A multi-scale roughened surface steel pipe concrete arch, and a preparation method and application thereof

Abstract

The application discloses a kind of multi-scale roughened surface steel pipe concrete arch and preparation method and application, the steel pipe concrete arch includes steel pipe arch, the outer surface of steel pipe arch is jetted concrete, multiple convex pieces are arranged on the outer wall surface of steel pipe arch at intervals, the convex piece is overall the cylindrical structure of cross section T letter shape, the small end of convex piece diameter is connected steel pipe arch, the big end of diameter is connected concrete, the fiber is mixed into the concrete;The steel pipe arch and convex piece are all carried out surface roughening treatment;Steel pipe concrete arch provided by the application, by setting bonding enhancement coating on the surface of steel pipe, doing hair processing, short convex piece, long convex piece and mixing steel fiber into concrete jointly constitute multi-scale enhancement connection system, and the connection strength of arch and jetted concrete is enhanced.

Description

Technical Field

[0001] This invention relates to the field of civil engineering technology, specifically to a multi-scale roughened surface steel-concrete composite arch frame, its preparation method, and its application. Background Technology

[0002] The support structure for underground engineering projects such as tunnels mainly includes primary support and secondary lining. The primary support structure is generally composed of anchor bolts, metal mesh, shotcrete, and arch frames. The arch frames are generally made of lattice steel frames or I-beam steel arch frames. With the increasing demand for energy and transportation in recent years, more and more tunnel engineering projects in mines, highways, and railways are being built in complex geological conditions. These underground engineering projects are often characterized by high surrounding rock pressure, and conventional support structures such as I-beam steel arch frames and lattice steel frames are sometimes insufficient to meet the requirements, resulting in engineering problems such as large deformation, buckling, and fracture, leading to engineering risks.

[0003] Concrete-filled steel tube (CFST) structures combine the advantages of both steel and concrete, with a load-bearing capacity twice or more than that of I-beam arches using the same amount of steel. However, existing CFST arch support structures have several drawbacks that limit their widespread application in tunnel engineering. One of the most significant is the weak bond between the outer surface of the CFST arch and the shotcrete, leading to easy delamination. CFST arches are typically fabricated from pre-fabricated steel tubes, resulting in a relatively smooth outer surface. While the two can work together under low stress, under higher stress, they easily delaminate, preventing them from cooperating in load-bearing. This significantly reduces the support capacity, leading to concrete detachment from the arch, cracking, spalling, and ultimately, buckling failure of the arch. Furthermore, detachment and cracking of the shotcrete from the arch can easily cause water seepage in the initial support and accelerated weathering of the surrounding rock. These problems directly affect the long-term stability of the tunnel structure.

[0004] Currently, technological innovations and inventions in the field of underground engineering involving steel-concrete composite arches generally focus on the pressure relief of the arches, combined structures and assembly processes, or arch testing equipment and technologies. They also include innovations in material forms such as steel fiber reinforced concrete and membrane-bag concrete arches. However, none of these works address the bonding problem between the steel-concrete composite arches and shotcrete. Chinese invention patent CN104790981A discloses a structure and method for enhancing the connection performance between the shotcrete layer and the arch. This is achieved by connecting the metal mesh shell on the side of the arch away from the surrounding rock to the arch, thereby improving the connection capacity and solving this problem to some extent. However, the problem of easy peeling between the arch side and the shotcrete remains unresolved, and the material input and construction intensity are relatively high. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a multi-scale roughened surface steel-concrete composite arch frame, its preparation method, and its application, which can effectively improve the bonding ability between the outer surface of the steel-concrete composite arch frame and the shotcrete.

[0006] The technical solution of the present invention is as follows:

[0007] In a first aspect of the invention, a multi-scale roughened surface steel-concrete composite arch frame includes a steel-concrete composite arch frame, the outer surface of which is sprayed with concrete, and a plurality of protrusions are spaced apart on the outer wall surface of the steel-concrete composite arch frame. The protrusions are cylindrical structures with a T-shaped cross-section. The end of the protrusion with a smaller diameter is connected to the steel-concrete composite arch frame, and the end with a larger diameter is connected to the concrete. Fibers are incorporated into the concrete. Both the steel-concrete composite arch frame and the protrusions undergo surface roughening treatment.

[0008] In some embodiments of the present invention, the plurality of protrusions are evenly arranged on the outer wall surface of the steel pipe arch frame, with adjacent protrusions spaced 2-5 cm apart.

