and ends of the structural embankment respectively to increase the seepage path of the water head in the depth direction and the horizontal direction.

[0024] The present invention will be described in further detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 1 is a schematic diagram of the construction of the roadbed overhead system in an embodiment of the present invention;

[0026] Figure 2 1 is a schematic diagram of the construction of a cross bridge head according to an embodiment of the present invention;

[0027] Figure 3 1 is a schematic diagram of the construction of a structural embankment according to an embodiment of the present invention;

[0028] Figure 4 This is a schematic diagram of a combined structure when the embankment is restricted from passing under the existing railway subgrade in an embodiment of the present invention;

[0029] Figure 5 2 is a schematic structural diagram of a cross bridge head in an embodiment of the present invention.

[0030] Explanation of the accompanying symbols: 1. Overhead pile; 2. Overhead bridge deck; 3. Existing railway roadbed; 4. First pile foundation; 5. Continuous rigid frame; 6. Cross bridge head; 7. Second pile foundation; 8. Anti-seepage wall; 9. Third pile foundation; 10. Bottom plate; 11. Baffle part; 12. Support part; 13. Structural embankment; 14. Barbed wall; 15. Retaining wall; 16. Bridge head cone slope; 17. Connecting beam; 18. Fill embankment; 19. Ramp; 20. Pier; 21. Pad layer. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0032] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship 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 device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0033] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "install", "connect" and "connect" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, a conflicting connection or an integral connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] The terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include one or more of such features; in the description of the present invention, unless otherwise specified, "plurality" or "several" means two or more.

[0035] This embodiment provides a method for constructing an embankment under an existing railway subgrade when restrictions are imposed. The specific construction process is as follows:

[0036] (1) Figure 1 As shown in the figure, the construction roadbed overhead system is to overhead three sections of the existing railway roadbed within the flood discharge range, so that the railway can still be temporarily operated during the construction period; then the existing railway roadbed 3 within the planned flood discharge range is excavated and filled section by section, thereby increasing the construction space under the embankment to pass through the existing railway roadbed while ensuring the operation of the existing railway.

[0037] Specifically, the roadbed overhead system includes an overhead bridge deck 2 and a number of overhead piles 1 supported at the bottom of the overhead bridge deck 2. The overhead bridge deck 2 fully covers the existing railway roadbed 3 section within the flood discharge range, and both ends of the overhead bridge deck 2 extend to the existing railway roadbed 3 outside the flood discharge range. After the existing railway roadbed 3 within the flood discharge range is removed, the overhead bridge deck 2 is used to replace the removed section of the existing railway roadbed 3 for temporary driving, ensuring the normal operation of the existing railway. Among them, the specific process of constructing the overhead piles 1 and the overhead bridge deck 2 on the existing railway roadbed 3 section within the flood discharge range is a conventional method in this field, and its specific operation process will not be repeated here.

[0038] (2) Construct a number of first pile foundations 4 below the roadbed overhead system, and cast the lower foundation of the continuous rigid frame 5 on the first pile foundations 4. Preferably, the first pile foundations 4 are arranged at equal intervals along the axis of the existing railway roadbed 3.

[0039] (3) Figure 2 As shown, several second pile foundations 7 are constructed at the planned axis of the embankment, and a cross bridge head 6 is jointly built at the intersection of the planned axis of the embankment and the axis of the existing railway roadbed 3. The cross bridge head 6 is located below the roadbed overhead system and supported on the second pile foundations 7. The cross bridge head 6 adopts a concrete structure and serves as the main body of the embankment under the railway section. It ensures the functional continuity of the embankment while facilitating construction; and then the upper structure of the continuous rigid frame 5 is constructed.

