A highway tunnel fabricated steel-concrete thin-walled reinforcing structure and design method

Abstract

The present application provides a kind of highway tunnel fabricated steel structure-concrete thin-walled type reinforcing structure, including multiple groups of support structure, multiple groups of support structure are sequentially connected along the length direction of tunnel, support structure includes: two groups of fixed base, respectively set in the bottom wall both sides of tunnel;Two groups of duct piece structure, symmetrically set in the top wall both sides of tunnel, duct piece structure includes thin-walled duct piece and the support duct piece connected to the upper and lower ends of thin-walled duct piece, the thickness of thin-walled duct piece is less than the thickness of support duct piece, the support duct piece located in the lower end of thin-walled duct piece is connected with the top of fixed base on the same side, and the distal ends of two support duct pieces located in the upper end of thin-walled duct piece are connected with each other.The present application also provides a kind of design method of highway tunnel fabricated steel structure-concrete thin-walled type reinforcing structure.Thin-walled duct piece is treated with hierarchical stepped thin-walled, which can ensure that the construction limit of highway tunnel is not affected by reinforcement, and provides sufficient clearance for large vehicles to pass through the tunnel.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, specifically to a prefabricated steel-concrete thin-walled reinforcement structure and design method for highway tunnels. Background Technology

[0002] my country's tunnel mileage, especially long and extra-long tunnels, has increased significantly. The role of tunnel structures in transportation is constantly improving, and the requirements for smooth and safe operation are continuously rising. Furthermore, with the ongoing development of transportation infrastructure, many tunnel projects have transitioned from the construction phase to the operation and maintenance phase. As operating time increases, the workload for treating tunnel defects rises dramatically. Many tunnels are beginning to experience structural problems such as cracking, water seepage, and lining spalling. Minor issues can detract from the tunnel's visual appeal and distract drivers; serious problems can directly lead to safety accidents, resulting in significant economic losses and adverse social impacts. Therefore, tunnel maintenance and reinforcement are of paramount importance.

[0003] However, the need to add new reinforcement structures during tunnel maintenance will compress the internal space of the tunnel to some extent, resulting in a reduction in the clearance for large vehicles to pass through the tunnel.

[0004] Therefore, how to both reinforce and maintain tunnels to improve their compressive strength and load-bearing capacity, and reduce the compression of the internal space of the tunnel to increase the safe distance for vehicles to pass, is a problem that needs to be solved in tunnel maintenance. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention proposes a prefabricated steel-concrete thin-walled reinforcement structure and design method for highway tunnels, in order to solve the aforementioned problems.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] This invention provides a prefabricated steel-concrete thin-walled reinforcement structure for highway tunnels, comprising multiple sets of support structures. These support structures circumferentially cover the existing inner wall of the tunnel structure. The multiple sets of support structures are sequentially connected along the length of the tunnel. Each support structure includes:

[0008] Two sets of fixed bases are respectively set on both sides of the bottom wall of the tunnel;

[0009] Two sets of segment structures are symmetrically arranged on both sides of the tunnel roof. The segment structure includes thin-walled segments and supporting segments connected to the upper and lower ends of the thin-walled segments. The thickness of the thin-walled segments is less than the thickness of the supporting segments. The supporting segments located at the lower end of the thin-walled segments are connected to the top of the fixed base on the same side. The two supporting segments located at the upper end of the thin-walled segments are connected to each other at their far ends.

[0010] Furthermore, both the fixed base and the supporting segments are concrete structures, while the thin-walled segments are steel structures.

[0011] Furthermore, the thin-walled tube sheet includes a thinning section and transition sections located at the upper and lower ends of the thinning section. The thickness of the thinning section is less than the thickness of the transition section, and the transition section is thinned in a stepped or oblique manner towards the thinning section.

[0012] Furthermore, the thin-walled tube segment has multiple interfacial tensile and shear reinforcing bars and T-shaped studs evenly distributed at its upper and lower ends.

[0013] Furthermore, the interior of the thin-walled tube segment is provided with a filling area, and multiple crisscrossing reinforcing ribs are arranged in the filling area. Adjacent reinforcing ribs divide the filling area into multiple partitions, and filling holes connecting the partitions are opened on the reinforcing ribs.

