A rockfall-proof shed tunnel for mountain railway bridge

Abstract

The utility model discloses a rockfall-proof shed tunnel for railway bridges in mountainous areas, wherein the main beam comprises longitudinal beams A, B, C, D and transverse beams A, B, C, D, E which are crisscrossed, and is designed as a "grid" type in which longitudinal and transverse beams intersect, and both the transverse beams and longitudinal beams are prestressed reinforced concrete components. The structure of the utility model can ensure the structural safety of the main beam of the rockfall-proof shed tunnel for railway bridges during the construction and operation stages, so that the bearing capacity and stress of the main beam of the rockfall-proof shed tunnel for railway bridges during the construction and operation processes meet the safety requirements of the specifications, and the method is simple, the construction period is reasonable, and it has important social and economic significance.

Description

Technical Field

[0001] The utility model belongs to the technical field of railway protection engineering design and construction, in particular to a rockfall prevention shed tunnel for railway bridges in mountainous areas. Background Art

[0002] Railway projects in mountainous areas of southwest my country are facing the threat of dangerous rocks and falling rocks. Once they are damaged, they will affect the construction and operation of railways and cause huge losses. In order to protect railway projects, some railway line areas will set up rockfall-proof sheds above railway projects. Bridge projects in railway projects have special structures. The span and size of rockfall-proof sheds will "accommodate" the bridges and make them longer and larger. Therefore, the main beams of rockfall-proof sheds should be designed as a "grid" type with longitudinal and transverse beams crossing, and prestressed steel strands should be configured for the longitudinal and transverse beams. The "Code for Design of Concrete Structures of Railway Bridges and Culverts" (TB10092-2017) stipulates that the maximum compressive stress of concrete in the force transmission and anchoring stage is 20.1MPa, and the maximum tensile stress of concrete is 1.73MPa. Due to the intersection of the main longitudinal beam and the main transverse beam, the prestressing of a single beam is bound to affect the force changes of the surrounding longitudinal and transverse beams. If a reasonable method for prestressing the steel strands of the main beams of the rockfall-proof sheds cannot be formulated, it is very likely that when beam A is tensioned, beam B will be affected and cracked.

[0003] Therefore, it is necessary to develop a design and tensioning method for prestressed steel strands of the main beam of the large-span rockfall protection shed tunnel of railway bridges to ensure the safety of the shed tunnel main beam structure during construction and operation. Summary of the invention

[0004] The purpose of the utility model is to provide a rockfall-proof shed tunnel for railway bridges in mountainous areas, which is a large-span rockfall-proof shed tunnel, including the design of the prestress of the main beam and the formulation of the tensioning method, which can ensure that the main beam structure is in a safe and reasonable stress state during the operation process after the construction is completed, and well solve the stress overlimit problem of the longitudinal main beam and the transverse main beam of the rockfall-proof shed tunnel during the prestressing tensioning process. Through reasonable prestressed steel beam design and tensioning method, the purpose of the internal force and stress of the concrete of the large-span rockfall-proof shed tunnel main beam meeting the regulatory requirements during the construction and operation process can be achieved, and the safety of the shed tunnel main beam structure can be guaranteed.

[0005] In order to solve the above problems, the utility model adopts the following technical solutions:

[0006] A rockfall prevention tunnel for a railway bridge in a mountainous area, wherein the main beam comprises longitudinal beams A, B, C, D, transverse beams A, B, C, D and E, and is designed in a grid pattern in which longitudinal and transverse beams intersect, and both the transverse beams and longitudinal beams are prestressed reinforced concrete components.

[0007] Preferably, longitudinal beams A and D are divided into four types of prestressed steel bundles according to the linear shape of the steel bundle arrangement, numbered N1~N4. The four types of steel bundles all use 7-strand steel wires with the same number of wires. All steel bundles are not provided with horizontal bends, the N1 steel bundle is not provided with vertical bends, and the vertical bend radius of the N2~N4 steel bundles is R=6000cm.

