Reinforcement Structure and Construction Method of Culvert Based on UHPC and Steel Plate Combination

Abstract

This invention discloses a culvert reinforcement structure and construction method based on a combination of UHPC and steel plates, relating to the field of highway bridge reinforcement technology. The structure includes a high-strength metal base plate, shear connectors, and a UHPC concrete layer. The high-strength metal base plate is supported below the original culvert via lateral support components. The shear connectors are welded to the base plate and embedded in the roughened layer at the bottom of the original culvert. The UHPC concrete layer fills the space between the base plate and the original culvert, forming a composite beam structure. This invention utilizes the high tensile and compressive strength of ultra-high performance concrete combined with the high ductility of steel plates, achieving synergistic stress distribution between the old and new structures through shear connectors. This structure not only significantly improves the load-bearing capacity and crack resistance of the culvert, but also allows the high-strength metal base plate to serve as a permanent formwork during construction, achieving a "permanent-temporary combination," without encroaching on the culvert clearance, and facilitating construction. It is particularly suitable for the rapid reinforcement and repair of existing highway culverts.

Description

Technical Field

[0001] This invention relates to the field of highway engineering reconstruction and expansion technology, specifically to a culvert reinforcement structure based on a combination of UHPC and steel plates and its construction method for rapid reinforcement and repair of existing culverts. Background Technology

[0002] With the rapid development of my country's transportation infrastructure, early-built culverts, due to their low design load standards and long service life, are now experiencing structural defects such as concrete cracking, mid-span deflection of the culvert, steel corrosion, and reduced load-bearing capacity under the current surge in traffic volume and frequent overloaded vehicles. This is especially true in road reconstruction and expansion projects, where the load on the upper part of the culverts increases significantly to meet the need for roadbed elevation, making it difficult for the original structure to meet current load-bearing requirements. However, as a crucial component of the highway network, the reinforcement and reconstruction of culverts must balance traffic flow, construction time, and structural safety, posing a serious challenge to traditional reinforcement methods. Therefore, developing a new reinforcement technology that does not damage the original road surface, does not encroach on the culvert's internal clearance, is quick to construct, and significantly improves load-bearing capacity has become an urgent need in highway maintenance and reconstruction projects.

[0003] Currently, the main methods for reinforcing culverts both domestically and internationally include demolition and reconstruction, external concrete encasing, and the addition of sleeves or steel structure supports. While demolition and reconstruction can completely solve the problem, it is costly, time-consuming, and requires traffic interruption, making it suitable for low-traffic, non-critical road sections. External concrete encasing and the addition of sleeves can improve load-bearing capacity to some extent, but the construction procedures are cumbersome and significantly occupy the internal space of the culvert, affecting drainage function and clearance, making them unsuitable for culverts with limited clearance. In recent years, some patented technologies have attempted to strengthen culverts by adding supporting structures. For example, Chinese patent CN211713718U uses a large number of supporting members to form a truss system, but the dense members severely encroach on the passage space and are complicated to install. CN218291633U proposes to add exposed steel I-beams under the cover plate, which improves the load-bearing capacity, but the exposed steel is easily damaged by vehicle collisions and reduces the net width of the culvert by about 0.8 meters, resulting in poor durability. CN218436685U uses corrugated steel and concrete lining for composite reinforcement, which enhances the overall integrity, but significantly reduces the net height and width, and the filling concrete is prone to cracking, limiting the reinforcement effect.

[0004] A comprehensive analysis of existing technologies reveals the following main drawbacks: First, they generally encroach on the internal clearance of culverts, affecting drainage and the passage of vehicles and pedestrians, making them particularly unsuitable for urban culverts or low-lying culverts with limited clearance. Second, construction is complex, requiring prolonged traffic closures, impacting road operational efficiency. Third, some structures are exposed, making them susceptible to environmental erosion or mechanical impacts, resulting in insufficient durability. Fourth, concrete-filled technologies are prone to cracking, leading to long-term performance instability. Fifth, most solutions do not adequately consider the additional loads caused by roadbed elevation during the reconstruction and expansion of existing roads, resulting in limited improvement in bearing capacity. Furthermore, existing technologies often focus on structural reinforcement while neglecting construction convenience and interference control with existing traffic, failing to meet the requirements of modern highway maintenance for "fast, efficient, and low-interference" operations.

