A bridge and road anti-differential settlement transition structure, design method and construction method

Abstract

The present invention relates to a road and bridge differential settlement resistant transition structure, a design method and a construction method. The rigid support structure located at the abutment is formed by the pile body, the upper cross beam, the lower cross beam and the bearing platform slab, and the stiffness change point of the road and bridge transition section is shifted from the road and 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 impact on the smoothness of the road and bridge transition section; the retaining wall panels are used to enclose the backfill of the abutment and part of the fill of the transition section. Compared with the backfill of the abutment, large-scale machinery can be used for compaction of the fill of the transition section, and the compaction degree of the fill can meet the design requirements; this structure can effectively solve the problem of differential settlement in the road and bridge transition section of high-speed railways or expressways, ensure the operation safety of high-speed railway trains and expressway vehicles, and is convenient and feasible for construction, with broad application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of road and bridge construction engineering, in particular to a road and bridge differential settlement resistant transition structure, a design method and a construction method thereof. Background Technique

[0002] China already has the world's largest-scale and highest-operating-speed high-speed railway network. High-speed railways require the track structure to have high smoothness. The transition section between the subgrade 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 the smooth and comfortable operation of trains on the road and bridge transition section. Excessive differential settlement in the road and bridge transition section will pose a threat to the operation safety of high-speed railways. The current "Code for Design of High-Speed Railways" is extremely strict on the control of differential settlement in the road and bridge transition section. The post-construction differential settlement at the junction of the subgrade and the bridge should not be greater than 5 mm, and the deflection angle caused by uneven settlement should not be greater than 1 / 1000. At present, the road and bridge transition section of high-speed railways usually adopts an inverted trapezoidal transition structure form along the longitudinal direction of the line close to the back of the abutment, and the transition structure is filled with graded crushed stone mixed with 3% cement.

[0003] In the existing road and bridge transition section structure, large-scale mechanical compaction construction cannot be carried out at the back of the abutment. It is difficult to meet the compaction standard requirements by using small-scale mechanical ramming, and it is easy to exceed the settlement control index of the subgrade near the back of the abutment, affecting the line smoothness of the bridge and road transition section and threatening the operation safety of trains. Summary of the Invention

[0004] The purpose of the present invention is to: aiming at the problems existing in the prior art that large-scale mechanical compaction construction cannot be carried out at the back of the abutment of the existing road and bridge transition section structure, it is difficult to meet the compaction standard requirements by using small-scale mechanical ramming, and it is easy to exceed the settlement control index of the subgrade near the back of the abutment, affecting the line smoothness of the bridge and road transition section and threatening the operation safety of trains, provide a road and bridge differential settlement resistant transition structure, a design method and a construction method thereof, which can be used for differential settlement resistance of the road and bridge transition section of high-speed railways.

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

[0006] A road and bridge differential settlement resistant transition structure for connecting an abutment and a subgrade. The transition structure includes a rigid support structure and a stiffness transition structure. The rigid support structure includes a plurality of pile bodies. The pile bodies are arranged on both sides of the line behind the abutment. The adjacent pile bodies are arranged at intervals and connected with retaining plates. A retaining plate is provided between the abutment and the adjacent pile body. The oppositely arranged pile bodies are connected by an upper cross beam and a lower cross beam. A bearing platform plate is provided on the upper cross beam. The bearing platform plate is used for laying the track structure. The stiffness transition structure includes backfill soil of the abutment and fill soil of the transition section. The backfill soil of the abutment in an inverted trapezoidal shape is filled in the rigid support structure, and the fill soil of the transition section is filled between the rigid support structure and the subgrade.

[0007] Adopt a road and bridge differential settlement resistant transition structure according to the present invention. The rigid support structure at the abutment is formed by the pile body, the upper cross beam, the lower cross beam and the bearing platform slab, and the stiffness change point of the road and bridge transition section is shifted from the road and 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 soil of the abutment and reducing its impact on the smoothness of the road and bridge transition section. The backfill soil of the abutment and part of the backfill soil of the transition section are enclosed by the retaining plate. Compared with the backfill soil of the abutment, the backfill soil of the transition section can be compacted by large-scale machinery, and the compaction degree of the filler can meet the design requirements. This structure can effectively solve the problem of differential settlement in the road and bridge transition section of high-speed railways or highways, ensure the operation safety of high-speed railway trains and highway vehicles, and is convenient and feasible for construction with broad application prospects.

