Construction method of road and bridge transition section rigidity gradient embankment structure

Abstract

The invention discloses a construction method of a road and bridge transition section rigidity gradual change embankment structure, and belongs to the technical field of embankment fill construction, the construction method of the road and bridge transition section rigidity gradual change embankment structure comprises the following steps: S1, determining an embankment data set, a tire stack data set and a foam concrete data set, and selecting a foam concrete model; s2, calculating the thickness of a tire pile body; s3, the underlying soil foundation is reinforced, and a gravel drainage layer is laid; s4, foam concrete is constructed, and anchoring parts and anchor rods are synchronously embedded in the foam concrete; S5, tire bundles are laid on the foam concrete to form a tire pile body; s6, a pressure dispersing plate is constructed above the tire pile body and the foam concrete; and S7, the anchor rod and the anchor head are connected, and the initial strain of the tire pile body is adjusted through the anchoring system. The rigidity gradient between the bridge abutment and the conventional embankment can be realized, uniform supporting force is provided for the pressure dispersing plate, and the influence of vehicle load on tire compression settlement is reduced, so that the problem of vehicle bump at the bridge head is effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of embankment filling construction, and particularly relates to a construction method for a road-bridge transition section stiffness-gradual change embankment structure. Background Art

[0002] In the construction of embankment filling, the road-bridge transition section behind the abutment is one of the most difficult parts to control the construction quality. Due to the large stiffness difference from the abutment and insufficient compaction degree of the filling material in this area, problems such as vehicle bumping at the bridge head are likely to occur, which will further affect the driving comfort and the service life of the road.

[0003] Traditional solutions usually use a bridge approach slab for transition, that is, one end of the bridge approach slab is directly lapped on the abutment, and the other end is supported on the sleeper beam behind the abutment. However, the embankment filling behind the abutment gradually settles under the influence of multiple factors such as rainwater infiltration, consolidation, and repeated cyclic action of the top pressure, resulting in voids under the slab. After the slab has been used for a long time, a stress mode with one end hinged and one end flexibly supported and a beam support structure with voids in the middle will be formed. This will not only cause the filling soil under the end of the slab far from the abutment to continue to sink due to excessive stress, but also cause cracks or even fractures in the slab due to insufficient reinforcement, further aggravating the vehicle bumping disease at the bridge head.

[0004] In addition, in the current construction technology of the road-bridge transition section stiffness-gradual change embankment, the setting of the stiffness-gradual change embankment structure is blind, lacking a construction method determined based on the engineering characteristics of the embankment filling material in the road-bridge transition section and the principle of consistent settlement calculation, resulting in the inability to completely cure the existing vehicle bumping disease at the road-bridge transition section. Summary of the Invention

[0005] The present invention aims to at least solve one of the technical problems existing in the prior art. For this purpose, the present invention provides a construction method for a road-bridge transition section stiffness-gradual change embankment structure, which can realize the stiffness gradual change between the abutment transition section and the conventional embankment and the consistency of settlement, thereby solving the problem of vehicle bumping at the bridge head.

[0006] The construction method for a road-bridge transition section stiffness-gradual change embankment structure according to an embodiment of the present invention includes: S1: Define the embankment data group, the tire stack data group, and the foamed concrete data group, and select the foamed concrete model according to the highway grade and traffic load grade; S2: Calculate the thickness of the tire stack according to the embankment data group, the tire stack data group, and the foamed concrete data group; S3: Perform foundation treatment on the underlying soil subgrade, and lay a gravel drainage layer on the treated underlying soil subgrade to ensure smooth drainage; S4: Construct the foamed concrete so that the thickness of the foamed concrete gradually decreases in a stepped shape along the direction from the abutment to the embankment, and synchronously embed anchor elements and connect anchor rods in the foamed concrete: S5: Lay tire bundles on the foamed concrete to form a tire stack, making the tire stack flush with the top of the foamed concrete and reaching a preset embankment height, and enabling the anchor rods to pass through the gaps between the tire bundles. S6: Construct a dispersion plate above the tire stack and the foamed concrete, and ensure that the anchor rods are exposed outside the dispersion plate. S7: Connect the anchor rods to the anchor heads, and adjust the locking force of the anchor rods through the anchoring system to apply an initial additional strain to the tire stack to a preset value.