[0005] Therefore, there is an urgent need for a new type of culvert reinforcement structure that can achieve rapid construction and significant load-bearing capacity improvement without damaging the original road or encroaching on the space inside the culvert, and overcome the systemic defects of existing technologies in terms of space occupation, durability, and construction efficiency. Summary of the Invention

[0006] In view of the above-mentioned defects or improvement needs of the existing technology, the present invention provides a culvert reinforcement structure and construction method based on the combination of UHPC and steel plate to solve the problems of insufficient bearing capacity, cracking and water seepage of existing culverts, while achieving "permanent and temporary combination" without encroaching on the culvert clearance.

[0007] To achieve the above objectives, according to a first aspect of the present invention, a culvert reinforcement structure based on a combination of UHPC and steel plate is provided, comprising: A high-strength metal base plate is installed below the original cover plate, and its width is less than the net width of the culvert. Shear connectors are fixed in an array on the upper surface of the high-strength metal base plate, and the top of the shear connectors extends upward and is embedded in the interface treatment layer at the bottom of the original cover plate. The UHPC concrete layer is filled between the high-strength metal base plate and the original cover plate, and the shear connector is wrapped in it, so that the high-strength metal base plate, the UHPC concrete layer and the original cover plate form a combined load-bearing structure. Lateral support components are installed on the inner wall of the culvert platform to support the high-strength metal base plate; The high-strength metal base plate has pre-drilled grouting holes, through which the UHPC concrete layer is pumped and filled.

[0008] Furthermore, the lateral support component is a triangular support frame; The triangular support frame includes angle steel, angle steel and connecting steel plate, which are welded together to form a triangular truss structure; the triangular support frame is anchored to the inner walls of both sides of the culvert abutment by high-strength expansion bolts, and its top supports the high-strength metal base plate.

[0009] Furthermore, the high-strength metal base plate is a high-strength metal base plate with a thickness of 2cm; The high-strength metal base plate is welded with reinforcing ribs on its upper surface, and the high-strength metal base plate is disconnected at the location corresponding to the settlement joint of the original cover plate.

[0010] Furthermore, the shear connector is characterized in that it is a shear connector made of ML15 special weld stud steel; The shear connectors are arranged in a staggered, quincunx pattern on the high-strength metal base plate, and are densely arranged in the support area near the culvert abutment.

[0011] Furthermore, expansion joint fillers are provided between the UHPC concrete layers of adjacent segments; The expansion joint filler is made of asphalt foam board, which also serves as a lateral template during pouring and as a filling material for expansion joints.

[0012] Furthermore, the compressive strength of the UHPC concrete layer is ≥150MPa, and the tensile strength is ≥8.2MPa.

[0013] According to another aspect of the present invention, a construction method for a culvert reinforcement structure based on a combination of UHPC and steel plate is provided, comprising the following steps: S1. Interface treatment: The bottom of the original cover plate is roughened to form a rough interface; S2. Install the support system: Anchor the lateral support components to the inner walls on both sides of the culvert abutment; S3. Install the combined base plate: Place the high-strength metal base plate with welded shear connectors on the lateral support assembly, so that the top of the shear connectors abuts against or is embedded in the bottom of the original cover plate; S4. Template and sealing: Install lateral templates on both sides of the middle part of the cover plate and seal the gap between the high-strength metal base plate and the lateral templates; S5. Grouting reinforcement: Ultra-high performance concrete is pumped through the reserved holes on the high-strength metal base plate, and the reserved holes are sealed after being filled and compacted. S6. Curing: After the UHPC concrete layer reaches the design strength, the temporary facilities shall be removed and traffic shall be opened.

[0014] Furthermore, in S1, the chiseling depth is controlled at 10~15mm, and the chiseling rate is not less than 90%.

[0015] Furthermore, in S3, the lower end of the shear connector is fixed to the high-strength metal base plate by perforated plug welding, and the upper end is in contact with the roughened interface of the original cover plate (1).

[0016] Furthermore, in S5, the ultra-high performance concrete is poured symmetrically from the center outwards.

[0017] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects: 1. This invention utilizes the extremely high compressive strength of UHPC ( The high tensile strength of the 150MPa (150MPa) and the high-strength metal base plate forms a highly rigid combined load-bearing structure. This structure can significantly improve the bending load-bearing capacity and crack resistance of the original cover plate, effectively compensating for the insufficient resistance of the old culvert structure.

[0018] 2. This invention uses a lateral support component (triangular support frame) and a high-strength metal base plate to act as a formwork system for UHPC pumping grouting during the construction phase, eliminating the need for additional support structures; during the operation phase, it transforms into part of the permanent structure, continuously providing lateral support and lifting force, significantly shortening the construction period and reducing overall costs.