[0014] Furthermore, the thin-walled segments are respectively provided with anchoring holes, grouting holes, air outlet holes, hoisting holes and tensioning holes;

[0015] Multiple anchoring holes penetrate both sides of the thin-walled tube segment and are distributed longitudinally in a quincunx pattern. A first bolt sleeve is provided on the path of the anchoring holes within the filling area.

[0016] The grouting hole and the air outlet hole respectively penetrate both sides of the thin-walled tube segment;

[0017] Multiple of the aforementioned hoisting holes are opened on the side of the thin-walled segment close to the inner wall of the existing tunnel structure;

[0018] Multiple tensioning holes are respectively opened on both sides of the transition section and the connection with the adjacent thin-walled tube segment. A second bolt sleeve is provided on one side of the tensioning hole located in the filling area, and a reaction structure is provided on the outside of the tensioning hole.

[0019] This invention provides a design method for a prefabricated steel-concrete thin-walled reinforcement structure for highway tunnels. The method includes the inner wall of the existing tunnel structure and the reinforcement structure. The reinforcement structure comprises a supporting structure and a grouting layer of reinforcing steel between the supporting structure and the existing structure. First, the thickness of the steel structure is obtained by balancing the bending moment of the reinforcing steel with that of the steel structure. Then, the thickness of different parts of the thin-walled segment is obtained by balancing the bending performance of the same surface area. Finally, the dimensions and stress conditions of the reinforcing steel are determined by applying the principle that the bending moment of the compression portion of the existing structure is equal to the tensile bending moment of the reinforcing steel in the reinforcement structure, and by applying the principle of force balance.

[0020] Furthermore, considering the thin-walled design as the worst-case scenario, the theoretical value of the bending moment of the thin-walled segment should be greater than the bending moment value of the support reaction force of the reinforced structure itself, thus obtaining the design value of the thickness of different parts of the thin-walled segment.

[0021] Furthermore, the minimum design value of the thin-walled segment thickness is obtained by combining the bending moment formula of the steel reinforcement and the bending moment formula of the steel structure. Then, based on the equal bending resistance of the equal surface, the minimum design value of the thickness of different parts of the thin-walled segment is obtained. By comparing the above calculations, the minimum design value of the thickness of each part of the thin-walled segment under different conditions is obtained, and finally the maximum value is taken.

[0022] Furthermore, after the thin-walled segments are connected and assembled, each metal part is treated with an anti-corrosion coating.

[0023] As can be seen from the above technical solution, the present invention provides a prefabricated steel-concrete thin-walled reinforcement structure and design method for highway tunnels:

[0024] The prefabricated steel-concrete thin-walled reinforcement structure, featuring thin-walled tunnel segments and supporting segments, not only satisfies the advantages of rapid and efficient prefabrication but also benefits from the flexibility and light weight of steel structures. Therefore, buildings in the same seismic intensity and on the same site experience less seismic force, thus mitigating the associated earthquake damage. The thin-walled tunnel segments employ a graded, stepped thin-walling treatment, ensuring that the tunnel's clearance is not affected by the reinforcement, providing ample clearance for large vehicles, and reducing steel consumption while maintaining component strength, further ensuring that the clearance space remains unaffected. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention, the accompanying drawings used in the specific embodiments will be briefly described below. In all the drawings, the elements or parts are not necessarily drawn to scale.

[0026] Figure 1 This is a schematic diagram of the main structure of the present invention;

[0027] Figure 2 This is a schematic diagram of the segment structure in this invention;

[0028] Figure 3 This is a schematic diagram of the internal structure of the thin-walled tube sheet in this invention;

[0029] Figure 4 This is a schematic diagram showing the numerical values ​​of each region in the existing structure-reinforced grouting layer-thin-walled segment connection structure of the present invention;

[0030] Figure 5 This is a schematic diagram showing the numerical values ​​of each region in the thin-walled tube sheet of the present invention;

[0031] Figure label:

[0032] Fixed base 1;

[0033] Thin-walled segment 2, thinning section 201, transition section 202, interface tensile and shear reinforcement 203, T-shaped stud 204, filling area 205, reinforcing rib 206, filling hole 2061, anchoring hole 207, grouting hole 208, vent hole 209, hoisting hole 210, tensioning hole 211, first bolt sleeve 212, second bolt sleeve 213;

[0034] Support segment 3;

[0035] Existing structure 4;

[0036] 5. Grouting layer for reinforcing bars. Detailed Implementation

[0037] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the invention; therefore, the invention is not limited to the specific embodiments disclosed below.