[0008] Preferably, the pile body is a flange pile, and the retaining plate abuts against the flange position of the flange pile.

[0009] Preferably, steps are respectively provided at the junctions of the backfill soil of the transition section with the backfill soil of the abutment and the subgrade soil.

[0010] Preferably, the filling slope ratio at the junctions of the backfill soil of the abutment, the backfill soil of the transition section and the subgrade soil is 1:1.

[0011] Preferably, the subgrade includes an embankment at the lower part and a roadbed at the upper part.

[0012] Preferably, a taper slope is provided at the external junction of the backfill soil of the transition section and the rigid support structure.

[0013] The present invention also provides a construction method for a road and bridge differential settlement resistant transition structure for constructing a road and bridge differential settlement resistant transition structure as described in any one of the above. The method includes the following steps:

[0014] S1. Construct the pile body, lower the steel reinforcement cage, reserve a steel reinforcement interface at the connection of the pile body with the upper cross beam and the lower cross beam, and then pour concrete to form the pile body;

[0015] S2. Erect the formwork, lay the steel bars of the lower cross beam, fixedly connect the steel bars at the connection of the lower cross beam with the pile body, and then pour concrete to form the lower cross beam;

[0016] S3. Synchronously and layer by layer fill the backfill soil of the abutment, the backfill soil of the transition section and the subgrade soil up to the upper cross beam. The backfill soil of the abutment is compacted by small-scale machinery, and the backfill soil of the transition section and the subgrade soil are compacted by large-scale machinery;

[0017] S4. During the filling process of the backfill of the abutment and the backfill of the transition section, the surrounding retaining plates are hoisted synchronously, and the retaining plates are connected to the pile bodies or the abutment.

[0018] S5. Erect the formwork, lay the steel bars of the upper cross beam, and fixedly connect the steel bars at the connection between the upper cross beam and the pile body, and then pour concrete to form the upper cross beam.

[0019] S6. Reserve the position of the bearing platform slab, and continue to synchronously fill the backfill of the abutment, the backfill of the transition section, and the subgrade fill in layers, and hoist the surrounding retaining plates and connect them to the pile bodies or the abutment until the design elevation of the subgrade.

[0020] S7. Hoist the precast bearing platform slab.

[0021] Adopt the construction method of a road-bridge differential settlement resistance transition structure of the present invention. Through the pile bodies, the upper cross beam, the lower cross beam and the bearing platform slab, the rigid support structure at the abutment is formed, and 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 rigid transition structure, avoiding the differential settlement caused by insufficient compaction of the backfill of the abutment and reducing its impact on the smoothness of the road-bridge transition section; by using the retaining plates to enclose the backfill of the abutment and part of the backfill of the transition section, compared with the backfill of the abutment, the backfill of the transition section can be compacted by large-scale machinery, and the compaction degree of the filler can meet the design requirements; this method can effectively solve the problem of differential settlement in the road-bridge transition section of high-speed railways or expressways, ensure the operation safety of high-speed railway trains and expressway vehicles, and is convenient and feasible for construction, with broad application prospects.

[0022] Preferably, the pile bodies below the ground are formed by the method of manual hole digging, and the formwork is erected for the pile bodies above the ground.

[0023] Preferably, grouting holes are reserved on the bearing platform slab, and the gap between the lower part of the bearing platform slab and the fill is filled by grouting through the grouting holes.

[0024] Preferably, the backfill of the abutment is filled with Group A, B, and C fillers, the compaction coefficient K≥0.93, and the foundation coefficient K 30 ≥130 MPa / m.

[0025] Preferably, the backfill of the transition section is filled with graded crushed stone admixed with 3% cement, the compaction coefficient K≥0.95, the foundation coefficient K 30 ≥150 MPa / m, and the dynamic deformation modulus E vd ≥50 MPa.

[0026] Preferably, when filling the backfill of the abutment, the backfill of the transition section, and the subgrade fill, the paving and compaction thickness is 15 cm to 30 cm.

