A ballastless track bridge transition structure, design method and construction method

Abstract

The present invention relates to a ballastless track road-bridge transition structure, a design method and a construction method. A rigid support structure located at the abutment is formed by a retaining wall, a corbel, a bearing beam and a pile cap slab, so that the stiffness change point of the road-bridge transition section is shifted from the road-bridge boundary to the boundary between the rigid support structure and the stiffness transition structure, avoiding differential settlement caused by insufficient compaction of the backfill of the abutment and reducing its influence on the smoothness of the road-bridge transition section; by using the retaining wall to enclose the backfill of the abutment and part of the fill in the transition section, compared with the backfill of the abutment, large mechanical equipment can be used to compact the fill in the transition section, and the compaction degree of the fill can meet the design requirements; at the same time, the gravity loads of the bearing beam, the pile cap slab and the track structure, as well as the dynamic load of the train can be transmitted to the retaining wall through the corbel, increasing the positive pressure of the retaining wall acting on the foundation and offsetting part of the bending moment borne by the retaining wall, and increasing the anti-slip and anti-overturning stability of the retaining wall; this structure can effectively solve the problem of differential settlement in the road-bridge transition section of high-speed railways.

Description

Technical Field

[0001] The invention relates to the technical field of road and bridge construction engineering, in particular to a ballastless track road and bridge transition structure and a design method and a construction method. Background Art

[0002] my country already has the world's largest and fastest high-speed railway network, and high-speed railways require track structures to have high smoothness. The transition section between the roadbed and the bridge is an important part of the high-speed railway and has a significant impact on the line smoothness. Differential settlement is the main control factor for whether the train runs smoothly and comfortably in the transition section. Excessive differential settlement in the transition section will pose a threat to the safety of high-speed railway operations. The current "High-speed Railway Design Specifications" have extremely strict control over the differential settlement of the ballastless track-bridge transition section. The post-construction differential settlement at the junction of the roadbed and the bridge should not be greater than 5mm, and the angle caused by uneven settlement should not be greater than 1 / 1000. At present, the high-speed railway road-bridge transition section usually adopts an inverted trapezoidal transition structure close to the end of the bridge abutment along the longitudinal direction of the line, and the transition structure is filled with graded crushed stone mixed with 3% cement.

[0003] It is impossible to carry out large-scale mechanical rolling construction on the back of the abutment of the existing road-bridge transition section structure, and it is difficult to meet the compaction standard requirements by using small-scale mechanical compaction. The roadbed settlement control indicators near the end of the abutment may easily exceed the limit, affecting the smoothness of the bridge-road transition section and threatening the safety of train operation. Summary of the invention

[0004] The purpose of the present invention is to provide a ballastless track bridge-road transition structure and a design method and a construction method for resisting differential settlement of a high-speed railway bridge-road transition section, in view of the problems that large-scale mechanical rolling construction cannot be carried out at the back of the abutment of the existing road-bridge transition section structure in the prior art, and it is difficult to meet the compaction standard requirements by using small-scale mechanical compaction, and the roadbed settlement control index near the end of the abutment is easily exceeded, which affects the smoothness of the bridge-road transition section and threatens the safety of train operation.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A ballastless track road-bridge transition structure is used to connect an abutment and a roadbed. The transition structure includes a rigid supporting structure and a rigid transition structure. The rigid supporting structure includes a retaining wall. The retaining walls are respectively arranged on both sides of the track behind the abutment. A plurality of brackets are arranged on the inner side of the retaining wall. The brackets arranged opposite to each other on the two retaining walls are provided with supporting beams. The supporting beams are provided with a capping plate. The capping plate is used to lay a track structure. The rigid transition structure includes a backfill and a transition section fill. The backfill of the abutment is filled with an inverted trapezoid in the rigid supporting structure, and the transition section fill is filled between the rigid supporting structure and the roadbed.