[0038] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0040] like Figure 1-5 As shown, this embodiment provides a prefabricated steel-concrete thin-walled reinforcement structure for highway tunnels, including multiple sets of support structures. The support structures circumferentially cover the inner wall of the existing structure 4 of the tunnel. The multiple sets of support structures are connected sequentially along the length of the tunnel. The support structure includes two sets of fixed bases 1 and two sets of segment structures.

[0041] Two sets of fixed bases 1 are respectively set on both sides of the bottom wall of the tunnel.

[0042] Two sets of segment structures are symmetrically arranged on both sides of the tunnel roof. The segment structure includes thin-walled segment 2 and supporting segment 3 connected to the upper and lower ends of thin-walled segment 2. The thickness of thin-walled segment 2 is less than the thickness of supporting segment 3. The supporting segment 3 located at the lower end of thin-walled segment 2 is connected to the top of the fixed base 1 on the same side. The two supporting segments 3 located at the upper end of thin-walled segment 2 are connected to each other at their far ends.

[0043] Preferably, the fixed base 1 and the supporting segment 3 are both concrete structures, and the thin-walled segment 2 is a steel structure.

[0044] Steel structures are flexible structures with a relatively light weight. Therefore, buildings in the same seismic intensity and on the same site experience less seismic force, thus reducing the risk of earthquake damage. Using steel structures in earthquake-prone areas will reduce casualties and property losses, offering considerable comprehensive benefits. Steel structures have the advantages of high strength and light weight, generally reducing the building's weight by about one-third. For example, if the strength of steel is G550 and the strength of concrete is C25, for the same mass of components, the load-bearing capacity of a steel structure is twice that of concrete; correspondingly, for the same load-bearing capacity, a steel component weighs only half as much as a concrete component.

[0045] like Figures 2-5 As shown, the thin-walled segment 2 includes a thinned section 201 and transition sections 202 located at the upper and lower ends of the thinned section 201. The thinned section 201 and the transition section 202 are integrally formed, and the thickness of the thinned section 201 is less than the thickness of the transition section 202. The thin-walled segment 2 is designed with a thin-walled treatment to ensure that the construction clearance of the highway tunnel is not affected by reinforcement, providing sufficient clearance for large vehicles to pass through the tunnel. The transition section 202 is thinned towards the thinned section 201 in a stepped or oblique manner. When multiple stages are used, its length l is not less than 5 cm and its height h is not less than 3 cm. The staged approach can reduce steel consumption while ensuring that the strength of the component remains unchanged, further ensuring that the space of the construction clearance is not affected. After the thin-walled treatment, the structural width of the thin-walled segment 2 gradually becomes the width of the concrete part. Therefore, it is necessary to control the length of the thin-walled segment 2 to not exceed 10 cm at its maximum width.

[0046] Furthermore, multiple interfacial tensile and shear-resistant reinforcing bars 203 and T-shaped studs 204 are evenly distributed at both the upper and lower ends of the thin-walled segment 2, serving to resist tension and shear. The interfacial tensile and shear-resistant reinforcing bars 203 are the same size as the reinforcing bars in the concrete, with a 10-15 cm margin. The T-shaped studs 204, with a diameter of approximately 2 cm and a length of 3-5 cm, are welded to the thin-walled segment 2, forming an inverted T-shape. Their distribution needs to be staggered, and on the outer side, while meeting the required protective layer thickness, the spacing between the T-shaped studs 204 and the interfacial tensile and shear-resistant reinforcing bars 203 is 15d to achieve the best effect.

[0047] Specifically, the thin-walled segment 2 has an internal filling area 205, within which multiple crisscrossing reinforcing ribs 206 are installed. This ensures the strength and overall stability of the steel structure while saving materials, reducing weight, and facilitating transportation and assembly. After grouting between the existing structure 4 and the segment structure, the filling area 205 is filled, forming a prefabricated steel-concrete thin-walled reinforced structure, improving overall strength and stability. Adjacent reinforcing ribs 206 divide the filling area 205 into multiple zones. Filling holes 2061, connecting these zones, are provided on the reinforcing ribs 206. The diameter of the filling holes 2061 should be no less than 3 cm to allow concrete material to pass through during filling. The spacing between the reinforcing ribs 206 should be greater than 15d and less than 30 cm, and the thickness should be 3-5 mm. The reinforcing ribs 206 are reinforced with welded steel mesh to enhance the interface shear strength after backfilling.

