A multi-stage seismic isolation structure for a tunnel crossing an active fault zone

Abstract

The present invention provides a multi-stage seismic isolation structure for a tunnel crossing an active fault zone. A portal seismic isolation structure and a tunnel body fracture zone seismic isolation structure are sequentially arranged in the tunnel longitudinal direction. The portal seismic isolation structure and the tunnel body fracture zone seismic isolation structure each include multiple sub-structures. Each sub-structure adopts a multi-stage seismic isolation layer design on the tunnel cross section. The portal seismic isolation structure includes a portal extension sub-structure, a portal shallow buried sub-structure, and a portal impact sub-structure. The tunnel body fracture zone seismic isolation structure includes a tunnel body impact sub-structure, a tunnel body transition sub-structure, and a tunnel body core sub-structure. Based on seismic isolation and shock absorption design concepts such as over-excavation design, articulated design, and isolation and energy dissipation design, the present invention implements a multi-stage seismic isolation structure design for the tunnel portal and the tunnel body passing through the fault fracture zone, which can effectively prevent the impact of earthquakes on the tunnel.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel design, in particular to a multi-stage seismic isolation structure of a tunnel passing through an active fault zone. Background Art

[0002] The hazard modes of tunnels caused by active fault zones can be categorized as direct damage to the tunnel structure due to fault movement, vibration damage to the tunnel caused by earthquakes, and a chain of earthquake-induced geological hazards. Fault movement directly causes shear displacement of the surrounding rock, which is usually confined to a narrow range around the active fault. However, the damage to the tunnel caused by this sudden displacement is catastrophic and difficult for the structure to withstand, resulting in the destruction of the main tunnel structure. Seismic waves cause the tunnel lining to vibrate or oscillate violently, generating cyclical alternations of compressive and tensile strains that are superimposed on the existing strain of the tunnel lining. When the superimposed strain exceeds the ultimate strain that the tunnel lining can withstand, the tunnel structure fails, which is known as tunnel seismic damage. The coupling of external forces such as earthquakes, groundwater, and high ground temperatures can also trigger a series of geological hazard chains in shallow and deep tunnel sections within active fault zones.

[0003] Currently, tunnel designs crossing active faults are primarily based on avoidance, maintaining a specified avoidance distance. When such a route cannot be avoided and must pass through, guidelines and recommendations are often provided, such as passing through narrow sections of the fault zone at a steep angle. Existing engineering cases and literature on tunnels crossing active faults indicate that the seismic design approach for underground tunnels (holes) is traditionally based on "hard-core" earthquake resistance, involving increased structural cross-sections, higher concrete grades to enhance strength and rigidity, increased thickness, and higher reinforcement ratios.

[0004] In response to the problems of the prior art, the present invention provides a multi-stage seismic isolation structure for a tunnel passing through an active fault zone. Summary of the Invention

[0005] To solve the problems in the prior art, the present invention provides a multi-stage seismic isolation structure for a tunnel crossing an active fault zone. A portal seismic isolation structure and a tunnel body fracture zone seismic isolation structure are sequentially arranged in the tunnel longitudinal direction. The portal seismic isolation structure and the tunnel body fracture zone seismic isolation structure each comprise multiple sub-structures, and each sub-structure adopts a multi-stage seismic isolation layer design on the tunnel cross section, wherein:

[0006] The opening seismic isolation structure includes an opening extension section structure, a opening shallow buried section structure, and an opening influence section structure, wherein the opening extension section structure and the opening shallow buried section structure are based on steel corrugated plate lining, and the steel corrugated plates are longitudinally connected by flexible connectors, and the opening shallow buried section structure and the opening influence section structure include a seismic isolation layer;

[0007] The seismic isolation structure of the tunnel body fracture zone includes a tunnel body influence section structure, a tunnel body transition section structure, and a tunnel body core section structure, wherein the tunnel body influence section structure, the tunnel body transition section structure, and the tunnel body core section structure include a seismic isolation layer, and the tunnel body transition section structure and the tunnel body core section structure are based on steel corrugated plate lining and are designed for expansion. The steel corrugated plates are connected longitudinally with flexible connectors.

[0008] According to one embodiment of the present invention, the portal extension substructure adopts a steel corrugated plate lining and a buffer layer to prevent the collapse and rockfall of the tunnel slope caused by earthquakes.

