Highway tunnel thin-wall composite reinforcing structure and design method

Abstract

The highway tunnel thin-wall composite reinforcing structure comprises multiple sets of reinforcing segments, the multiple sets of reinforcing segments are sequentially spliced in the length direction of a tunnel, each set of reinforcing segments comprises two reinforcing segments, the tops of the two reinforcing segments are connected with each other and arranged in a left-right staggered mode, and the bottoms of the reinforcing segments are connected with a ground beam in the tunnel. The reinforcing duct piece is of a concrete prefabricated structure; each reinforcing pipe piece comprises a thinning part and main body supporting parts connected to the two sides of the thinning part, the height from the thinning part to the ground is 4-5 m, the thickness of the thinning part is smaller than that of the main body supporting parts, the normal compression resistance and bearing performance of the thinning part and the normal compression resistance and bearing performance of the main body supporting parts are the same, and each reinforcing pipe piece is provided with a hole used for hoisting or grouting or connecting. The design method is used for designing the thin-wall composite reinforcing structure of the highway tunnel, an isobaric strength method is adopted for design, the compressive property and the bearing capacity of the tunnel can be improved, and meanwhile the useful passing space of the tunnel can be increased.

Description

Technical Field

[0001] The invention relates to the technical field of tunnels, and in particular to a thin-walled composite reinforcement structure and a design method for a highway tunnel. Background Art

[0002] With the continuous advancement of infrastructure construction such as transportation and water conservancy, the demand for tunnel engineering is growing. As an important transportation channel, tunnels have higher and higher requirements for construction technology and quality. At the same time, with the continuous advancement of highway tunnel projects, many tunnel projects have shifted from the construction stage to the operation and maintenance stage. As the service life of tunnels increases, potential defects in their design and construction gradually surface, resulting in frequent highway tunnel diseases. These diseases, such as cracking, water seepage, and lining block loss, can damage the visual beauty of the tunnel and distract drivers when they are minor, while serious diseases may directly cause safety accidents such as collapse and falling, causing significant economic losses and negative social impacts. Therefore, in the design and construction stage of tunnels, how to improve their compressive performance, bearing capacity and structural durability has become a key technical issue to ensure the long-term safe operation of tunnels.

[0003] In addition, from the perspective of tunnel functional requirements, the effective space available for passage inside the tunnel is an important indicator to measure the rationality of its design. Under the premise of meeting structural safety and durability, how to maximize the effective space inside the tunnel has become another important technical challenge in tunnel design and construction. Therefore, how to optimize the tunnel section design to expand the passage space while improving the tunnel's compressive performance and bearing capacity to extend its service life is a core technical problem that needs to be solved in the current tunnel engineering field. Summary of the invention

[0004] In view of the deficiencies in the prior art, the technical problem to be solved by the present invention is to provide a thin-walled composite reinforcement structure and a design method for a highway tunnel, which can improve the compressive performance and bearing capacity of the tunnel while increasing its useful passage space.

[0005] In order to achieve the above object, the present invention is implemented through the following technical solutions: a thin-walled composite reinforcement structure for a highway tunnel, comprising:

[0006] It comprises a plurality of groups of reinforcement segments which are spliced ​​in sequence along the length direction of the tunnel, each group of the reinforcement segments comprises two reinforcement segments, the tops of the two reinforcement segments are mutually connected and staggered left and right, the bottoms of the reinforcement segments are connected to the inner beams of the tunnel, and the reinforcement segments are prefabricated concrete structures; the reinforcement segments comprise a thinning portion and a main body support portion connected to both sides of the thinning portion, the height of the thinning portion from the ground is 4-5 meters, the thickness of the thinning portion is less than the thickness of the main body support portion, the normal compressive bearing performance of the thinning portion is the same as that of the main body support portion, and each of the reinforcement segments is provided with a hole for hoisting, grouting or connection.

[0007] Furthermore, the reinforcement segments are divided into wide reinforcement segments and narrow reinforcement segments, and the width of the wide reinforcement segments is twice that of the narrow reinforcement segments, along the length direction of the tunnel.

[0008] Furthermore, the thinning portion includes a middle thin portion and transition portions located on both sides, and the transition portions gradually thicken from the center to both sides.

[0009] Furthermore, the inner surface of the thinned portion is provided with reinforcement.

[0010] Furthermore, the holes include hoisting holes, grouting holes, anchor holes, bottom support holes, top bolt holes, hand holes, longitudinal quick-insert bolt holes, longitudinal prestressed holes and positioning tenon holes:

[0011] The lifting holes are arranged on both side surfaces, inner side surface and outer side surface of the reinforced pipe segment. The number of lifting holes on a single side should not be less than 2, and they are symmetrically arranged along the central axis of symmetry where the center of gravity is located.

[0012] The grouting holes are evenly distributed on the edge or surface of the reinforced pipe segment, the circumferential spacing of the grouting holes is 1.5m to 2m, and the longitudinal spacing of the grouting holes is 0.5m to 1m;

[0013] The anchor holes are distributed at equal intervals along the joints between the reinforced segments and the original lining, and the diameter of the anchor holes is 30 to 50 mm larger than the diameter of the anchor cables;

[0014] The bottom support hole is arranged at the bottom of the reinforced segment and is used for connecting with the ground beam;

[0015] The top bolt holes are arranged along the middle of the thickness direction of the reinforced segment, and the hole size is equal to or less than 1 / 4 of the segment thickness;

[0016] The hand hole is arranged on the reinforced segment, and the width of the hand hole along the tunnel circumferential direction is greater than or equal to 15 cm, and the width of the hand hole along the tunnel longitudinal direction is greater than or equal to 15 cm;

[0017] The single distance between the longitudinal quick-insert bolt holes is 4 to 6 meters;

[0018] The longitudinal prestressed holes are symmetrically arranged on both sides of the longitudinal quick-insertion bolt holes, and are at a distance from the quick-insertion bolt holes to make the entire structure more stable;

[0019] The positioning tenon holes are provided with two positioning tenon holes on the longitudinal side of each of the reinforced pipe segments.