[0007] The construction method of the stiffness-gradual change embankment structure for the road-bridge transition section according to the embodiment of the present invention has at least the following beneficial effects: First, it promotes the resource utilization of waste tires and makes full use of the relatively high elastic modulus and water stability of the tire stack. The foamed concrete and the tire stack are mutually coordinated to form a double-layer composite material gradual change structure, so that the thickness of the tire stack increases step by step from the abutment to the embankment, and the thickness of the foamed concrete gradually decreases step by step from the abutment to the embankment, realizing the gradual change of stiffness between the abutment and the conventional embankment. Since the mechanical properties of the tire stack are stable after being immersed in water and its deformation is recoverable elastic deformation, and the lower-layer foamed concrete is regarded as an elastic body, the initial strain can be applied vertically along the tire stack by using the anchoring system to adjust the required thickness of the tire bundle stack. The double-layer composite material gradual change structure can always provide uniform supporting force for the dispersion plate, and the settlement at the connection between the end of the tire stack and the conventional section is consistent, thus effectively solving the problem of bump at bridge heads.

[0008] According to some embodiments of the present invention, in S1, the embankment data group includes the embankment height, the compression modulus of the filler in the conventional embankment section, the unit weight of the filler in the conventional embankment section, the bedding coefficient of the underlying soil foundation, and the equivalent uniform surface load of the road surface. The tire stack data group includes the deformation modulus of the tire stack, the unit weight of the tire stack, and the length of the gradual change section of the tire stack. The foamed concrete data group includes the deformation modulus of the foamed concrete and the unit weight of the foamed concrete.

[0009] According to some embodiments of the present invention, in S2, calculating the thickness of the tire stack includes: calculating the thickness of the tire stack; judging whether the calculated thickness of the tire stack meets the layout requirements of the stepped structure; if the calculated thickness of the tire stack does not meet the layout requirements of the stepped structure, increasing the initial additional strain and continuously recalculating the thickness of the tire stack; repeating the above steps until the calculated thickness of the tire stack meets the layout requirements of the stepped structure.

[0010] According to some embodiments of the present invention, in S2, the calculation formula for the thickness of the tire stack is: ; In the formula, is the thickness of the tire stack, is the equivalent uniform surface load of the road surface, is the embankment height, is the bedding coefficient of the underlying soil subgrade, is the deformation modulus of the tire stack, is the deformation modulus of the foamed concrete, is the compression modulus of the filler in the conventional embankment section, is the unit weight of the tire stack, is the unit weight of the foamed concrete, is the unit weight of the filler in the conventional embankment section, is the initial compressive strain of the tire stack.

[0011] According to some embodiments of the present invention, the tire stack applies an initial additional strain through the anchoring system to ensure consistent compressive deformation of the tire stack under additional loads.

[0012] According to some embodiments of the present invention, the calculation formula for the anchor bolt locking force is: ; In the formula, is the anchor bolt locking force, is the number of anchor bolts set on the same row of steps, is the deformation modulus of the tire stack, is the width of the dispersion plate, is the initial compressive strain of the tire stack.

[0013] According to some embodiments of the present invention, in S4, after the construction of the foamed concrete is completed, a waterproof layer is provided at the interface between the foamed concrete and the tire stack, a waterproof layer is provided at the interface between the foamed concrete and the embankment, and a water stop is connected between the anchor bolt and the waterproof layer.

[0014] According to some embodiments of the present invention, in S5, the tire bundles are laid in a preset manner to form a tire stack. After laying every 2 to 3 layers of tire bundles, a layer of geogrid is laid, and the laid geogrid is extended into the interior of the conventional embankment to change the required thickness of the tire stack and make the tire bundles closely connected.

[0015] 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 vertically, and the adjacent two tire layers are arranged with staggered joints. The staggering width is one tire radius. Each row of tire layers has multiple tires, and the multiple tires are arranged in sequence along the straight line in the radial direction and kept tangent.

[0016] According to some embodiments of the present invention, in S5, the tire bundle is compressed along the tire axis to of the original stacked total thickness, and then tied with high-strength steel wires. The tied tire bundles are stacked to form a tire stack.

[0017] According to some embodiments of the present invention, in S4 and S5, the construction progress of the foamed concrete and the tire stack 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 section.

[0018] According to some embodiments of the present invention, in S6, one end of the spreader plate starts from the abutment, and the other end sequentially crosses the tire stack and the reinforced embankment backfill soil and extends towards the top of the conventional embankment.

[0019] According to some embodiments of the present invention, each level of the foamed concrete steps has the same height-width ratio, and the range of the height-width ratio is from 1:8 to 1:2, and the minimum thickness of the tire stack is ≥3m.

