Construction method for embankment structure with gradually changing stiffness in road-bridge transition section

Abstract

The present invention discloses a construction method for a road-bridge transition section embankment structure with a gradually varying stiffness, belonging to the technical field of embankment fill construction. The construction method comprises the following steps: S1: defining an embankment data set, a tire pile data set, and a foam concrete data set, and selecting a foam concrete model; S2: calculating the tire pile thickness; S3: reinforcing the underlying soil base and laying a gravel drainage layer; S4: constructing foam concrete, and simultaneously embedding anchors and anchor rods in the foam concrete; S5: laying tire bundles on the foam concrete to form a tire pile; S6: constructing a pressure plate above the tire pile and foam concrete; and S7: connecting the anchor rods and anchor heads, and adjusting the initial strain of the tire pile through the anchoring system. The present invention can achieve a gradual change in stiffness between the abutment and the conventional embankment, provide uniform support for the pressure plate, and reduce the impact of vehicle load on tire compression settlement, thereby effectively solving the problem of vehicle bouncing at the bridge head.

Description

Technical Field

[0001] The present invention relates to the technical field of embankment filling construction, and in particular to a construction method of an embankment structure with gradually varying stiffness in a road-bridge transition section. Background Art

[0002] During the construction of embankment filling, the road-bridge transition section behind the abutment is one of the most difficult parts to control construction quality. This area is prone to bridge-head jumping problems due to the large difference in stiffness with the abutment and insufficient compaction of the filler, which in turn affects driving comfort and road service life.

[0003] Traditional solutions typically use a bridgehead slab for transition, meaning one end of the slab is directly attached to the abutment, while the other end is supported on a corbel behind the abutment. However, the fill embankment behind the abutment gradually settles due to multiple factors, including rainwater infiltration, consolidation, and repeated cycles of top pressure. This causes voids under the slab. Over time, the slab develops a stress pattern characterized by hinged support at one end and flexible support at the other, with a beam support structure that is hollow in the middle. This not only causes the fill beneath the slab, away from the abutment, to continue sinking due to excessive stress, but also causes the slab to crack or even break due to insufficient reinforcement, further exacerbating the bridgehead bouncing problem.

[0004] In addition, in the current construction technology of the embankment with gradually varying stiffness in the transition section of the road bridge, the setting of the embankment structure with gradually varying stiffness is blind, and there is a lack of construction methods determined according to the engineering characteristics of the embankment filling material in the transition section of the road bridge and based on the principle of consistent settlement calculation, which leads to the inability to fundamentally solve the existing bridgehead bouncing problem in the transition section of the road bridge. Summary of the Invention

[0005] The present invention aims to address at least one of the technical problems existing in the prior art. To this end, the present invention proposes a construction method for a road-bridge transition section embankment structure with a gradual stiffness change. This method achieves a gradual stiffness change across the abutment transition section, as well as consistent stiffness change and settlement between conventional embankments, thereby resolving the problem of vehicle bouncing at the bridge head.

[0006] A construction method for a road bridge transition section embankment structure with gradually varying stiffness according to an embodiment of the present invention includes:

[0007] S1: Identify the embankment data set, tire pile data set, and foam concrete data set, and select the foam concrete model based on the highway grade and traffic load level;

[0008] S2: Calculate the tire pile thickness based on the embankment data set, the tire pile data set, and the foam concrete data set;

[0009] S3: Treat the underlying soil and lay a gravel drainage layer on the treated underlying soil to ensure smooth drainage;

[0010] S4: Construct foam concrete so that its thickness gradually decreases in a step-like manner from the abutment toward the embankment. Simultaneously embed anchors in the foam concrete and connect anchor rods:

[0011] S5: laying tire bundles on the foam concrete to form a tire pile, so that the tire pile is flush with the top of the foam concrete and reaches the preset embankment height, and the anchor rods pass through the gaps between the tire bundles;

[0012] S6: Construct a pressure plate above the tire pile and foam concrete, and ensure that the anchor rods are exposed on the pressure plate;

[0013] S7: Connect the anchor rod and the anchor head, and adjust the anchor rod locking force through the anchoring system to apply initial additional strain to the tire pile to a preset value.

[0014] The construction method of the embankment structure with a gradual stiffness change in the bridge transition section according to an embodiment of the present invention has at least the following beneficial effects: first, it promotes the resource utilization of discarded tires and fully utilizes the high elastic modulus and water stability of the tire pile. Foam concrete and the tire pile cooperate with each other to form a double-layer composite material gradient structure, so that the thickness of the tire pile increases in a step-like manner from the abutment to the embankment, and the thickness of the foam concrete gradually decreases in a step-like manner from the abutment to the embankment, thereby realizing a gradual stiffness change between the abutment and the conventional embankment. Since the mechanical properties of the tire pile are stable after being immersed in water, its deformation is a recoverable elastic deformation, and the lower layer of foam concrete is regarded as an elastic body. By applying initial strain vertically along the tire pile using the anchoring system, the required thickness of the tire bundle can be adjusted. The double-layer composite material gradient structure can always provide uniform support for the pressure plate, and the settlement of the end of the tire pile and the junction with the conventional road section is consistent, thereby effectively solving the problem of vehicle jumping at the bridge head.