[0048] When manufacturing thin-walled pipe segment 2, a double-layer steel mesh needs to be laid on the outside of thin-walled pipe segment 2. The bottom layer is connected to thin-walled pipe segment 2 by welding, so that the upper steel mesh is more tightly connected to the grouting part. The spacing of the steel mesh is no more than 15cm, and the diameter of the steel bars in the steel mesh is no more than 8cm, so as to achieve the best interface treatment effect.

[0049] Furthermore, the thin-walled tube segment 2 is provided with anchoring holes 207, grouting holes 208, air outlet holes 209, hoisting holes 210 and tensioning holes 211.

[0050] Multiple anchor holes 207 penetrate both sides of the thin-walled segment 2 and are distributed longitudinally in a staggered pattern. First bolt sleeves 212 are installed along the path of the anchor holes 207 within the filling area 205, forming an internal and external isolation to prevent material seepage after grouting and filling. The anchor holes 207 connect the thin-walled segment 2, the reinforcing steel grouting layer 5, and the existing structure 4, enhancing the strength and stability of the structure. Multiple anchor holes 207 are distributed along the central axis of the thin-walled segment 2, arranged in a four-part division. When the spacing of the thin-walled segments 2 is no greater than 1m, they are arranged longitudinally in a ring / 60cm pattern. When the width of the thin-walled segment 2 is 60cm, one row of anchor holes 207 is arranged longitudinally; when it is 1.2m, two rows of anchor holes 207 are arranged.

[0051] Grouting holes 208 and vent holes 209 extend through both sides of the thin-walled tube segment 2. During fabrication, a sleeve is pre-installed to form a through-hole in the thin-walled tube segment 2. After the tube segment assembly is completed, grout is injected through this grouting hole 208 for rapid grouting. When setting the grouting hole 208, vent holes 209 must also be pre-installed to determine whether the grout has filled completely. These vent holes are distributed side-by-side in the filling area 205, with a distance of no more than 2 meters between them.

[0052] Multiple lifting holes 210 are provided on the side of the thin-walled tunnel segment 2 near the inner wall of the existing tunnel structure 4. The lifting holes 210 are used to connect the lifting equipment to the thin-walled tunnel segment 2, enabling precise installation of the thin-walled tunnel segment 2. The location, number, and size of the lifting holes 210 must meet the requirements of the lifting operation to ensure a smooth lifting process. Four M24×80 lifting holes 210 are provided, symmetrically positioned at points 520mm from the steel structure, 200mm from the centerline, and 2055mm from the steel structure and 200mm from the centerline, respectively.

[0053] Multiple tensioning holes 211 are respectively opened on both sides of the transition section 202 and the adjacent thin-walled tube segment 2. A second bolt sleeve 213 is provided on the side of the tensioning hole 211 located in the filling area 205, and a reaction structure is provided on the outside of the tensioning hole 211 to prevent structural damage during tensioning. After the assembly is completed, the pre-tightening effect is applied to the front and rear thin-walled tube segments 2 by pre-stressed screws to make the structure more stable.

[0054] This invention satisfies the characteristics of quick and efficient prefabrication, enabling factory production and on-site assembly. It requires less material and is a green, environmentally friendly, and sustainable circular building.

[0055] This embodiment provides a design method for a prefabricated steel-concrete thin-walled reinforcement structure for highway tunnels. The method includes the inner wall of the existing tunnel structure 4 and the reinforcement structure. The reinforcement structure includes a supporting structure and a reinforced concrete grouting layer 5 between the supporting structure and the existing structure 4. The main considerations in both the reinforcement structure and the existing structure 4 are bending and compressive resistance. First, by balancing the bending moment of the reinforcing steel with that of the steel structure, the initial thickness d1 of the steel structure can be obtained. Then, by balancing the bending moment of the same surface, the thicknesses d1, d2, d3, and d4 of different parts of the thin-walled segment 2 can be determined. Finally, by applying the principle that the bending moment of the compression portion of the existing structure 4 is equal to the tensile bending moment of the reinforcing steel in the reinforcement structure, and the principle of force balance, the dimensions and stress conditions of the reinforcing steel are obtained.