[0019] 3. This invention benefits from the excellent mechanical properties of UHPC and steel, resulting in a thin and lightweight overall reinforcement layer (e.g., a metal base plate of only 2cm). While significantly improving strength, it almost completely preserves the original height and width of the culvert. This feature ensures the original drainage and passage capacity of the culvert, avoiding the reduction of the flow cross-section caused by traditional reinforcement methods.

[0020] 4. This invention achieves a rigid combination between the original cover plate, the UHPC concrete layer, and the metal steel plate through shear connectors (special welded stud steel) arranged in a staggered, quincunx pattern and with a denser arrangement in the support area. This design effectively solves the problem of easy peeling and insufficient bonding at the reinforced interface, ensuring that the three components work together to bear the load and significantly improving the fatigue life of the structure.

[0021] 5. This invention employs an in-tunnel operation mode throughout the entire process, using pre-reserved grouting holes for pumping and filling, eliminating the need to remove the old culvert top slab or excavate the road surface. Combined with the lateral template function of the expansion joint filler (asphalt foam board), precise pre-reservation of expansion joints between adjacent segments is achieved, ensuring minimal disruption to existing traffic during the reinforcement process. Attached Figure Description

[0022] Figure 1 This is a cross-sectional view of a culvert cover plate reinforcement structure based on a combination of UHPC and steel plate, according to an embodiment of the present invention. Figure 2 This is a detailed drawing of the triangular support frame for the culvert reinforcement structure based on a combination of UHPC and steel plate, according to an embodiment of the present invention. Figure 3 This is a schematic diagram of the adjacent cover plate reinforcement structure of the culvert based on the combination of UHPC and steel plate in an embodiment of the present invention. Figure 4 This is a construction flowchart of a culvert reinforcement structure based on a combination of UHPC and steel plate, according to an embodiment of the present invention.

[0023] In all the accompanying drawings, the same reference numerals denote the same technical features, specifically: 1-cover plate; 2-culvert abutment; 3-foundation; 4-high-strength metal base plate; 5-reinforcing rib plate; 6-UHPC concrete layer; 7-first angle steel; 8-second angle steel; 9-high-strength expansion bolt; 10-connecting steel plate; 11-expansion joint filler; 12-shear connector. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0025] like Figure 1 As shown, this embodiment provides a culvert reinforcement structure based on a combination of UHPC and steel plates. From an overall structural perspective, this reinforcement structure mainly consists of a high-strength metal base plate 4, shear connectors 12, a UHPC concrete layer 6, and lateral support components. By constructing an ultra-high performance composite section beneath the original culvert 1, utilizing the superior compressive toughness of the UHPC concrete layer 6 and the high tensile strength of the high-strength metal base plate 4, combined with the mechanical interlocking force of the shear connectors 12, the newly added reinforcement layer is solidified with the existing structure into a unified load-bearing entity, achieving stress redistribution and a leap in load-bearing capacity. This structure achieves a doubling of bending stiffness with minimal structural thickness increase through material modulus matching, solving the problem of encroachment on the net width or height of the culvert; the self-formwork system formed by the lateral support components and the high-strength metal base plate 4 achieves permanent and temporary integration, greatly reducing the difficulty of formwork support and construction costs inside the culvert; finally, the shear connectors 12 with variable density effectively overcome the pain point of interface bonding failure in traditional reinforcement schemes, ensuring the long-term durability of the structure under heavy load impact.

[0026] like Figure 2As shown, the high-strength metal base plate 4 serves as the bottom tensile member and construction reference surface of this composite structure. In this embodiment, the base material of the high-strength metal base plate 4 is preferably a weathering steel plate with a thickness of 2cm. The selection of this material is not only based on its high yield strength, but also on the fact that its dense oxide layer formed by alloying elements can effectively resist electrochemical corrosion in the humid environment inside the culvert, ensuring the cross-sectional effectiveness of the reinforcement layer throughout its entire life cycle. Based on the culvert's net width measurement data, the high-strength metal base plate 4 is processed into a rectangular plate with a width slightly less than the culvert's net width by 2cm, and the small gaps reserved on both sides serve as venting and overflow channels when pumping UHPC. The upper surface of the high-strength metal base plate 4 is fixed with crisscrossing reinforcing ribs 5 by an automatic welding process. The working principle of the reinforcing rib 5 is as follows: During the construction phase, it increases the local moment of inertia of the high-strength metal base plate 4 to resist the downward deflection caused by the self-weight of the 10cm thick UHPC grout, ensuring the flatness of the culvert bottom surface after reinforcement; During the operation phase, the reinforcing rib 5 is embedded in the UHPC matrix, playing a role in lateral anchoring and enhancing the anti-slip stiffness between the steel plate and the concrete. For the settlement joints of the existing structure, the high-strength metal base plate 4 is physically disconnected, giving the reinforcement system the flexible coordination ability to adapt to the non-uniform settlement of the original structure.