[0015] According to some embodiments of the present invention, in S1, the embankment data group includes the embankment height, the compression modulus of the conventional embankment section filler, the weight of the conventional embankment section filler, the base bed coefficient of the underlying soil base, and the equivalent uniformly distributed load of the pavement; the tire pile data group includes the deformation modulus of the tire pile, the weight of the tire pile, and the length of the tire pile transition section; and the foam concrete data group includes the deformation modulus of the foam concrete and the weight of the foam concrete.

[0016] According to some embodiments of the present invention, in S2, calculating the tire stack thickness includes: calculating the tire stack thickness; determining whether the calculated tire stack thickness meets the layout requirements of the step structure; if the calculated tire stack thickness does not meet the layout requirements of the step structure, increasing the initial additional strain and continuously recalculating the tire stack thickness; repeating the above steps until the calculated tire stack thickness meets the layout requirements of the step structure.

[0017] According to some embodiments of the present invention, in S2, the calculation formula for the tire stack thickness is:

[0018] ;

[0019] Where, is the tire stack thickness, is the equivalent uniformly distributed load on the road surface, is the embankment height, is the base bed coefficient of the underlying soil foundation, is the deformation modulus of the tire stack, is the deformation modulus of foam concrete, is the compression modulus of the conventional embankment filler, is the weight of the tire pile, is the density of foam concrete, is the density of the fill material in the conventional embankment section, is the initial compressive strain of the tire stack.

[0020] According to some embodiments of the present invention, an initial additional strain is applied to the tire stack through the anchoring system to ensure that the compression deformation of the tire stack under the additional load is consistent.

[0021] According to some embodiments of the present invention, the formula for calculating the anchor bolt locking force is:

[0022] ;

[0023] Where, is the anchor locking force, is the number of anchor rods set on the same row of steps, is the deformation modulus of the tire stack, is the width of the pressure plate, is the initial compressive strain of the tire stack.

[0024] According to some embodiments of the present invention, in S4, after the construction of the foam concrete is completed, a waterproof layer is set at the interface between the foam concrete and the tire pile, and a waterproof layer is set at the interface between the foam concrete and the embankment, and a water stop is connected between the anchor rod and the waterproof layer.

[0025] According to some embodiments of the present invention, in S5, tire bundles are laid in a preset manner to form a tire pile. After laying 2 to 3 layers of tire bundles, a layer of geogrid is laid, and the laid geogrid is extended to the interior of the conventional embankment to change the required thickness of the tire pile and ensure that the tire bundles are tightly connected.

[0026] According to some embodiments of the present invention, in S5, the tire bundle includes multiple rows of tire layers and high-strength steel wires, the multiple tire layers are stacked in a vertical direction, and adjacent tire layers are staggered with a staggered width of one tire radius. Each row of tire layers has multiple tires, and the multiple tires are arranged sequentially along a straight line in the radial direction and remain tangent.

[0027] According to some embodiments of the present invention, in S5, the tire bundle is compressed along the tire axial direction to a total thickness of the original stack. , and then use high-strength steel wire to bundle the tires. The bundled tires are stacked to form a tire pile.

[0028] According to some embodiments of the present invention, in S4 and S5, the construction progress of the foam concrete and tire pile should be synchronized with the filling operation of the conventional embankment in terms of height to ensure the integrity and stability between the road-bridge transition section and the conventional road section.

[0029] According to some embodiments of the present invention, in S6, one end of the pressure plate starts from the abutment, and the other end sequentially crosses the tire pile and the reinforced embankment backfill and extends toward the top of the conventional embankment.

[0030] According to some embodiments of the present invention, each level of foam concrete steps adopts the same aspect ratio, the aspect ratio range is 1:8 to 1:2, and the minimum thickness of the tire stack is ≥3m.

[0031] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0033] Figure 1 Schematic diagram of the process of the construction method of the embankment structure with gradually varying stiffness in the transition section of a road bridge according to an embodiment of the present invention;

[0034] Figure 2 This is a structural schematic diagram of a stiffness gradient road-bridge transition structure according to an embodiment of the present invention;

[0035] Figure 3 This is a diagram illustrating the effect of initial additional strain on post-construction settlement;

[0036] Figure 4 is a schematic diagram of the equivalent stiffness distribution curve;

[0037] Figure 5 for Figure 2 The middle AA position is based on a simplified diagram of tire layer thickness calculation with equal road surface settlement;

[0038] Figure 6 for Figure 1 Schematic diagram of the structure of the tire bundle.

