Transition structure of frozen soil variable stiffness road bridge and its construction technology

Abstract

The present application provides a frozen soil variable-rigidity road bridge transition structure and its construction process. The frozen soil variable-rigidity road bridge transition structure includes a bridge abutment and a roadbed. The roadbed includes a graded crushed stone cushion layer, a reinforced concrete retaining wall, a block crushed stone filling layer, a fill layer, and a rigid slab. The reinforced concrete retaining wall is provided with multiple filling areas, and the reinforced concrete retaining wall is connected to the bridge abutment. The block crushed stone filling layer is provided within the multiple filling areas, and a slope is provided on the side of the block crushed stone filling layer facing away from the graded crushed stone cushion layer, and the height of the slope gradually decreases from the side close to the bridge abutment to the side away from the bridge abutment; the rigid slab is supported by the block crushed stone filling layer and connected to the bridge abutment. Not only does the variable-rigidity roadbed design improve the differential compaction settlement disease caused by the sudden change in stiffness of the roadbed under long-term dynamic loads, but the cooling effect of the block crushed stone filling layer is also used to prevent the permafrost foundation from melting, effectively improving the problem of vehicle jumping at the bridge head while also improving the durability of the road project.

Description

Technical Field

[0001] The present invention relates to the field of road and bridge construction, and in particular to a frozen soil variable-rigidity road and bridge transition structure and a construction process thereof. Background Art

[0002] Frozen soil is soil and rock with a temperature below 0°C and partially frozen water. The total area of ​​frozen soil (seasonal frozen soil and permafrost) accounts for about 75% of my country's land area. The construction of numerous infrastructure such as roads and bridges in permafrost areas has become an indispensable means of development. However, the properties of frozen soil are closely related to temperature changes. Its unfrozen water content will change with changes in the external ambient temperature. This characteristic determines that the mechanical and thermal properties of frozen soil are highly dynamic and unstable, which can easily cause roadbed instability in road projects, leading to serious engineering diseases. For road-bridge transition sections, uneven road surface settlement and cracking lead to frequent vehicle jumping at the bridge head, seriously affecting driving safety and road traffic capacity. At the same time, the impact load caused by vehicle jumping and bumping on the abutments accelerates the deterioration of abutments, bearings, etc., reducing the service life of the road.

[0003] Research has found that the existing frozen soil variable stiffness road bridge transition structure has the following shortcomings:

[0004] It cannot simultaneously meet the variable stiffness requirements of the transition section roadbed and the roadbed stability, and cannot protect the frozen soil base. Summary of the Invention

[0005] The purpose of the present invention is to provide a frozen soil variable stiffness road bridge transition structure and a construction process for the frozen soil variable stiffness road bridge transition structure, which can not only meet the variable stiffness requirements of the roadbed in the road bridge transition section, but also ensure the stability of the roadbed, prevent its fracture and slippage, and have a cooling and protective effect on the frozen soil base.

[0006] The embodiment of the present invention is achieved as follows:

[0007] In a first aspect, the present invention provides a frozen soil variable stiffness road-bridge transition structure, comprising:

[0008] Used for bridge abutments and roadbeds located on the ground base;

[0009] The roadbed includes:

[0010] Used for graded crushed stone cushion layer on the foundation;

[0011] A reinforced concrete retaining wall is provided on the graded crushed stone cushion layer, wherein the reinforced concrete retaining wall has a plurality of filling areas arranged at intervals in the extension direction of the roadbed; the reinforced concrete retaining wall is connected to the abutment;

[0012] A block crushed stone filling layer is provided in the plurality of filling areas, wherein a slope is provided on a side of the block crushed stone filling layer facing away from the graded crushed stone cushion layer, and the height of the slope gradually decreases from the side close to the abutment to the side away from the abutment;

[0013] Fill layers on slopes;

[0014] and a rigid slatted plate provided between the fill layer and the abutment, wherein the rigid slatted plate is supported by the crushed stone fill layer and connected to the abutment.