[0020] A design method for a thin-walled composite reinforcement structure of a highway tunnel is used to design the above-mentioned thin-walled composite reinforcement structure of a highway tunnel, and is characterized by comprising:

[0021] According to the concrete structural performance of the thinning portion and the main body support portion connected to both sides of the thinning portion, the thickness of the thinning portion and the main body support portion is determined by using the isostatic strength method;

[0022] The area of ​​reinforcement at the thinning part is calculated using the ultimate bending resistance value M;

[0023] The size of the transition part is designed by gradually thickening;

[0024] The interface of the reinforced segment is designed in an uneven manner;

[0025] Design the corresponding hole positions and sizes according to the length and width of the tunnel, the casting method of the reinforcement segments, and the installation method of the reinforcement segments;

[0026] By assembling, multiple groups of reinforced segments are connected in sequence along the length direction of the tunnel. Each group of reinforced segments includes two reinforced segments. The tops of the two reinforced segments are connected to each other and arranged staggered left and right, and the tops of the two reinforced segments are connected to each other.

[0027] Furthermore, the specific method of determining the local thinning thickness using the isobaric strength method is as follows:

[0028] According to the isobaric strength method, the compressive bearing performance of the thinned part is consistent with that of the non-thinned part. The calculation formula for the thinned part is:

[0029]

[0030] —Compressive strength of the first type of concrete

[0031] d1—thickness corresponding to the first type of concrete

[0032] —Compressive strength of the second concrete

[0033] d2—Thickness corresponding to the second type of concrete.

[0034] Furthermore, the specific method for calculating the area of ​​reinforcement at the local thinning location using the ultimate bending resistance value M is:

[0035] The reinforcement structure is reinforced according to the "equal bending performance" of the entire ring of the reinforced structure. During the calculation process, the existing tunnel structure is not considered because its contribution to the bending moment of the thinned section and the unthinned section is similar. In the process of determining the thickness, the bending performance of the reinforced structure is calculated based on the unthinned section to determine the ultimate bending value M. On this basis, the above-mentioned bending moment value M is used to calculate the concrete width of the compression zone and the steel bar area of ​​the reinforced structure.

[0036] Furthermore, the specific method of designing the size of the transition part by gradually thickening is: making the length of the transition part 3 to 5 times the thickness of the interface.

[0037] Furthermore, the method also includes roughening the surface of the reinforced pipe segment.

[0038] Beneficial effects of the present invention:

[0039] The above-mentioned highway tunnel thin-walled composite reinforcement structure, the highway tunnel thin-walled composite reinforcement structure, includes a highway tunnel thin-walled composite reinforcement structure, including a plurality of groups of reinforced segments, and the plurality of groups of reinforced segments are sequentially spliced ​​along the length direction of the tunnel. Each group of reinforced segments includes two reinforced segments, the tops of the two reinforced segments are connected to each other and staggered left and right, the bottoms of the reinforced segments are connected to the inner beams of the tunnel, and the reinforced segments are prefabricated concrete structures. The reinforced segments include a thinning portion and a main support portion connected to both sides of the thinning portion. The height of the thinning portion from the ground is 4-5 meters, the thickness of the thinning portion is less than the thickness of the main support portion, the normal compressive bearing capacity of the thinning portion and the main support portion is the same, and each reinforced segment is provided with holes for hoisting, grouting or connection. The design method is used to design this highway tunnel thin-walled composite reinforcement structure.

[0040] The above-mentioned highway tunnel thin-walled composite reinforcement structure adopts the method of prefabrication followed by assembly, which shortens the construction period, overcomes the risk of tunnel structure settlement, and ensures the safety of the boundary between the segment structure and the building; in addition, since the segment is locally thinned while ensuring the same overall compressive bearing performance, the on-site applicability of the segment is improved without reducing the bearing force, thereby achieving the purpose of increasing the useful passage space of the tunnel; at the same time, by using concrete with different compressive bearing properties to form NC-UHPC-NC combined reinforced segments, the tunnel thin-walled composite reinforcement structure can be easily realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the specific implementation of the present invention, the following will briefly introduce the drawings required for use in the specific implementation. In all the drawings, each element or part is not necessarily drawn according to the actual scale.

[0042] Figure 1 A schematic diagram of a highway tunnel thin-walled composite reinforcement structure after installation provided by an embodiment of the present invention;

[0043] Figure 2 for Figure 1 A side view of a single reinforced segment in a thin-walled composite reinforcement structure of a highway tunnel is shown;

[0044] Figure 3 for Figure 1 A schematic diagram of a thinning portion in a thin-walled composite reinforcement structure of a highway tunnel is shown;

[0045] Figure 4 for Figure 1 A schematic diagram of assembling a thin-walled composite reinforcement structure for a highway tunnel is shown;

[0046] Figure 5 for Figure 1 A top view of a reinforced pipe segment of a highway tunnel thin-walled composite reinforcement structure is shown (a is a schematic diagram of a wide reinforcement segment, b is a schematic diagram of a narrow reinforcement segment);