[0020] Additional aspects and advantages of the present invention will be given in part in the following description, will become apparent in part from the following description, or will be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, wherein: Figure 1 is a schematic flow chart of the construction method of the stiffness-gradual embankment structure for the road-bridge transition section according to the embodiment of the present invention; Figure 2 is a schematic structural diagram of the stiffness-gradual road-bridge transition structure according to the embodiment of the present invention; Figure 3 is an explanatory diagram of the influence of the initial additional strain on the post-construction settlement; Figure 4 is a schematic diagram of the equivalent stiffness distribution curve; Figure 5 is Figure 2 a simplified calculation diagram of the tire layer thickness based on equal pavement settlement at the A-A position in Figure 6 is Figure 1 a schematic structural diagram of the tire bundle in

[0022] Reference numerals: tire stack 100, tire bundle 110, tire layer 111, tire 1111, high-strength steel wire 112, geogrid 120; foamed concrete 200, waterproof layer 210; gravel drainage layer 300; anchor rod 400, anchor 410, anchor head 420; spreader plate 500; subgrade 10, embankment 20, reinforced embankment backfill soil 21, unreinforced embankment backfill soil 22, pavement paving layer 30, abutment 40; Equivalent stiffness line C, equivalent stiffness at the position of section A D 。 Detailed implementation manners

[0023] In the description of the present invention, it should be understood that the orientation descriptions involved, such as up, down, front, back, left, right, etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0024] In the description of the present invention, the meaning of "several" is one or more, the meaning of "multiple" is more than two, understandings such as greater than, less than, exceeding, etc. do not include the present number, and understandings such as "above", "below", "within" etc. include the present number. If there is a description of "first", "second", etc., it is only for the purpose of distinguishing technical features and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence relationship of the indicated technical features.

[0025] In the description of the present invention, unless otherwise clearly defined, words such as "set", "installed", "connected", etc. should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above words in the present invention in combination with the specific content of the technical solution.

[0026] Please refer to Figure 1 , this embodiment discloses a construction method for a road and bridge transition section stiffness-gradual change embankment structure, including: S1: Define the data group of embankment 20, the data group of tire stack 100, and the data group of foamed concrete 200, and select the model of foamed concrete 200 according to the highway grade and traffic load grade; S2: Calculate the thickness of the tire stack 100 according to the data group of embankment 20, the data group of tire stack 100, and the data group of foamed concrete 200; S3: Carry out foundation treatment on the underlying soil foundation 10, and lay a gravel drainage layer 300 on the treated underlying soil foundation 10 to ensure unobstructed drainage; S4: Construct the foamed concrete 200 so that the thickness of the foamed concrete 200 gradually decreases in a stepped manner along the direction from the bridge abutment 40 to the embankment 20, and synchronously embed anchor parts 410 and anchor bolts 400 in the foamed concrete 200: S5: Lay the tire bundle 110 on the foamed concrete 200 until the tire bundle 110 is flush with the top of the foamed concrete 200 to reach the preset embankment 20 height; S6: Construct the loose pressing plate 500 above the tire stack 100 and the foamed concrete 200, and ensure that the anchor bolts 400 are exposed outside the loose pressing plate 500; S7: Connect the anchor rod 400 to the anchor head 420, and adjust the locking force of the anchor rod through the anchoring system to apply an initial additional strain to the tire stack to a preset value and tightly connect the tire bundles 110 to each other.

[0027] It should be noted that traditional backfill behind the bridge has plastic properties. Under the action of long-term loads and rain erosion, etc., it is prone to settlement, resulting in a gradual loss of its supporting force for the approach slab, and then causing voids to appear in the middle and below the approach slab. Such voids will lead to uneven stress on the approach slab and ultimately cause fractures, resulting in serious problems of bump at bridge heads.

[0028] First, promote the resource utilization of waste tires 1111, and make full use of the relatively high elastic modulus and water stability of the tire stack 100. A double-layer composite material gradient structure is formed by the mutual cooperation of the foam concrete 200 and the tire stack 100, so that the thickness of the tire stack 100 increases step by step from the abutment 40 to the embankment 20, and the thickness of the foam concrete 200 gradually decreases step by step from the abutment 40 to the embankment 20, realizing 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 immersion in water and its deformation is recoverable elastic deformation, and the lower-layer foam concrete 200 is regarded as an elastic body, strains are applied vertically along the tire stack 100 by the anchoring system to adjust the thickness of the tire bundle 110 stack, so that the double-layer composite material gradient structure can always provide uniform supporting force for the spreader plate 500, realizing a smooth transition of road surface settlement, making the stress distribution of the structure more reasonable under the action of the spreader plate 500, reducing the influence of vehicle loads on the compression settlement of the tire stack 100, and thus effectively solving the problem of bump at bridge heads.

[0029] As Figure 4 shown, since the deformation modulus of the tire stack 100 is much smaller than that of the foam concrete 200, among them, the formula for calculating the equivalent stiffness per unit area of the double-layer composite material with a step-like change in thickness composed of the two is as follows: ; In the formula, is the thickness of the tire stack 100, is the height of the embankment 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 far away from the abutment 40, decreases as increases, thus realizing a gradual change in stiffness.