[0007] By adopting the ballastless track road-bridge transition structure described in the present invention, the rigid support structure located at the abutment is formed by the retaining wall, the corbel, the joist and the cap plate, and the stiffness change point of the road-bridge transition section is moved from the road-bridge boundary to the boundary between the rigid support structure and the stiffness transition structure, thereby avoiding differential settlement caused by insufficient rolling of the abutment backfill and reducing its influence on the smoothness of the road-bridge transition section; the abutment backfill and part of the transition section fill are enclosed by the retaining wall, compared with the abutment backfill, The transition section backfill can be compacted by large-scale machinery, and the compaction degree of the backfill can meet the design requirements; at the same time, the gravity load of the support beam, the pedestal plate, the track structure and the dynamic load of the train can be transmitted to the retaining wall through the corbel, thereby increasing the positive pressure of the retaining wall on the foundation, and offsetting a part of the bending moment of the retaining wall, thereby increasing the stability of the retaining wall against slippage and overturning; the structure can effectively solve the problem of differential settlement of the high-speed railway road-bridge transition section, ensure the safe operation of high-speed railway trains, and is convenient and feasible in construction, with broad application prospects.

[0008] Preferably, steps are respectively provided at the junctions of the transition section fill, the platform back fill and the roadbed fill.

[0009] Preferably, the roadbed comprises a lower embankment and an upper base bed.

[0010] Preferably, the filling slope at the junction of the platform backfill, the transition section fill and the roadbed fill is 1:1.

[0011] Preferably, a conical slope is provided at the outer interface between the transition section fill and the rigid support structure.

[0012] The present invention also provides a construction method for a ballastless track-road-bridge transition structure, which is used to construct the ballastless track-road-bridge transition structure as described in any one of the above items, and the method comprises the following steps:

[0013] S1, constructing the retaining wall, erecting the formwork, laying the steel cage, arranging the corbels on the retaining wall, and then pouring concrete to form the pile body and the corbels;

[0014] S2, synchronously filling the backfill of the platform, the transition section fill, and the roadbed fill to the joist in layers, the backfill of the platform is compacted by a small machine, and the transition section fill and the roadbed fill are compacted by a large machine;

[0015] S3, hoisting the prefabricated joist;

[0016] S4, reserving the position of the cap plate, and continuing to synchronously fill the backfill of the platform, the transition section fill, and the roadbed fill in layers until the roadbed is at the designed elevation;

[0017] S5. Hoisting the prefabricated foundation plate.

[0018] By adopting the construction method of the ballastless track road-bridge transition structure described in the present invention, the rigid support structure located at the abutment is formed by the retaining wall, the corbel, the support beam and the cap plate, and the stiffness change point of the road-bridge transition section is moved from the road-bridge boundary to the boundary between the rigid support structure and the stiffness transition structure, thereby avoiding differential settlement caused by insufficient rolling of the abutment backfill and reducing its influence on the smoothness of the road-bridge transition section; the abutment backfill and part of the transition section fill are enclosed by the retaining wall, compared with the abutment backfill Filling, the transition section filling can be compacted by large-scale machinery, and the compaction degree of the filling can meet the design requirements; at the same time, the gravity load of the support beam, the pedestal plate, the track structure and the dynamic load of the train can be transmitted to the retaining wall through the corbel, thereby increasing the positive pressure of the retaining wall on the foundation, and offsetting a part of the bending moment of the retaining wall, thereby increasing the stability of the retaining wall against slippage and overturning; this method can effectively solve the problem of differential settlement in the transition section of the high-speed railway road and bridge, ensure the safe operation of high-speed railway trains, and is convenient and feasible in construction, with broad application prospects.

[0019] Preferably, grouting holes are reserved on the foundation plate, and the gap between the foundation plate and the backfill is filled with grouting through the grouting holes.

[0020] Preferably, the gap between the abutment and the retaining wall is closed by hoisting a retaining plate.

[0021] Preferably, the backfill of the platform is filled with fillers of groups A, B, and C, with a compaction coefficient K ≥ 0.93 and a foundation coefficient K 30 ≥130MPa / m.

