UHPC prefabricated guardrail for expressway

Abstract

The UHPC prefabricated guardrail for the expressway comprises a sheet framework and a UHPC shell, the sheet framework is composed of metal flat wires and carbon fibers, the metal flat wires are woven into negative poisson ratio plane units of chiral lattice structures, at least three layers of chiral lattice structures are arranged in the direction of any side line of a rectangle of each negative poisson ratio plane unit, and the negative poisson ratio plane units are arranged in the direction of any side line of a rectangle of each negative poisson ratio plane unit. The carbon fibers are connected in series by taking the negative poisson ratio plane units as section units to form a sheet framework; and the sheet framework is infiltrated, coated and cured by UHPC to form a prefabricated guardrail module. Metal flat wires and carbon fibers are adopted to form a framework, a UHPC material is poured to form the prefabricated wave-shaped guardrail, the energy absorption capacity and the impact resistance of the guardrail are improved while the self weight is reduced, the guardrail has a hydrophobic surface to achieve the anti-corrosion effect by magnetically controlling the density of micro-straight steel fibers in the UHPC material and the exposure form of the UHPC curing surface, and the service life of the guardrail is prolonged.

Description

Technical Field

[0001] This invention relates to the field of highway guardrail technology, and specifically to a UHPC prefabricated guardrail for highways. Background Technology

[0002] With the increasing number of newly built highways each year, guardrails are a crucial link and important guarantee for highway operation and traffic safety. Highway traffic accidents have become a significant factor affecting the efficiency of highway operations. If the safety performance of crash barriers is inadequate, vehicles can easily overturn and fall off. Qualified guardrails should provide blocking, buffering, and guiding functions for out-of-control vehicles. However, currently, guardrails are mainly traditional steel or aluminum alloy guardrails. Traditional structures are very heavy, increasing the burden on the road. After long-term service, they age and have limited energy absorption under high-speed rigid collisions, making them prone to fracture and displacement, thus losing their guiding function. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a UHPC prefabricated guardrail for highways. It employs a framework of flat metal wires and carbon fiber, and casts UHPC material to form a prefabricated corrugated guardrail. This reduces weight while enhancing the guardrail's energy absorption and impact resistance. Furthermore, by controlling the density of the micro-straight steel fibers within the magnetically controlled UHPC material and the exposed morphology of the cured UHPC surface, it achieves a hydrophobic surface, thus providing corrosion resistance and extending the guardrail's lifespan.

[0004] A UHPC prefabricated guardrail for highways includes a sheet frame and a UHPC shell: The sheet skeleton is composed of metal flat wires and carbon fibers. The metal flat wires are woven into negative Poisson's ratio planar units with chiral lattice structures. The rectangular side of the negative Poisson's ratio planar unit has at least three layers of chiral lattice structures. The carbon fibers are connected in series with the negative Poisson's ratio planar units as cross-sectional units to form the sheet skeleton. The thin-film skeleton is formed into a prefabricated guardrail module after being impregnated, coated and cured by UHPC.

[0005] Furthermore, the chiral lattice structure is any one of a three-ligament chiral lattice structure, a four-ligament chiral lattice structure, or a four-ligament antichiral lattice structure.

[0006] Furthermore, the UHPC micro-straight steel fibers have a length of less than 0.1 mm, a diameter of less than 15 μm, and a dosage of 0.8 to 6 wt%.

[0007] Furthermore, the surface of the UHPC housing has a hydrophobic surface with a density of at least 300 micro-straight steel fibers exposed perpendicular to the UHPC housing surface, and a contact angle greater than 120° and less than 160°.

[0008] Furthermore, the amount of UHPC micro-straight steel fiber is 4.65 wt%.

[0009] Furthermore, the short rectangular side of the negative Poisson's ratio planar unit determines the thickness of the sheet skeleton, and the thickness of the sheet skeleton is at least 5 mm.

[0010] Furthermore, the thin-sheet skeleton is wave-bent and then impregnated and covered with UHPC to form a prefabricated wave guardrail module.

[0011] Furthermore, the thin-sheet skeleton is rolled into a cylindrical shape and then impregnated and coated with UHPC to form a prefabricated hollow guardrail module.

[0012] Furthermore, the prefabricated hollow guardrail module is filled with lightweight foamed clay or Newtonian bodies.

[0013] Furthermore, the prefabricated guardrail module is provided with reserved installation holes.