[0030] Specifically, the derivation process of the formula for the equivalent stiffness per unit area of the tire stack 100 and the foam concrete 200 is as follows: The double-layer composite material is simplified to a series spring to calculate the equivalent stiffness. When the two materials are in series, the force F they receive is the same, and the total deformation ; According to Hooke's law , it can be obtained that , that is ; Substitute and into , and it can be obtained that: ; After transformation, it can be obtained that ; On the other hand, the post-construction settlement of the bridgehead subgrade in soft soil areas is likely to exceed the limit value, and the cost of using soft foundation treatment to reduce settlement is high. The double-layer lightweight material can control the post-construction settlement more economically, and realize the gradual change of stiffness by adjusting the gradual change of the thickness of the two structural layers. Thus, the dual effects of gradual change of stiffness and reduction of post-construction settlement of the road are achieved simultaneously.

[0031] It should be noted that when the traditional embankment is filled with cohesive soil, the permeability coefficient is small, and it is easy to have problems of poor drainage in the embankment. The gaps between the tire stacks 100 are natural drainage channels, and the accumulated water in the embankment 20 can be easily discharged. Further, a gravel drainage layer 300 is laid at the bottom of the foam concrete 200 and the conventional embankment 20. The gravel drainage layer 300 is wrapped by geotextiles, and then the water infiltrating into the embankment 20 is discharged in time, effectively preventing the erosion of the transition section structure by water, avoiding the settlement problem of the embankment 20 caused by water accumulation, and extending the service life of the structure.

[0032] In some specific embodiments of the present invention, in S1, the embankment 20 data group includes the embankment 20 height, the compression modulus of the filler in the conventional embankment 20 section, the unit weight of the filler in the conventional embankment 20 section, the bedding coefficient of the underlying soil foundation 10, and the equivalent uniform surface load of the road surface. The tire stack 100 data group includes the deformation modulus of the tire stack 100, the unit weight of the tire stack 100, and the length of the gradual change section of the tire stack 100. The foam concrete 200 data group includes the deformation modulus of the foam concrete 200 and the unit weight of the foam concrete 200.

[0033] 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 stepped structure. If the calculated thickness of the tire stack 100 does not meet the layout requirements of the stepped structure, increase the initial additional strain and continuously recalculate the thickness of the tire stack 100, and repeat the above steps until the calculated thickness of the tire stack 100 meets the layout requirements of the stepped structure.

[0034] In some specific embodiments of the present invention, in S2, the calculation formula for the thickness of the tire stack 100 is: ; In the formula, is the thickness of the tire stack 100, is the equivalent uniform load of the road surface, is the height of the embankment 20, is the bedding coefficient of the underlying soil foundation 10, is the deformation modulus of the tire stack 100, is the deformation modulus of the foamed concrete 200, is the compression modulus of the filler in the conventional embankment 20 section, is the unit weight of the tire stack 100, is the unit weight of the foamed concrete 200, is the unit weight of the filler in the conventional embankment 20 section, is the initial compressive strain of the tire stack 100.

[0035] In some specific embodiments of the present invention, the tire stack 100 applies an initial additional strain through the anchoring system to change the required thickness of the tire stack 100 and make the tire bundles 110 tightly connected.

[0036] In some specific embodiments of the present invention, the calculation formula for the locking force of the anchor rod 400 is: ; In the formula, is the locking force of the anchor rod 400, is the number of anchor rods 400 arranged on the same row of steps, is the deformation modulus of the tire stack 100, is the width of the dispersion pressure plate 500, is the initial compressive strain of the tire stack 100.

[0037] Thus, the construction personnel can apply the calculated initial additional strain through the anchoring system, such as adjusting the tension degree of the anchor rod 400, etc., 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.

[0038] It should be noted that, as Figure 3 shown, after applying the locking force to the tire stack 100, an initial strain and an initial settlement are generated, and the tire stacks 100 are tightly pressed against each other. Subsequently, only settlement will occur over time, rather than before applying the initial strain. Due to , so the post-construction settlement of the tire stack 100 will be significantly reduced due to the application of the initial strain.

[0039] In some specific embodiments of the present invention, in S4, after the construction of the foamed concrete 200 is completed, a waterproof layer 210 is provided at the interface between the foamed concrete 200 and the tire stack 100, and a waterproof layer 210 is provided at the interface between the foamed concrete 200 and the embankment 20. A water stop is used to connect between the anchor rod 400 and the waterproof layer 210. As Figure 2 shown, the top surface and the side surface of the foamed concrete 200 are both pasted with a waterproof layer 210, and a water stop ring is provided at the position where the anchor rod 400 penetrates the waterproof layer 210 to strengthen the sealing treatment measures to prevent water from seeping into the foamed concrete 200 layer and affecting the structural performance.