[0047] Figure 6 for Figure 1 A schematic diagram of holes on a reinforced pipe segment of a highway tunnel thin-walled composite reinforcement structure is shown (a is a top view, b is a sectional view 1-1 in Figure a, and c is a sectional view 2-2 in Figure a);

[0048] Figure 7 for Figure 1 A schematic diagram of the connection between a thin-walled composite reinforcement structure and a ground beam of a highway tunnel is shown;

[0049] Figure 8 for Figure 1 A schematic diagram of a partially raised keyway on a thinned portion of a highway tunnel thin-wall composite reinforcement structure is shown;

[0050] Fig. 9 for Figure 1 A schematic diagram of all raised keyways on a thinned portion of a highway tunnel thin-wall composite reinforcement structure is shown;

[0051] Fig.10 for Figure 1 A schematic diagram of connecting steel bars in a thin-walled composite reinforcement structure of a highway tunnel is shown;

[0052] Fig.11 for Figure 1 The effect diagram of the thinned portion of the reinforced pipe segment in a highway tunnel thin-wall composite reinforcement structure after interface water washing is performed;

[0053] Fig.12 for Figure 1The effect diagram of the main support part of the reinforced segment in a highway tunnel thin-wall composite reinforcement structure after interface water washing is shown;

[0054] Fig.13 Schematic diagram of the belt to avoid chiseling;

[0055] Fig.14 for Figure 1 The effect diagram of a highway tunnel thin-wall composite reinforcement structure after the reinforcement segment is treated with a roughening-free tape;

[0056] Fig.15 for Figure 1 The effect diagram of a highway tunnel thin-wall composite reinforcement structure after the reinforcement segment is treated with a roughening-free tape;

[0057] Reference numerals:

[0058] 100, reinforcement segment; 110, thinning portion; 111, middle thin portion; 112, transition portion; 120, main support portion; 201, lifting hole; 202, grouting hole; 203, anchor hole; 204, bottom support hole; 300, ground beam. DETAILED DESCRIPTION

[0059] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the invention is not limited by the specific implementation disclosed below.

[0060] See also Figures 1 to 14 The present invention provides a thin-walled composite reinforcement structure for a highway tunnel, comprising a plurality of groups of reinforcement segments 100, which are spliced ​​in sequence along the length direction of the tunnel. Each group of reinforcement segments 100 includes two reinforcement segments 100, the tops of the two reinforcement segments 100 are connected to each other and staggered left and right, the bottoms of the reinforcement segments 100 are connected to the inner beams 300 of the tunnel, and the reinforcement segments 100 are prefabricated concrete structures. The reinforcement segments 100 include a thinning portion 110 and a main support portion 120 connected to both sides of the thinning portion 110. The height of the thinning portion 110 from the ground is 4-5 meters, the thickness of the thinning portion 110 is less than the thickness of the main support portion 120, the normal compressive bearing performance of the thinning portion 110 and the main support portion 120 is the same, and each reinforcement segment 100 is provided with a hole for hoisting, grouting or connection.

[0061] In specific implementation, the concrete materials of the main support part 120 and the thinning part 110 can be selected from ordinary concrete materials (NC) and ultra-high performance concrete (UHPC) materials, respectively (e.g., if the main support part 120 is C35 concrete, the thinning part 110 can be C50, C55, C60 concrete; if the main support part 120 is C50, C55, C60 concrete, the thinning part 110 can be UHPC, i.e. UC120~UC180 materials): During construction, the thinning part 110 and the main support part 120 are first prefabricated in the factory, and then spliced ​​into the reinforced pipe segment 100, and then transported to the construction site for assembly with the ground beam 300. In addition, the height of the thinning part 110 can be adjusted according to the height of the tunnel.

[0062] The above-mentioned highway tunnel thin-wall composite reinforcement structure is prefabricated and then assembled (refer to Figure 4 ), shortening the construction period, while overcoming the risk of tunnel structure settlement and ensuring the safety of the segment structure and the boundary between the building; in addition, because the segment is locally thinned while ensuring the same overall compressive bearing performance, the on-site applicability of the segment is improved without reducing the bearing force, thereby achieving the purpose of increasing the useful passage space of the tunnel. At the same time, by using concrete with different compressive bearing properties to form NC-UHPC-NC combined reinforced segments, the tunnel thin-walled composite reinforcement structure can be easily realized.

[0063] Please refer to Figure 5 In the specific implementation, the reinforcement segments 100 can be set to have two widths of reinforcement segments 100, one of which is a wide reinforcement segment A ( Figure 5 The other is a narrow reinforcement piece B ( Figure 5 (b in the middle), and the width of the wide reinforcement piece is twice that of the narrow reinforcement piece. Along the length of the tunnel, the horizontal staggered assembly is adopted. The basic type is B, A, A, (A is an even-numbered piece) B, that is, the segments on both sides of the assembled structure are rotationally symmetrical. During the assembly process, half of the segments of the previous ring can be used as the support point of the next segment, so that each segment except the first segment can form a load-bearing ring after installation to ensure the stability of the structure.

[0064] Please refer to Figure 3 In this embodiment, the thinning portion 110 includes a middle thin portion 111 and transition portions 112112 located on both sides, and the transition portions 112112 gradually thicken from the center to both sides.

[0065] This method has the following advantages:

[0066] First, it can make stress transition smoothly and prevent stress concentration caused by the difference in stiffness of two different concretes, thereby improving the durability and bearing capacity of the interface;

[0067] Second, the gradual thinning of the interface can reduce the peak values ​​of shear stress and tensile stress, avoid interface cracking or peeling, enhance the interface bonding effect, and a reasonable transition length design can improve the bonding performance between two different concretes and improve the interface bearing capacity;

[0068] Third, it can optimize the overall performance of the structure, improve the stress transfer efficiency in the transition area, and make the entire structure more stable and reliable.