[0056] After the overall fabrication of the segment structure is completed, before assembly, the thin-walled structure is considered as the most unfavorable situation. The theoretical value of the bending moment of the thin-walled segment 2 should be greater than the bending moment value of the support reaction force of the reinforced structure itself. Therefore, the design values ​​of the thickness of different parts of the thin-walled segment 2, d'1, d'2, d'3, and d'4, can be obtained.

[0057] Considering that the stress on the concrete reinforcement inside the reinforced structure is less than or equal to the design strength of the thin-walled segment 2, the minimum design value d1 of the thickness of a certain part of the thin-walled segment 2 is solved by combining the reinforcement bending moment formula and the steel structure bending moment formula. ” Based on the principle that the bending resistance of the same surface is equal, the minimum design value d1 of the thickness of different parts of the thin-walled tube segment 2 can be obtained.” d2 ” d3 ” d2 ” Based on the above calculations and comparisons, the minimum design values ​​d3, d'3, and d3 for the thickness of various parts of the thin-walled tube segment 2 under different conditions are obtained. ” To satisfy all of the above conditions simultaneously, the maximum value among them can be taken.

[0058] Specifically, for the overall structure of the supporting structure, based on the principle that the bending resistance performance in the same plane is the same, after the type of thin-walled segment 2 is determined, the thickness values ​​of each part of thin-walled segment 2 are designed and verified. Utilizing the fact that the bending moment generated in the compression zone of the existing structure 4 is the same as the bending moment of the reinforced structure; and that the stress on the concrete reinforcement in the reinforced structure is less than or equal to the design strength of thin-walled segment 2, the minimum thickness values ​​d1, d2, d3, and d4 of each part of the assembled thin-walled segment 2 can be designed.

[0059] M = A S1 ·f sd (l R +l C -x d -a S1 )+A S2 ·f sd ·(l C -x d +a S1 )

[0060] M = M G =A S ·f sd ·(l C -2a S )

[0061] A S1 : Area of ​​the lower reinforcement bars in the tension zone of the structure;

[0062] A S2 : Area of ​​the upper reinforcement bars in the tension zone of the reinforced structure;

[0063] f sd Design value of tensile strength of reinforcing steel bars:

[0064] l R Width value of the reinforced area;

[0065] l C Existing structural width value:

[0066] x d Width of the existing structure's compression zone:

[0067] a S1 Thickness of the concrete protective layer for reinforced structures.

[0068] N = A S2 ·f sd +A S1 ·f sd -x d ·f c

[0069] A S1 : Area of ​​the lower reinforcement bars in the tension zone of the structure;

[0070] A S2 : Area of ​​the upper reinforcement bars in the tension zone of the reinforced structure;

[0071] f sd Design value of tensile strength of reinforcing steel bars:

[0072] x d Width of the existing structure's compression zone:

[0073] f c Design value of concrete compressive strength

[0074] From this, we can deduce the size A of the reinforcing steel in the thin-walled segment 2 concrete. S1 A S1 Similarly, the thickness of each part of the thin-walled tube segment 2 can be calculated using the above formula;

[0075] When the structure is a multi-level stepped structure:

[0076] Based on the fact that the bending resistance of the same surface is the same, the conversion factor between the tensile properties of the thin-walled segment 2 and the steel reinforcement is set to obtain:

[0077] d As ·l As =d1·l1&

[0078] d1·l1=d2·l2=d3·l3

[0079] To ensure the rationality of the structural design, when the width of the steel structure of the thin-walled segment 2 reaches its maximum value, the thickness of the steel structure on both the front and rear sides should be consistent. Therefore, d1 = d4.

[0080] d1, d2, d3, d4: Thickness values ​​of different parts of the thin-walled segment steel structure;

[0081] l1, l2, l3: Width values ​​of different parts of the thin-walled segment steel structure;

[0082] d As Diameter of reinforcing bars in concrete sections;

[0083] &: The conversion factor between the tensile properties of thin-walled segments and reinforcing steel is &=1.2;

[0084] l As: The distance between the reinforcing steel bars and the interface in the concrete section.