[0040] In some specific embodiments of the present invention, in S5, the tire bundles 110 are laid in a preset manner to form the tire stack 100. After every 2 to 3 layers of tire bundles 110 are laid, a layer of geogrid 120 is laid, and the laid geogrid 120 is extended into the interior of the conventional embankment 20 to reduce the differential settlement between the tire bundles 110 and between the transition section of the tire stack 100 and the conventional embankment 20 section.

[0041] 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 two tire layers 111 are arranged with staggered joints. The staggering width is the radius of one tire 1111. Each row of tire layers 111 has multiple tires 1111, and the multiple tires 1111 are arranged in sequence along the straight line in the radial direction and are kept tangent.

[0042] It should be noted that the high-strength steel wire is made of high-quality high-carbon steel wire rod through a patenting process, 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 demanding material performance requirements.

[0043] In some specific embodiments of the present invention, in S5, the tire bundle 110 is axially compressed along the tire 1111 to of the original stacked total thickness, and then tied with high-strength steel wires 112. The tied tire bundles 110 are stacked to form the tire stack 100.

[0044] In some specific embodiments of the present invention, in S4 and S5, the construction progress of the foamed concrete 200 and the tire stack 100 should be synchronized with the filling operation of the conventional embankment 20 in height to ensure the integrity and stability between the road-bridge transition section and the conventional section.

[0045] It should be noted that one end of the traditional approach slab is lapped on the abutment 40 with relatively high stiffness, and the other end is usually provided with a sleeper beam support to avoid the problem of excessive stiffness difference at both ends of the approach slab. Although this method results in relatively small settlement of the road surface in the approach slab section, it will transfer the differential settlement between the road and the bridge to the end of the approach slab, causing the secondary bumping disease. As Figure 2 shown, one end of the spreader plate 500 is not lapped on the abutment 40 with very high stiffness, so there will be no problem of excessive stiffness difference at both ends of the support, and thus there is no need to set a sleeper beam. At the same time, the stiffness change under the spreader plate 500 is more uniform, and the settlement of the end of the double-layer composite material is consistent with that of the road surface in the conventional section, avoiding the phenomenon of bumping at the bridge head.

[0046] In some specific embodiments of the present invention, in S6, one end of the spreader plate 500 starts from the abutment 40, and the other end sequentially crosses the tire heap 100 and the reinforced embankment backfill soil 21 and extends towards the top of the conventional embankment 20. On the one hand, it can prevent the spreader plate 500 from tilting too much, and on the other hand, it plays a role in crossing the differential settlement, avoiding Figure 5 the differential settlement and reflection cracks caused by excessive material difference on both sides of the structural section as shown.

[0047] Specifically, the width of the spreader plate 500 is the same as the width of the tire heap 100, so as to achieve the effect of dispersing the vehicle load and reducing the compression deformation of the tire heap 100, thereby ensuring the settlement consistency between the transition section and the conventional section.

[0048] Specifically, as Figure 2 shown, the embankment 20 backfill soil in contact with the tire heap 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 stepped manner in the direction away from the tire heap 100, thereby ignoring the change in the stiffness of the embankment 20 backfill soil caused by the reinforcement effect.

[0049] Referring to Figure 2 and Figure 5 , the calculation formula for the thickness of the tire heap 100 is derived. Take the Figure 2 unit body for analysis. As Figure 5 shown, ignoring the change in the stiffness of the embankment 20 caused by the reinforcement in the backfill soil of the embankment 20 structure, that is, regarding the compression modulus of the reinforced transition section composed of the reinforced embankment backfill soil 21 and the unreinforced embankment backfill soil 22 as the compression modulus of the embankment 20 backfill soil in the conventional section.

[0050] Specifically, each level of the foam concrete 200 steps has the same height-width ratio, and the range of the height-width ratio is 1:8 to 1:2, and the minimum thickness of the tire heap 100 ≥ 3m.

[0051] Reference Figure 2 and Figure 5 , the calculation formula for the thickness of the tire stack 100 is derived.

[0052] Obtain the unit weight of the tire stack 100 in the left - hand structure γ 1. Deformation modulus E 1. Thickness h 1 and the initial compressive strain and the length of the transition section L ; Obtain the unit weight of the foamed concrete 200 in the left - hand structure γ 2. Deformation modulus E 2 and thickness h 2; Obtain the unit weight of the fill material of the conventional embankment section 20 in the right - hand structure γ 3. Compression modulus E 3 and thickness H , where H = h 1 +h 2; Obtain the equivalent uniform road surface load q 、The subgrade reaction coefficient of the underlying soil subgrade 10 is k s .