[0039] Reference numerals:

[0040] Tire pile 100, tire bundle 110, tire layer 111, tire 1111, high-strength steel wire 112, geogrid 120;

[0041] Foam concrete 200, waterproof layer 210;

[0042] Gravel drainage layer 300;

[0043] Anchor rod 400, anchor member 410, anchor head 420;

[0044] Pressure plate 500;

[0045] Subgrade 10, embankment 20, reinforced embankment backfill 21, unreinforced embankment backfill 22, road pavement 30, abutment 40;

[0046] Equivalent stiffness line C, equivalent stiffness at section A D . DETAILED DESCRIPTION

[0047] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0048] In the description of the present invention, "several" means one or more, "multiple" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, and "above," "below," and "within" are understood to include the number itself. The use of terms such as "first" and "second" is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0049] In the description of the present invention, unless otherwise clearly defined, words such as “setting”, “installation” and “connection” should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above words in the present invention based on the specific content of the technical solution.

[0050] Please refer to Figure 1 This embodiment discloses a construction method for a road-bridge transition section embankment structure with gradually varying stiffness, comprising:

[0051] S1: Define the data set of embankment 20, tire pile 100 and foam concrete 200, and select the foam concrete 200 model according to the highway grade and traffic load level;

[0052] S2: Calculating the thickness of the tire stack 100 based on the embankment 20 data set, the tire stack 100 data set, and the foam concrete 200 data set;

[0053] S3: Performing foundation treatment on the underlying soil base 10 and laying a gravel drainage layer 300 on the treated underlying soil base 10 to ensure smooth drainage;

[0054] S4: Construct foamed concrete 200 so that the thickness of the foamed concrete 200 gradually decreases in a step-like manner along the abutment 40 toward the embankment 20 , and simultaneously embed anchors 410 and anchor rods 400 in the foamed concrete 200 :

[0055] S5: Laying the tire bundle 110 on the foam concrete 200 until the tire bundle 110 is flush with the top of the foam concrete 200 and reaches the preset height of the embankment 20;

[0056] S6: constructing a pressure-distributing plate 500 above the tire stack 100 and the foam concrete 200, and ensuring that the anchor rods 400 are exposed on the pressure-distributing plate 500;

[0057] S7: Connect the anchor rod 400 and the anchor head 420, and adjust the anchor rod locking force through the anchoring system to apply initial additional strain to the tire stack to a preset value, and ensure that the tire bundles 110 are tightly connected.

[0058] It should be noted that conventional backfill behind bridges has plastic properties and is prone to sinking under long-term loads and rain erosion, causing it to gradually lose its support for the bridgehead slab, resulting in gaps in the middle and lower parts of the slab. This gap leads to uneven stress on the slab, ultimately causing it to break and resulting in serious bridgehead vehicle bouncing problems.

[0059] First, the resource utilization of discarded tires 1111 is promoted, fully utilizing the high elastic modulus and water stability of the tire stack 100. A double-layer composite material gradient structure is formed by combining foamed concrete 200 with the tire stack 100. The thickness of the tire stack 100 increases in steps from the abutment 40 to the embankment 20, while the thickness of the foamed concrete 200 decreases in steps from the abutment 40 to the embankment 20, achieving a gradual change in stiffness between the abutment 40 and the conventional embankment 20. Since the mechanical properties of the tire stack 100 are stable after being immersed in water, its deformation is a recoverable elastic deformation, and the lower layer of foam concrete 200 is regarded as an elastic body. The anchoring system is used to apply strain vertically along the tire stack 100, and the thickness of the tire bundle 110 is adjusted, so that the double-layer composite material gradient structure can always provide uniform support for the pressure plate 500, achieving a smooth transition of road surface settlement. Under the action of the pressure plate 500, the structural force distribution is made more reasonable, reducing the influence of vehicle load on the compression settlement of the tire stack 100, thereby effectively solving the problem of vehicle jumping at the bridge head.

[0060] like Figure 4 As shown, since the deformation modulus of the tire stack 100 is much smaller than that of the foam concrete 200, the equivalent stiffness per unit area of the double-layer composite material with a step-like thickness formed by the tire stack 100 is calculated as follows:

[0061] ;

[0062] Where, The thickness of the tire stack is 100, For embankment height 20, is the deformation modulus of the tire stack 100, is the deformation modulus of the foam concrete 200. It should be noted that when away from the abutment 40, along with decreases as the stiffness increases, thus achieving a gradual change in stiffness.

[0063] Specifically, the derivation process of the equivalent stiffness per unit area formula of the tire stack 100 and the foam concrete 200 is as follows:

[0064] The double-layer composite material is simplified as a series spring to calculate the equivalent stiffness. When the two materials are connected in series, the force F they receive is the same, and the total deformation ;

[0065] By Hooke's law , we can get ,Right now ;

[0066] Will and Substitution In the above equation, we can get:

[0067] ;

[0068] After transformation, ;

[0069] On the other hand, the post-construction settlement of the bridgehead roadbed in soft soil areas is prone to exceed the limit, and the cost of using soft foundation treatment to reduce the settlement is high. Double-layer lightweight materials can control the post-construction settlement more economically, and achieve a gradual change in stiffness by adjusting the gradual change in the thickness of the two structural layers, thereby achieving the dual effects of gradual change in stiffness and reducing post-construction settlement of the road.