[0069] Please refer to Figure 6 In this embodiment, the holes include a hoisting hole 201, a grouting hole 202, an anchor hole 203, a bottom support hole 204, a top bolt hole, a hand hole, a longitudinal quick-insert bolt hole, a longitudinal prestressed hole and a positioning tenon hole.

[0070] The setting of the hoisting hole 201 provides a connection point for the hoisting rope or hoisting device, so that the component can be hoisted and moved safely and stably. Reasonable setting of the hoisting hole 201 can evenly distribute the hoisting force, avoid cracks or damage to the component due to uneven force during the hoisting process, and ensure the safety of the construction process. The position of the hoisting hole 201 is determined according to the shape of the component, the center of gravity position and the hoisting method, and is as close to the center of gravity of the component as possible to reduce tilting and shaking during the hoisting process.

[0071] Specifically, the hoisting holes 201 are set on both sides of the reinforced segment 100 as well as the inner and outer sides to meet the functional requirements of segment hoisting and flipping. The number of single-sided hoisting holes 201 should not be less than 2, and they should be arranged symmetrically along the symmetry center axis where the center of gravity is located. The spacing between the hoisting holes 201 should not be greater than 4m. For the inner and outer hoisting holes 201, through holes can be used for integration to avoid multiple openings. The size of the hoisting hole 201 should not be less than M20, and M24 is often used.

[0072] Grouting holes 202 are small holes reserved on the concrete segments for injecting grout. In tunnel construction, after the segments are installed, grouting holes 202 are evenly distributed on the edge or surface of the segments. The purpose is to inject grouting material into the gap behind the segments through the grouting holes 202 to fill the gap and enhance the bonding between the segments and the original lining. In order to avoid clogging of the grouting material, the hole diameter will be larger, set to 50-60mm, and prefabricated components are used.

[0073] The spacing of the grouting holes 202 is usually determined according to the diameter of the reinforcement segment 100 and the specific construction requirements. Generally speaking, for highway tunnels, the spacing of the circumferential grouting holes 202 can be 1.5m to 2m, and the spacing of the longitudinal grouting holes 202 can be set to 0.5m to 1m. For example, for thin-walled prefabricated reinforcement of tunnels, when the width of the wide reinforcement segment is 1.2m, the width of the narrow reinforcement segment is 0.6m, and the circumferential length is about 8m, the circumferential spacing of the grouting holes 202 can be 2m, and one ring of grouting holes is arranged in each ring of the longitudinal segment.

[0074] In tunnel reinforcement, the circumferential position of the anchor holes 203 of the reinforced segments 100 should take into account the stress conditions of the original lining and the assembly method of the reinforced segments 100. Generally, they are evenly spaced along the joints between the reinforced segments 100 and the original lining, and the spacing is usually between 2m and 3m. For tunnels with larger diameters and more complex stress conditions, the spacing can be smaller, 1.0 to 2.0m, to ensure the uniformity and stability of the connection between the segments and the original lining.

[0075] From a longitudinal perspective, the anchor holes 203 can be determined based on factors such as the length of the reinforced segment 100 and the longitudinal slope of the tunnel. If the length of the reinforced segment 100 is 1 to 2 meters, 2 to 3 longitudinal anchor holes 203 can be set on each reinforced segment 100. For tunnels with a certain longitudinal slope, the density of the anchor holes 203 can be appropriately increased at the contact point between the segment and the original lining in the downhill direction of the tunnel to resist the downward force of the segment due to gravity.

[0076] The aperture of the anchor hole 203 is determined according to the selected anchor material and the size of the anchor rod (cable). When using an anchor cable, due to its relatively complex structure and the presence of a protective sleeve, the aperture needs to be 30 to 50 mm larger than the diameter of the anchor cable. For example, if the diameter of the anchor cable is 15 mm, the aperture of the anchor hole 203 is 45 to 65 mm. Therefore, the anchor hole 203 can be shared with the grouting hole 202, and grouting is performed after anchoring. In general, the aperture of the anchor hole 203 is relatively small and can be shared with the hoisting hole 201.

[0077] See also Figure 7 The bottom support holes 204 of the segments are specific holes reserved at the bottom of the precast concrete segments. Their core purpose is to install supports to provide stable support for the segments. During the tunnel reinforcement process, when the reinforced segments 100 are assembled ring by ring, the ground beams 300 are firmly connected to the reinforced segments 100 through these reserved holes, and the vertical loads (including deadweight, upper covering soil pressure, and operational loads such as trains) carried by the reinforced segments 100 are safely and efficiently transferred to the ground beams 300 below, such as to the cushion layer, foundation or roadbed at the bottom of the tunnel, so as to ensure the vertical stability of the tunnel structure and prevent the reinforced segments 100 from sinking, displacement and other adverse conditions.

[0078] The connection of the bottom support is as follows: each group of bottom support holes 204 consists of two holes, which are used to connect the original lining structure and the lower support respectively. Generally, at least two groups of support holes are set for the reinforced pipe segment 100 to maintain structural stability. To ensure uniform force, the single distance of each group of support holes is not greater than 0.6m. To facilitate construction and prevent the bolts from being able to smoothly rotate in or out after the support is slightly deformed, the support holes adopt a non-full thread design. To reduce costs, the lower nut and the upper steel pipe are welded.