[0009] In some embodiments of the present invention, the protrusion includes a first protrusion and a second protrusion, wherein the length of the first protrusion is less than the length of the second protrusion.

[0010] In some embodiments of the present invention, the steel pipe arch frame is provided with first protrusions on the two sides away from the surrounding rock and the two sides close to the surrounding rock, and the remaining two sides are provided with first protrusions and second protrusions spaced apart.

[0011] In some embodiments of the present invention, the protrusion is an integral structure formed by two cylinders arranged coaxially, wherein the diameter of the upper cylinder is larger than the diameter of the lower cylinder, and the height of the upper cylinder is smaller than the height of the lower cylinder.

[0012] In some embodiments of the invention, the protrusion is welded onto the steel pipe arch.

[0013] In a second aspect of the invention, a method for preparing a steel-concrete composite arch with a multi-scale roughened surface is provided, comprising the following steps:

[0014] The protrusion blank is made using a protrusion mold, and a flux coating is applied to the end of the protrusion blank with a smaller diameter.

[0015] The steel pipe is heated using a hot bending machine, and the softened steel pipe is then roughened on the surface and bent as needed.

[0016] The protrusion is welded to the surface of the steel pipe;

[0017] Spray with cold water, and after cooling and drying, spray a reinforced concrete bonding and durability coating onto the surface of the steel pipe.

[0018] In some embodiments of the present invention, the length of the protrusion blank is 1 cm greater than the length of the installed protrusion.

[0019] In a third aspect of the invention, a method for constructing a multi-scale roughened surface steel-concrete composite arch frame is provided, comprising the following steps:

[0020] The arch frame was transported to the site and assembled, and concrete was poured and filled inside the steel pipe arch frame.

[0021] Add an appropriate amount of fiber to the shotcrete;

[0022] According to the technical requirements for shotcrete in tunnels, fiber-infused concrete is sprayed onto the outer surface of the steel pipe arch frame.

[0023] In some embodiments of the present invention, the steel pipe arch frame can be effectively used in conjunction with the metal mesh or the transverse connecting parts of the arch frame.

[0024] One or more technical solutions of the present invention have the following beneficial effects:

[0025] (1) The steel-concrete composite arch frame provided by the present invention has a multi-scale reinforced connection system formed by setting an adhesive reinforcing coating, roughening treatment, short protrusions, long protrusions on the surface of the steel pipe and adding steel fibers into the concrete, thereby enhancing the connection strength between the arch frame and the shotcrete.

[0026] (2) The method for preparing steel pipe concrete arch frame provided by the present invention involves roughening the surface of the steel pipe arch frame, installing protruding parts and hot bending the pipe in the same sequence, heating once and using multiple steps, which is economical and efficient.

[0027] (3) In this invention, the shotcrete and the arch frame work together to bear the load, and their respective performances are better utilized, which solves problems such as cracking, peeling and falling off of shotcrete and water seepage, and improves the safety factor of the support system. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the cross-section of the steel-concrete composite arch frame of the present invention when it is working in the surrounding rock.

[0029] Figure 2 for Figure 1 A magnified view of a portion of point A in the middle;

[0030] Figure 3 This is a schematic cross-sectional view of the steel-concrete composite arch frame of the present invention;

[0031] Figure 4 for Figure 3 A magnified view of point B in the diagram;

[0032] Figure 5This is a schematic diagram of the structure of the protrusion of the present invention;

[0033] Figure 6 This is a process flow diagram for the preparation of the steel-concrete composite arch frame of the present invention.

[0034] In the diagram: 1. Steel pipe arch; 2. Metal mesh; 3. Shotcrete; 4. Protrusions; 5. Fiber; 6. Bonding reinforcement and durable coating; 7. Flux coating; 8. Surrounding rock. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0036] Example 1

[0037] In a typical embodiment of the present invention, a steel-concrete composite arch frame with a multi-scale roughened surface is proposed, such as... Figure 1 It includes a steel pipe arch frame 1, which is made of bent square steel pipes. The outer surface of the steel pipe arch frame 1 is sprayed with concrete 3. Multiple steel pipe arch frames 1 are connected end to end to form a ring channel installed in the surrounding rock 8. Figure 2 As shown, multiple protrusions 4 are spaced apart on the outer wall of the steel pipe arch frame 1. The protrusions 4 are cylindrical structures with a T-shaped cross-section. The end with the smaller diameter of the protrusion is connected to the steel pipe arch frame 1, and the end with the larger diameter is connected to the concrete. Fibers 5 are added to the concrete to improve the strength of the concrete connection. A metal mesh 5 is set between the protrusions 4 and the cofferdam to further enhance the connection effect between the steel pipe arch frame 1 and the concrete 3.