[0053] (1) Calculate the compression settlement of the left - hand embankment fill.

[0054] For the tire stack 100, according to Hooke's law, the compression amount caused by the additional load is: ; For the foamed concrete 200, the compression amount caused by the additional load is: ; Then the total compression settlement of the left - hand embankment fill is: ; (2) Calculate the compression settlement of the right - hand embankment fill.

[0055] The compression settlement of the right - hand embankment 20 under the action of the additional load is: ; (3) Calculate the total pressure at the bottom of the left - hand embankment 20.

[0056] The pressure at the bottom of the left - hand embankment 20 is generated by the upper - layer tire stack 100, the lower - layer foamed concrete 200, and the road surface additional load : ; (4)Calculate the total pressure at the bottom of the right embankment 20.

[0057] The pressure at the bottom of the right embankment 20 is generated by the right conventional fill and the additional pavement load q as follows: ; (5)Calculate the compression deformation of the underlying soil bases 10 on the left and right sides.

[0058] According to the assumption, the compression deformation of the left underlying soil base 10: ; The compression deformation of the right underlying soil base 10: ; (6)Calculate the total settlement of the road surfaces on the left and right sides.

[0059] The total settlement of the left road surface: ; The total settlement of the right road surface: ； (7)Solve according to the condition that the settlements of the road surfaces on the left and right sides are the same.

[0060] Because s L =s R , that is: ; After rearranging the equation and further simplifying and solving, the expression of is: ; When it is required that the total settlements on both sides of the transition section are the same, within a reasonable range of parameter variations, h 1 increases with the increase of the deformation modulus E 1 and the initial compressive strain of the tire stack 100.

[0061] The following is illustrated by a set of example calculations to show how to calculate h 1 and how the initial strain of the tire stack 100 affects the thickness of the tire stack 100: Assume that the unit weight γ1 of the 1111-piece tire stack is 5 kN / m 3 , the deformation modulus E1 = 1500 kPa, the initial compressive strain of the 1111-piece tire stack, and the length of the gradual change section of the tire stack 100 is L = 20 m.

[0062] The unit weight γ2 of the foamed concrete 200 is 7 kN / m 3, the deformation modulus E2 = 8.0×10 5 kPa.

[0063] On the right side of the embankment 20, the unit weight of the conventional filler γ3 = 19 kN / m 3 , the compression modulus E3 = 1.5×10 4 kPa, and the thickness H = 10 m.

[0064] The additional load on the road surface is q = 25 kPa, and the subgrade coefficient of subgrade reaction is k s = 8.0×10 3 kN / m 3 ; Then: ; Then the height-width ratio of the step 7.1:20 = 1:2.82 is within the range of 1:8 to 1:2. After judgment, the thickness of the tire stack 100 meets the layout requirements of the step structure.

[0065] ; ; ; ; ; It should be noted that under the above given conditions such as applying the initial strain, the settlement of the road surface is very small and meets the post-construction settlement requirements of the subgrade. However, if the initial additional strain is not applied, that is, the initial compressive strain of the tire stack 100 When m < 3 m < 7.1 m, that is, when keeping the settlement of the road surfaces on both sides the same, the required height of the tire stack 100 is very small, and at this time, the height-width ratio of the step 1.91:20 and the thickness of the tire stack do not meet the layout requirements of the step structure.

[0066] The following describes the construction method of the gradually varying stiffness embankment structure of the road-bridge transition section through specific embodiments.

[0067] S1: Determine the height of the embankment 20, the compression modulus of the filler in the conventional embankment 20 section, the unit weight of the filler in the conventional embankment 20 section, the subgrade coefficient of subgrade reaction of the underlying soil foundation 10, the equivalent uniform load on the road surface, the length of the gradually varying section of the tire stack 100, the deformation modulus of the tire stack 100, the unit weight of the tire stack 100, the deformation modulus of the foamed concrete 200, and the unit weight of the foamed concrete 200, and select the type of foamed concrete 200 according to the highway grade and traffic load grade; 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 stepped structure. If the calculated thickness of the tire stack 100 does not meet the layout requirements of the stepped structure, increase the initial additional strain and continuously 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 stepped structure.

[0068] Among them, the calculation formula for the thickness of the tire stack 100 is: ; In the formula, is the thickness of the tire stack 100, is the equivalent uniform load of the road surface, is the height of the embankment 20, is the bedding coefficient of the underlying soil foundation 10, is the deformation modulus of the tire stack 100, is the deformation modulus of the foamed concrete 200, is the compression modulus of the filler in the conventional embankment 20 section, is the unit weight of the tire stack 100, is the unit weight of the foamed concrete 200, is the unit weight of the filler in the conventional embankment 20 section, is the initial compressive strain of the tire stack 100.