[0027] The present invention also provides a design method for a road-bridge differential settlement resistant transition structure for designing the road-bridge differential settlement resistant transition structure as described in any one of the above, and the method includes the following steps:

[0028] Step 1: Settlement deformation calculation of the subgrade

[0029] Convert the train load, track load, self-weight load of the bearing platform slab, and self-weight load of the upper cross beam into the total uniform load acting on the upper cross beam;

[0030] Calculate the moment of inertia of the cross section of the upper cross beam;

[0031] Determine the maximum deflection of the upper cross beam according to the total uniform load acting on the upper cross beam and the moment of inertia of the cross section of the upper cross beam;

[0032] The maximum deflection of the upper cross beam is less than or equal to the allowable settlement value of the subgrade, and the allowable settlement value of the subgrade is obtained according to the corresponding design specifications;

[0033] Step 2: Bearing capacity calculation of the pile body

[0034] Calculate the average vertical force of the pile body;

[0035] Calculate the ultimate bearing capacity of the pile body to obtain the characteristic value of the vertical bearing capacity of the pile body;

[0036] The average vertical force of the pile body is less than or equal to 1.2 times the characteristic value of the vertical bearing capacity of the pile body.

[0037] By adopting the design method for a road-bridge differential settlement resistant transition structure of the present invention, by strictly controlling the maximum deflection of the upper cross beam to be less than or equal to the allowable settlement value of the subgrade, and by strictly setting the bearing capacity of the pile body to be able to resist the vertical load, the rigid support structure has sufficient rigidity, and 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. The steps of this design method are simple, the calculation is convenient, and the effect is good.

[0038] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are:

[0039] 1. A road and bridge differential settlement resistant transition structure and construction method according to the present invention form the rigid support structure at the abutment through the pile body, the upper cross beam, the lower cross beam and the bearing platform plate, and shift the stiffness change point of the road and bridge transition section from the road and bridge boundary to the boundary between the rigid support structure and the rigid transition structure, avoiding differential settlement caused by insufficient compaction of the backfill soil of the abutment and reducing its impact on the smoothness of the road and bridge transition section; by enclosing the backfill soil of the abutment and part of the transition section soil with the retaining plate, compared with the backfill soil of the abutment, the transition section soil can be compacted by large-scale machinery, and the compaction degree of the filler can meet the design requirements; this structure and construction method can effectively solve the differential settlement problem of the road and bridge transition section of high-speed railways or highways, ensure the operation safety of high-speed railway trains and highway vehicles, and is convenient and feasible for construction with broad application prospects.

[0040] 2. A design method of a road and bridge differential settlement resistant transition structure according to the present invention makes the rigid support structure have sufficient rigidity by strictly controlling the maximum deflection of the upper cross beam to be less than or equal to the allowable settlement value of the subgrade and by strictly setting the bearing capacity of the pile body to be able to resist the vertical load, and shifts the stiffness change point of the road and bridge transition section from the road and bridge boundary to the boundary between the rigid support structure and the rigid transition structure. This design method has simple steps, convenient calculation and good effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is the front view schematic diagram of the road and bridge differential settlement resistant transition structure;

[0042] Figure 2 is the top view schematic diagram of the road and bridge differential settlement resistant transition structure;

[0043] Figure 3 is Figure 2 the longitudinal section schematic diagram in the A-A direction of

[0044] Figure 4 is Figure 2 the cross section schematic diagram in the B-B direction of

[0045] Markings in the figure: 1 - abutment, 2 - pile body, 3 - retaining plate, 4 - upper cross beam, 5 - lower cross beam, 6 - bearing platform plate, 7 - backfill soil of the abutment, 8 - transition section soil, 9 - subgrade, 10 - embankment, 11 - subgrade bed, 12 - taper slope. DETAILED DESCRIPTION OF THE INVENTION

[0046] The present invention will be described in detail below with reference to the accompanying drawings.

[0047] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be 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.

[0048] Embodiment 1

[0049] As Figures 1 to 4 shown, a road and bridge differential settlement resistance transition structure according to the present invention is used to connect the abutment 1 and the subgrade 9. The transition structure includes a rigid support structure and a stiffness transition structure.

[0050] The rigid support structure includes pile bodies 2, retaining plates 3, upper cross beams 4, lower cross beams 5 and a bearing platform slab 6.

[0051] A number of the pile bodies 2 are respectively arranged on both sides of the line behind the abutment 1. The adjacent pile bodies 2 are arranged at intervals and connected to the retaining plates 3. The retaining plates 3 include a number of blocks and are stacked from low to high. The retaining plates 3 are also arranged between the abutment 1 and the adjacent pile bodies 2 and are stacked from low to high; specifically, the pile bodies 2 are flange piles, and the retaining plates 3 are abutted against the flange positions of the flange piles.