[0009] According to one embodiment of the present invention, the structure of the shallow buried section of the tunnel entrance adopts advanced surrounding rock grouting and additional anchor rods to reinforce the surrounding rock, steel arch frames and high-toughness shotcrete are used as initial support layers, convex shell drainage boards and foam concrete are used as seismic isolation layers, steel corrugated plate lining is used as secondary lining layers, and flexible connectors are used for longitudinal connection to solve the seismic boundary amplification effect of the shallow buried section of the tunnel entrance.

[0010] According to one embodiment of the present invention, anchor rods are added to the structure of the section affecting the tunnel entrance to reinforce the surrounding rock, steel arch frames and high-toughness shotcrete are used as the initial support layer, convex shell-type drainage boards are used as the seismic isolation layer, reinforced concrete is used as the secondary lining layer, and wide deformation joints are set longitudinally to facilitate transition and connection with the lining of the ordinary section of the tunnel body.

[0011] According to one embodiment of the present invention, anchor rods are added to the affected section structure of the tunnel body to reinforce the surrounding rock, steel arch frames and high-toughness shotcrete are used as the initial support layer, convex shell drainage boards are used as the seismic isolation layer, reinforced concrete is used as the secondary lining layer, and wide deformation joints are set in the longitudinal direction.

[0012] According to one embodiment of the present invention, the tunnel transition section substructure is designed for expansion, and surrounding rock grouting is adopted and anchor rods are added to reinforce the surrounding rock. Steel arch frames and high-toughness shotcrete are used as the initial support layer, convex shell drainage boards and foam concrete are used as the seismic isolation layer, steel corrugated plate lining is used as the secondary lining layer, and flexible connectors are used for longitudinal connections to reduce the vibration damage to the tunnel structure caused by earthquakes.

[0013] According to one embodiment of the present invention, the core section structure of the tunnel body is designed for expansion, and advanced surrounding rock grouting is adopted and anchor rods are added to reinforce the surrounding rock. Steel arch frames and high-toughness shotcrete are used as initial support layers, convex shell drainage boards and foam concrete are used as seismic isolation layers, steel corrugated plate lining is used as secondary lining layer, and flexible connectors are used for longitudinal connections to reduce vibration damage to the tunnel structure caused by earthquakes.

[0014] According to one embodiment of the present invention, the stiffness and thickness of the seismic isolation layer are determined with the goal of isolating earthquakes and waterproofing, the thickness of the steel corrugated plate lining is determined with the goal of stiffness and stability, and the length and stiffness of the flexible connector are determined with the amount of fault displacement and the predicted seismic intensity.

[0015] According to another aspect of the present invention, a method for designing a multi-stage seismic isolation structure for a tunnel crossing an active fault zone is also provided. The method is used to design a multi-stage seismic isolation structure for a tunnel as described in any of the above items, and sequentially arranges a portal seismic isolation structure and a tunnel body fracture zone seismic isolation structure in the longitudinal direction of the tunnel. The portal seismic isolation structure and the tunnel body fracture zone seismic isolation structure each include multiple substructures, and each substructure adopts a multi-stage seismic isolation layer design on the tunnel cross section. The method comprises the following steps:

[0016] For the portal seismic isolation structure, a portal extension substructure, a portal shallow buried substructure, and a portal influencing substructure are provided, wherein the portal extension substructure and the portal shallow buried substructure are based on steel corrugated plate lining, and the steel corrugated plates are longitudinally connected by flexible connectors, and the portal shallow buried substructure and the portal influencing substructure include a seismic isolation layer;

[0017] For the seismic isolation structure of the broken zone of the tunnel body, the tunnel body influence section structure, the tunnel body transition section structure and the tunnel body core section structure are set up, wherein the tunnel body influence section structure, the tunnel body transition section structure and the tunnel body core section structure contain seismic isolation layers, the tunnel body transition section structure and the tunnel body core section structure are based on steel corrugated plate lining, and are designed for expansion, and the steel corrugated plates are connected longitudinally with flexible connectors.

[0018] According to another aspect of the present invention, a storage medium is provided, which contains a series of instructions for executing the method steps described above.