[0022] Preferably, the transition section fill is made of graded crushed stone mixed with 3% cement, with a compaction coefficient K≥0.95 and a foundation coefficient K 30 ≥150MPa / m, dynamic deformation modulus E vd ≥50MPa.

[0023] Preferably, when the backfill of the platform, the transition section fill and the roadbed fill are filled, the paving and rolling thickness is 15 cm to 30 cm.

[0024] The present invention also provides a design method for a ballastless track-road-bridge transition structure, which is used to design a ballastless track-road-bridge transition structure as described in any one of the above items, and the method comprises the following steps:

[0025] Step 1: Check and calculate the subgrade settlement and deformation

[0026] Converting the train load, the track load, the deadweight load of the cap plate, and the deadweight load of the joist into a total uniformly distributed load acting on the joist;

[0027] calculating the moment of inertia of the cross section of the joist;

[0028] determining a maximum deflection of the joist based on a total uniformly distributed load acting on the joist and a moment of inertia of a section of the joist;

[0029] The maximum deflection of the joist is less than or equal to the allowable settlement value of the roadbed, and the allowable settlement value of the roadbed is obtained according to the corresponding design specifications;

[0030] Step 2: Checking the bearing capacity of the retaining wall foundation

[0031] Correcting the characteristic value of foundation bearing capacity, and calculating the foundation bearing capacity of the retaining wall using the corrected characteristic value of foundation bearing capacity;

[0032] Step 3: Use the bearing capacity of the retaining wall foundation to perform small eccentricity check on the retaining wall.

[0033] By adopting the design method of a ballastless track road-bridge transition structure described in the present invention, the maximum deflection of the support beam is strictly controlled to be less than or equal to the allowable settlement value of the roadbed, and the bearing capacity of the retaining wall foundation is strictly set to be able to resist the vertical force of the load and large eccentricity, so that the rigid support structure has sufficient rigidity, and the stiffness change point of the road-bridge transition section is moved from the road-bridge boundary to the boundary between the rigid support structure and the stiffness transition structure. The design method has simple steps, convenient calculation and good effect.

[0034] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0035] 1. The ballastless track road-bridge transition structure and construction method described in the present invention forms the rigid support structure located at the abutment through the retaining wall, the corbel, the joist and the cap plate, and moves the stiffness change point of the road-bridge transition section from the road-bridge boundary to the boundary between the rigid support structure and the stiffness transition structure, thereby avoiding differential settlement caused by insufficient rolling of the abutment backfill and reducing its influence on the smoothness of the road-bridge transition section; the abutment backfill and part of the transition section fill are enclosed by the retaining wall, compared with the abutment backfill, The transition section filling can be rolled by large-scale machinery, and the compaction degree of the filling can meet the design requirements; at the same time, the gravity load of the support beam, the cap plate, the track structure and the dynamic load of the train can be transmitted to the retaining wall through the bracket, thereby increasing the positive pressure of the retaining wall on the foundation, and offsetting a part of the bending moment of the retaining wall, thereby increasing the anti-slip and anti-overturning stability of the retaining wall; the structure and construction method can effectively solve the problem of differential settlement of the high-speed railway road-bridge transition section, ensure the safe operation of high-speed railway trains, and the construction is convenient and feasible, with broad application prospects;

[0036] 2. The design method of a ballastless track road-bridge transition structure described in the present invention strictly controls the maximum deflection of the support beam to be less than or equal to the allowable settlement value of the roadbed, and strictly sets the bearing capacity of the retaining wall foundation to be able to resist the vertical force of the load and large eccentricity, so that the rigid support structure has sufficient rigidity, and the stiffness change point of the road-bridge transition section is moved from the road-bridge boundary to the boundary between the rigid support structure and the stiffness transition structure. The design method has simple steps, convenient calculation and good effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the main view of the ballastless track-road-bridge transition structure;

[0038] Figure 2 It is a top view schematic diagram of the ballastless track road-bridge transition structure;

[0039] Figure 3 for Figure 2 Schematic diagram of longitudinal section along AA direction;

[0040] Figure 4 for Figure 2 Schematic diagram of the cross section along the middle BB direction;

[0041] Figure 5 Schematic diagram of retaining wall stress analysis.