[0069] Specifically, the construction personnel can use the anchoring system to apply the calculated initial additional strain, so as to achieve precise control of the initial additional strain. Among them, the calculation formula for the locking force of the anchor rod 400 is: ； In the formula, is the locking force of the anchor rod 400, is 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 loose pressing plate 500, is the initial compressive strain of the tire stack 100.

[0070] S3: Carry out ground treatment on the underlying soil foundation 10, and lay a gravel drainage layer 300 on the treated underlying soil foundation 10 to ensure unobstructed drainage; S4: Construct the foamed concrete 200 so that the thickness of the foamed concrete 200 gradually decreases in a stepped shape along the direction from the abutment 40 to the embankment 20, and synchronously bury the anchor fittings 410 and the anchor rods 400 in the foamed concrete 200: It should be noted that the foam concrete steps at all levels adopt the same height-width ratio, and the range of the height-width ratio is 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 at the interface between the foam concrete 200 and the tire stack 100, and a waterproof layer 210 is set at the interface between the foam concrete 200 and the embankment 20. A water stop is used to connect between the anchor rod 400 and the waterproof layer 210. As Figure 2 shown, waterproof layers 210 are pasted on the top surface and side surface of the foam concrete 200, and a water stop ring is set at the position where the anchor rod 400 penetrates through the waterproof layer 210 and other measures are taken to strengthen the sealing treatment to prevent water from seeping into the foam concrete 200 layer and affecting the structural performance.

[0071] S5: Lay the tire bundle 110 on the foam concrete 200 to form the tire stack 100, make the tire stack 100 flush with the top of the foam concrete 200 and reach the preset height of the embankment 20, and make the anchor rod 400 pass through the gap between the tire bundles 110; Specifically, the tire bundle 110 includes 10 rows of tire layers 111. 19 tire layers 111 are stacked vertically, and the adjacent two tire layers 111 are arranged with staggered joints. 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. Multiple tires 1111 are connected in sequence along the straight line where the radial direction is located. Lay the tire bundle 110 in a preset manner to form the tire stack 100, and compress the tire bundle 110 along the axial direction of the tire 1111 to of the original stacked total thickness. For every 2 layers of tire bundles 110 laid, a layer of geogrid 120 is laid, and the laid geogrid 120 is extended into the interior of the conventional embankment 20 to reduce the differential settlement between the tire bundles 110 and between the transition section of the tire stack 100 and the conventional embankment 20 section.

[0072] 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 section.

[0073] S6: Construct the spreader plate 500 above the tire stack 100 and the foam concrete 200, make one end of the spreader plate 500 start from the abutment 40, and the other end sequentially cross the tire stack 100 and the reinforced embankment backfill soil 21 and extend towards the top of the conventional embankment 20, and ensure that the anchor rod 400 is exposed outside the spreader plate 500.

[0074] Specifically, the width of the spreader plate 500 is the same as the width of the tire stack 100.

[0075] Specifically, as Figure 2As shown, the backfill soil of the embankment 20 connecting with the tire stack 100 and the foamed 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 stepped manner in the direction away from the tire stack 100.

[0076] S7: Connect the anchor rod 400 with the anchor head 420, and adjust the locking force of the anchor rod 400 through the anchoring system to apply an initial additional strain to the tire stack 100 to a reasonable value, so as to adjust the thickness of the tire stack 100 to meet the requirements of the stepped structure layout. Lay the road pavement layer 30 on the dispersion pressure plate 500. Thus, the construction is completed.

[0077] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those of ordinary skill in the art, various changes can be made without departing from the purpose of the present invention.

Claims

1. A construction method for a road embankment structure with gradually changing stiffness at the road-bridge transition section, characterized in that, Including: S1: Define the embankment data set, tire stack data set, and foamed concrete data set, and select the foamed concrete model according to the highway grade and traffic load grade; S2: Calculate the thickness of the tire stack based on the embankment data set, tire stack data set, and foamed concrete data set; S3: Conduct ground treatment on the underlying soil subgrade, and lay a gravel drainage layer on the treated underlying soil subgrade to ensure unobstructed drainage; S4: Construct the foamed concrete so that the thickness of the foamed concrete gradually decreases in a stepped manner along the direction from the abutment to the embankment. Anchor parts are buried synchronously in the foamed concrete and connected with anchor rods: S5: Lay tire bundles on the foamed concrete to form a tire stack, making the tire stack flush with the top of the foamed concrete and reaching the preset embankment height, and passing the anchor rods through the gaps between the tire bundles; S6: Construct a dispersion plate above the tire stack and the foamed concrete, and ensure that the anchor rods are exposed outside the dispersion plate; S7: Connect the anchor rods with the anchor heads, and adjust the locking force of the anchor rods through the anchoring system to apply an initial additional strain to the tire stack to a preset value.