[0015] In an optional embodiment, the reinforced concrete retaining wall includes a frame-type wall body, which includes a wall heel plate and a plurality of first wall panels connected to the wall heel plate. The heights of the plurality of first wall panels gradually decrease from the side close to the abutment to the side away from the abutment. The wall heel plate and the plurality of first wall panels jointly define a plurality of filling areas.

[0016] In an optional embodiment, the frame wall also includes two second wall panels of equal height, both of which are connected to the wall heel plate, and both of which are located on the side of the first wall panel with the highest height among the multiple first wall panels close to the abutment. The two second wall panels are spaced apart in the extension direction of the roadbed, and the second wall panel farther away from the first wall panel among the two second wall panels is connected to the abutment.

[0017] In an optional embodiment, the block stone filling layer includes a block stone filling layer and a crushed stone leveling layer, the block stone filling layer is provided in a plurality of filling areas, and the crushed stone leveling layer is provided on the block stone filling layer and is located between the two second wall panels;

[0018] The rigid shiplap is supported by both the crushed stone screed and the two secondary wall panels.

[0019] In an optional embodiment, a tension steel bar is provided between at least two of the plurality of wall panels of the frame wall.

[0020] In an optional embodiment, the graded crushed stone cushion layer includes a first graded crushed stone cushion layer, a first geogrid layer, a second graded crushed stone cushion layer, a second geogrid layer and a third graded crushed stone cushion layer, which are arranged in sequence from bottom to top.

[0021] In an optional embodiment, the abutment includes a platform foundation, a platform body and a platform top arranged in sequence from bottom to top. The platform foundation is used to connect to the foundation layer, and part of the platform foundation is connected to the side of the graded gravel cushion layer away from the reinforced concrete retaining wall.

[0022] In an optional embodiment, a concrete backfill layer is provided between the platform foundation and the graded crushed stone cushion layer.

[0023] In an optional embodiment, the abutment is pre-embedded with a first connecting steel bar, the rigid slab is provided with a second connecting steel bar, and the first connecting steel bar and the second connecting steel bar are connected by a threaded sleeve.

[0024] In a second aspect, the present invention provides a construction process for a frozen soil variable stiffness road bridge transition structure, the construction process comprising the following steps:

[0025] Lay a graded crushed stone cushion on the subgrade with abutments;

[0026] A reinforced concrete retaining wall with multiple filling areas is set on the graded crushed stone cushion layer, and the reinforced concrete retaining wall is abutted against the abutment;

[0027] A crushed stone filling layer is provided in a plurality of filling areas, and a slope is formed on the side of the crushed stone filling layer away from the abutment;

[0028] Setting up fill layers on slopes;

[0029] A rigid slab is provided between the fill layer and the abutment. The rigid slab is supported by the reinforced concrete retaining wall and the block gravel filling layer at the same time, and the rigid slab is fixedly connected to the abutment.

[0030] The beneficial effects of the embodiments of the present invention are:

[0031] In summary, the frozen soil variable-stiffness road-bridge transition structure provided in this embodiment forms a sloped structure at the junction of the block-gravel fill layer and the fill layer, achieving a variable-stiffness connection between the abutment and the roadbed at the road-bridge transition. This avoids the step-like compaction and settlement caused by the different stiffnesses of the abutment and roadbed. Combined with the installation of rigid slats at the back of the abutment, this structure allows for a uniform transfer of dynamic loads from the road surface to the roadbed, preventing fragmentation or regional compaction of the block-gravel fill layer. This effectively prevents uneven settlement of this section of road surface under long-term dynamic loads due to sudden changes in stiffness and the compaction effect of the block-gravel fill layer. Furthermore, compared to ordinary fill layers, the block-gravel fill layer can significantly dissipate the dynamic stress generated by passing trains, effectively reducing the adverse effects on the roadbed structure and increasing its stability and service life.