[0040] Specifically, such as Figure 5 As shown, the cross bridge head 6 includes a cross-shaped base plate 10 and a baffle portion 11 and a support portion 12 arranged on the base plate 10. The base plate 10 is supported on the second pile foundation 7. There are two baffle portions 11, which are relatively arranged on both sides of the horizontal section of the cross-shaped base plate, that is, the baffle portions 11 are arranged parallel to the planned axis direction of the embankment. The space enclosed by the two baffle portions 11 and the base plate 10 can be used as a channel; optionally, a cushion layer 21 can be provided on the base plate 10 in the channel for connection with the ramp 19 of subsequent construction. There are two support parts 12, which are arranged on the vertical section of the cross-shaped bottom plate 10 and are respectively located on the outside of the two baffle parts 11, that is, the support parts 12 are arranged along the axial direction of the existing railway roadbed 3, and the support part 12 on the side of the existing railway roadbed 3 that has not been removed outside the flood discharge range is connected with the existing railway roadbed 3 of this section, and the support part 12 on the side of the existing railway roadbed 3 that has not been removed outside the flood discharge range is connected with the continuous rigid frame 5 within the flood discharge range, playing a supporting role similar to that of a bridge pier, and can be used to bear the subsequent load of the railway section; at the same time, a connecting beam 17 is provided between the two baffle parts 11, and the two support parts 12 are connected into a whole by the connecting beam 17, and the upper surface of the support part 12 and the upper surface of the connecting beam 17 are located in the same plane; and a space for flood control vehicles and maintenance personnel to pass through is formed between the connecting beam 17 and the cushion layer 21.

[0041] Preferably, the cross bridge head 6 in this embodiment can be in the form of a prefabricated structure integrally cast and formed with the bottom plate 10, the baffle part 11, the support part 12 and the connecting beam 17, thereby improving the construction efficiency.

[0042] Further, the side edges of the support part 12 connected with the continuous rigid frame 5 are provided with piers for supporting the end part of the superstructure of the continuous rigid frame 5, so that the superstructure of the continuous rigid frame 5 is connected with the cross bridge head 6.

[0043] Optimally, a cutoff wall 8 is constructed at the foundation of the embankment plan, which is located directly below the cross bridge head 6 and extends along the axis direction of the embankment plan, and the cutoff wall 8 is designed below the cross bridge head 6 to increase the seepage path of the water head along the depth direction. Further, the cutoff wall 8 extends beyond the end part of the cross bridge head 6 at both ends, and preferably the end part of the cutoff wall 8 extends to the bottom of the designed fill embankment 18.

[0044] (4) As shown in the figure, the structural embankment 13 is constructed at both ends of the cross bridge head 6 corresponding to the embankment, and the fill embankment 18 is backfilled, and the cross sections of the structural embankment 13 and the fill embankment 18 are connected in sequence. Figure 3

[0045] In this embodiment, the structural embankment 13 is in the form of gradually expanding from the cross bridge head 6 to the width of the fill embankment 18, so as to be connected in sequence with the fill embankment 18; the structural embankment 13 is located on the axis of the embankment plan, therefore, the bottom of the structural embankment 13 is also supported by the second pile foundation 7 to reduce the deformation influence of its load on the existing railway. Optimally, the retaining wall 15 is constructed at the end part of the structural embankment 13, which is arranged along the direction perpendicular to the axis of the embankment plan, and the retaining wall 15 is located between the structural embankment 13 and the fill embankment 18 to meet the need of retaining soil at the section difference between the fill section (i.e. the fill embankment) and the structural section (i.e. the structural embankment); similarly, in order to reduce the deformation influence of the load of the retaining wall 15 on the existing railway, the third pile foundation 9 is arranged at the bottom of the retaining wall 15 to support it.

[0046] Further, the stab wall 14 is constructed at the connection part between the structural embankment 13 and the fill embankment 18 before backfilling the fill embankment 18, which is arranged along the axis direction of the embankment plan, and the seepage path of the water head along the horizontal direction is increased by the stab wall 14; preferably, the stab wall 14 is arranged on the cutoff wall 8, so that the horizontal anti-seepage structure (i.e. the stab wall 14) and the vertical anti-seepage structure (i.e. the cutoff wall 8) can jointly act to achieve more effective anti-seepage purpose.

[0047] Optionally, after backfilling the fill embankment 18, the inside of the structural embankment 13 is backfilled with lightweight concrete counterweight and poured into the ramp 19 to connect the passageway of the cross bridge head 6 with the upper surface of the fill embankment 18, which serves as a maintenance passageway under the cross bridge head 6, and the filling density in the inside of the structural embankment is determined according to the deformation calculation of the existing railway.​

[0048] Optionally, a bridge head cone slope 16 is constructed at the cross intersection of the cross bridge head 6 to ensure the stability of the connection between the railway section and the embankment structure and prevent scouring.