[0079] In the project, in order to ensure that the embedded parts of the bottom support hole 204 and the concrete structure form a bearing whole, a connecting steel plate with a thickness of 3 to 5 mm can be set at the bottom of the bottom support hole 204. The single distance between the two anchor holes 203 should be 5 to 10 cm, which should not be too large or too small. If it is too large, the steel plate will be too large, which is not conducive to construction control, and if it is too small, it will be not conducive to concrete pouring. Vertical anchor steel bars are set on both sides of the steel plate, with a length of not less than 10 cm. Horizontal anchor steel bars are set on the top of the embedded parts, and the length of the steel bars is not less than 30 cm.

[0080] The tunnel segments are assembled in the circumferential direction, that is, the segments are connected into a whole by bolts. A continuous ring structure is formed with high overall stiffness and stability, so that the segment structure can withstand large external loads, such as groundwater pressure, soil pressure, etc., to ensure the safety and stability of the tunnel. In the circumferential assembly, the connection between the segments is tighter, which can more effectively transfer and disperse the load. At the same time, the bolt connection between the segments can form a certain prestress, which improves the tunnel's ability to resist deformation.

[0081] In specific implementation, the top bolt holes are arranged in the middle of the segment thickness direction, and the hole size should not be larger than 1 / 4 of the segment thickness, that is, for a segment 15cm thick, the hole size should not be larger than 4cm. And the net thickness of concrete after subtracting concrete thickness from hole size should not be less than the concrete thickness of the non-thickened section.

[0082] When selecting the matching bolt diameter of the top bolt hole, the reserved bolt hole size, the segment manufacturing errors, the structural construction errors and the joint force transmission requirements should be comprehensively considered. Generally, the difference between the bolt diameter and the bolt hole diameter is 10mm. According to the load-bearing requirements, when the bolt diameter is 30mm, the bolt hole diameter is 40mm. If there is no special load-bearing requirement, when the bolt hole diameter is 40mm, the maximum bolt diameter can be 30mm. In fact, for the convenience of construction, a smaller value can be appropriately taken, such as a bolt diameter of 25mm.

[0083] In addition to the bolt holes, the bolt installation work also requires the provision of hand holes on the reinforced pipe segment 100. To facilitate bolt tightening, the width of the hand holes along the tunnel annular direction should not be less than 15 cm, and the width of the hand holes along the tunnel longitudinal direction should not be less than 15 cm. If the thickness of the concrete main structure is 15 cm and the thickness of the external concrete is less than 50 mm, the hand holes should be designed as through holes that penetrate the inside and outside. If the thickness of the external concrete is greater than 50 mm, the hand holes should not be designed as internal and external through holes, and the concrete outside the hand holes should be reinforced in the middle to meet the load-bearing requirements. To facilitate the construction of the hand holes, the hand hole structure should be an unequal thickness section with a larger inner side and a smaller outer side. For the pipe segments on both sides of the reinforcement structure, from an aesthetic point of view, end operation holes should be set, and the diameter of the end operation hole - the diameter of the bolt hole>5 cm.

[0084] For tunnel structures with large deformation and longitudinal uneven deformation, the segments need to be equipped with longitudinal connecting bolts, which consist of three parts: embedded nuts on both sides, middle linings and connecting screws. The embedded nuts on both sides are embedded during the casting process of the segments, and the connecting screws are pressed into the embedded nuts by longitudinal compressive stress. For assembled segments, the single distance of longitudinal quick-insert bolt holes should be 4 to 6m, and the number of longitudinal quick-insert bolts for a single segment should not be less than 2, and the segments should be evenly distributed.

[0085] The longitudinal prestressed holes of the segments are reserved in the longitudinal direction of the segments for inserting prestressed tendons, and the hole depth runs through the entire longitudinal thickness of the segments. These holes run through the longitudinal part of the segments and are mainly used for longitudinal tightening of the segments or installation of quick-insert bolts. This improves the crack resistance and structural integrity of the segments, making the tunnel structure more stable in the longitudinal direction and improving the overall bearing capacity of the tunnel.

[0086] The longitudinal prestressed holes are symmetrically arranged on both sides of the longitudinal quick-insert bolt holes, 20 to 40 cm away from the quick-insert bolt holes; to prevent the distance from being too small, causing local stress concentration, causing local cracking or damage to the structure, and to prevent the distance from being too large, making it impossible to fully tighten the quick-insert bolts. Generally, the hole diameter should be 10 to 20 mm larger than the diameter of the prestressed tendon to facilitate the insertion of the prestressed tendon and subsequent grouting operations. The diameter of the prestressed tendon is 15.2 mm, and the diameter of the prestressed hole is designed to be 25 to 35 mm.

[0087] In this embodiment, two positioning tenon holes are provided on the longitudinal side of each reinforced pipe segment 100. The positioning tenon matched with the positioning tenon hole is a spindle-shaped structure, the maximum diameter of the middle part should not be greater than 1 / 2 of the tunnel pipe segment, the minimum diameter on both sides should not be less than 3 cm, and the length of the positioning tenon should not be less than 15 cm (7.5 cm on each side); in order to prevent the local stress of the pipe segment at the position where the positioning tenon acts from causing damage to the pipe segment, the positioning tenon should be set at the thickened connection part of the structure, that is, on both sides of the pipe segment. During the construction process, by using the positioning tenon, the position and direction of the pipe segment during the assembly and installation process can be ensured to be accurate, which can avoid the dislocation, offset or tilt of the pipe segment and ensure the accuracy of the geometric shape and longitudinal extension of the tunnel.