[0032] At the same time, the crushed stone filler layer provides excellent heat shielding and cold exchange for foundations in permafrost areas, providing cooling protection for the frozen ground and preventing thawing and settlement of the permafrost foundation, further alleviating roadbed collapse and uneven road surface settlement. Furthermore, a ramped crushed stone filler layer is installed on the side of the bridge transition section, replacing the traditional tapered concrete slope protection used in bridge transition sections. This not only addresses the problem of excessive heat absorption caused by the excessive concrete slab area, but also reduces the average temperature within the frozen ground through the cooling effect of the crushed stone filler layer, thus protecting the frozen ground. Furthermore, the heat shielding effect of the crushed stone filler layer prevents the strong water erosion of the frozen ground caused by water flowing under the bridge, thus preventing the frozen ground from remaining in a state of long-term instability.

[0033] In addition, the block gravel filling layer is arranged in the filling area formed by the reinforced concrete retaining wall. The dynamic load acting on the roadbed is transmitted to the reinforced concrete retaining wall and the block gravel filling layer. Since the reinforced concrete retaining wall has a restraining effect on the block gravel filling layer, it can improve the slippage phenomenon of the block gravel filling layer, thereby improving the roadbed settlement phenomenon, and then improving the stability of the roadbed. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 This is a structural schematic diagram of a frozen soil variable stiffness road bridge transition structure according to an embodiment of the present invention;

[0036] Figure 2 A schematic cross-sectional view of a frozen soil variable stiffness road bridge transition structure according to an embodiment of the present invention;

[0037] Figure 3 A schematic diagram of the three-dimensional structure of a road-bridge transition structure according to an embodiment of the present invention;

[0038] Figure 4 This is a schematic structural diagram of a reinforced concrete retaining wall according to an embodiment of the present invention;

[0039] Figure 5 A schematic diagram of a partial structure of a reinforced concrete retaining wall according to an embodiment of the present invention;

[0040] Figure 6 This is a structural diagram of a bridge abutment and a rigid slab according to an embodiment of the present invention;

[0041] Figure 7This is a partial structural diagram of the connection structure between the abutment and the rigid tack plate according to an embodiment of the present invention.

[0042] icon:

[0043] 001-base layer; 101-first bearing surface; 102-second bearing surface; 100-bridge abutment; 110-abutment foundation; 111-upper abutment; 112-lower abutment; 120-abutment body; 130-abutment top; 140-concrete backfill layer; 150-first connecting steel bar; 160-threaded sleeve; 200-roadbed; 300-graded crushed stone cushion; 400-reinforced concrete retaining wall; 410-frame wall; 411-wall Heel plate; 412-first wall panel; 413-second wall panel; 420-tension reinforcement; 430-filling area; 440-grouting sleeve; 441-grouting port; 442-discharge port; 450-reserved reinforcement; 500-crushed stone filling layer; 510-slope; 520-stone filling layer; 530-crushed stone leveling layer; 600-fill layer; 700-rigid lap plate; 710-second connecting reinforcement; 800-ventilation pipe. DETAILED DESCRIPTION

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0045] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0046] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0047] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" and the like indicate positions or locations based on the positions shown in the accompanying drawings, or the positions or locations in which the inventive product is typically placed when in use. These terms are intended solely to facilitate the description of the present invention and to simplify the description, and are not intended to indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third," etc., are used solely to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0048] Furthermore, terms such as "horizontal" and "vertical" do not necessarily mean that a component must be absolutely horizontal or overhanging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but rather that it can be slightly tilted.

[0049] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections or electrical connections; they may refer to direct connections or indirect connections through an intermediate medium; and they may refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0050] See also Figure 1-Figure 7 This embodiment provides a frozen soil variable-stiffness road-bridge transition structure, which is not prone to large-scale settlement during service, has high safety and long service life.

[0051] See also Figure 1 and Figure 2 In this embodiment, the frozen soil variable stiffness road-bridge transition structure includes an abutment 100 and a roadbed 200 arranged on a foundation layer 001, wherein the foundation layer 001 is a frozen soil foundation layer 001.