[0042] Markings in the figure: 1- abutment, 2- retaining wall, 3- corbel, 4- beam, 5- capping plate, 6- abutment back fill, 7- transition section fill, 8- roadbed, 9- embankment, 10- base bed, 11- cone slope. DETAILED DESCRIPTION

[0043] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0044] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0045] Example 1

[0046] like Figures 1 to 4 As shown, a ballastless track road-bridge transition structure described in the present invention is used to connect the abutment 1 and the roadbed 8, and the transition structure includes a rigid support structure and a rigidity transition structure.

[0047] The rigid supporting structure includes a retaining wall 2 , a corbel 3 , a joist 4 and a cap plate 5 .

[0048] The retaining walls 2 are respectively arranged on both sides of the line behind the abutment 1, and a plurality of corbels 3 are arranged inside the retaining walls 2. The corbels 3 arranged opposite to each other on the two retaining walls 2 are provided with the joists 4, and the capping plate 5 is arranged on the joists 4. The capping plate 5 is used for laying the track structure, and the capping plate 5 includes a plurality of blocks, such as Figure 2 As shown, the base plate 5 is formed by splicing two pieces, and each base plate 5 is connected to all the supporting beams 4.

[0049] The rigidity transition structure includes a platform backfill 6 and a transition section fill 7. Figure 3 As shown, the backfill 6 of the platform is filled with an inverted trapezoid in the rigid support structure, the transition section fill 7 is filled between the rigid support structure and the roadbed 8, the longitudinal section of the transition section fill 7 is rhombus-shaped, the transition section fill 7 extends into the rigid support structure, the roadbed 8 includes a lower embankment 9 and an upper base bed 10, the transition section fill 7 is provided with steps at the junction with the backfill 6 and the roadbed 8 fill, and the filling slope at the junction of the backfill 6, the transition section fill 7 and the roadbed 8 fill is 1:1, as shown in FIG. Figure 1 As shown, a conical slope 11 is provided at the outer interface between the transition section fill 7 and the rigid support structure.

[0050] The ballastless track road-bridge transition structure described in this embodiment forms the rigid support structure located at the abutment 1 through the retaining wall 2, the corbel 3, the joist 4 and the cap slab 5, and moves the stiffness change point of the road-bridge transition section from the road-bridge boundary to the boundary between the rigid support structure and the stiffness transition structure, thereby avoiding differential settlement caused by insufficient rolling of the abutment backfill 6 and reducing its influence on the smoothness of the road-bridge transition section; the retaining wall 2 encloses the abutment backfill 6 and part of the transition section fill 7, compared with the abutment backfill 6 The transition section fill 7 can be compacted by large-scale machinery, and the compaction degree of the filler can meet the design requirements; at the same time, the support beam 4, the cap plate 5, the gravity load of the track structure and the dynamic load of the train can be transmitted to the retaining wall 2 through the corbel 3, thereby increasing the positive pressure of the retaining wall 2 on the foundation, and offsetting a part of the bending moment of the retaining wall 2, thereby increasing the anti-slip and anti-overturning stability of the retaining wall 2; this structure can effectively solve the problem of differential settlement of the high-speed railway road-bridge transition section, ensure the safe operation of high-speed railway trains, and is convenient and feasible in construction, with broad application prospects.

[0051] Example 2

[0052] like Figures 1 to 4 As shown, a construction method of a ballastless track-road-bridge transition structure according to the present invention is used to construct the ballastless track-road-bridge transition structure as described in Example 1, and the method comprises the following steps:

[0053] S1, leveling the roadbed 8 base.

[0054] S2, construct the retaining wall 2, accurately locate the position of the retaining wall 2, set up the formwork, lay the steel cage, set the corbel 3 on the retaining wall 2, and then pour concrete to form the pile body 2 and the corbel 3.