[0049] (5) After all structures are constructed, the roadbed overhead system is dismantled to form Figure 4 The structure shown is constructed when the embankment is restricted from passing under the existing railway subgrade.

[0050] Furthermore, before dismantling the overhead roadbed system, ballast is constructed on the upper surface of the continuous rigid frame and the cross bridge head to fill the space between the overhead bridge deck and the upper surface of the continuous rigid frame and the cross bridge head, thereby restoring the smoothness of the existing railway.

[0051] The above examples are merely illustrative of the present invention and do not limit the scope of protection of the present invention. Any design that is identical or similar to the present invention falls within the scope of protection of the present invention.

Claims

1. A method for constructing an embankment under an existing railway subgrade when the embankment is restricted, characterized in that: The steps include: 1) Construct a roadbed overhead system to overhead the existing railway roadbed section within the flood discharge range, and then remove the existing railway roadbed within the flood discharge range; 2) Construct several first pile foundations below the roadbed overhead system, and cast the lower foundation of the continuous rigid frame on the first pile foundations; 3) Construct several second pile foundations at the planned embankment axis and build a cross bridge head at the intersection of the planned embankment axis and the existing railway subgrade axis. The cross bridge head is located below the subgrade overhead system and supported on the second pile foundations. Then, a continuous rigid frame superstructure is constructed. The cross bridge head includes a cross-shaped bottom plate and a baffle portion and a support portion provided on the bottom plate. The baffle portions are relatively provided on both sides of the horizontal section of the cross-shaped bottom plate. There are two support portions provided on the vertical section of the cross-shaped bottom plate and respectively located outside the two baffle portions. The two support portions are respectively connected to the continuous rigid frame and the existing railway roadbed outside the flood discharge range. A connecting beam is provided between the two baffle portions. The two support portions are connected to form a whole by the connecting beam. The upper surface of the support portion and the upper surface of the connecting beam are located in the same plane. 4) Construct structural embankments at both ends of the embankment corresponding to the cross bridge head, and backfill the earth-filled embankment, with the cross-section of the structural embankment and the earth-filled embankment connected smoothly; 5) Dismantle the roadbed overhead system.

2. The method for constructing an embankment under an existing railway subgrade when conditions are limited as claimed in claim 1, characterized in that: The elevated roadbed system includes an elevated bridge deck and several elevated piles supported at the bottom of the elevated bridge deck. The elevated bridge deck fully covers the existing railway roadbed section within the flood discharge range, and both ends of the elevated bridge deck extend to the existing railway roadbed outside the flood discharge range.

3. The method for constructing an embankment under an existing railway subgrade when conditions are limited as claimed in claim 1, characterized in that: In the step 3), an anti-seepage wall is constructed at the planned foundation of the embankment. The anti-seepage wall is located directly below the cross bridge head and extends along the planned axis of the embankment to the bottom of the structural embankment.

4. The method for constructing an embankment under an existing railway subgrade when conditions are limited as claimed in claim 1, characterized in that: The structural embankment adopts a structural form in which the width gradually expands from the cross bridge head to the fill embankment.

5. The method for constructing an embankment under an existing railway subgrade when conditions are limited as claimed in claim 1, characterized in that: The step 4) further includes constructing a retaining wall at the end of the structural embankment, wherein the retaining wall is arranged in a direction perpendicular to the planned axis of the embankment, and a third pile foundation is provided at the bottom of the retaining wall.

6. The method for constructing an embankment under an existing railway subgrade when conditions are limited as claimed in claim 1, characterized in that: The step 4) further includes constructing barbed walls at the junctions between the two ends of the structural embankment and the fill embankment, wherein the barbed walls are arranged along the planned axis of the embankment.

7. The method for constructing an embankment under an existing railway subgrade when conditions are limited as claimed in claim 1, characterized in that: The step 4) also includes backfilling lightweight concrete inside the structural embankment to form an underpass inspection channel connecting the upper surface of the fill embankment and the cross bridge head.

8. The method for constructing an embankment under an existing railway subgrade when restrictions are imposed as claimed in claim 1, characterized in that: The step 4) also includes constructing a bridge head cone slope at the cross intersection of the cross bridge head.

9. A combined structure for the purpose of limiting the passage of an embankment under an existing railway subgrade, characterized in that: The method according to any one of claims 1 to 8 is used for construction.

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