[0052] The pile bodies 2 arranged oppositely on both sides of the line are connected by the upper cross beams 4 and the lower cross beams 5. The upper cross beams 4 are provided with the bearing platform slab 6, and the bearing platform slab 6 is used for laying the track structure. The bearing platform slab 6 includes a number of blocks. As Figure 2 shown, the bearing platform slab 6 is formed by splicing two blocks, and each block of the bearing platform slab 6 is connected to all the upper cross beams 4.

[0053] The stiffness transition structure includes backfill soil 7 of the abutment and transition section fill 8. As Figure 3 shown, the trapezoidal backfill soil 7 of the abutment is filled in the rigid support structure, the transition section fill 8 is filled between the rigid support structure and the subgrade 9, the longitudinal section of the transition section fill 8 is in a diamond shape, the transition section fill 8 extends into the rigid support structure, the subgrade 9 includes an embankment 10 at the lower part and a subgrade bed 11 at the upper part, steps are respectively provided at the junctions of the transition section fill 8 with the backfill soil 7 of the abutment and the fill of the subgrade 9, and the slope ratio at the junction of the backfill soil 7 of the abutment, the transition section fill 8 and the fill of the subgrade 9 is 1:1. As Figure 1 shown, a taper slope 12 is provided at the external junction of the transition section fill 8 and the rigid support structure.

[0054] A road and bridge differential settlement resistant transition structure described in this embodiment forms the rigid support structure at the abutment 1 through the pile body 2, the upper cross beam 4, the lower cross beam 5 and the bearing platform slab 6, shifting the stiffness change point of the road and bridge transition section from the road and 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 soil 7 of the abutment, and reducing its impact on the smoothness of the road and bridge transition section; by using the retaining plate 3 to enclose the backfill soil 7 of the abutment and part of the transition section fill 8, compared with the backfill soil 7 of the abutment, the transition section fill 8 can be compacted by large machinery, and the compaction degree of the fill can meet the design requirements; this structure can effectively solve the problem of differential settlement in the road and bridge transition section of high-speed railways or highways, ensure the operation safety of high-speed railway trains and highway vehicles, and is convenient and feasible for construction, with broad application prospects.

[0055] Embodiment 2

[0056] As Figures 1 to 4 shown, a construction method of a road and bridge differential settlement resistant transition structure described in the present invention is used to construct the road and bridge differential settlement resistant transition structure as described in Embodiment 1, and this method includes the following steps:

[0057] S1. Construct the pile body 2, accurately position the positions of each pile body 2, use the method of manual hole digging for the part of the pile body 2 below the ground, erect steel formwork for the part of the pile body 2 above the ground, lower the steel reinforcement cage, reserve steel reinforcement interfaces at the joints of the pile body 2 with the upper cross beam 4 and the lower cross beam 5, and then pour concrete to form the pile body 2.

[0058] S2. Level the base of the subgrade 9.

[0059] S3. Erect steel formwork, lay the steel reinforcement of the lower cross beam 5, weld the steel reinforcement at the joint of the lower cross beam 5 and the pile body 2 firmly, and then pour concrete to form the lower cross beam 5.

[0060] S4. Synchronously fill the backfill soil 7 of the abutment, the transition section fill 8, and the subgrade 9 fill in layers up to the upper cross beam 4. The backfill soil 7 of the abutment is filled with Group A, B, and C fillers, with a compaction coefficient K≥0.93 and a foundation coefficient K 30 ≥130 MPa / m. The backfill soil 7 of the abutment is compacted by small machinery. The transition section fill 8 is filled with graded crushed stone admixed with 3% cement, with a compaction coefficient K≥0.95 and a foundation coefficient K 30 ≥150 MPa / m, and the dynamic deformation modulus E vd ≥50 MPa. The transition section fill 8 and the subgrade 9 fill are compacted by large machinery. When filling the backfill soil 7 of the abutment, the transition section fill 8, and the subgrade 9 fill, the paving and compaction thickness is 15 cm - 30 cm.

[0061] S5. During the filling process of the backfill soil 7 of the abutment and the transition section fill soil 8, the surrounding retaining plates 3 are hoisted synchronously, and the retaining plates 3 are connected to the pile bodies 2 or the abutment 1.

[0062] S6. Erect steel formwork, lay the steel bars of the upper cross beam 4, and weld the steel bars at the connection of the upper cross beam 4 and the pile bodies 2 firmly, and then pour concrete to form the upper cross beam 4.