[0085] The above calculations can be used to obtain d1, d2, d3, and d4 for the corresponding conditions.

[0086] After the thin-walled segment 2 is fabricated as a whole, before assembly, the thin-walled structure is considered as the most unfavorable case, and the overall structural load is regarded as a uniformly distributed load. Based on this, the minimum design value d' of the thickness of the thin-walled segment 2 is obtained. At this time, the left and right supports are reaction forces with a magnitude of F1 = F2, which is 1 / 2 of the overall self-weight of the structure.

[0087] M a =F1·d a

[0088] M a Design bending moment;

[0089] F1: Support reaction force value;

[0090] d a The effective distance of the support reaction force;

[0091] Based on the equal planar bending resistance, considering the performance of thin-walled segment 2, the design value coefficient and backfill concrete must meet the following requirements:

[0092] M t >1.2M a

[0093] M t Theoretical value of bending moment for thin-walled tunnel segments;

[0094] M t1 =f d ·h1·d'1l

[0095] M t2 =f d ·h2·d'2l

[0096] M t3 =f d ·h3·d'3l

[0097] h1, h2, h3: Width values ​​of different parts of the thin-walled tube segment;

[0098] d'1, d'2, d'3: Thickness values ​​of different parts of the thin-walled tube segment

[0099] The design values ​​of d'1, d'2, and d'3 can be obtained from the above calculations.

[0100] Considering that the stress on the reinforced concrete inside the reinforced structure is less than or equal to the design strength of the steel structure, the safety factor should meet αM. t ≥M G,

[0101] M G =f sd ·(h x -x d )·A S

[0102] M G Design strength value of reinforced concrete;

[0103] h x Width value of concrete structure in reinforced structures;

[0104] x d : Protective layer thickness value;

[0105] α: Safety factor is set to 1.4

[0106] The concrete h can be obtained x The design value, h, can be determined in structural design. x =h, through M t =f d ·h·d ” l can yield d1 ” d2 ” d3 ” Minimum design value.

[0107] The above calculations and comparisons yield the values ​​of d3, d'3, and d3 under different conditions. ” The minimum design value is determined by taking the maximum value among the above conditions to satisfy all of them simultaneously.

[0108] To be more specific, taking a real-world example, the existing structure is made of C35 concrete, 20 cm thick, with a longitudinal length of 1 meter. The steel reinforcement is arranged according to C22@200. The thin-walled segment 2 is designed in a graded, stepped manner, with a minimum width of l3 = 5 cm, l2 = 10 cm, and l3 = 15 cm. The overall self-weight of the supporting structure is set at 2 t, and the length is 4.5 meters. The filling area 205 is backfilled with C60 concrete.

[0109] M = A S1 ·f sd (l R +l C -x d -a S1 )+A S2 ·f sd ·(l C -x d +a S1 )

[0110] M = M G =A S ·f sd ·(lC -2a S )

[0111] N = A S2 ·f sd +A S1 ·f sd -x d ·f c

[0112] Solving the simultaneous equations yields A. S1 =63mm 2 And the value of the steel reinforcement in the reinforced structure should be C10;

[0113] d As ·l As =d1·l1&

[0114] d1·l1=d2·l2=d3·l3

[0115] We can solve for d1, which should be greater than 1.2 mm. Therefore, we take d1 = 1.2 mm, d2 = 1.8 mm, and d3 = 3.6 mm.

[0116] M a =F1·d a

[0117] M t >1.1M a

[0118] M t1 =f d ·h1·d'1·l

[0119] Solving the simultaneous equations, we can find d'1 = 1.8 mm. Therefore, we can conclude that: d'1 = 1.8 mm, d'2 = 2.7 mm, d'3 = 1.8 mm.

[0120] =5.4mm.

[0121] M G =f sd ·(h x -x d )·A S ,

[0122] αM t ≥M G

[0123] M t =f d ·h·d ” l

[0124] The simultaneous equations can be used to solve for d1. ” =1.3, therefore we can conclude that: d1 ”=1.3mm d2 ” =1.9mm d3 ” =3.9mm

[0125] Based on the above calculations, the weakest point d3 of the thin-walled tube segment 2 is selected as the comparison object. To meet safety requirements, the maximum value of the three d3 values ​​is selected under the most extreme conditions. Therefore, d3 is selected as 5.4mm under these conditions. Thus, d1 = 1.8mm, d2 = 2.7mm, and d3 = 5.4mm.