[0052] The roadbed 200 includes a graded crushed stone cushion layer 300 for installation on the subgrade 001, a reinforced concrete retaining wall 400 installed on the graded crushed stone cushion layer 300, a crushed stone filling layer 500, a fill layer 600 installed on a slope 510, and a rigid buttress plate 700 installed between the fill layer 600 and the abutment 100. The reinforced concrete retaining wall 400 has multiple filling areas 430 spaced apart along the extension direction of the roadbed 200 and is connected to the abutment 100. The crushed stone filling layer 500 is located within the multiple filling areas 430. A slope 510 is provided on the side of the crushed stone filling layer 500 facing away from the graded crushed stone cushion layer 300, with the height of the slope 510 gradually decreasing from the side closest to the abutment 100 to the side away from the abutment 100. The rigid buttress plate 700 is supported by the crushed stone filling layer 500 and connected to the abutment 100.

[0053] The beneficial effects of the frozen soil variable stiffness road-bridge transition structure provided by this embodiment include, for example:

[0054] The frozen soil variable-stiffness road-bridge transition structure provided in this embodiment primarily relies on a combination of a crushed stone filling layer 500 and a fill layer 600 to achieve a gradual change in stiffness at the road-bridge transition section. Furthermore, the crushed stone filling layer 500 is reinforced with a reinforced concrete retaining wall 400. This not only alleviates the lateral slippage of the crushed stone filling layer 500 under long-term dynamic loads, but also reduces heat absorption by the base layer 001 by reducing the surface area of ​​the concrete slab, thereby protecting the frozen soil base layer 001. Furthermore, the frozen soil variable-stiffness road-bridge transition structure utilizes the cooling effect of the crushed stone filling layer 500 to prevent melting and settlement of the frozen soil foundation, further protecting the permafrost and effectively resolving the bridgehead vehicle bouncing problem caused by uneven road surface settlement.

[0055] See also Figure 1 In this embodiment, it should be understood that the foundation layer 001 includes two bearing surfaces with a height difference, both bearing surfaces are horizontally arranged, the height of the first bearing surface 101 is lower than the height of the second bearing surface 102, and the first bearing surface 101 and the second bearing surface 102 are connected by a vertical surface.

[0056] See also Figure 3 In this embodiment, before setting the roadbed 200, the abutment 100 is first laid on the first bearing surface 101. The abutment 100 includes a base 110, a body 120, and a top 130, which are arranged in order from bottom to top. The base 110 is used to connect to the first bearing surface 101 of the foundation layer 001.

[0057] Optionally, the cross-section of the platform base 110 is T-shaped. In other words, the platform base 110 includes an upper platform 111 and a lower platform 112. The width of the upper platform 111 in the direction of extension of the roadbed 200 is smaller than the width of the lower platform 112 in the lengthwise direction of the roadbed 200, resulting in a T-shaped cross-section of the platform base 110. After the platform base 110 is secured to the first bearing surface 101, a height difference exists between the lower platform 112 and the second bearing surface 102. A concrete backfill layer 140 is provided on the side of the lower platform 112 and the upper platform 111 closer to the second bearing surface 102. The top surface of the concrete backfill layer 140 is flush with the second bearing surface 102.

[0058] The platform body 120 is fixed to the top surface of the upper platform 111 , and a first connecting steel bar 150 is pre-embedded on one side of the platform top 130 close to the second bearing surface 102 . The first connecting steel bar 150 is used to connect to the rigid bridge plate 700 .

[0059] Furthermore, the platform foundation 110 adopts C50 reinforced concrete, and the rest of the abutment 100 adopts C35 reinforced concrete. During pouring, the concrete is discharged using a full-length conduit string to ensure that the free fall of the concrete does not exceed 2m, and a layered pouring method is adopted, with the thickness of each layer not exceeding 30cm, thereby reducing the impact of the concrete during pouring and ensuring the compressive strength of the abutment 100.