[0008] Preferably, longitudinal beams B and C are divided into four types of prestressed steel bundles according to the linear shape of the steel bundle arrangement, numbered N5~N8. The four types of steel bundles all use 7-strand steel wires with the same number of wires. All steel bundles are not provided with horizontal bends, the N5 steel bundle is not provided with vertical bends, and the vertical bend radius of the N6~N8 steel bundles is R=6000cm.

[0009] Preferably, cross beam A and cross beam E are divided into 4 types of prestressed steel bundles according to the linear shape of the steel bundle arrangement, numbered N9~N12, and the 4 types of steel bundles all use 7-strand steel wires, the number of wires of N9 and N10 is the same, the number of wires of N11 and N12 is the same and is greater than that of N9 and N10, all steel bundles are not provided with horizontal bends, the N9 steel bundle is not provided with vertical bends, and the vertical bend radius of the N10~N12 steel bundles is R=6000cm.

[0010] Preferably, beams B, C and D are divided into two types of prestressed steel bundles according to the linear shape of the steel bundle arrangement, numbered N13~N14. Both types of steel bundles use 7-strand steel wire with the same number of wires. All steel bundles are not provided with flat bends, and the vertical bend radius of N13~N14 steel bundles is R=6000cm.

[0011] The utility model has the following advantages:

[0012] (1) The main beam of the large-span rockfall protection tunnel of the mountain railway bridge was designed using the prestressing method to ensure that the main beam structure meets the regulatory requirements when the bridge is in operation and is safe and reasonable.

[0013] (2) Compared with the structure of a one-way beam, the main beam of the rockfall protection shed tunnel contains both longitudinal beams and transverse beams. During the prestressing process, the forces on the longitudinal and transverse beams affect each other. By formulating a matching and reasonable prestressing method, the structural safety of the main beam during construction is guaranteed and the occurrence of cracks that affect the overall project quality can be avoided.

[0014] (3) The project was implemented smoothly, with simple methods, short construction period, economic rationality and technological innovation. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a cross-section diagram of the rockfall prevention shed cave;

[0016] Figure 2 This is a schematic diagram of the longitudinal section of the rockfall prevention shed cave;

[0017] Figure 3 This is a plan view of the main beam of the rockfall protection shed tunnel;

[0018] Figure 4 This is the elevation layout of the prestressed steel strands of A and D longitudinal beams;

[0019] Figure 5 It is the plan layout of the prestressed steel strands of A and D longitudinal beams;

[0020] Figure 6 It is a schematic diagram of the cross section of the steel bundle at the mid-span of the A and D longitudinal beams;

[0021] Figure 7 It is a schematic diagram of the cross section of the steel bundle at the anchorage of the A and D longitudinal beams;

[0022] Figure 8 This is the elevation layout of the prestressed steel strands of the B and C longitudinal beams;

[0023] Fig. 9 It is the plan layout of the prestressed steel tendons of B and C longitudinal beams;

[0024] Fig.10 It is a schematic diagram of the cross section of the steel bundle at the mid-span of the B and C longitudinal beams;

[0025] Fig.11 It is a schematic diagram of the cross section of the steel bundle at the anchorage of the B and C longitudinal beams;

[0026] Fig.12 This is the elevation layout of the prestressed steel strands of beams A and E;

[0027] Fig.13 This is the plan layout of the prestressed steel tendons of beams A and E;

[0028] Fig.14 This is a schematic diagram of the cross section of the steel bundle at the mid-span of beams A and E;

[0029] Fig.15 It is a schematic diagram of the cross section of the steel bundle at the anchorage of the A and E beams;

[0030] Fig.16 This is the elevation layout of the prestressed steel strands of the B, C, and D beams;

[0031] Fig.17 This is the plan layout of the prestressed steel strands of beams B, C, and D;

[0032] Fig.18 This is a schematic diagram of the cross section of the steel bundle at the mid-span of the B, C, and D beams;

[0033] Fig.19 It is a schematic diagram of the cross section of the steel bundle at the anchorage of the B, C, and D beams;

[0034] Fig. 20 It is the method of tensioning the prestressed steel tendons of the main beam.