[0014] The technical advantages achieved by this invention are: 1. This invention designs a UHPC prefabricated guardrail frame with chiral lattice structure and negative Poisson's ratio planar unit. The negative Poisson's ratio planar unit with chiral lattice structure absorbs impact energy and achieves better buffering and blocking function. The integrated curing of carbon fibers in series enhances the toughness of the guardrail and reduces the possibility of guardrail breakage, thus achieving better guiding function. 2. This invention uses magnetic force to control the magnetized micro-straight steel fibers, forming a hydrophobic surface with a contact angle greater than 120° and less than 160°, which avoids corrosion from the natural environment after installation and effectively extends the life of the guardrail. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the negative Poisson's ratio square planar unit in Embodiment 1; Figure 2 This is a schematic diagram of the sheet skeleton structure in Embodiment 1; Figure 3 It is the hydrophobic surface of the prefabricated guardrail module; Figure 4 This is a schematic diagram illustrating the hydrophobic principle of the rough surface formed by exposed micro-straight steel fibers. Figure 5 This is a schematic diagram of a prefabricated wave guardrail module; Figure 6 This is a schematic diagram of assembling prefabricated wave guardrail modules; Figure 7 This is a left-side 3D view of the hollow guardrail module; Figure 8 This is a right-side 3D view of the hollow guardrail module.

[0016] Figure label: 1-Negative Poisson's ratio square planar unit, 2-Carbon fiber part, 3-Prefabricated wave guardrail module, 4-Stainless steel anti-blocking block, 5-Bolt, 6-Post, 7-Post cap. Detailed Implementation

[0017] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a further explanation of a UHPC prefabricated guardrail for highways according to the present invention: Example 1

[0018] Metal flat wires with a width of 10mm and a thickness of 0.5mm are woven into a shape that resembles... Figure 1 The chiral lattice structure shown has a negative Poisson's ratio square planar unit 1 with four layers of chiral lattice structure along its edge, and the edge length is 1.5 cm. Fifty negative Poisson's ratio planar units are connected in series using Toray T700-12K carbon fiber precursor, and then carbonized to form a thin sheet skeleton with a thickness of 1.5 cm and a length of 50 cm. Figure 2 As shown in Table 1, micro-straight steel fibers with a length of less than 0.05 mm and a diameter of 5 μm are magnetically polarized and then UHPC slurry is prepared according to Table 1. The UHPC slurry is poured into a mold that holds the thin-sheet skeleton, and after curing, it is demolded to obtain a prefabricated guardrail module with a thickness of 3 cm.

[0019] Table 1 UHPC slurry ratio

[0020] G represents polarized micro-straight steel fibers. Example 2

[0021] Metal flat wires with a width of 10mm and a thickness of 0.5mm are woven into a shape that resembles... Figure 1 The chiral lattice structure shown has a negative Poisson's ratio square planar unit 1 with four layers of chiral lattice structure along its edge, and the edge length is 1.5 cm. Fifty negative Poisson's ratio planar units are connected in series using Toray T700-12K carbon fiber precursor, and then carbonized to form a thin sheet skeleton with a thickness of 1.5 cm and a length of 50 cm. Figure 2 As shown in Table 1, micro-straight steel fibers with a length less than 0.05 mm and a diameter of 5 μm were magnetically polarized and then mixed with UHPC slurry. The UHPC slurry was poured into a mold containing a thin-film skeleton. A 0.5T strong planar magnetic field was used to sweep the surface of the UHPC slurry across the future guardrail surface three times at a distance of 10 cm from the surface of the UHPC slurry, at a speed of 15 m / s. After curing, the surface was demolded to obtain a hydrophobic surface (e.g., ...). Figure 3The prefabricated guardrail module shown in Table 1 is 3cm thick. The exposed micro-straight steel fibers have a density of 120 to 220 fibers / mm², resulting in a hydrophobic surface with a contact angle of approximately 100° to 150°. Table 1 shows different micro-straight steel fiber ratios. At a dosage of 4.65wt%, the exposed micro-straight steel fiber density is the most uniform, around 200 fibers / mm², with a contact angle of approximately 150°. Increasing the dosage further does not improve hydrophobicity; instead, the contact angle decreases, reaching only 120° at a dosage of 6wt%.

[0022] Furthermore, carbon fiber precursors, by connecting negative Poisson's ratio planar units in series and undergoing wave bending and carbonization processes, followed by impregnation and coating with UHPC, can form a structure such as... Figure 5 3. Prefabricated wave guardrail module. Similarly, carbon fiber precursors are connected in series with negative Poisson's ratio planar units, wound into a cylindrical shape, and carbonized. After being impregnated, coated, cured, and demolded by UHPC, a prefabricated hollow guardrail module can be obtained, such as... Figure 7 and 8 As shown.

[0023] Furthermore, lightweight filling materials such as foamed soil or Newtonian bodies are installed inside the prefabricated hollow guardrail modules to dissipate energy when the guardrail is subjected to impact.

[0024] In Examples 1 and 2, the planar or three-dimensional structure composed of the outer frame of the negative Poisson's ratio square planar unit serves as the main surface to withstand impact or shock. That is, the outer frame of the negative Poisson's ratio square planar unit receives the impact, and the frame compresses the chiral lattice inward to generate deformation and absorb energy.