[0088] Also, see Fig.15 The present invention also discloses a design method for a thin-walled composite reinforcement structure of a highway tunnel, which is used to design the above-mentioned thin-walled composite reinforcement structure of a highway tunnel, comprising:

[0089] S110, according to the concrete structural properties of the thinning portion 110 and the main body support portion 120 connected to both sides of the thinning portion 110, the thickness of the thinning portion 110 and the main body support portion 120 is determined by using an isostatic strength method;

[0090] S120, calculating the area of ​​the reinforcement at the thinning portion 110 using the ultimate bending resistance value M;

[0091] S130, the size of the transition part is designed by gradually thickening;

[0092] S140, designing the interface of the reinforced segment 100 in an uneven manner;

[0093] S150, designing corresponding hole positions and sizes according to the length and width of the tunnel, the casting method of the reinforcement segment 100, and the installation method of the reinforcement segment 100;

[0094] S160. Use an assembly method to connect multiple groups of reinforced segments 100 in sequence along the length direction of the tunnel. Each group of reinforced segments 100 includes two reinforced segments 100. The tops of the two reinforced segments 100 are connected to each other and arranged staggered left and right. The tops of the two reinforced segments 100 are connected to each other.

[0095] In the specific implementation, considering the bearing force of the pipe segment to ensure its stability and strength, the thinning part of the pipe segment is designed according to the "isostatic strength" method. The basic idea is that the pipe segment itself, under the action of the external normal support, makes the compressive bearing performance of the thinned part consistent with the non-thinned part. The material of the thinned part is selected according to the space requirements of the thinning. In general, if the main support part 120 is C35 concrete, the thinned part can use C50, C55, C60 concrete; if the main support part 120 is C50, C55, C60 concrete, the thinned part can use UHPC, that is, UC120~UC180 materials.

[0096] The calculation formula for the thinning part 110 is:

[0097]

[0098] The specific method for determining the local thinning thickness using the isobaric strength method is as follows:

[0099] According to the isobaric strength method, the compressive bearing performance of the thinned part is consistent with that of the non-thinned part. The calculation formula for the thinned part is:

[0100]

[0101] —Compressive strength of the first type of concrete

[0102] d1—thickness corresponding to the first type of concrete

[0103] —Compressive strength of the second concrete

[0104] d2—Thickness corresponding to the second type of concrete.

[0105] Local thinning thickness calculation example

[0106] Taking C35 with a thickness of 25 cm as an example, the isobaric thickness of UHPC is

[0107] 35×25=120×d2

[0108] The calculated isobaric thickness of UHPC is 7.2 cm.

[0109] In actual engineering, parameter values ​​are generally rounded up. For this, you can refer to the following table to determine the thickness.

[0110] Table 1 Calculation diagram of cross-section isobaric material thickness

[0111]

[0112]

[0113] Note: Minimum thickness (C50~C60 not less than 10cm, UHPC not less than 5cm)

[0114] In this embodiment, the specific method of calculating the area of ​​the reinforcement at the thinning portion using the limit bending value M includes a local thinning reinforcement determination method and a local thinning reinforcement calculation method, wherein:

[0115] The method for determining local thinning reinforcement is:

[0116] In order to ensure the coordination and unification of the stress of the reinforced structure and the existing lining, the reinforcement of the structure is carried out according to the "equal bending performance" of the entire ring of the reinforced structure from the most unfavorable stress angle. During the calculation process, the existing tunnel structure is not considered because its contribution to the bending moment of the thinned section and the unthinned section is similar. In the process of determining the thickness, the bending performance of the reinforced structure is calculated based on the unthinned section to determine the ultimate bending value M. On this basis, the above-mentioned bending moment value M is used to calculate the concrete width of the compression zone and the steel bar area of ​​the reinforced structure.

[0117] The calculation method for local thinning reinforcement is:

[0118] When the concrete material of the non-thinning part is conventional concrete such as C35-C60, the calculation formula for the bending performance of the composite structure is as follows:

[0119]

[0120] l1=D l +D r ―C+D gr ―x d

[0121] l2=D l +C+D gr ―x d

[0122] Where: M—total bending moment borne by the composite structure

[0123] x d —Compression area of ​​composite structure

[0124] f cd —Concrete compressive strength corresponding to the grade

[0125] f cd —Tensile strength of steel bars

[0126] —C35 segment lower reinforcement area

[0127] —C35 segment upper reinforcement area

[0128] l1—Tensile moment of the steel bars at the bottom of the C35 segment

[0129] l2—Tensile moment of the upper reinforcement of the C35 segment

[0130] D l —Original lining thickness

[0131] D r —Segment thickness

[0132] D gr - Thickness of grouting material

[0133] C—segment protective layer thickness.

[0134] When the thinning portion 110 is made of UHPC (ultra-high performance concrete) material, in addition to considering the tensile properties of the steel bars, the tensile properties of the UHPC material itself must also be considered. The calculation formula for the composite structure reinforcement is as follows:

[0135]

[0136] l1=D l +D r ―C+D gr ―x d

[0137] l2=D l +C+D gr ―x d

[0138]

[0139] Where: —UHPC segment lower reinforcement area

[0140] —UHPC segment upper reinforcement area

[0141] b—UHPC segment width

[0142] f tk —UHPC tensile strength

[0143] l1—Tensile moment of the steel bars at the bottom of the UHPC segment

[0144] l2—Tensile moment of the upper reinforcement of the UHPC segment

[0145] l3—Tensile moment of UHPC segment cross section

[0146] The meanings of other symbols are the same as above.