[0019] The present invention provides a multi-stage seismic isolation structure for a tunnel crossing an active fault zone. Based on seismic isolation and shock absorption design concepts such as over-excavation design, articulated design, and isolated energy dissipation design, the tunnel portal and the tunnel body passing through the fault fracture zone are designed with multi-segment / stage seismic isolation structures in the longitudinal and transverse sections of the tunnel, which can effectively prevent the impact of earthquakes on the tunnel. The steel corrugated plate lining structure adopted in the present invention has strong deformation adaptability and good overall stability. It has unique advantages in maintainability and durability. In addition, compared with reinforced concrete lining, the steel corrugated plate lining structure can reduce longitudinal and circumferential cracks. The present invention adopts steel corrugated plate lining to provide tunnel seismic resistance. Under the conditions of meeting the engineering indicators of surrounding rock pressure and seismic response deformation, it has a certain toughness, which can dissipate the energy generated by the earthquake in the structure and reduce the structural response of the earthquake.

[0020] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purposes and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0022] Figure 1 A diagram showing a multi-stage seismic isolation structure system for a tunnel crossing an active fault zone according to one embodiment of the present invention is shown;

[0023] Figure 2 A cross-sectional view of a hole seismic isolation structure according to an embodiment of the present invention is shown;

[0024] Figure 3 A cross-sectional view of a seismic isolation structure in a broken zone of a tunnel according to an embodiment of the present invention is shown;

[0025] Figure 4 A cross-section of a tunnel lined with corrugated steel sheets according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0026] To make the objectives, technical solutions and advantages of the present invention more clear, embodiments of the present invention are described in further detail below with reference to the accompanying drawings.

[0027] Figure 1 A diagram of a multi-stage seismic isolation structure system of a tunnel crossing an active fault zone according to an embodiment of the present invention is shown.

[0028] The portal seismic isolation structure and the broken zone seismic isolation structure of the tunnel body are successively arranged in the longitudinal direction of the tunnel. The portal seismic isolation structure and the broken zone seismic isolation structure of the tunnel body respectively include multiple sub-structures. Each sub-structure adopts a multi-level seismic isolation layer design on the cross section of the tunnel to realize a three-dimensional multi-dimensional seismic isolation system in the longitudinal direction and cross section of the tunnel.

[0029] like Figure 1 As shown, the portal seismic isolation structure includes a portal extension section structure, a portal shallow buried section structure, and a portal influencing section structure. The portal extension section structure and the portal shallow buried section structure are based on steel corrugated plate lining, and the steel corrugated plates are longitudinally connected by flexible connectors. The portal shallow buried section structure and the portal influencing section structure include seismic isolation layers.

[0030] In one embodiment, the portal extension substructure is constructed with corrugated steel plate lining, a buffer layer, and foamed concrete to prevent earthquake-induced collapse and rockfall on the tunnel slope. Flexible connectors are used to connect the corrugated steel plate linings.

[0031] In one embodiment, the substructure of the shallow buried section of the tunnel entrance includes a surrounding rock reinforcement layer, an initial support layer, a seismic isolation layer and a secondary lining layer, wherein advanced surrounding rock grouting and additional anchor rods are used to reinforce the surrounding rock, steel arch frames and high-toughness shotcrete (high-toughness shotcrete) are used as the initial support layer, convex shell drainage boards and foam concrete are used as seismic isolation layers, and steel corrugated plate lining is used as the secondary lining layer. Flexible connectors are used for longitudinal connection to solve the seismic boundary amplification effect of the shallow buried section of the tunnel entrance.

[0032] In one embodiment, the structure of the tunnel entrance influencing section includes a surrounding rock reinforcement layer, an initial support layer, a seismic isolation layer and a secondary lining layer, wherein a system anchor rod is added to reinforce the surrounding rock, a steel arch frame and high-toughness shotcrete are used as the initial support layer, a convex shell type drainage board is used as the seismic isolation layer, reinforced concrete is used as the secondary lining layer, and a wide deformation joint is set longitudinally to facilitate transition and connection with the ordinary section lining of the tunnel body.

[0033] like Figure 1 As shown, the seismic isolation structure of the tunnel body fracture zone includes the tunnel body influence section structure, the tunnel body transition section structure, and the tunnel body core section structure. Among them, the tunnel body influence section structure, the tunnel body transition section structure, and the tunnel body core section structure include seismic isolation layers. The tunnel body transition section structure and the tunnel body core section structure are based on steel corrugated plate lining and are designed for expansion. The steel corrugated plates are connected longitudinally with flexible connectors.

[0034] In one embodiment, the structure of the tunnel body affected section includes a surrounding rock reinforcement layer, an initial support layer, a seismic isolation layer and a secondary lining layer, wherein a system anchor rod is added to reinforce the surrounding rock, a steel arch frame and high-toughness shotcrete are used as the initial support layer, a convex shell type drainage board is used as the seismic isolation layer, reinforced concrete is used as the secondary lining layer, and a wide deformation joint is set in the longitudinal direction.