[0060] See also Figure 6 and Figure 7 Furthermore, a 1.5m long first connecting steel bar 150 is provided on the right side of the top 130 of the abutment 100 along the extension direction of the roadbed 200 for connecting the rigid slat 700; the first connecting steel bar 150 adopts Φ8 threaded steel bars arranged at a spacing of 200mm; the concrete backfill layer 140 is formed by C15 plain concrete backfill.

[0061] In this embodiment, a graded gravel cushion layer 300 is optionally used for laying on the second bearing surface 102. The thickness of the graded gravel cushion layer 300 is set to 50 cm. After the graded gravel cushion layer 300 is laid, the graded gravel cushion layer 300 is connected to the upper platform 111 and the concrete backfill layer 140, and the top surface of the graded gravel cushion layer 300 is located in the same plane as the top surface of the upper platform 111, that is, the top surface height of the graded gravel cushion layer 300 is equal to the top surface height of the upper platform 111. The graded gravel cushion layer 300 is mainly composed of crushed granite with good permeability and a particle size of 5-6 cm. The compressive strength of the graded gravel layer is not less than 80 MPa, the crushing value should be not less than 35%, the soft particle content is less than 5%, the mud content is less than 2%, the flat and slender gravel content is less than 20%, and the compaction coefficient is not less than 0.95.

[0062] Furthermore, the graded crushed stone layer includes a first graded crushed stone cushion layer 300, a first geogrid layer, a second graded crushed stone cushion layer 300, a second geogrid layer, and a third graded crushed stone cushion layer 300, which are stacked in order from bottom to top. The first graded crushed stone cushion layer 300, the second graded crushed stone cushion layer 300, and the third graded crushed stone cushion layer 300 are all laid manually followed by mechanical compaction, with the height difference after compaction being no greater than ±15 mm. The overlap length of the first and second geogrid layers should be greater than 30 cm, the tensile strength should be no less than 25 MPa, and the tensile modulus should be no less than 650 MPa.

[0063] See also Figure 4 In this embodiment, the reinforced concrete retaining wall 400 optionally includes a framed wall 410 and tensioning steel bars 420. The framed wall 410 includes a wall heel plate 411 and a plurality of wall panels connected to the wall heel plate 411. The plurality of wall panels are perpendicular to the wall heel plate 411, and the spacing between adjacent wall panels is equal in the extension direction of the roadbed 200.

[0064] Optionally, the plurality of wall panels include a plurality of first wall panels 412 and two second wall panels 413. The height of the plurality of first wall panels 412 gradually decreases from the side closest to the abutment 100 to the side away from the abutment 100. The wall heel plate 411 and the plurality of first wall panels 412 jointly define a plurality of fill areas 430. The two second wall panels 413 are both located on the side of the tallest first wall panel 412 among the plurality of first wall panels 412, closer to the abutment 100. The two second wall panels 413 are spaced apart in the direction of extension of the roadbed 200. The second wall panel 413, which is farther away from the first wall panel 412, is affixed to and connected to the abutment body 120 of the abutment 100. The two second wall panels 413 and the wall heel plate 411 jointly define a fill area 430. The wall heel plate 411 is laid on the graded crushed stone cushion 300 and connected to a portion of the top surface of the upper abutment 111.

[0065] It should be understood that the first wall panel 412 with the shortest height among the multiple first wall panels 412 is spaced apart from the side of the wall heel plate 411 away from the abutment 100 , and the first wall panel 412 with the shortest height and the wall heel plate 411 form a filling area 430 of a right triangle.

[0066] The number of the tensioning steel bars 420 is set as needed, and at least one tensioning steel bar 420 is provided between two adjacent wall panels, thereby enhancing the structural stability of the reinforced concrete retaining wall 400.

[0067] See also Figure 5In this embodiment, it should be noted that the reinforced concrete retaining wall 400 is a prefabricated component that can be prefabricated in a factory and then transported to the site for assembly. For example, the reinforced concrete retaining wall 400 is connected using a full grouting sleeve 440. That is, the grouting sleeve 440 is first threaded, and then the reserved steel bars 450 to be connected are threaded. The reserved steel bars 450 and the sleeve are connected through a threaded connection, and finally, grouting material is poured. It should be understood that the grouting sleeve 440 is provided with a grouting port 441 and a grouting outlet 442, and grouting material is injected from the grouting port 441.