[0025] like Figure 6 As shown, prefabricated corrugated guardrail modules 3 are assembled end-to-end along the highway direction and fixed to stainless steel anti-collision blocks 4 by bolts 5 at the crests or troughs of the contour. The stainless steel anti-collision blocks 4 are fixed by through bolts on the posts 6. The posts 6 are installed inside the support sleeve of the fixing device, and post caps 7 are fixed to the top of the posts. The fixing device includes a mounting base, a support sleeve, and anchor bolts. The inner diameter of the support sleeve is larger than the outer diameter of the post 6. Double-ended bolts penetrate the diameter of the fitting part between the support sleeve and the post to prevent relative rotation, and fixing adhesive is injected into the gap. The support sleeve is welded to the mounting base, which is fixed to the roadbed by anchor bolts. Furthermore, the bolts at the crests or troughs of the contour of the prefabricated corrugated guardrail modules 3 can be connected to rigid springs before being fixed to the stainless steel anti-collision blocks, further improving the effect of buffering impact force.

[0026] against Figure 6The guardrail structure in the test, under the conditions in Table 2, did not break. After the impact, the internal energy of the guardrail was 823 kJ. The internal energy of the 3 mm thick ferritic stainless steel corrugated beam guardrail was 427 kJ after the impact, nearly doubling its energy absorption capacity. After the impact, the displacement of the prefabricated corrugated guardrail module 3 was 103.27 mm (far below the 500 mm limit required by the existing national standard for guardrails), while the displacement of the 3 mm thick ferritic stainless steel corrugated beam guardrail after the impact was 270.34 mm.

[0027] The prefabricated corrugated guardrail modules obtained by the methods in Examples 1 and 2, along with the ferritic stainless steel corrugated beam guardrail, were placed in an environment with a temperature of 60°C and a humidity of 70% for four weeks of aging. Afterward, a collision test was conducted under the conditions shown in Table 2. The prefabricated corrugated guardrail modules obtained by the methods in Examples 1 and 2 did not break. The displacement of the prefabricated corrugated guardrail module obtained by the method in Example 1 was 208.27 mm, the displacement of the prefabricated corrugated guardrail module obtained by the method in Example 2 was 117.36 mm, and the displacement of the ferritic stainless steel corrugated beam guardrail was 451.27 mm. It is evident that the hydrophobic treatment with magnetization prevents corrosion and aging, effectively extending the guardrail's lifespan and protective capability.

[0028] Table 2

[0029] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Various changes that can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A UHPC prefabricated guardrail for highways, characterized in that, Includes a thin-film skeleton and a UHPC housing: The sheet skeleton is composed of metal flat wires and carbon fibers. The metal flat wires are woven into negative Poisson's ratio planar units with chiral lattice structures. The rectangular side of the negative Poisson's ratio planar unit has at least three layers of chiral lattice structures. The carbon fibers are connected in series with the negative Poisson's ratio planar units as cross-sectional units to form the sheet skeleton. The thin-film skeleton is formed into a prefabricated guardrail module after being impregnated, coated and cured by UHPC. The surface of the UHPC housing has a hydrophobic surface with a density of at least 300 micro-straight steel fibers exposed perpendicular to the UHPC housing surface, and a contact angle greater than 120° and less than 160°.

2. The UHPC prefabricated guardrail for highways according to claim 1, characterized in that, The chiral lattice structure is any one of a three-ligament chiral lattice structure, a four-ligament chiral lattice structure, or a four-ligament antichiral lattice structure.

3. The UHPC prefabricated guardrail for highways according to claim 1, characterized in that, The micro-straight steel fibers are less than 0.1 mm in length, less than 15 μm in diameter, and are added at a dosage of 0.8-6 wt%.

4. The UHPC prefabricated guardrail for highways according to claim 3, characterized in that, The amount of UHPC micro-straight steel fiber is 4.65 wt%.

5. The UHPC prefabricated guardrail for highways according to claim 1, characterized in that, The short rectangular side of the negative Poisson's ratio planar unit determines the thickness of the sheet skeleton, and the thickness of the sheet skeleton is at least 5 mm.

6. The UHPC prefabricated guardrail for highways according to any one of claims 1-5, characterized in that, The prefabricated guardrail module is provided with reserved installation holes.

7. The UHPC prefabricated guardrail for highways according to any one of claims 1-5, characterized in that, The thin-sheet skeleton is wave-bent and then impregnated and covered with UHPC to form a prefabricated wave guardrail module.

8. The UHPC prefabricated guardrail for highways according to any one of claims 1-5, characterized in that, The thin-sheet skeleton is rolled into a cylindrical shape and then impregnated and coated with UHPC to form a prefabricated hollow guardrail module.

9. The UHPC prefabricated guardrail for highways according to claim 8, characterized in that, The prefabricated hollow guardrail module is filled with lightweight foamed clay or Newtonian bodies.

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