[0070] It should be noted that the low permeability coefficient of the viscous fill behind a conventional embankment 20 can easily lead to poor drainage of the embankment 20. However, the gaps between the tire stacks 100 serve as natural drainage channels, easily draining accumulated water from the embankment 20. Furthermore, a gravel drainage layer 300, wrapped in geotextile fabric, is laid beneath the foamed concrete 200 and conventional embankment 20. This layer effectively drains water that has infiltrated the embankment 20, effectively preventing water erosion in the transition section structure, avoiding settlement of the embankment 20 due to water accumulation, and extending the service life of the structure.

[0071] In some specific embodiments of the present invention, in S1, the embankment 20 data group includes the height of the embankment 20, the compression modulus of the conventional embankment 20 section filler, the weight of the conventional embankment 20 section filler, the base bed coefficient of the underlying soil base 10, and the equivalent uniformly distributed load of the pavement; the tire stack 100 data group includes the deformation modulus of the tire stack 100, the weight of the tire stack 100, and the length of the gradual transition section of the tire stack 100; and the foam concrete 200 data group includes the deformation modulus of the foam concrete 200 and the weight of the foam concrete 200.

[0072] In some specific embodiments of the present invention, in S2, calculating the thickness of the tire stack 100 includes: calculating the thickness of the tire stack 100, determining whether the calculated thickness of the tire stack 100 meets the layout requirements of the step structure, if the calculated thickness of the tire stack 100 does not meet the layout requirements of the step structure, increasing the initial additional strain and continuously recalculating the thickness of the tire stack 100, and repeating the above steps until the calculated thickness of the tire stack 100 meets the layout requirements of the step structure.

[0073] In some specific embodiments of the present invention, in S2, the thickness of the tire stack 100 is calculated as follows:

[0074] ;

[0075] Where, The thickness of the tire stack is 100, is the equivalent uniformly distributed load on the road surface, For embankment height 20, is the base bed coefficient of the underlying soil foundation 10, is the deformation modulus of the tire stack 100, is the deformation modulus of foam concrete 200, is the compression modulus of 20 sections of filler for conventional embankment, is the weight of the tire stack 100, For the weight of foam concrete 200, It is the weight of 20 sections of filler in conventional embankment. is the initial compressive strain of the tire stack 100.

[0076] In some specific embodiments of the present invention, the tire stack 100 is subjected to initial additional strain through the anchoring system to change the desired thickness of the tire stack 100 and to ensure tight connection between the tire bundles 110 .

[0077] In some specific embodiments of the present invention, the calculation formula of the locking force of the anchor rod 400 is:

[0078] ;

[0079] Where, is the locking force of anchor rod 400, The number of anchor rods 400 set on the same row of steps, is the deformation modulus of the tire stack 100, is the width of the pressure scattering plate 500, is the initial compressive strain of the tire stack 100.

[0080] Therefore, construction personnel can apply the calculated initial additional strain through the anchoring system, such as adjusting the tension of the anchor rod 400, so as to achieve precise control of the initial additional strain, ensure that the tire stack 100 can meet the design requirements in the project and ensure the stability and safety of the structure.

[0081] It should be noted that if Figure 3 As shown, the initial strain is generated after the locking force is applied to the tire stack 100. and initial settlement The tire stack 100 is tightly squeezed against each other, and only sedimentation will occur over time. , rather than the initial strain before ,because Therefore, the post-construction settlement of the tire stack 100 will be significantly reduced due to the application of the initial strain.

[0082] In some specific embodiments of the present invention, in S4, after the construction of the foam concrete 200 is completed, a waterproof layer 210 is provided on the interface between the foam concrete 200 and the tire stack 100, and a waterproof layer 210 is provided on the interface between the foam concrete 200 and the embankment 20, and a water stop is connected between the anchor rod 400 and the waterproof layer 210. Figure 2 As shown, the top and side surfaces of the foam concrete 200 are both affixed with a waterproof layer 210, and a water stop ring is provided at the position where the anchor rod 400 passes through the waterproof layer 210 to strengthen the sealing measures to prevent moisture from penetrating into the foam concrete 200 layer and affecting the structural performance.

[0083] In some specific embodiments of the present invention, in S5, tire bundles 110 are laid in a preset manner to form a tire pile 100. After laying 2 to 3 layers of tire bundles 110, a layer of geogrid 120 is laid, and the laid geogrid 120 is extended to the interior of the conventional embankment 20 to reduce differential settlement between the tire bundles 110 and between the transition section of the tire pile 100 and the conventional embankment 20.