[0068] Furthermore, both the wall heel plate 411 and the wall panel are designed to be 160mm thick, in accordance with the requirements of seismic resistance level 2. Φ16 threaded steel bars are evenly spaced 200mm apart within the wall, along with stirrups. The horizontal and vertical reinforcement ratios are no less than 0.2%. 30cm of steel bars are reserved in advance for anchoring at the locations of the tension bars 420. The length of the wall heel plate 411 along the extension direction of the roadbed 200 is 100m.

[0069] Furthermore, the tensioning steel bars 420 are Q235 plain round steel bars with a diameter of 12 mm, and are arranged at equal intervals of 1 m in the height direction. The number of tensioning steel bars 420 in each row gradually decreases from bottom to top.

[0070] In this embodiment, each filling area 430 is optionally filled with a crushed stone filler layer 500. The multiple crushed stone filler layers 500 in the filling areas 430 form a structure with a roughly rectangular trapezoidal outline. The upper base of the rectangular trapezoid faces away from the graded crushed stone filler cushion layer, while the lower base contacts the wall heel plate 411. Optionally, the upper base is 10 meters long, and the lower base is 100 meters long. The upper base is formed between the filling areas 430 formed by the two second wall panels 413. The upper base and the top surfaces of the two second wall panels 413 are located at the same height, that is, they are located in the same plane as the top surfaces of the two second wall panels 413. This plane is used to support the rigid strapping 700.

[0071] See also Figure 3 Optionally, the crushed stone filling layer 500 includes a crushed stone filling layer 520 and a crushed stone leveling layer 530. The maximum particle size of the stones in the crushed stone filling layer 520 is no more than 150 mm, the compacted thickness of each layer is no more than 30 cm, the settlement after compaction should be less than 3 mm, and the porosity is no more than 28%. The crushed stone leveling layer 530 is 20 cm thick and is filled and compacted with 5-6 cm crushed stones. The crushed stone leveling layer 530 is arranged on top of the crushed stone filling layer 520, and the top surface of the crushed stone leveling layer 530 is the upper base of the crushed stone filling layer 500. That is, the crushed stone leveling layer 530 is located on top of the crushed stone filling layer 520 between the two second wall panels 413, and together with the second wall panels 413, supports the rigid strapping 700.

[0072] In this embodiment, the fill layer 600 is constructed using a mixture of soil and sandy clay with a fine-grain content of less than 30%. The maximum compacted thickness of each layer does not exceed 20 cm, and a slope ratio of 1:1.5 is used for slope reduction. After the fill layer 600 is laid, its top surface is higher than the top surface of the crushed stone screed 530, forming a rectangular groove between the fill layer 600 and the platform top 130 for the rigid tack board 700.

[0073] In this embodiment, optionally, the length of the rigid strap 700 is set to 10m, the thickness of the strap is not less than 30cm, and the second connecting steel bars 710 with a diameter of 8mm and a spacing of 200mm are arranged inside the plate. The rigid strap 700 is set on the gravel leveling layer 530 and is in contact with the two second wall panels 413 at the same time. The rigid strap 700 is connected to the platform top 130 and the fill layer 600 on both sides of the extension direction of the roadbed 200, and the second connecting steel bars 710 on the rigid strap 700 are connected to the first connecting steel bars 150 on the platform top 130 through the threaded sleeve 160, and are poured with C30 concrete.