[0035] In one embodiment, the tunnel transition section substructure is excavated and designed to include a surrounding rock reinforcement layer, an initial support layer, a seismic isolation layer, and a secondary lining layer. Surrounding rock grouting is used and anchor rods are added to reinforce the surrounding rock. Steel arches and high-toughness shotcrete are used as the initial support layer. Convex shell drainage boards and foam concrete are used as seismic isolation layers. Steel corrugated plate lining is used as the secondary lining layer. Flexible connectors are used for longitudinal connections to reduce vibration damage to the tunnel structure caused by earthquakes.

[0036] In one embodiment, the core section structure of the tunnel body is expanded and designed, including a surrounding rock reinforcement layer, an initial support layer, a seismic isolation layer and a secondary lining layer. Among them, advanced surrounding rock grouting is used and anchor rods are added to reinforce the surrounding rock. Steel arch frames and high-toughness shotcrete are used as the initial support layer. Convex shell drainage boards and foam concrete are used as seismic isolation layers. Steel corrugated plate lining is used as the secondary lining layer. Flexible connectors are used for longitudinal connections to reduce the vibration damage to the tunnel structure caused by earthquakes.

[0037] The present invention utilizes corrugated steel plate lining as a secondary lining layer in the portal extension substructure, the shallow portal substructure, the tunnel transition substructure, and the tunnel core substructure. Compared to existing reinforced concrete linings and steel structure linings, the corrugated steel plate lining structure can reduce longitudinal and circumferential cracks. While meeting engineering specifications for surrounding rock pressure and seismic response deformation, it exhibits a certain degree of toughness, allowing earthquake energy to be dissipated structurally, reducing seismic structural response. Furthermore, compared to the tunnel impact substructure, the tunnel transition substructure and the tunnel core substructure not only expand the tunnel cross-section to increase reserved space, but also incorporate surrounding rock grouting / advanced surrounding rock grouting to improve the surrounding rock's seismic resistance.

[0038] Figure 2 FIG1 shows a cross-sectional view of a hole seismic isolation structure according to an embodiment of the present invention. Figure 2 As shown, section 1-1 is located in the portal extension substructure, comprising a seismic isolation layer, foam concrete, and a steel corrugated plate lining, connected to the steel corrugated plate lining via flexible connectors (flexible joints). Section 2-2 is located in the shallow-buried portal substructure, comprising advanced anchor pipe grouting, a steel arch frame, high-toughness shotcrete, a convex shell drainage board, foam concrete, a steel corrugated plate lining, and flexible connectors. Section 3-3 is located in the portal impact substructure, comprising system anchors, a steel arch frame, high-toughness shotcrete, a convex shell drainage board, reinforced concrete, and wide expansion joints.

[0039] Figure 3 The cross-section of the tunnel body fracture zone seismic isolation structure according to one embodiment of the present invention is shown. In the part where the tunnel body passes through the fault fracture zone, the tunnel body fracture zone seismic isolation structure is adopted, such as Figure 3 As shown, section 1-1 is located in the tunnel's impact section and includes system anchors, steel arches, high-toughness shotcrete, convex shell drainage panels, reinforced concrete, and wide expansion joints. Section 2-2 is located in the tunnel's core section and includes advanced anchor pipe grouting, steel arches, high-toughness shotcrete, convex shell drainage panels, foam concrete, corrugated steel sheet lining, and flexible connectors.

[0040] In one embodiment, the present invention adopts an over-excavation design concept and adopts an expanded excavation design in the tunnel transition section structure and the tunnel core section structure. The over-excavation design increases the cross-sectional size and fills the space between the inner and outer linings with porous materials or does not fill it. This is conducive to the rapid repair of the tunnel structure after a certain period of use or after an earthquake. However, the expanded excavation cross-sectional size requires further research because the dislocation mode and amount of dislocation of active faults may not be accurate and reliable. Furthermore, the tunnel expanded excavation cross-sectional size needs to be determined comprehensively based on the earthquake intensity and the fault displacement, which is conducive to rapid post-disaster repair.