[0055] S3, synchronously fill the backfill 6, the transition section fill 7, and the roadbed 8 in layers to the joist 4. The backfill 6 is filled with A, B, and C group fillers, with a compaction coefficient K ≥ 0.93 and a foundation coefficient K 30 ≥130MPa / m, the backfill 6 is compacted by small machinery, the transition section fill 7 is filled with graded crushed stone mixed with 3% cement, the compaction coefficient K≥0.95, the foundation coefficient K 30 ≥150MPa / m, dynamic deformation modulus E vd ≥50MPa, the transition section fill 7 and the roadbed 8 fill are compacted by large-scale machinery, and the paving and compacting thickness of the backfill 6, the transition section fill 7 and the roadbed 8 fill is 15cm to 30cm when they are filled.

[0056] S4, hoisting the prefabricated supporting beam 4.

[0057] S5, reserve the position of the capping plate 5, and continue to synchronously fill the backfill 6, the transition section fill 7, and the roadbed 8 in layers until the roadbed 8 reaches the designed elevation.

[0058] S6, hoisting the prefabricated cap plate 5 and installing it on the supporting beam 4, the cap plate 5 is provided with grouting holes, and the gap between the cap plate 5 and the backfill is filled with grouting through the grouting holes.

[0059] S7. The gap between the abutment 1 and the retaining wall 2 is closed by hoisting a retaining plate.

[0060] The construction method of a ballastless track road-bridge transition structure described in this embodiment forms the rigid support structure located at the abutment 1 through the retaining wall 2, the corbel 3, the support beam 4 and the cap plate 5, and moves the stiffness change point of the road-bridge transition section from the road-bridge boundary to the boundary between the rigid support structure and the stiffness transition structure, thereby avoiding differential settlement caused by insufficient rolling of the abutment backfill 6 and reducing its influence on the smoothness of the road-bridge transition section; the retaining wall 2 is used to enclose the abutment backfill 6 and part of the transition section fill 7, compared with the abutment backfill Soil 6, the transition section fill 7 can be compacted by large-scale machinery, and the compaction degree of the filler can meet the design requirements; at the same time, the support beam 4, the cap plate 5, the gravity load of the track structure and the dynamic load of the train can be transmitted to the retaining wall 2 through the corbel 3, thereby increasing the positive pressure of the retaining wall 2 on the foundation, and offsetting a part of the bending moment of the retaining wall 2, thereby increasing the anti-slip and anti-overturning stability of the retaining wall 2; this method can effectively solve the problem of differential settlement in the transition section of the high-speed railway road and bridge, ensure the safe operation of high-speed railway trains, and is convenient and feasible in construction, with broad application prospects.

[0061] Example 3

[0062] like Figures 1 to 5 As shown, a design method for a ballastless track-road-bridge transition structure according to the present invention is used to design the ballastless track-road-bridge transition structure as described in Example 1, and the method comprises the following steps:

[0063] Step 1: Checking the settlement and deformation of the roadbed 8

[0064] R1. Convert the train load, track load, deadweight load of the cap plate 5, and deadweight load of the joist 4 into a total uniformly distributed load acting on the joist 4:

[0065] q=q 1 +q 2 +q 3 +q 4

[0066]

[0067]

[0068]

[0069] Where: q is the total uniformly distributed load acting on the joist 4, kN / m;

[0070] q 1 is the uniformly distributed load of the train load acting on the joist 4, kN / m;

[0071] q 2is the uniformly distributed load of the track load acting on the joist 4, kN / m;

[0072] q 3 is the uniformly distributed load of the deadweight load of the cap plate 5 acting on the joist 4, kN / m;

[0073] q 4 is the uniformly distributed load of the deadweight load of the joist 4 acting on the joist 4, kN / m;

[0074] p 1 is the train load per unit line length, kN / m;

[0075] p 2 is the track load per unit line length, kN / m;

[0076] l c is the length of the base plate 5, m;

[0077] k is the number of the joists 4 under each cap plate 5;

[0078] l is the length of the joist 4, m;

[0079] G 3 is the weight of a single piece of the said base plate 5, kN;

[0080] G 4 is the weight of a single joist 4, kN.