[0027] The shear connector 12 is a key component for realizing the core logic of combined force application in this invention. It is made of ML15 special weld stud steel and machined into a cylindrical rod with a diameter of 10mm and a length of 50mm. In terms of connection, the lower end of the shear connector 12 forms a rigid, molecular-level fusion with the high-strength metal base plate 4 through a perforated plug welding process, while its upper end extends vertically upwards, contacting the interface treatment layer at the bottom of the original cover plate 1. Through the physical encapsulation of the weld stud within the UHPC concrete layer 6, the horizontal shear force is transformed into a shear and compression state for the weld stud, thereby suppressing the relative slippage between the steel plate and concrete interface, and between the concrete and the original structure interface. This embodiment specifically employs a variable density layout strategy: in the mid-span region, the shear connectors 12 are arranged in a staggered 200mm×200mm pattern; while in the high shear zone near the culvert abutment 2, the density is increased to 150mm×150mm. This arrangement logic based on shear force envelope distribution significantly improves the end peel resistance and ensures the fatigue stability of the composite structure under high-frequency vehicle loads.

[0028] The lateral support component is the logical starting point and load support point of the entire reinforcement system, preferably a triangular support frame. This component is welded from a first angle steel, a second angle steel, and a connecting steel plate 10. In terms of connection, the triangular support frame is anchored to the inner wall of the culvert abutment 2 using an array of high-strength expansion bolts 9. The bolt anchoring depth and spacing have been verified through stress simulation, and the spacing must be controlled to be no more than 1.1m. All construction loads from the high-strength metal base plate 4 and above it are transferred to the side wall of the culvert abutment 2 through the geometric stability transformation of the triangular truss. By precisely controlling the cavity height of the top surface of the triangular support frame from the bottom of the original cover plate 1 to 10cm, precise spatial constraints are provided for subsequent UHPC filling. Its technical effect is that it achieves formwork replacement with supports, quickly constructing a high-precision stress reference surface through simple bolt anchoring within the limited working space inside the tunnel, significantly reducing construction labor intensity and shortening traffic interruption time.

[0029] like Figure 3 As shown, the UHPC concrete layer 6 fills the 10cm cavity between the high-strength metal base plate 4 and the original cover plate 1, serving as the core medium for reinforcing the load-bearing capacity. This embodiment uses ultra-high performance concrete with a compressive strength ≥150MPa and a tensile strength ≥8.2MPa. Its working principle lies in utilizing its extremely high density and steel fiber bridging force to tightly wrap the shear connector 12 and reinforcing ribs 5, forming a microscopic mechanical interlock at the interface layer. The grout is pumped through the pre-reserved grouting holes in the high-strength metal base plate 4, utilizing its self-compacting properties to fill every roughened pore at the bottom of the original cover plate 1. To ensure filling quality, a 2cm thick asphalt foam board is laid between adjacent segments as an expansion joint filler 11. This filler also serves as a lateral template during pouring, its technical effect being to absorb the hardening shrinkage of the UHPC and the thermal shrinkage stress during operation through an elastic closed-cell structure. The edges of the high-strength metal base plate 4 are flexibly sealed with polyurethane foam sealant. This structural logic of rigid reinforcement and flexible sealing ensures that the UHPC concrete layer 6 does not produce grout leakage honeycomb, ultimately forming a permanent reinforcement layer with extremely high waterproof and crack-resistant performance.