[0084] In some specific embodiments of the present invention, in S5, the tire bundle 110 includes multiple rows of tire layers 111 and high-strength steel wires 112. The multiple tire layers 111 are stacked in the vertical direction, and the adjacent tire layers 111 are staggered. The staggered width is the radius of one tire 1111. Each row of tire layers 111 has multiple tires 1111. The multiple tires 1111 are arranged in sequence along a straight line along the radial direction and remain tangent.

[0085] It should be noted that high-strength steel wire is made of high-quality high-carbon steel wire rod through sorbitizing, pickling, copper plating or phosphating and then cold drawing. It has extremely high tensile strength, hardness and durability, and is usually used in engineering fields with stringent requirements on material properties.

[0086] In some specific embodiments of the present invention, in S5, the tire bundle 110 is compressed axially along the tires 1111 to a total thickness of the original stack. The tire bundles 110 are then bundled using high-strength steel wires 112 , and the bundled tire bundles 110 are stacked to form a tire stack 100 .

[0087] In some specific embodiments of the present invention, in S4 and S5, the construction progress of the foam concrete 200 and the tire stack 100 should be synchronized with the filling operation of the conventional embankment 20 in terms of height to ensure the integrity and stability between the road-bridge transition section and the conventional road section.

[0088] It should be noted that one end of the traditional bridge head slab is overlapped on the abutment 40 with greater rigidity, and the other end is usually supported by a bolster to avoid the problem of excessive rigidity difference between the two ends of the slab. Although this method reduces the road surface settlement in the slab section, it will transfer the differential settlement of the road and bridge to the end of the slab, resulting in secondary vehicle jumping. Figure 2 As shown, one end of the pressure-releasing plate 500 is not connected to the abutment 40 with great rigidity, so there will not be a problem of excessive difference in support rigidity at both ends, so there is no need to set a sleeper beam. At the same time, the rigidity change below the pressure-releasing plate 500 is more uniform, and the end of the double-layer composite material is consistent with the pavement settlement of the conventional road section, avoiding the phenomenon of vehicle jumping at the bridge head.

[0089] In some specific embodiments of the present invention, in S6, one end of the pressure plate 500 starts from the abutment 40, and the other end sequentially crosses the tire pile 100 and the reinforced embankment backfill 21 and extends toward the top of the conventional embankment 20. On the one hand, it can prevent the pressure plate 500 from tilting too much, and on the other hand, it plays a role in bridging differential settlement to avoid Figure 5 The structural section shown has differential settlement and reflective cracks on both sides due to the large difference in materials.

[0090] Specifically, the width of the pressure spreading plate 500 is consistent with the width of the tire stack 100 to achieve the effect of dispersing the vehicle load and reducing the compression deformation of the tire stack 100, thereby ensuring the settlement consistency between the transition section and the conventional road section.

[0091] Specifically, if Figure 2 As shown, the backfill soil of the embankment 20 connected to the tire stack 100 and the foam concrete 200 is composed of two parts, one part is the reinforced embankment backfill soil 21, and the other part is the unreinforced embankment backfill soil 22. Among them, the reinforced embankment backfill soil 21 is arranged above the unreinforced embankment backfill soil 22, and the vertical thickness of the reinforced embankment backfill soil 21 gradually decreases in a step-like manner towards the direction away from the tire stack 100, thereby ignoring the change in the stiffness of the embankment 20 backfill soil caused by the reinforcement effect.

[0092] Reference Figure 2 and Figure 5 , the calculation formula of the thickness of the tire pile 100 is derived, and the Figure 2 Analyze the unit body in Figure 5 As shown, the change in the stiffness of the embankment 20 caused by the reinforcement in the backfill soil in the embankment 20 structure is ignored, that is, the compression modulus of the reinforced transition section composed of the reinforced embankment backfill soil 21 and the unreinforced embankment backfill soil 22 is regarded as the compression modulus of the backfill soil of the embankment 20 in the conventional section.

[0093] Specifically, each level of the foam concrete 200 steps adopts the same aspect ratio, and the aspect ratio range is 1:8 to 1:2, and the minimum thickness of the tire stack 100 is ≥3m.

[0094] Reference Figure 2 and Figure 5 , the calculation formula for the thickness of the tire stack 100 is derived.

[0095] Get the weight of the tire stack 100 in the left structure γ 1. Deformation modulus E 1. Thickness h 1 and initial compressive strain and the length of the gradient segment L ;

[0096] Get the weight of the foam concrete 200 in the left structure γ 2. Deformation modulus E 2 and thickness h 2;

[0097] Get the weight of the fill material of the 20th section of the conventional embankment in the right structure γ 3. Compression modulus E 3 and thickness H ,in H=h 1 +h 2;

[0098] Obtaining the equivalent uniformly distributed load on the pavement q , the base coefficient of the underlying soil foundation 10 is k s .