[0147] An example of calculation of local thinning reinforcement:

[0148] Take the segment material as C35, the segment width b as 1.2m, and the original lining thickness D l The thickness of the pipe segment is 35cm. r 25cm, grouting material thickness D gr The thickness of the protective layer is 2cm, and the thickness of the protective layer C is 3.5cm. The reinforcement is Ф20@200. The area of ​​the steel bar is 314.2mm 2 .

[0149]

[0150] Calculate x d =5cm, M=758kN / m.

[0151] If the main structure is C35 and the local structure is C60, the thickness of the C60 structure is 15cm according to the previous table, and the thickness of the grouting material is D gr The thickness of the protective layer C is 2.0 cm. Using the above M and formula, the reinforcement value can be obtained.

[0152]

[0153] It can be solved Reinforcement Ф20@150.

[0154] If the main structure is C60, 15cm thick, the grouting material thickness D gr The protective layer thickness C is 1.0 cm. Using the above M and the following formula, the UHPC reinforcement 1560 mm 2 , Reinforcement Ф20@200.

[0155]

[0156] The main function of the transition part is to ensure smooth transition of stress, prevent stress concentration caused by the stiffness difference between ordinary concrete and ultra-high performance concrete (UHPC), and thus improve the durability and bearing capacity of the interface; reduce interface cracking. Gradually thinning the interface can reduce the shear stress and tensile stress peaks and avoid interface cracking or peeling; enhance the interface bonding effect. A reasonable length design of the transition part can improve the bonding performance between ordinary concrete and UHPC and improve the interface bearing capacity; optimize the overall performance of the structure, improve the stress transfer efficiency in the transition area, and make the entire structure more stable and reliable.

[0157] The specific method of designing the size of the transition part by gradually thickening is: making the length of the transition part 3 to 5 times the thickness of the interface.

[0158] For example:

[0159] For the transition area between ordinary concrete and UHPC, the transition length is usually 3 to 5 times the interface thickness (or contact length). For example, if the interface thickness is 10 cm, the transition length is recommended to be 30 cm. By inversely calculating the transition angle, it can be obtained that the transition section angle is between 10 and 30 degrees.

[0160] The interface of the reinforced segment 100 is designed in an uneven manner and specifically includes:

[0161] First: When pouring ultra-high performance concrete (UHPC) first and pouring C60 concrete (NC) later, the production method is:

[0162] During the prefabrication process, a specially treated mold is used to make the UHPC have a protruding keyway at the connection between the UHPC and the NC. There are two types of keyways, one is a partially protruding keyway ( Figure 8 ), the keyway height is 20-30mm, the keyway width is 30-40mm, and the keyway spacing is 50-100mm; the other is a fully raised keyway ( Fig. 9 ) The groove depth is 20-30mm and the groove width is 30-40mm.

[0163] The UHPC is partially extended and embedded into the NC to strengthen the connection between the two different concretes and improve the shear mechanical properties at the interface. In addition to the keyway, the interface between the UHPC and NC also includes steel bar connection (10), interface water washing ( Fig.11 ) and other interface treatment methods to enhance the mechanical properties of the interface. When strengthening the reinforcement, the thickness of the steel bar protection layer is determined according to the requirements of the weaker side of the concrete, that is, C35~C45 is 35mm, C50~C80 is 20mm, and UC120 and above is 10mm; when washing the interface with water, the surface slurry must be completely washed away to expose the steel fibers.

[0164] Second: pour ordinary concrete (NC60) first, then pour ultra-high performance concrete (UHPC)

[0165] Production method:

[0166] During the prefabrication process, a specially treated mold is used to make the NC have a recessed keyway at the connection between UHPC and NC. There are two types of keyways, the same as above. Figure 8 , Fig. 9 The interface strengthening method is the same as above. Fig.10 , Fig.11 , that is, interface keyway + reinforcing steel bar + interface water washing. For the interface water washing of ordinary concrete, the quality requirement is to wash away the surface slurry and expose the concrete aggregate.

[0167] In addition, for the prefabricated segment, in order to ensure the interface connection performance between the segment and the grouting material, the surface of the reinforced segment 100 may be roughened. The specific method is as follows:

[0168] Use a non-chisel belt (such as Fig.13 ) or the grid silicone mold for roughening. It should be noted that the size of the no-chisel tape cannot be too small, the maximum protruding height should not be less than 5mm, the maximum particle spacing should not be greater than 3cm, and the protruding particle cross-section can be triangular, body-shaped, etc., to facilitate demolding. Compared with traditional manual chiseling, it is more beautiful, convenient, and saves labor costs and shortens chiseling time. In addition, the no-chisel tape can be reused, saving production costs and having significant economic advantages. In order to enhance the bonding strength between the pipe segment and the grouting material and ensure the stability of the structure, the effect of the finished pipe segment after treatment can be seen Fig.14 .

[0169] The thin-walled composite reinforcement structure of highway tunnels designed using the above design method shortens the construction period, overcomes the risk of tunnel structure settlement, and ensures the safety of the boundary between the segment structure and the building; in addition, it can improve the on-site applicability of the segment without reducing the bearing force, thereby achieving the purpose of increasing the useful passage space of the tunnel. At the same time, by using concrete with different compressive bearing capacity to form a segment reinforced with a combination of NC-UHPC-NC, the thin-walled composite reinforcement structure of the tunnel can be easily realized.