[0126] Preferably, alloying elements are added to the steel of the thin-walled tube segment 2 during the manufacturing process, and a zinc alloy coating is applied to improve its rust and corrosion resistance. After the thin-walled tube segment 2 is connected and assembled, each metal part is treated with an anti-corrosion coating to improve the rust and corrosion resistance of the steel structure itself. After the steel structure is manufactured, sacrificial anode protection is used, and zinc alloy is installed on the upper and lower parts of the thin-walled tube segment 2 to enhance the steel structure and delay corrosion. The thin-walled tube segment 2 is encapsulated with fire-retardant coating and steel wire mesh refractory mortar to prevent heat transfer. After the tube segment assembly is completed, a fireproof board is installed on the inside of the thin-walled tube segment 2, which not only provides fire protection but also improves the structural strength.

[0127] During the manufacturing process of thin-walled tube segments 2, alloying elements with rust-resistant properties (such as chromium, nickel, cobalt, and copper) are added to the steel, fundamentally improving its rust resistance compared to ordinary steel. Furthermore, before assembly, each section of the thin-walled tube segments 2 is immersed in molten zinc, forming a zinc alloy coating on the steel surface. Hot-dip galvanizing is suitable for steel structural components of various shapes and significantly enhances rust resistance.

[0128] After the thin-walled tube segment 2 is connected and assembled, each metal part needs to be coated with an anti-corrosion coating. Before the anti-corrosion treatment, the surface of the thin-walled tube segment 2 should be thoroughly cleaned, rust removed, and polished to ensure that the surface is clean and dry. During this process, polyurethane coating or chlorinated rubber coating should be used. Attention should be paid to the even application of the coating to avoid problems such as missed areas and bubbling, so as to improve the rust resistance of the thin-walled tube segment 2 itself.

[0129] After the thin-walled tube segment 2 is manufactured, it is protected by sacrificial anode. Zinc alloy, magnesium alloy or aluminum alloy is installed on the top and bottom surfaces of the filling area 205 as sacrificial anode. After backfilling is completed, the backfill material is used as a medium to make the thin-walled tube segment 2 form an electrochemical circuit as a whole, which plays a role in delaying corrosion.

[0130] After completing the anti-corrosion treatment, the resistance testing instrument is installed inside the filling area 205. The monitoring circuit is connected to the upper and lower ends of the reinforcing rib plate 206, so that the current runs through the entire thin-walled tube segment 2 to ensure real-time monitoring of each part of the thin-walled tube segment 2. After calibration, it is sealed to monitor the resistance and conductivity of the thin-walled tube segment 2 and the anode metal. As the degree of corrosion gradually increases, the resistance also gradually increases. Combining the corrosion rate and corrosion mechanism of the metal material and the degree of corrosion of the metal sample, when the resistance reaches 15% of the original value, manual inspection is required. When it reaches 50%, the degree of corrosion is relatively serious, the load-bearing capacity of the thin-walled tube segment 2 decreases, and repair is required. This is to monitor the corrosion of the thin-walled tube segment 2 in real time, providing an important basis for the maintenance, repair and replacement of the equipment.

[0131] The fire resistance of thin-walled tunnel segments 2 is greatly improved after being treated with fire-retardant coating. Applying fire-retardant coating to the surface of thin-walled tunnel segments 2 forms a heat insulation layer that prevents heat transfer. Because the tunnel is in a relatively enclosed space, a thick coating is required during spraying, with a thickness greater than 7mm and less than or equal to 45mm. The coating has a granular surface, low density, and low thermal conductivity, greatly improving the fire resistance limit. Furthermore, the thick coating provides non-combustibility, good insulation, and long fire resistance time. After the manufacture of thin-walled tunnel segments 2, applying the thick coating and backfilling with concrete will significantly improve the structural fire resistance.

[0132] In addition, the thin-walled tube segment 2 can be encapsulated by wrapping fireproof material inside the thin-walled tube segment 2 to form a heat insulation layer. After the tube segment assembly is completed, steel wire mesh fire-resistant mortar and fireproof board can be used to enhance the strength while providing fire protection.