[0099] (1) Calculate the compression settlement of the left embankment fill.

[0100] For the tire stack 100, according to Hooke's law, the additional load Amount of compression produced:

[0101] ;

[0102] For foam concrete 200, the additional load Amount of compression produced:

[0103] ;

[0104] The total compression settlement of the left embankment filling is:

[0105] ;

[0106] (2) Calculate the compression settlement of the right embankment fill.

[0107] Right embankment 20 in additional load Compression settlement under action: ;

[0108] (3) Calculate the total pressure at the bottom of the left embankment 20.

[0109] The pressure at the bottom of the left embankment 20 is caused by the tire stack 100 on the upper layer, the foam concrete 200 on the lower layer and the additional load of the road surface. produce:

[0110] ;

[0111] (4) Calculate the total pressure at the bottom of the right embankment 20.

[0112] The pressure at the bottom of the right embankment 20 is composed of the right conventional fill and the additional load of the road surface. q produce:

[0113] ;

[0114] (5) Calculate the compression deformation of the underlying soil foundation 10 on the left and right sides.

[0115] According to the assumption, the compression deformation of the left underlying soil foundation 10 is:

[0116] ;

[0117] Compression deformation of the underlying soil foundation 10 on the right side:

[0118] ;

[0119] (6) Calculate the total settlement of the road surface on the left and right sides.

[0120] Total settlement of left road surface:

[0121] ;

[0122] Total settlement of right road surface:

[0123] ；

[0124] (7) Solve the problem based on the consistent settlement of the road surface on the left and right sides.

[0125] because s L =s R ,Right now:

[0126] ;

[0127] Arrange the equation and further simplify the solution to get The expression is:

[0128] ;

[0129] When the total settlement on both sides of the transition section is required to be consistent, within a reasonable parameter variation range, h 1 Deformation modulus E 1 and the initial compressive strain of the tire stack 100 increases with the increase of .

[0130] The following is a set of example calculations to illustrate how to calculate h 1, and how the initial strain of the tire stack 100 affects the thickness of the tire stack 100:

[0131] Assume that the weight of a pile of 1111 tires is γ1 = 5kN / m 3 , deformation modulus E1 = 1500kPa, initial compressive strain of 1111 tire blocks The length of the gradual transition section of the tire stack 100 is L=20m.

[0132] The density of foam concrete 200g is γ2=7kN / m 3 , deformation modulus E2=8.0×10 5 kPa.

[0133] The density of conventional fill on the right side of embankment 20 is γ3=19kN / m 3 , compression modulus E3=1.5×10 4 kPa, thickness H=10m.

[0134] The additional load of the road surface is q=25kPa, and the roadbed coefficient is k s =8.0×10 3 kN / m 3 ;

[0135] but: ;

[0136] The step height-to-width ratio of 7.1:20 = 1:2.82 is within the range of 1:8 to 1:2. It is determined that the thickness of the tire stack 100 meets the requirements for the layout of the step structure.

[0137] ;

[0138] ;

[0139] ;

[0140] ;

[0141] ;

[0142] It should be noted that under the given conditions of applying the initial strain, the road surface settlement is very small, which meets the settlement requirements after the roadbed construction. hour, m<3m<7.1m, that is, when the settlement of the road surface on the left and right sides is kept consistent, the required height of the tire pile 100 is very small. At this time, the height-to-width ratio of the step 1.91:20 and the thickness of the tire pile do not meet the requirements of the step structure layout.

[0143] The construction method of the embankment structure with gradual stiffness change in the transition section of the bridge is described below through specific embodiments.

[0144] S1: Determine the height of the embankment 20, the compression modulus of the conventional embankment 20 filler, the density of the conventional embankment 20 filler, the base coefficient of the underlying soil base 10, the equivalent uniformly distributed load of the road surface, the length of the gradual transition section of the tire pile 100, the deformation modulus of the tire pile 100, the density of the tire pile 100, the deformation modulus of the foam concrete 200, and the density of the foam concrete 200. Select the type of foam concrete 200 based on the highway grade and traffic load grade.

[0145] S2: First, calculate the thickness of the tire stack 100, and determine whether the calculated thickness of the tire stack 100 meets the layout requirements of the step structure. If the calculated thickness of the tire stack 100 does not meet the layout requirements of the step structure, increase the initial additional strain and continue to recalculate the thickness of the tire stack 100. Repeat the above steps until the calculated thickness of the tire stack 100 meets the layout requirements of the step structure.

[0146] The calculation formula for the thickness of the tire stack 100 is:

[0147] ;

[0148] Where, The thickness of the tire stack is 100, is the equivalent uniformly distributed load on the road surface, For embankment height 20, is the base bed coefficient of the underlying soil foundation 10, is the deformation modulus of the tire stack 100, is the deformation modulus of foam concrete 200, is the compression modulus of 20 sections of filler for conventional embankment, is the weight of the tire stack 100, For the weight of foam concrete 200, It is the weight of 20 sections of filler in conventional embankment. is the initial compressive strain of the tire stack 100.