[0035] In the figure: 1-longitudinal beam, 11-longitudinal beam A, 12-longitudinal beam B, 13-longitudinal beam C, 14-longitudinal beam D, 2-cross beam, 21-cross beam A, 22-cross beam B, 23-cross beam C, 24-cross beam D, 25-cross beam E, 3-railway bridge in rockfall area. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and beneficial effects of the patent of the utility model clearer, the preferred implementation of the utility model will be described in detail below in conjunction with the accompanying drawings to facilitate the understanding of technical personnel.

[0037] like Figure 1-20 As shown, the utility model discloses a main beam prestressing design and tensioning method for a rockfall-proof shed tunnel of a mountain railway bridge, including the following implementation sequence and steps:

[0038] (1) Design of the model and layout of the prestressed steel strands of the main beam of the rockfall protection shed tunnel:

[0039] Applicable objects are rockfall protection shed tunnels for railway bridges in mountainous areas. The structure needs to adapt to the protected railway bridges. Therefore, the span and size of the main beam of the shed tunnel are relatively large, and it is necessary to design it into a prestressed reinforced concrete component with staggered longitudinal and transverse main beams. The schematic diagram of the shed tunnel structure is shown in Figure 1~Figure 3 ;

[0040] Longitudinal beams A and D are divided into 4 types of prestressed steel strands according to the arrangement line of steel strands, numbered N1~N4. All 4 types of steel strands use 7 strands of steel strands with the same number of wires. The specific number depends on the span and size of the main beam. All steel strands are not set with horizontal bends. N1 steel strand is not set with vertical bends. N2~N4 steel strands have a vertical bend radius of R=6000cm. The number of strands and cross-sectional arrangement are shown in Figures 4 and 5 The specific spacing between steel strands, the total length of steel strands, the length of the bend, and the location of the anchor points should be determined flexibly based on the span and size of the main beam while meeting the specifications and structural requirements. See the steel strand arrangement diagram for details. Figures 4 to 7 .

[0041] Longitudinal beams B and C are divided into 4 types of prestressed steel strands according to the steel strand arrangement line shape, numbered N5~N8. All 4 types of steel strands use 7 strands of steel strands with the same number of wires. The specific number depends on the span and size of the main beam. All steel strands are not set with horizontal bends, N5 steel strands are not set with vertical bends, and N6~N8 steel strands have a vertical bend radius of R=6000cm. The number of strands and cross-sectional arrangement are shown in Figures 6 and 7 The specific spacing between steel strands, the total length of steel strands, the length of the bend, and the location of the anchor points should be determined flexibly based on the span and size of the main beam while meeting the specifications and structural requirements. See the steel strand arrangement diagram for details. Figures 8 to 11 .

[0042] According to the arrangement line of steel strands, beams A and E are divided into 4 types of prestressed steel strands, numbered N9~N12. All 4 types of steel strands use 7-strand steel strands. The number of strands of N9 and N10 is the same, and the number of strands of N11 and N12 is the same and larger than that of N9 and N10. The specific number depends on the span and size of the main beam. All steel strands are not set with horizontal bends, and the N9 steel strand is not set with vertical bends. The vertical bend radius of N10~N12 steel strands is R=6000cm. The number of strands and cross-sectional arrangement are shown in Figures 8 and 9 The specific spacing between steel strands, the total length of steel strands, the length of the bend, and the location of the anchor points should be determined flexibly based on the span and size of the main beam while meeting the specifications and structural requirements. See the steel strand arrangement diagram for details. Figures 12 to 15 .

[0043] According to the arrangement line of steel strands, beams B, C and D are divided into two types of prestressed steel strands, numbered N13~N14. Both types of steel strands use 7 strands of steel strands with the same number of wires. The specific number depends on the span and size of the main beam. All steel strands are not set with flat bends. The vertical bend radius of N13~N14 steel strands is R=6000cm. The number of strands and cross-sectional arrangement are shown in Figures 10-11 The specific spacing between steel strands, the total length of steel strands, the length of the bend, and the location of the anchor points should be determined flexibly based on the span and size of the main beam while meeting the specifications and structural requirements. See the steel strand arrangement diagram for details. Figures 16 to 19 .