[0030] like Figure 4 As shown in the embodiment of the present invention, a construction method for a culvert reinforcement structure based on a combination of UHPC and steel plate is provided, including the following steps: This embodiment provides a construction method for reinforcing culvert covers based on a combination of UHPC and steel plates. This method achieves rapid reinforcement within a limited space through microscopic reshaping of the existing structural interface and macroscopic construction of novel composite materials. The specific implementation steps are described below: S1. Interface Treatment and Microscopic Interlocking Structure Remodeling Interface treatment is a prerequisite for ensuring stress transfer between the new reinforcement layer and the old concrete structure. First, a comprehensive defect inspection is conducted on the bottom surface of the original cover plate 1, and pre-repair is carried out on areas of weathering, spalling, or exposed reinforcement. Then, a high-frequency impact operation is performed along the mechanical baseline of the existing structure using an electric chisel. In terms of process parameter control, this step strictly controls the chiseling depth to be between 10mm and 15mm. This depth range is selected based on a meticulous consideration of the thickness of the original cover plate's protective layer, aiming to achieve a chiseling rate of no less than 90% by removing the surface laitance layer without damaging the main reinforcement, and ensuring that the exposed aggregate reaches 1 / 3 to 1 / 2 of its particle size. This uneven microstructure provides physical "anchor teeth" for the subsequent embedding of the UHPC concrete layer 6. After the operation is completed, all residual dust is removed by high-pressure water jet washing, ensuring the interface is saturated and surface-dry, thereby eliminating competitive absorption of moisture at the interface and guaranteeing the bonding quality of the subsequent cementitious materials.

[0031] S2. High-precision construction of the template and sealing system. The stability of the template and sealing system determines the geometric accuracy of the UHPC filling layer. An expansion joint filler 11 is installed at the settlement joint or segment location in the middle of the original cover plate 1. In this embodiment, a 2cm thick asphalt foam board is preferred, with its height strictly matching the 10cm reinforced cavity. This filler resists grouting pressure through its compression modulus, while the observation hole and vent hole reserved in the middle of the board constitute a "signal feedback point" during construction. Regarding the connection, polyurethane foam sealant is used to seal the joint gaps between the edge of the high-strength metal base plate 4 and the expansion joint filler 11, as well as the culvert abutment sidewall, through multiple sealing treatments. Its working principle is to fill the microwave gaps between the metal and non-metal interfaces through the high expansion rate of polyurethane material, forming a closed grouting cavity, effectively preventing grout leakage during high-pressure pumping of the high-fluidity UHPC, and ensuring the tightness of the shear connector 12 root.

[0032] S3. Dynamic Pumping and Molding Process of UHPC Concrete The molding process of UHPC concrete layer 6 is a crucial transformation point in the reinforced structure, converting it from a collection of components into a unified load-bearing entity. Material Performance Assurance: The ultra-high performance concrete prepared on-site requires gradation optimization to ensure its compressive strength. ,tensile strength The randomly distributed steel fibers inside generate bridging forces when crossing interface cracks, significantly improving the ductility of the structure. Staged pumping logic: Using high-pressure pumping equipment, grout is injected through pre-drilled 150mm diameter pouring holes on the high-strength metal base plate 4. Due to the extremely high self-leveling properties of UHPC, the grout is smoothly advanced from the center to both sides under pressure, expelling residual air from the cavity. Vibration coupling and compaction judgment: The attached vibrator is activated, transmitting high-frequency vibration energy through the high-strength metal base plate 4 to assist the grout in expelling internal micro-bubbles, with a focus on ensuring a tight envelope around the shear connector 12. When thick grout overflows from the observation hole without obvious bubble rupture, it is judged as compacted. In terms of pouring sequence, symmetrical construction from the center to both sides is maintained. This technique ensures that the lateral pressure on both sides of the high-strength metal base plate 4 is balanced, preventing lateral displacement of the triangular support frame or instability deformation of the formwork due to excessive pressure on one side.

[0033] S4. Thermal Coupling Curing and Structural Strength Evolution: During the curing stage, the temperature and humidity environment is controlled to accelerate the hydration reaction inside the UHPC, promoting rapid strength evolution. Steam Curing Environment Construction: After pouring, the culvert ends are quickly sealed, and a confined space is constructed using insulating tarpaulins. A simple steam generator is activated for 48 hours of constant-temperature steam curing. Maintaining a constant high-humidity and heat environment aims to eliminate the early high shrinkage risk of the UHPC and promote the compressive strength to reach the design level in a short time. Cooling Control and Facility Removal: After the curing period, graded cooling measures are implemented. The end baffles and insulating tarpaulins can only be removed when the internal temperature of the culvert naturally drops below 30℃ and the temperature difference with the external environment is less than 15℃, to prevent surface temperature cracks caused by excessive temperature gradients. Strength Assessment and Traffic Restoration: After simultaneous sampling and testing confirms that the measured strength index of the UHPC concrete layer 6 reaches the design value, the temporary lateral support components can be removed and traffic can be reopened. In the final reinforced structure, the UHPC concrete layer 6 perfectly encases the shear connector 12, achieving mechanical interlocking and coordinated stress distribution between the high-strength metal base plate 4, the reinforcing layer, and the original cover plate 1. The high-strength metal base plate 4 not only serves as a permanent formwork during the construction phase, reducing the clearance loss of traditional formwork, but also acts as the main tension member during the operation phase, achieving high efficiency and long-term effectiveness in the reinforcement of the culvert.