[0149] Specifically, the construction personnel can apply the calculated initial additional strain through the anchoring system, thereby achieving precise control of the initial additional strain. The calculation formula of the locking force of the anchor rod 400 is:

[0150] ；

[0151] Where, is the locking force of anchor rod 400, The number of anchor rods 400 set on the same row of steps, is the deformation modulus of the tire stack 100, is the width of the pressure scattering plate 500, is the initial compressive strain of the tire stack 100.

[0152] S3: Performing foundation treatment on the underlying soil base 10 and laying a gravel drainage layer 300 on the treated underlying soil base 10 to ensure smooth drainage;

[0153] S4: Construct foamed concrete 200 so that the thickness of the foamed concrete 200 gradually decreases in a step-like manner along the abutment 40 toward the embankment 20 , and simultaneously embed anchors 410 and anchor rods 400 in the foamed concrete 200 :

[0154] It should be noted that each level of foam concrete steps adopts the same aspect ratio, which ranges from 1:8 to 1:2. The minimum thickness of the tire stack is ≥3m. After the construction of the foam concrete 200 is completed, a waterproof layer 210 is set on the interface between the foam concrete 200 and the tire stack 100, and a waterproof layer 210 is set on the interface between the foam concrete 200 and the embankment 20. A water stop is used to connect the anchor rod 400 and the waterproof layer 210. Figure 2 As shown, the top and side surfaces of the foam concrete 200 are both affixed with a waterproof layer 210, and a water stop ring is provided at the position where the anchor rod 400 passes through the waterproof layer 210 to strengthen the sealing measures to prevent moisture from penetrating into the foam concrete 200 layer and affecting the structural performance.

[0155] S5: Laying tire bundles 110 on the foam concrete 200 to form a tire stack 100, so that the tire stack 100 is flush with the top of the foam concrete 200 and reaches the preset height of the embankment 20, and the anchor rods 400 pass through the gaps between the tire bundles 110;

[0156] Specifically, the tire bundle 110 includes 10 rows of tire layers 111, 19 tire layers 111 are stacked in the vertical direction, and the adjacent tire layers 111 are staggered. The odd-numbered rows of tire layers 111 have 4 tires 1111, and the even-numbered rows of tire layers 111 have 3 tires 1111. The tires 1111 are sequentially connected along a straight line in the radial direction. The tire bundle 110 is laid out in a preset manner to form a tire stack 100, and the tire bundle 110 is compressed axially along the tires 1111 to a total thickness of the original stack. A layer of geogrid 120 is laid every time two layers of tire bundles 110 are laid, and the laid geogrid 120 is extended to the interior of the conventional embankment 20 to reduce the differential settlement between the tire bundles 110 and between the gradual transition section of the tire pile 100 and the conventional embankment 20 section.

[0157] It should be noted that the construction progress of the foam concrete 200 and the tire stack 100 should be synchronized with the filling operation of the conventional embankment 20 in terms of height to ensure the integrity and stability between the road-bridge transition section and the conventional road section.

[0158] S6: Construct a pressure plate 500 above the tire stack 100 and the foam concrete 200, so that one end of the pressure plate 500 starts from the abutment 40 and the other end sequentially crosses the tire stack 100 and the reinforced embankment backfill 21 and extends toward the top of the conventional embankment 20, and ensure that the anchor rod 400 is exposed on the pressure plate 500.

[0159] Specifically, the width of the pressure plate 500 is consistent with the width of the tire stack 100 .

[0160] Specifically, if Figure 2 As shown, the backfill soil of the embankment 20 connected to the tire stack 100 and the foam concrete 200 is composed of two parts, one part is the reinforced embankment backfill soil 21, and the other part is the unreinforced embankment backfill soil 22, wherein the reinforced embankment backfill soil 21 is arranged above the unreinforced embankment backfill soil 22, and the vertical thickness of the reinforced embankment backfill soil 21 gradually decreases in a step-like manner towards the direction away from the tire stack 100.

[0161] S7: Connect the anchor rod 400 and the anchor head 420. Adjust the locking force of the anchor rod 400 through the anchoring system to apply the initial additional strain to the tire stack 100 to a reasonable value. This allows the thickness of the tire stack 100 to be adjusted to meet the requirements of the step structure layout. The road pavement layer 30 is laid on the pressure plate 500. The construction is now complete.

[0162] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the scope of the present invention.