[0074] It should be understood that at the road-bridge transition section, since the longitudinal slope changes little, the road surface in this section can be approximated as an arc. At this time, when a vehicle passes through, it will generate centripetal acceleration. Assuming M is the weight of the person or vehicle, the centripetal force is F = Mv 2 ÷R=μMg, when μ=0.1, the car is in a critical jump state, and it can be deduced that R=Mv 2 ÷F=v 2 Assuming that the slope of the rigid slat 700 is i and the gradient is α≈i, the critical longitudinal slope of the vehicle can be deduced to be i=L / R=L / v 2 It can be seen that both vehicle speed and the length of rigid slat 700 affect the vertical curve radius and slope change rate at the critical vehicle jump state. If the length of rigid slat 700 remains unchanged, the slope change rate at the critical vehicle jump state decreases with increasing speed, making vehicle jumps very likely. Therefore, the length of rigid slat 700 should be increased as the highway grade increases, and should generally be no shorter than 8 meters. In this embodiment, the length of rigid slat 700 is selected to be 10 meters to improve road conditions and enhance driving safety.

[0075] It should be understood that after the rigid buttress plates 700 are installed, the top surface of the rigid buttress plates 700 is flush with the top surface of the fill layer 600 .

[0076] In other embodiments, a plurality of ventilation pipes 800 are pre-buried in the block stone filling layer 520 . The ventilation pipes 800 extend along the width direction of the roadbed 200 , and both ends of the ventilation pipes 800 are open.

[0077] The frozen soil variable-stiffness road-bridge transition structure provided in this embodiment has high structural stability, long service life, and is safe and reliable.

[0078] This embodiment also provides a construction process for a frozen soil variable-stiffness road-bridge transition structure, comprising the following steps:

[0079] A. Before the start of construction of roadbed 200, the three connections and one leveling should be achieved, and the natural surface within the planning range of roadbed 200 should be treated by rolling. At the same time, measurement and alignment work should be carried out. The measurement accuracy shall be based on the requirements of the "Highway Route Survey Regulations".

[0080] B. Lay the first graded gravel cushion layer 300 on the prepared natural surface by manually spreading the material followed by mechanical compaction. Measure the flatness of the graded gravel cushion layer 300 to ensure it meets the requirements of the "Technical Specifications for Highway Roadbed Construction 200" before laying the geogrid. Repeat these steps from bottom to top to lay the second and third graded gravel cushion layers 300 and compact them.

[0081] C. After transporting the reinforced concrete retaining wall 400 to the construction site, assemble it using threaded sleeve connections as required. First, install rebar positioning fixtures and fixed seven-character brackets along the inner edge of the prefabricated wall to facilitate positioning of the prefabricated components. Use a mirror to verify that the rebar of the prefabricated components aligns with the grouting sleeves 440. Once positioned, adjust the verticality of the prefabricated wall using diagonal supports and secure the supports. Immediately seal the inner side of the wall in the grouting area to ensure the sealing mortar reaches the design strength grade before grouting, while also preventing contamination of the grouting area. Four hours after the mortar seal is completed, mechanical continuous grouting is performed, and test blocks are retained as required by the specification.

[0082] D. After the installed reinforced concrete retaining wall 400 is cured, tension steel bars 420 are arranged in its wall panel, and both ends of the tension steel bars 420 are anchored to the reserved steel bars 450 of the wall panel of the reinforced concrete retaining wall 400.

[0083] E. Fill the reinforced concrete retaining wall 400 with crushed stone filler in layers and compact it as required, with each layer no thicker than 30cm. Finally, lay a 20cm thick crushed stone screed layer 530. After transporting the crushed stone filler to the construction site, survey and lay out the lines. After manual spreading, rough leveling is performed using an excavator. Then, the excavator's crawler tracks are used to smooth out the pressure. A loader, in conjunction with manual work, is then used to fill the gaps between the stones with fine crushed stone. Finally, a vibratory roller is used to roll the filler 4-6 times until the compaction standard is met before paving the next layer.

[0084] F. The 600-meter fill layer is paved in layers using the 200-meter roadbed filler. Each layer is paved to a height of 25 cm. Use a steel-wheel roller for static compaction once, followed by 5-6 passes with a vibratory roller. Before each layer is constructed, sprinkle water on the upper layer of compacted fill to prevent damage to the 200-meter roadbed and reduce dust pollution.