[0081] R2. Calculate the cross-sectional moment of inertia of the joist 4:

[0082]

[0083] Where: I is the cross-sectional inertia moment of the joist 4, mm 4 ;

[0084] b 1 is the width of the joist 4, mm;

[0085] h is the height of the joist 4, mm.

[0086] R3. Consider the joist 4 as a simply supported beam and calculate the maximum deflection of the joist 4:

[0087]

[0088] Where: Y max is the maximum deflection of the joist 4 in the span, mm;

[0089] E is the elastic modulus of concrete, N / mm 2 ;

[0090] Among them, the elastic modulus of C35 concrete is E = 3.15 × 10 4 N / mm 2 , C40 concrete elastic modulus E = 3.25 × 10 4 N / mm 2 .

[0091] R4. Calculation of allowable settlement of the roadbed 8:

[0092] Y max ≤[Y]

[0093] Wherein: [Y] is the allowable settlement value of the roadbed 8, which is obtained according to the corresponding design specifications. For example, according to the requirements of the "High-speed Railway Design Specifications" TB10621-2014, the allowable settlement value of the roadbed 8 of the high-speed railway is [Y] = 15 mm.

[0094] Step 2: Checking the bearing capacity of the retaining wall 2 foundation

[0095] R5. Correction of characteristic value of foundation bearing capacity:

[0096] f a =f ak +η b γ(b-3)+η d γ m (d-0.5)

[0097] Where: f a is the corrected characteristic value of foundation bearing capacity, kPa;

[0098] f ak is the characteristic value of foundation bearing capacity, which can be calculated by load test or other in-situ test, formula, kPa;

[0099] η b , η m is the foundation bearing capacity correction coefficient of the bottom width and embedding depth of the retaining wall 2, and the value is obtained by looking up the table according to the type of soil under the base in the "Code for Design of Building Foundations";

[0100] γ is the weight of the soil below the bottom of the retaining wall 2, kN / m 3 ;

[0101] γ m is the weighted average density of the soil above the bottom of the retaining wall 2, kN / m 3 ;

[0102] b is the width of the retaining wall 2, m;

[0103] d is the embedding depth of the retaining wall 2, m.

[0104] R6. Calculation of the bearing capacity of the retaining wall 2 foundation:

[0105]

[0106]

[0107]

[0108]

[0109] Where: F is the vertical force transmitted to the retaining wall 2 through the corbel 3 by the train load, track load, the deadweight load of the cap slab 5, and the deadweight load of the joist 4, kN;

[0110] n is the number of the joists 4 supported by the retaining wall 2;

[0111] p k is the average pressure value at the bottom of the foundation, kPa;

[0112] p kmax is the maximum pressure value at the foundation edge, kPa;

[0113] G is the self-weight load of the retaining wall 2, kN;

[0114] N is the active earth pressure force on the retaining wall 2, kN;

[0115] δ is the angle between the active earth pressure force on the retaining wall 2 and the gravity;

[0116] A is the bottom area of ​​the retaining wall 2, m 2 ;

[0117] W is the resistance moment of the bottom surface of the retaining wall 2;

[0118] z is the length of the retaining wall 2, m;

[0119] l 1 is the distance between the vertical force F and the midpoint of the bottom surface of the retaining wall 2, m;

[0120] l 2 is the distance between the self-weight load G of the retaining wall 2 and the midpoint of the bottom surface of the retaining wall 2, m;

[0121] s is the distance between the active earth pressure resultant N exerted on the retaining wall 2 and the midpoint of the bottom surface of the retaining wall 2, m.

[0122] Step 3: The high-speed railway has high safety requirements for the retaining wall 2, and large eccentricity is not allowed. Small eccentricity check should be performed:

[0123]

[0124] Where: pmin The maximum pressure value at the foundation edge corresponding to the standard combination of actions, kPa.