[0063] S7. Reserve the position of the bearing platform slab 6, and continue to synchronously fill the backfill soil 7 of the abutment, the transition section fill soil 8, and the subgrade 9 fill soil in layers, and hoist the surrounding retaining plates 3 and connect them to the pile bodies 2 or the abutment 1 until the design elevation of the subgrade 9.

[0064] S8. Hoist the precast bearing platform slab 6 and install it on the upper cross beam 4. The bearing platform slab 6 is reserved with grouting holes, and the gap between the lower part of the bearing platform slab 6 and the fill soil is filled with grout through the grouting holes.

[0065] For the construction method of a road-bridge differential settlement resistance transition structure described in this embodiment, a rigid support structure located at the abutment 1 is formed by the pile bodies 2, the upper cross beam 4, the lower cross beam 5, and the bearing platform slab 6, and 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 soil 7 of the abutment and reducing its impact on the smoothness of the road-bridge transition section; by using the retaining plates 3 to enclose the backfill soil 7 of the abutment and part of the transition section fill soil 8, compared with the backfill soil 7 of the abutment, the transition section fill soil 8 can be compacted by large-scale machinery, and the compaction degree of the filler can meet the design requirements; this method can effectively solve the problem of differential settlement in the road-bridge transition section of high-speed railways or highways, ensure the operation safety of high-speed railway trains and highway vehicles, and is convenient and feasible for construction with broad application prospects.

[0066] Embodiment 3

[0067] As Figures 1 to 4 shown, a design method of a road-bridge differential settlement resistance transition structure described in the present invention is used to design the road-bridge differential settlement resistance transition structure described in Embodiment 1, and this method includes the following steps:

[0068] Step 1. Settlement deformation calculation of the subgrade 9

[0069] R1. Convert the train load, track load, self-weight load of the bearing platform slab 6, and self-weight load of the upper cross beam 4 into a uniform load acting on the upper cross beam 4:

[0070] q = q 1 + q 2 + q 3 + q4

[0071]

[0072]

[0073]

[0074] Where: q is the total uniform load acting on the upper cross beam 4, kN / m;

[0075] q 1 is the uniform load of the train load acting on the upper cross beam 4, kN / m;

[0076] q 2 is the uniform load of the track load acting on the upper cross beam 4, kN / m;

[0077] q 3 is the uniform load of the self-weight load of the bearing platform slab 6 acting on the upper cross beam 4, kN / m;

[0078] q 4 is the uniform load of the self-weight load of the upper cross beam 4 acting on the upper cross beam 4, kN / m;

[0079] p 1 is the train load per unit line length, kN / m;

[0080] p 2 is the track load per unit line length, kN / m;

[0081] l c is the length of the bearing platform slab 6, m;

[0082] k is the number of the upper cross beams 4 under each bearing platform slab 6;

[0083] l is the length of the upper cross beam 4, m;

[0084] G 3 is the weight of a single bearing platform slab 6, kN;

[0085] G 4 is the weight of a single upper cross beam 4, kN.

[0086] R2. Calculate the section moment of inertia of the upper cross beam 4:

[0087]

[0088] Where: I is the section moment of inertia of the upper cross beam 4, mm 4 ;

[0089] b is the width of the upper cross beam 4, in mm;

[0090] h is the height of the upper cross beam 4, in mm.

[0091] R3. Consider the upper cross beam 4 as a beam fixed at both ends, and calculate the maximum deflection of the upper cross beam 4:

[0092]

[0093] In the formula: Y max is the maximum deflection at the mid-span of the upper cross beam 4, in mm;

[0094] E is the elastic modulus of concrete, in N / mm 2 ;

[0095] Among them, the elastic modulus E of C35 concrete = 3.15×10 4 N / mm 2 , and the elastic modulus E of C40 concrete = 3.25×10 4 N / mm 2 .

[0096] R4. Check the allowable settlement of the subgrade 9:

[0097] Y max ≤ [Y]

[0098] In the formula: [Y] is the allowable settlement value of the subgrade 9, obtained according to the corresponding design specifications. For example, according to the requirements of the "Design Code for High-Speed Railways" TB10621-2014, the allowable settlement value [Y] of the subgrade 9 of high-speed railways = 15 mm.

[0099] Step 2. Check the bearing capacity of the pile body 2

[0100] R5. Calculate the average vertical force of the pile body 2:

[0101]

[0102] In the formula: F is the average vertical force of the pile body 2 under the action of the standard combination of load effects and axial vertical force, in kN;

[0103] G 5 is the total weight of the upper cross beam 4, the lower cross beam 5 and the two side pile bodies 2, in kN.