[0133] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A prefabricated steel-concrete thin-walled reinforcement structure for highway tunnels, characterized in that, It includes multiple sets of support structures, which circumferentially cover the existing inner wall of the tunnel. These multiple sets of support structures are sequentially connected along the length of the tunnel. The support structures include: Two sets of fixed bases are respectively set on both sides of the bottom wall of the tunnel; Two sets of segment structures are symmetrically arranged on both sides of the top wall of the tunnel. The segment structure includes thin-walled segments and supporting segments connected to the upper and lower ends of the thin-walled segments. The thickness of the thin-walled segments is less than the thickness of the supporting segments. The supporting segments located at the lower end of the thin-walled segments are connected to the top of the fixed base on the same side. The two supporting segments located at the upper end of the thin-walled segments are connected to each other at their far ends. Both the fixed base and the supporting segments are concrete structures, while the thin-walled segments are steel structures. The thin-walled tube sheet includes a thinning section and transition sections located at the upper and lower ends of the thinning section. The thickness of the thinning section is less than the thickness of the transition section, and the transition section is thinned in a stepped or oblique manner towards the thinning section. The thin-walled tube segment has multiple interfacial tensile and shear-resistant steel bars and T-shaped studs evenly distributed at its upper and lower ends. The thin-walled tube has a filling area inside, and multiple crisscrossing reinforcing ribs are arranged in the filling area. Adjacent reinforcing ribs divide the filling area into multiple partitions, and filling holes that connect the partitions are opened on the reinforcing ribs. The thin-walled tubular segments are respectively provided with anchoring holes, grouting holes, air outlet holes, hoisting holes and tensioning holes; Multiple anchoring holes penetrate both sides of the thin-walled tube segment and are distributed longitudinally in a quincunx pattern. A first bolt sleeve is provided on the path of the anchoring holes within the filling area. The grouting hole and the air outlet hole respectively penetrate both sides of the thin-walled tube segment; Multiple of the aforementioned hoisting holes are opened on the side of the thin-walled segment close to the inner wall of the existing tunnel structure; Multiple tensioning holes are respectively opened on both sides of the transition section and the connection with the adjacent thin-walled tube segment. A second bolt sleeve is provided on one side of the tensioning hole located in the filling area, and a reaction structure is provided on the outside of the tensioning hole.

2. A design method for a prefabricated steel-concrete thin-walled reinforcement structure for highway tunnels, used to design the prefabricated steel-concrete thin-walled reinforcement structure for highway tunnels as described in claim 1, characterized in that, This includes the inner wall of the existing tunnel structure and the reinforcement structure. The reinforcement structure includes the supporting structure and the grouting layer of steel reinforcement between the supporting structure and the existing structure. First, the thickness of the steel structure is obtained by equalizing the bending moment of the steel reinforcement and the steel structure. Then, the thickness of different parts of the thin-walled segment is obtained by equalizing the bending performance of the same surface. Finally, the steel reinforcement size and stress condition are obtained by using the principle that the bending moment of the compression part of the existing structure is equal to the bending moment of the steel reinforcement in the reinforcement structure and the principle of force balance.

3. The design method for the prefabricated steel-concrete thin-walled reinforcement structure for highway tunnels according to claim 2, characterized in that, Taking the thin-walled design as the worst-case scenario, the theoretical value of the bending moment of the thin-walled segment should be greater than the bending moment of the support reaction force of the reinforced structure itself, thus obtaining the design value of the thickness of the thin-walled segment at different parts.

4. The design method for the prefabricated steel-concrete thin-walled reinforcement structure for highway tunnels according to claim 3, characterized in that, The minimum design value of the thin-walled segment thickness is obtained by combining the bending moment formula of the steel reinforcement and the bending moment formula of the steel structure. Then, the minimum design value of the thickness of different parts of the thin-walled segment is obtained based on the equal bending resistance of the equal surface. By comparing the above calculations, the minimum design value of the thickness of each part of the thin-walled segment under different conditions is obtained. Finally, the maximum value is taken.

5. The design method for the prefabricated steel-concrete thin-walled reinforcement structure for highway tunnels according to claim 2, characterized in that, After the thin-walled pipe segments are connected and assembled, each metal part is treated with an anti-corrosion coating.

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