[0125] The design method of a ballastless track road-bridge transition structure described in this embodiment strictly controls the maximum deflection of the support beam 4 to be less than or equal to the allowable settlement value of the roadbed 8, and strictly sets the bearing capacity of the foundation of the retaining wall 2 to be able to resist the vertical force of the load and large eccentricity, so that the rigid support structure has sufficient rigidity, and the stiffness change point of the road-bridge transition section is moved from the road-bridge boundary to the boundary between the rigid support structure and the stiffness transition structure. The design method has simple steps, convenient calculation and good effect.

[0126] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A design method for a ballastless track bridge approach structure, characterized in that, it is used for designing a ballastless track bridge approach structure, and the approach structure is used to connect the abutment (1) and the subgrade (8). The approach structure includes a rigid support structure and a stiffness transition structure. The rigid support structure includes a retaining wall (2). The retaining walls (2) are respectively arranged on both sides of the track behind the abutment (1). A number of corbels (3) are provided inside the retaining wall (2). A bearing beam (4) is provided on the corbels (3) arranged oppositely on the two retaining walls (2). A bearing platform slab (5) is provided on the bearing beam (4). The stiffness transition structure includes backfill soil of the abutment (6) and backfill soil of the transition section (7). The backfill soil of the abutment (6) in an inverted trapezoid shape is filled inside the rigid support structure, and the backfill soil of the transition section (7) is filled between the rigid support structure and the subgrade (8); This method includes the following steps: Step 1. Settlement deformation calculation of the subgrade (8) Convert the train load, track load, self-weight load of the bearing platform slab (5), and self-weight load of the bearing beam (4) into the total uniform load acting on the bearing beam (4); Calculate the section moment of inertia of the bearing beam (4); Determine the maximum deflection of the bearing beam (4) according to the total uniform load acting on the bearing beam (4) and the section moment of inertia of the bearing beam (4); The maximum deflection of the bearing beam (4) is less than or equal to the allowable settlement value of the subgrade (8), and the allowable settlement value of the subgrade (8) is obtained according to the corresponding design specifications; Step 2. Subgrade bearing capacity calculation of the retaining wall (2) Correct the characteristic value of subgrade bearing capacity, and check the subgrade bearing capacity of the retaining wall (2) by using the corrected characteristic value of subgrade bearing capacity; Step 3. Perform a small eccentricity check on the retaining wall (2) by using the subgrade bearing capacity of the retaining wall (2).

2. The design method for a ballastless track bridge approach structure according to claim 1, characterized in that, Steps are respectively provided at the junctions of the backfill soil of the transition section (7) with the backfill soil of the abutment (6) and the backfill soil of the subgrade (8).

3. The design method for a ballastless track bridge approach structure according to claim 1, characterized in that, The subgrade (8) includes an embankment (9) at the lower part and a subgrade bed (10) at the upper part.

4. The design method for a ballastless track bridge approach structure according to claim 1, characterized in that, The slopes of the fills at the junctions of the backfill soil of the abutment (6), the backfill soil of the transition section (7), and the backfill soil of the subgrade (8) are 1:

1.

5. The design method for a ballastless track bridge approach structure according to claim 1, characterized in that, A taper slope (11) is provided at the external junction of the backfill soil of the transition section (7) and the rigid support structure.

6. The design method for a ballastless track bridge approach structure according to claim 1, characterized in that, The backfill soil (6) is filled with Group A, B, and C fillers, and the compaction coefficient K ≥ 0.93, and the foundation coefficient K 30 ≥ 130 MPa / m.

7. The design method for a ballastless track bridge approach structure according to claim 1, characterized in that, The filling soil (7) of the transition section is filled with graded broken stone admixed with 3% cement, and the compaction coefficient K ≥0.95, and the foundation coefficient K 30 ≥150 MPa / m, and the dynamic deformation modulus E vd ≥50 MPa.

8. The design method for a ballastless track bridge approach structure according to any one of claims 1-7, characterized in that, When filling the backfill soil (6) of the abutment, the transition section fill soil (7), and the subgrade (8), the paving and compaction thickness is 15 cm to 30 cm.

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