[0104] R6. Calculate the bearing capacity of the pile body 2:

[0105] Q uk = Q sk + Q pk = u∑q sik l i + q pk Ap

[0106]

[0107] Where: Q uk is the standard value of the ultimate bearing capacity of the pile body 2, kN;

[0108] Q sk is the standard value of the ultimate side resistance of the pile body 2, kN;

[0109] Q pk is the standard value of the ultimate tip resistance of the pile body 2, kN;

[0110] u is the perimeter of the pile body 2, m;

[0111] q sik is the standard value of the ultimate side resistance of the i-th layer of soil on the pile side of the pile body 2, kPa;

[0112] l i is the thickness of the i-th layer of soil around the pile of the pile body 2, m;

[0113] q pk is the standard value of the ultimate tip resistance of the pile body 2, kPa;

[0114] A p is the pile tip area of the pile body 2, m 2 ;

[0115] R a is the characteristic value of the vertical bearing capacity of the pile body 2, kN;

[0116] K is the safety factor, and K = 2 is taken.

[0117] R7. The bearing capacity of the pile body 2 should satisfy: F ≤ 1.2R a .

[0118] In the design method of a road-bridge differential settlement transition structure described in this embodiment, by strictly controlling the maximum deflection of the upper cross beam 4 to be less than or equal to the allowable settlement value of the roadbed 9, and by strictly setting the bearing capacity of the pile body 2 to be able to resist the vertical load, the rigid support structure has sufficient rigidity, and 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. This design method has simple steps, convenient checking, and good effects.

[0119] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A design method for a road and bridge differential settlement resistant transition structure, characterized in that, it is used to design a road and bridge differential settlement resistant transition structure for connecting the abutment (1) and the subgrade (9). The transition structure includes a rigid support structure and a stiffness transition structure. The rigid support structure includes a number of pile bodies (2), and the pile bodies (2) are arranged on both sides of the line behind the abutment (1). The adjacent pile bodies (2) are arranged at intervals and connected with retaining plates (3). There is a retaining plate (3) between the abutment (1) and the adjacent pile body (2). The relatively arranged pile bodies (2) are connected by an upper cross beam (4) and a lower cross beam (5). A bearing platform plate (6) is arranged on the upper cross beam (4). The stiffness transition structure includes backfill soil (7) of the abutment and fill soil (8) of the transition section. The trapezoidal backfill soil (7) of the abutment is filled in the rigid support structure, and the fill soil (8) of the transition section is filled between the rigid support structure and the subgrade (9); This method includes the following steps: Step 1. Settlement deformation calculation of the subgrade (9) Convert the train load, track load, self-weight load of the bearing platform plate (6), and self-weight load of the upper cross beam (4) into the total uniform load acting on the upper cross beam (4); Calculate the section moment of inertia of the upper cross beam (4); Determine the maximum deflection of the upper cross beam (4) according to the total uniform load acting on the upper cross beam (4) and the section moment of inertia of the upper cross beam (4); The maximum deflection of the upper cross beam (4) is less than or equal to the allowable settlement value of the subgrade (9), and the allowable settlement value of the subgrade (9) is obtained according to the corresponding design specifications; Step 2. Bearing capacity calculation of the pile body (2) Calculate the average vertical force of the pile body (2); Calculate the ultimate bearing capacity of the pile body (2) to obtain the characteristic value of the vertical bearing capacity of the pile body (2); The average vertical force of the pile body (2) is less than or equal to 1.2 times the characteristic value of the vertical bearing capacity of the pile body (2).

2. A design method for a road and bridge differential settlement resistant transition structure according to claim 1, characterized in that, the pile body (2) is a flange pile, and the retaining plate (3) abuts against the flange position of the flange pile.

3. A design method for a road and bridge differential settlement resistant transition structure according to claim 1, characterized in that, steps are respectively provided at the junctions of the fill soil (8) of the transition section with the backfill soil (7) of the abutment and the fill soil of the subgrade (9).

4. A design method for a road and bridge differential settlement resistant transition structure according to claim 1, characterized in that, the subgrade (9) includes an embankment (10) at the lower part and a subgrade bed (11) at the upper part.

5. A design method for a road and bridge differential settlement resistant transition structure according to any one of claims 1-4, characterized in that, a tapered slope (12) is provided at the external junction of the fill soil (8) of the transition section and the rigid support structure.

Images