[0038] By setting protrusions on the steel pipe arch frame, the bonding ability between the outer surface of the steel pipe arch frame and the shotcrete is improved, solving the problem that the shotcrete cannot be tightly bonded to the outer wall of the steel pipe arch frame, thereby enhancing the long-term collaborative working ability between the shotcrete and the arch frame.

[0039] In this embodiment, the protrusions are installed on the steel pipe by welding. The protrusions are spaced 2-5cm apart. The specific spacing can be adjusted according to the project needs. The spacing between the protrusions should not be too small, as too small a spacing will result in more protrusions and waste of materials. It should also not be too large, as too large a spacing will not achieve a good connection effect. By limiting the distance between the protrusions to within 2-5cm, materials are saved while ensuring a good connection effect.

[0040] In this embodiment, the protrusion includes a first protrusion and a second protrusion. The length of the first protrusion is shorter than the length of the second protrusion. The first protrusion is the short protrusion, and the second protrusion is the long protrusion. The short protrusion has a length of 2-3 cm, and the long protrusion has a length of 8-10 cm. Figure 3As shown, considering the thickness of the concrete protective layer and the effective gap of the steel pipe arch frame on the two sides away from and close to the surrounding rock, short protrusions are set on the two sides away from and close to the surrounding rock. The remaining two sides are set with short and long protrusions alternately to better connect with the concrete. The specific lengths of the short and long protrusions can also be selected according to the actual thickness of the concrete protective layer.

[0041] In this embodiment, the protrusion consists of two coaxial cylinders, with the upper cylinder being short and thick, and the lower cylinder being long and slender. Specifically, the diameter of the upper cylinder is larger than that of the lower cylinder, and the height of the upper cylinder is smaller than that of the lower cylinder. The diameter of the upper cylinder is 1-2.5 cm, preferably 1 cm, and the diameter of the lower cylinder is 2-5 cm, preferably 2 cm. The lower end of the lower cylinder is connected to the steel pipe arch frame, and the upper cylinder is connected to the concrete. The protrusion formed by the two cylinders increases the contact area with the sprayed concrete, thereby enhancing the connection ability between the protrusion and the concrete.

[0042] To further enhance the bond between the protrusion and the concrete, the surface of the protrusion is made relatively rough.

[0043] Furthermore, to enhance the collaborative working ability between the steel pipe arch frame and the concrete, the outer surface of the steel pipe arch frame is relatively rough.

[0044] Furthermore, in order to extend the service life of the steel pipe arch frame, the surface of the steel pipe arch frame and protrusions is coated with an adhesive-enhancing and durable coating.

[0045] The multi-scale roughened surface steel-concrete arch frame provided in this embodiment forms a multi-scale reinforced connection system by setting an adhesive reinforcement coating, roughening treatment, short protrusions, long protrusions and steel fibers on the surface of the steel pipe, which makes the connection strength between the steel pipe arch frame and the shotcrete higher.

[0046] Example 2

[0047] In a typical embodiment of the present invention, a method for preparing a multi-scale roughened surface steel-concrete composite arch frame is proposed, such as... Figure 6 As shown, it includes the following steps:

[0048] The protrusion blank is made using a protrusion mold, and a flux coating is applied to the smaller diameter end of the protrusion blank.

[0049] Specifically, a mold for the protruding part is made, with the inner wall of the mold having a pre-defined roughness. A blank for the protruding part is prepared using molten steel casting. The length of the blank is approximately 1 cm longer than the installed protruding part; this 1 cm allowance is used to apply a flux coating to achieve welding to the steel pipe. Figure 5As shown, a flux coating 7 is applied to the protruding blank. The flux coating is only distributed about 1 cm at one end of the small end of the protruding blank. In this embodiment, the protruding part can be prepared in batches in advance.

[0050] The steel pipe is heated using a hot bending machine, and the softened steel pipe undergoes surface roughening treatment and bending treatment as needed.

[0051] Specifically, the steel pipe is softened by bending it with three rollers, and the position of the rollers is adjusted according to the curvature of the steel pipe as needed.

[0052] Weld the protrusion to the surface of the steel pipe:

[0053] Specifically, a robotic arm is used to weld the protrusion onto the surface of the steel pipe. The port of the robotic arm is an annular window, which can output the protrusion according to the settings and make it weld to the surface of the steel pipe.