[0041] In one embodiment, the present invention is based on the concept of hinged design, and flexible connectors are used to connect the steel corrugated plate linings. The hinged design minimizes the length of the tunnel segments so that the fault zone and the segments within a certain range on both sides remain relatively independent. Flexible connections with relatively low stiffness are used between each rigid tunnel segment. The length of the mid-segment and the shear stiffness of the flexible connection require further research. Furthermore, the length and stiffness of the flexible connector are determined based on the amount of fault displacement and the predicted intensity of the earthquake motion, and the flexible connector is installed between the steel corrugated plate linings. The use of flexible connectors between the steel corrugated plate linings concentrates the damage caused by disasters such as earthquakes on the connection parts, which can reduce damage to the tunnel itself.

[0042] In one embodiment, the present invention utilizes isolation and energy dissipation design as its principle, installing seismic isolation layers within the shallow entrance substructure, the entrance impact substructure, the tunnel body impact substructure, the tunnel body transition substructure, and the tunnel body core substructure. This isolation and energy dissipation design employs single structures for seismic isolation or vibration reduction, such as polymer isolation layers, silicone isolation materials, and rubber sand isolation layers. These layers have demonstrated excellent results and are suitable for seismic isolation and vibration reduction designs in tunnels located within active fault zones. Furthermore, the stiffness and thickness of the seismic isolation layers are calculated with the goal of seismic isolation and waterproofing.

[0043] In one embodiment, the present invention employs corrugated steel lining in the tunnel entrance extension substructure, the shallow buried tunnel entrance substructure, the tunnel transition substructure, and the tunnel core substructure. Corrugated steel linings are easy to install and replace, and the greater the thickness, the greater the rigidity and stability. Furthermore, the thickness of the corrugated steel lining is calculated with rigidity and stability as the goals.

[0044] In one embodiment, the present invention utilizes high-toughness shotcrete in the shallow-buried portal substructure, the portal-affecting substructure, the tunnel-body-affecting substructure, the tunnel-body transition substructure, and the tunnel-body core substructure. The stiffness and thickness of the high-toughness shotcrete need to be determined. Furthermore, based on the formation of active fault zones traversed by railway tunnels in specific regions, the stiffness and thickness of the high-toughness shotcrete need to be determined by considering conditions such as left-lateral and right-lateral strike-slip, left-lateral strike-slip with normal faulting, left-lateral strike-slip with reverse faulting, and left-lateral strike-slip on reverse faults.

[0045] In one embodiment, wide expansion joints are installed in both the tunnel entrance and tunnel body sections, and their waterproofing performance must also be considered. Furthermore, the waterstops at these wide expansion joints are a key waterproofing consideration, not only for ease of construction and installation but also for tunnel displacement and durability during operation.

[0046] In addition, the present invention provides a method for designing a multi-stage seismic isolation structure for a tunnel crossing an active fault zone, wherein a tunnel entrance seismic isolation structure and a tunnel body crushing zone seismic isolation structure are sequentially arranged in the longitudinal direction of the tunnel, wherein the tunnel entrance seismic isolation structure and the tunnel body crushing zone seismic isolation structure respectively include multiple sub-structures, and each sub-structure adopts a multi-stage seismic isolation layer design on the tunnel cross section, comprising the following steps: for the tunnel entrance seismic isolation structure, a tunnel entrance extension sub-structure, a tunnel entrance shallow buried sub-structure, and a tunnel entrance influence sub-structure are arranged, wherein the tunnel entrance extension sub-structure and the tunnel entrance shallow buried sub-structure are steel corrugated The corrugated plate lining is the basis, and the steel corrugated plates are connected longitudinally with flexible connectors. The shallow buried section structure of the tunnel entrance and the tunnel entrance influencing section structure include a seismic isolation layer. For the seismic isolation structure of the broken zone of the tunnel body, the tunnel body influencing section structure, the tunnel body transition section structure, and the tunnel body core section structure are set. Among them, the tunnel body influencing section structure, the tunnel body transition section structure, and the tunnel body core section structure include a seismic isolation layer. The tunnel body transition section structure and the tunnel body core section structure are based on the steel corrugated plate lining and are designed for expansion. The steel corrugated plates are connected longitudinally with flexible connectors.

[0047] The multi-stage seismic isolation structure for a tunnel crossing an active fault zone provided by the present invention may also be used in conjunction with a computer-readable storage medium having a computer program stored thereon. The computer program is executed to implement a method for designing a multi-stage seismic isolation structure for a tunnel crossing an active fault zone. The computer program is capable of executing computer instructions, which include computer program code. The computer program code may be in source code form, object code form, executable file, or some intermediate form.

[0048] Computer-readable storage media may include: any entity or device that can carry computer program code, recording media, USB flash drives, mobile hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc.