Claims

1. A construction method for a road-bridge transition section embankment structure with gradually varying stiffness, characterized in that: include: S1: Identify the embankment data set, tire pile data set, and foam concrete data set, and select the foam concrete model based on the highway grade and traffic load level; S2: Calculate the tire pile thickness based on the embankment data set, the tire pile data set, and the foam concrete data set; Calculation of tire pile thickness includes: Calculate tire pile thickness; Determine whether the calculated tire stack thickness meets the layout requirements of the step structure; If the calculated tire stack thickness does not meet the layout requirements of the step structure, increase the initial additional strain and continue to recalculate the tire stack thickness; The calculation formula for the tire pile thickness is: ； Where, is the tire stack thickness, is the equivalent uniformly distributed load on the road surface, is the embankment height, is the base bed coefficient of the underlying soil foundation, is the deformation modulus of the tire stack, is the deformation modulus of foam concrete, is the compression modulus of the conventional embankment filler, is the weight of the tire pile, is the density of foam concrete, is the density of the fill material in the conventional embankment section, is the initial compressive strain of the tire stack; Repeat the above steps until the calculated tire stack thickness meets the step structure layout requirements; S3: Treat the underlying soil and lay a gravel drainage layer on the treated underlying soil to ensure smooth drainage; S4: Construct foam concrete so that its thickness gradually decreases in a step-like manner from the abutment toward the embankment. Simultaneously embed anchors in the foam concrete and connect anchor rods: S5: laying tire bundles on the foam concrete to form a tire pile, so that the tire pile is flush with the top of the foam concrete and reaches the preset embankment height, and the anchor rods pass through the gaps between the tire bundles; Tire bundles are laid in a pre-set pattern to form a tire pile. After every 2 to 3 layers of tire bundles, a layer of geogrid is laid. The laid geogrid is extended into the interior of the conventional embankment to reduce differential settlement between tire bundles and between the transition section of the tire pile and the conventional embankment section. S6: Construct a pressure plate above the tire pile and foam concrete, and ensure that the anchor rods are exposed on the pressure plate; S7: Connect the anchor rod and the anchor head, and adjust the anchor rod locking force through the anchoring system to apply initial additional strain to the tire pile to a preset value.

2. The construction method of the embankment structure with gradually changing stiffness in the transition section of a road bridge according to claim 1 is characterized in that: In S1, the embankment data group includes the embankment height, the compression modulus of the conventional embankment section filler, the weight of the conventional embankment section filler, the base bed coefficient of the underlying soil base, and the equivalent uniformly distributed load of the pavement; the tire pile data group includes the deformation modulus of the tire pile, the weight of the tire pile, and the length of the tire pile gradient section; and the foam concrete data group includes the deformation modulus and weight of the foam concrete.

3. The construction method of the embankment structure with gradually changing stiffness in the transition section of a road bridge according to claim 1 is characterized in that: The tire stack is subjected to initial additional strain through the anchoring system to change the required thickness of the tire stack and to ensure tight connection between the tire bundles.

4. The construction method of the embankment structure with gradually changing stiffness in the transition section of a road bridge according to claim 3 is characterized in that: The calculation formula of anchor locking force is: ； Where, is the anchor locking force, is the number of anchor rods set on the same row of steps, is the deformation modulus of the tire stack, is the width of the pressure plate, is the initial compressive strain of the tire stack.

5. The construction method of the embankment structure with gradually changing stiffness in the transition section of a road bridge according to claim 1 is characterized in that: In S4, after the construction of the foam concrete is completed, a waterproof layer is provided at the interface between the foam concrete and the tire pile, a waterproof layer is provided at the interface between the foam concrete and the embankment, and the anchor rods and the waterproof layer are connected by water stoppers.

6. The construction method of the embankment structure with gradually changing stiffness in the transition section of a road bridge according to claim 5 is characterized in that: In S5, the tire bundle includes multiple rows of tire layers and high-strength steel wires. The multiple tire layers are stacked in a vertical direction, and adjacent tire layers are staggered with a stagger width of one tire radius. Each row of tire layers has multiple tires, and the multiple tires are arranged sequentially along a straight line along the radial direction and remain tangent.

7. The construction method of the embankment structure with gradually changing stiffness in the transition section of a road bridge according to claim 1 is characterized in that: In S5, the tire bundle is compressed along the tire axial direction to a total thickness of the original stack. , and then use high-strength steel wire to bundle the tires. The bundled tires are stacked to form a tire pile.

8. The construction method of the embankment structure with gradually changing stiffness in the transition section of a road bridge according to claim 1 is characterized in that: In S4 and S5, the construction progress of foam concrete and tire piles should be synchronized with the filling operation of conventional embankment in terms of height to ensure the integrity and stability between the road-bridge transition section and the conventional road section.

9. The construction method of the embankment structure with gradually changing stiffness in the transition section of a road bridge according to claim 1 is characterized in that: In S6, one end of the pressure plate starts from the abutment, and the other end extends over the tire pile and reinforced embankment backfill toward the top of the conventional embankment.

10. The construction method of the embankment structure with gradually changing stiffness in the transition section of a road bridge according to claim 1 is characterized in that: Each level of foam concrete steps adopts the same height-to-width ratio, ranging from 1:8 to 1:2, and the minimum thickness of the tire pile is ≥3m.

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