[0170] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A thin-walled composite reinforcement structure for a highway tunnel, characterized in that: It comprises a plurality of groups of reinforcement segments which are spliced ​​in sequence along the length direction of the tunnel, each group of the reinforcement segments comprises two reinforcement segments, the tops of the two reinforcement segments are mutually connected and staggered left and right, the bottoms of the reinforcement segments are connected to the inner beams of the tunnel, and the reinforcement segments are prefabricated concrete structures; the reinforcement segments comprise a thinning portion and a main body support portion connected to both sides of the thinning portion, the height of the thinning portion from the ground is 4-5 meters, the thickness of the thinning portion is less than the thickness of the main body support portion, the normal compressive bearing performance of the thinning portion is the same as that of the main body support portion, and each of the reinforcement segments is provided with a hole for hoisting, grouting or connection.

2. The thin-walled composite reinforcement structure for a highway tunnel according to claim 1 is characterized in that: The reinforcement segments are divided into wide reinforcement segments and narrow reinforcement segments. The width of the wide reinforcement segments is twice that of the narrow reinforcement segments and is located along the length direction of the tunnel.

3. The thin-walled composite reinforcement structure for a highway tunnel according to claim 1 or 2, characterized in that: The thinning portion includes a middle thin portion and transition portions located on both sides, and the transition portions gradually thicken from the center to both sides.

4. The thin-walled composite reinforcement structure for a highway tunnel according to claim 1 or 2, characterized in that: The inner surface of the thinned portion is provided with reinforcement.

5. The thin-walled composite reinforcement structure for a highway tunnel according to claim 1 is characterized in that: The holes include hoisting holes, grouting holes, anchor holes, bottom support holes, top bolt holes, hand holes, longitudinal quick-insert bolt holes, longitudinal prestressed holes and positioning tenon holes: The lifting holes are arranged on both side surfaces, inner side surface and outer side surface of the reinforced pipe segment. The number of lifting holes on a single side should not be less than 2, and they are symmetrically arranged along the central axis of symmetry where the center of gravity is located. The grouting holes are evenly distributed on the edge or surface of the reinforced pipe segment, the circumferential spacing of the grouting holes is 1.5m to 2m, and the longitudinal spacing of the grouting holes is 0.5m to 1m; The anchor holes are distributed at equal intervals along the joints between the reinforced segments and the original lining, and the diameter of the anchor holes is 30 to 50 mm larger than the diameter of the anchor cables; The bottom support hole is arranged at the bottom of the reinforced segment and is used for connecting with the ground beam; The top bolt holes are arranged along the middle of the thickness direction of the reinforced segment, and the hole size is equal to or less than 1 / 4 of the segment thickness; The hand hole is arranged on the reinforced segment, and the width of the hand hole along the tunnel circumferential direction is greater than or equal to 15 cm, and the width of the hand hole along the tunnel longitudinal direction is greater than or equal to 15 cm; The single distance between the longitudinal quick-insert bolt holes is 4 to 6 m; The longitudinal prestressed holes are symmetrically arranged on both sides of the longitudinal quick-insertion bolt holes and are 20 to 40 cm away from the quick-insertion bolt holes; The positioning tenon holes are provided with two positioning tenon holes on the longitudinal side of each of the reinforced pipe segments.

6. A design method for a thin-walled composite reinforcement structure of a highway tunnel, used for designing a thin-walled composite reinforcement structure of a highway tunnel as claimed in claim 4, characterized in that: include: According to the concrete structural performance of the thinning portion and the main body support portion connected to both sides of the thinning portion, the thickness of the thinning portion and the main body support portion is determined by using the isostatic strength method; The area of ​​reinforcement at the thinning part is calculated using the ultimate bending resistance value M; The size of the transition part is designed by gradually thickening; The interface of the reinforced segment is designed in an uneven manner; Design the corresponding hole positions and sizes according to the length and width of the tunnel, the casting method of the reinforcement segments, and the installation method of the reinforcement segments; By assembling, multiple groups of reinforced segments are connected in sequence along the length direction of the tunnel. Each group of reinforced segments includes two reinforced segments. The tops of the two reinforced segments are connected to each other and arranged staggered left and right, and the tops of the two reinforced segments are connected to each other.

7. The design method of the thin-walled composite reinforcement structure of a highway tunnel according to claim 5 is characterized in that: The specific method for determining the local thinning thickness using the isobaric strength method is as follows: According to the isobaric strength method, the compressive bearing performance of the thinned part is consistent with that of the non-thinned part. The calculation formula for the thinned part is: —Compressive strength of the first type of concrete d1—thickness corresponding to the first type of concrete —Compressive strength of the second concrete d2—Thickness corresponding to the second type of concrete.

8. The design method of the thin-walled composite reinforcement structure of a highway tunnel according to claim 5 is characterized in that: The specific method for calculating the area of ​​reinforcement at the local thinning location using the ultimate bending resistance value M is: The reinforcement structure is reinforced according to the "equal bending performance" of the entire ring of the reinforced structure. During the calculation process, the existing tunnel structure is not considered because its contribution to the bending moment of the thinned section and the unthinned section is similar. During the thickness determination process, the bending performance of the reinforced structure is calculated for the unthinned section to determine the ultimate bending value M. On this basis, the above-mentioned bending moment value M is used to calculate the concrete width of the compression zone and the steel bar area of ​​the reinforced structure.

9. The design method of the thin-walled composite reinforcement structure of a highway tunnel according to claim 5 is characterized in that: The specific method of designing the size of the transition part by gradually thickening is: making the length of the transition part 3 to 5 times the thickness of the interface.

10. The design method of the thin-walled composite reinforcement structure of a highway tunnel according to claim 5 is characterized in that: The method also includes roughening the surface of the reinforced pipe segment.

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