2. The construction method for a road embankment structure with gradually changing stiffness at the road-bridge transition section according to claim 1, characterized in that, In S1, the embankment data set includes the embankment height, the compression modulus of the filler in the conventional embankment section, the unit weight of the filler in the conventional embankment section, the subgrade coefficient of the underlying soil subgrade, and the equivalent uniform surface load of the pavement. The tire stack data set includes the deformation modulus of the tire stack, the unit weight of the tire stack, and the length of the gradual change section of the tire stack. The foamed concrete data set includes the deformation modulus of the foamed concrete and the unit weight of the foamed concrete.

3. The construction method for a road embankment structure with gradually changing stiffness at the road-bridge transition section according to claim 2, characterized in that, In S2, calculating the thickness of the tire stack includes: Calculating the thickness of the tire stack; Judging whether the calculated thickness of the tire stack meets the layout requirements of the stepped structure; If the calculated thickness of the tire stack does not meet the layout requirements of the stepped structure, increase the initial additional strain and continuously recalculate the thickness of the tire stack; Repeat the above steps until the calculated thickness of the tire stack meets the layout requirements of the stepped structure.

4. The construction method for a road embankment structure with gradually changing stiffness at the road-bridge transition section according to claim 1, characterized in that, In S2, the calculation formula for the thickness of the tire stack is: ； In the formula, is the thickness of the tire stack, is the equivalent uniform load of the road surface, is the height of the embankment, is the bedding coefficient of the underlying soil subgrade, is the deformation modulus of the tire stack, is the deformation modulus of the foamed concrete, is the compression modulus of the filler in the conventional embankment section, is the unit weight of the tire stack, is the unit weight of the foamed concrete, is the unit weight of the filler in the conventional embankment section, is the initial compressive strain of the tire stack.

5. The construction method for a road embankment structure with gradually changing stiffness at the road-bridge transition section according to claim 4, characterized in that, The tire stack applies an initial additional strain through the anchoring system to change the required thickness of the tire stack and make the tire bundles tightly connected.

6. The construction method for a road embankment structure with gradually changing stiffness at the road-bridge transition section according to claim 5, characterized in that, The calculation formula for the locking force of the anchor rod is: ； In the formula, is the bolt locking force, is the number of bolts set on the same row of steps, is the deformation modulus of the tire stack, is the width of the loose pressing plate, is the initial compressive strain of the tire stack.

7. The construction method for a road embankment structure with gradually changing stiffness at the road-bridge transition section according to claim 1, characterized in that, In S4, after the construction of the foamed concrete is completed, a waterproof layer is set at the interface between the foamed concrete and the tire stack, a waterproof layer is set at the interface between the foamed concrete and the embankment, and a water stop piece is used to connect between the anchor rod and the waterproof layer.

8. The construction method for a road embankment structure with gradually changing stiffness at the road-bridge transition section according to claim 1, characterized in that, In S5, lay the tire bundles in a preset manner to form a tire stack. After laying every 2 to 3 layers of tire bundles, conduct the laying operation of one layer of geogrid, and extend the laid geogrid into the interior of the conventional embankment to reduce the differential settlement between the tire bundles and between the gradual change section of the tire stack and the conventional embankment section.

9. The construction method for a road embankment structure with gradually changing stiffness at the road-bridge transition section according to claim 8, 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 vertically, and the adjacent two tire layers are arranged with staggered joints, and the staggering width is one tire radius. Each row of tire layers has multiple tires, and the multiple tires are arranged in sequence along the straight line in the radial direction and kept tangent.

10. The construction method for a road embankment structure with gradually changing stiffness at the road-bridge transition section according to claim 1, characterized in that, In S5, the tire bundle is axially compressed along the tire to of the original total stacking thickness, and then tied with high-strength steel wires. After tying, the tire bundles are stacked to form a tire stack.

11. The construction method of the road and bridge transition section stiffness-gradual embankment structure according to claim 1, characterized in that, In S4 and S5, the construction progress of the foamed concrete and the tire stack 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 section.

12. The construction method of the road and bridge transition section stiffness-gradual embankment structure according to claim 1, characterized in that, In S6, one end of the loose pressing plate starts from the abutment, and the other end sequentially crosses the tire stack and the reinforced embankment backfill soil and extends towards the top of the conventional embankment.

13. The construction method of the road and bridge transition section stiffness-gradual embankment structure according to claim 1, characterized in that, Each level of the foamed concrete steps has the same height-width ratio, and the range of the height-width ratio is 1:8 to 1:

2. The minimum thickness of the tire stack is ≥3m.

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