[0034] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A culvert reinforcement structure based on a combination of UHPC and steel plate, characterized in that, include: A high-strength metal base plate (4) is placed below the original cover plate (1), and its width is less than the net width of the culvert; Shear connectors (12) are fixed in an array on the upper surface of the high-strength metal base plate (4), and the top of the shear connectors (12) extends upward and is embedded in the interface treatment layer at the bottom of the original cover plate (1). The UHPC concrete layer (6) is filled between the high-strength metal base plate (4) and the original cover plate (1), and the shear connector (12) is wrapped in it, so that the high-strength metal base plate (4), the UHPC concrete layer (6) and the original cover plate (1) form a combined load-bearing structure. Lateral support components are provided on the inner wall of the culvert (2) to support the high-strength metal base plate (4). The high-strength metal base plate (4) has pre-reserved grouting holes, and the UHPC concrete layer (6) is pumped and filled through the grouting holes.

2. The culvert reinforcement structure based on a combination of UHPC and steel plate according to claim 1, characterized in that, The lateral support component is a triangular support frame; The triangular support frame includes angle steel a (7), angle steel b (8) and connecting steel plate (10), which are welded together to form a triangular truss structure; the triangular support frame is anchored to the inner walls of both sides of the culvert (2) by high-strength expansion bolts (9), and its top supports the high-strength metal base plate (4).

3. The culvert reinforcement structure based on a combination of UHPC and steel plate according to claim 2, characterized in that, The high-strength metal base plate (4) is a high-strength metal base plate with a thickness of 2cm; The upper surface of the high-strength metal base plate (4) is welded with reinforcing ribs (5), and the high-strength metal base plate (4) is disconnected at the position corresponding to the settlement joint of the original cover plate (1).

4. The culvert reinforcement structure based on a combination of UHPC and steel plate according to any one of claims 1-3, characterized in that, The shear connector (12) is a shear connector made of ML15 special weld stud steel; The shear connectors (12) are arranged in a staggered, quincunx pattern on the high-strength metal base plate (4), and are densely arranged in the support area near the culvert (2).

5. The culvert reinforcement structure based on a combination of UHPC and steel plate according to any one of claims 1-3, characterized in that, Expansion joint filler (11) is provided between adjacent UHPC concrete layers (6); The expansion joint filler (11) is made of asphalt foam board, which also serves as a lateral template and expansion joint filling material during pouring.

6. The culvert reinforcement structure based on a combination of UHPC and steel plate according to claim 5, characterized in that, The compressive strength of the UHPC concrete layer (6) is ≥150MPa and the tensile strength is ≥8.2MPa.

7. A construction method for a culvert reinforcement structure based on a combination of UHPC and steel plate as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Interface treatment: The bottom of the original cover plate (1) is roughened to form a rough interface; S2. Install the support system: Anchor the lateral support components to the inner walls on both sides of the culvert abutment (2); S3. Install the combined base plate: Place the high-strength metal base plate (4) with the welded shear connector (12) on the lateral support assembly, so that the top of the shear connector (12) abuts against or is embedded in the bottom of the original cover plate (1); S4. Template and sealing: Install side templates on both sides of the middle part of the cover plate (1) and seal the gap between the high-strength metal base plate (4) and the side templates; S5. Grouting reinforcement: Ultra-high performance concrete is pumped through the reserved holes on the high-strength metal base plate (4), and the reserved holes are sealed after being filled and compacted. S6. Curing: After the UHPC concrete layer (6) reaches the design strength, the temporary facilities shall be removed and traffic shall be opened.

8. The construction method according to claim 7, characterized in that, In S1, the chiseling depth is controlled at 10~15mm, and the chiseling rate is not less than 90%.

9. The construction method according to claim 7, characterized in that, In S3, the lower end of the shear connector (12) is fixed to the high-strength metal base plate (4) by perforation plug welding, and the upper end is embedded in the original cover plate (1) to a depth of ≥25mm.

10. The construction method according to claim 7, characterized in that, In S5, the ultra-high performance concrete is poured symmetrically from the middle to both sides.

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