[0054] The method for preparing a multi-scale roughened surface steel-concrete arch frame provided in this embodiment involves roughening the surface of the arch frame, installing protruding parts, and hot bending the pipe in the same sequence. It achieves the advantages of economic efficiency by heating only once and using multiple steps with leverage.

[0055] Spray with cold water, and after cooling and drying, spray a reinforced concrete bonding and durability coating onto the surface of the steel pipe.

[0056] Example 3

[0057] In a typical embodiment of the present invention, a construction method for a multi-scale roughened surface steel-concrete composite arch frame is proposed, comprising the following steps:

[0058] The arch frame was transported to the site and assembled, and concrete was poured and filled inside the steel pipe arch frame.

[0059] Add an appropriate amount of fiber to the shotcrete; in order to ensure that the fiber is evenly dispersed in the concrete, do not use a pickaxe during mixing, so that the fiber is three-dimensionally randomized, ensuring the uniformity of tensile strengthening of the concrete by the fiber in all directions.

[0060] According to the technical requirements for shotcrete in tunnels, fiber-infused concrete is sprayed onto the outer surface of the steel pipe arch frame, or conventional shotcrete without fibers can be sprayed.

[0061] In this embodiment, the steel pipe arch frame can be effectively used in conjunction with auxiliary components such as metal mesh or transverse connecting parts of the arch frame, which can further enhance the connection effect between the arch frame and the shotcrete.

[0062] The embodiments described above provide a detailed explanation of the technical solution of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, or similar substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A steel-concrete composite arch frame with a multi-scale roughened surface, characterized in that, The system includes a steel pipe arch frame, the outer surface of which is sprayed with concrete, and multiple protrusions are spaced apart on the outer wall of the steel pipe arch frame. Each protrusion is a cylindrical structure with a T-shaped cross-section. The end of the protrusion with a smaller diameter is connected to the steel pipe arch frame, and the end with a larger diameter is connected to the concrete. Fibers are incorporated into the concrete. The steel pipe arch and protrusions are all subjected to surface roughening treatment; The protrusion includes a first protrusion and a second protrusion, wherein the length of the first protrusion is less than the length of the second protrusion. The steel pipe arch frame has a first protrusion on the two sides away from the surrounding rock and the two sides close to the surrounding rock, and the remaining two sides are provided with a first protrusion and a second protrusion alternately.

2. The multi-scale roughened surface steel-concrete arch frame as described in claim 1, characterized in that, The multiple protrusions are evenly arranged on the outer wall of the steel pipe arch frame, with adjacent protrusions spaced 2-5cm apart.

3. The multi-scale roughened surface steel-concrete arch frame as described in claim 1, characterized in that, The protrusion is an integral structure formed by two coaxial cylinders, with the diameter of the upper cylinder being larger than that of the lower cylinder and the height of the upper cylinder being smaller than that of the lower cylinder.

4. The steel-concrete composite arch frame with a multi-scale roughened surface as described in claim 1, characterized in that, The protrusion is installed on the steel pipe arch by welding.

5. A method for preparing a multi-scale roughened surface steel-concrete composite arch frame according to any one of claims 1-4, characterized in that, Includes the following steps: The protrusion blank is made using a protrusion mold, and a flux coating is applied to the end of the protrusion blank with a smaller diameter. The steel pipe is heated using a hot bending machine, and the softened steel pipe is then roughened on the surface and bent as needed. The protrusion is welded to the surface of the steel pipe; Spray with cold water, and after cooling and drying, spray a reinforced concrete bonding and durability coating onto the surface of the steel pipe.

6. The steel-concrete composite arch with a multi-scale roughened surface as described in claim 5, characterized in that, The length of the protruding blank is 1 cm longer than the length of the installed protruding part.

7. A construction method for a multi-scale roughened surface steel-concrete composite arch frame as described in any one of claims 1-4, characterized in that, Includes the following steps: The arch frame was transported to the site and assembled, and concrete was poured and filled inside the steel pipe arch frame. Add an appropriate amount of fiber to the shotcrete; According to the technical requirements for shotcrete in tunnels, fiber-infused concrete is sprayed onto the outer surface of the steel pipe arch frame.

8. The construction method of the multi-scale roughened surface steel-concrete arch frame as described in claim 7, characterized in that, Steel pipe arch frames can be effectively used in conjunction with metal mesh or transverse arch frame connectors.

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