[0044] (2) Design of prestressed steel tendon tensioning method during the construction phase of the main beam of the rockfall shed tunnel:

[0045] The main longitudinal beam and the main transverse beam intersect, and the prestressing of a single beam will inevitably affect the force changes of the surrounding longitudinal and transverse beams. If a reasonable prestressing method for the main beam of the rockfall shed tunnel cannot be formulated, it is very likely that when a beam is tensioned, the adjacent beams will be affected and cracked. The tensioning method should avoid using a single beam as a unit, that is, tensioning all the steel strands of a longitudinal beam before tensioning all the steel strands of another transverse beam. Instead, use the steel strand model as a unit, that is, tensioning a certain type of steel strand of a longitudinal beam before tensioning a certain type of steel strand of another transverse beam, and then alternate between the longitudinal and transverse beams. After finite element calculation and analysis, the final steel strand tensioning method is obtained, and the tensioning sequence is shown in Fig. 20 ;

[0046] (3) Establish a three-dimensional finite element model to verify the bearing capacity and stress of the main beam of the rockfall shed during the construction and operation stages;

[0047] (4) Set up the support and carry out the construction of the lower structure of the shed;

[0048] (5) Set up the support, tie the ordinary steel bars of the upper structure main beam, arrange the prestressed steel bars, and then cast the upper structure main beam;

[0049] (6) When the concrete strength and elastic modulus of the beam segment reach 100% of the design value and the age of the concrete is not less than 10 days, the prestressed tendons of the longitudinal and transverse beams are tensioned and anchored according to the tensioning method proposed in step (2), and finally the pipe grouting is carried out.

[0050] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the utility model.

Claims

1. A rockfall-proof tunnel for railway bridges in mountainous areas, characterized in that: The main beam includes longitudinal beam A, longitudinal beam B, longitudinal beam C, longitudinal beam D, transverse beam A, transverse beam B, transverse beam C, transverse beam D and transverse beam E, which are designed in a grid type with longitudinal and transverse beams intersecting. Both the transverse beams and longitudinal beams are prestressed reinforced concrete components.

2. The rockfall prevention tunnel for mountain railway bridge according to claim 1 is characterized in that: Longitudinal beams A and D are divided into four types of prestressed steel strands according to the linear shape of the steel strands, numbered N1~N4. All four types of steel strands use 7-strand steel wire with the same number of wires. All steel strands are not set with horizontal bends. N1 steel strand is not set with vertical bends. The vertical bend radius of N2~N4 steel strands is R=6000cm.

3. The rockfall prevention tunnel for mountain railway bridge according to claim 1 is characterized in that: Longitudinal beams B and C are divided into four types of prestressed steel strands according to the linear shape of the steel strands, numbered N5~N8. All four types of steel strands use 7-strand steel wire with the same number of wires. All steel strands are not equipped with horizontal bends. N5 steel strand is not equipped with vertical bends. The vertical bend radius of N6~N8 steel strands is R=6000cm.

4. The rockfall-proof tunnel for mountain railway bridge according to claim 1, characterized in that: According to the linear shape of the steel bundles, beams A and E are divided into 4 types of prestressed steel bundles, numbered N9~N12. All 4 types of steel bundles use 7-strand steel wires. The number of wires of N9 and N10 is the same, the number of wires of N11 and N12 is the same and larger than that of N9 and N10. All steel bundles are not set with horizontal bends, the N9 steel bundle is not set with vertical bends, and the vertical bend radius of N10~N12 steel bundles is R=6000cm.

5. The rockfall prevention tunnel for mountain railway bridge according to claim 1 is characterized in that: According to the arrangement line of steel bundles, beams B, C and D are divided into two types of prestressed steel bundles, numbered N13~N14. Both types of steel bundles use 7-strand steel wire with the same number of wires. All steel bundles are not equipped with flat bends. The vertical bend radius of N13~N14 steel bundles is R=6000cm.

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