[0085] G. Tie the steel bars on the upper layer of the block gravel roadbed 200, connect the left side to the reserved steel bars 450 through the threaded sleeve 160, then support the formwork according to the panel size of the rigid lap plate 700, use C30 concrete for pouring, and maintain for 14 days after pouring.

[0086] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A frozen soil variable stiffness road-bridge transition structure, characterized in that: include: Used for bridge abutments and roadbeds on frozen soil; The roadbed comprises: A graded crushed stone cushion layer provided on the frozen soil base; A reinforced concrete retaining wall is provided on the graded crushed stone cushion layer, wherein the reinforced concrete retaining wall is provided with a plurality of filling areas arranged at intervals in the extension direction of the roadbed; the reinforced concrete retaining wall is connected to the abutment; a block crushed stone filling layer provided in the plurality of filling areas, wherein a slope is provided on a side of the block crushed stone filling layer facing away from the graded crushed stone cushion layer, and a height of the slope gradually decreases in a direction from a side close to the abutment to a side away from the abutment; a fill layer provided on the slope; and a rigid buttress plate provided between the earth fill layer and the abutment, the rigid buttress plate being supported by the block gravel fill layer and connected to the abutment; The reinforced concrete retaining wall includes a frame-type wall body, the frame-type wall body includes a wall heel plate and a plurality of first wall panels connected to the wall heel plate, the heights of the plurality of first wall panels gradually decrease from a side close to the abutment to a side away from the abutment, and the wall heel plate and the plurality of first wall panels together define the plurality of filling areas; The frame wall further includes two second wall panels of equal height, the two second wall panels are both connected to the wall heel plate, the two second wall panels are both located on a side of a first wall panel with the highest height among the plurality of first wall panels close to the abutment, the two second wall panels are spaced apart in the extending direction of the roadbed, and the second wall panel farther away from the first wall panel is connected to the abutment; The block stone filling layer includes a block stone filling layer and a crushed stone leveling layer, the block stone filling layer is arranged in the plurality of filling areas, and the crushed stone leveling layer is arranged on the block stone filling layer and between the two second wall panels; The rigid butt-jointed plate is supported by the crushed stone leveling layer and the two second wall panels at the same time; The abutment includes a platform foundation, a platform body and a platform top arranged in sequence from bottom to top. The platform foundation is used to connect with the foundation layer, and part of the platform foundation is connected to the side of the graded gravel cushion layer away from the reinforced concrete retaining wall.

2. The frozen soil variable stiffness road-bridge transition structure according to claim 1, characterized in that: Tensile steel bars are provided between at least two of the multiple wall panels of the frame-type wall.

3. The frozen soil variable stiffness road-bridge transition structure according to claim 1, characterized in that: The graded crushed stone cushion layer comprises a first graded crushed stone cushion layer, a first geogrid layer, a second graded crushed stone cushion layer, a second geogrid layer and a third graded crushed stone cushion layer which are arranged in sequence from bottom to top.

4. The frozen soil variable stiffness road-bridge transition structure according to claim 1, characterized in that: A concrete backfill layer is provided between the platform foundation and the graded crushed stone cushion layer.

5. The frozen soil variable stiffness road-bridge transition structure according to claim 1, characterized in that: The abutment is pre-embedded with a first connecting steel bar, the rigid slab is provided with a second connecting steel bar, and the first connecting steel bar and the second connecting steel bar are connected by a threaded sleeve.

6. A construction process for a frozen soil variable stiffness road bridge transition structure, characterized in that: The construction process comprises the following steps: Lay a graded crushed stone cushion on the subgrade with abutments; A reinforced concrete retaining wall having a plurality of filling areas is arranged on the graded crushed stone cushion layer, wherein the reinforced concrete retaining wall abuts against the abutment; Arranging a crushed stone filling layer in the plurality of filling areas, and forming a slope on a side of the crushed stone filling layer away from the abutment; providing a fill layer on the slope; A rigid slab is provided between the fill layer and the abutment. The rigid slab is supported by the reinforced concrete retaining wall and the block gravel filling layer, and the rigid slab is fixedly connected to the abutment.

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