[0049] It should be noted that the content contained in computer-readable storage media can be appropriately increased or decreased according to the requirements of legislation and patent practices in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practices, computer-readable storage media do not include electrical carrier signals and telecommunications signals.

[0050] In summary, the present invention provides a multi-stage seismic isolation structure for a tunnel crossing an active fault zone. Based on seismic isolation and shock absorption design concepts such as over-excavation design, articulated design, and isolated energy dissipation design, the tunnel portal and the tunnel body passing through the fault fracture zone are designed with multi-segment / stage seismic isolation structures in the longitudinal and transverse sections, which can effectively prevent the impact of earthquakes on the tunnel. The steel corrugated plate lining structure adopted in the present invention has strong deformation adaptability and good overall stability. It has unique advantages in maintainability and durability. In addition, compared with reinforced concrete lining, the steel corrugated plate lining structure can reduce longitudinal and circumferential cracks. The present invention adopts steel corrugated plate lining to provide tunnel seismic resistance. Under the conditions of meeting the engineering indicators of surrounding rock pressure and seismic response deformation, it has a certain toughness, which can dissipate the energy generated by the earthquake in the structure and reduce the structural response of the earthquake.

[0051] It should be understood that the embodiments disclosed herein are not limited to the specific structures, processing steps, or materials disclosed herein, but should extend to equivalent substitutions of these features understood by those skilled in the relevant art. It should also be understood that the terminology used herein is for the purpose of describing specific embodiments only and is not intended to be limiting.

[0052] In the description of the present invention, unless otherwise specified, "plurality" means two or more; terms such as "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," and "tail" indicate positions or relationships based on those shown in the accompanying drawings. These terms are intended solely to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present invention. Furthermore, terms such as "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0053] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integral connection; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0054] References in this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Therefore, appearances of the phrases "one embodiment" or "an embodiment" in various places throughout this specification do not necessarily refer to the same embodiment.

[0055] The embodiments of the present invention are presented for purposes of illustration and description and are not intended to be exhaustive or to limit the invention to the disclosed forms. Many modifications and variations will be apparent to those skilled in the art. The embodiments are chosen and described in order to better illustrate the principles of the invention and its practical application and to enable those skilled in the art to understand the invention and design various embodiments with various modifications as suited for specific applications.

[0056] Although the embodiments disclosed herein are as described above, the contents described herein are merely embodiments for facilitating understanding of the present invention and are not intended to limit the present invention. Any person skilled in the art of the present invention may make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed herein. However, the scope of patent protection of the present invention shall still be subject to the scope defined by the appended claims.

Claims

1. A multi-stage seismic isolation structure for a tunnel crossing an active fault zone, characterized in that: The tunnel entrance seismic isolation structure and the tunnel body crushing zone seismic isolation structure are sequentially arranged in the longitudinal direction of the tunnel. The tunnel entrance seismic isolation structure and the tunnel body crushing zone seismic isolation structure respectively include multiple sub-structures. Each sub-structure adopts a multi-level seismic isolation layer design on the tunnel cross section, wherein: The opening seismic isolation structure includes an opening extension section structure, a opening shallow buried section structure, and an opening influence section structure, wherein the opening extension section structure and the opening shallow buried section structure are based on steel corrugated plate lining, and the steel corrugated plates are longitudinally connected by flexible connectors, and the opening shallow buried section structure and the opening influence section structure include a seismic isolation layer; The tunnel body fracture zone seismic isolation structure includes a tunnel body influence section structure, a tunnel body transition section structure, and a tunnel body core section structure, wherein the tunnel body influence section structure, the tunnel body transition section structure, and the tunnel body core section structure include a seismic isolation layer, and the tunnel body transition section structure and the tunnel body core section structure are based on steel corrugated plate lining and are designed for expansion, and the steel corrugated plates are connected longitudinally with flexible connectors; The tunnel extension section substructure adopts steel corrugated plate lining and buffer layer to prevent the tunnel slope collapse and rockfall caused by earthquakes; The shallow buried section of the tunnel entrance adopts advanced surrounding rock grouting and additional anchor rods to reinforce the surrounding rock. Steel arches and high-toughness shotcrete are used as the initial support layer. Convex shell drainage board and foam concrete are used as the seismic isolation layer. Steel corrugated plate lining is used as the secondary lining layer. Flexible connectors are used for longitudinal connection to solve the earthquake boundary amplification effect in the shallow buried section of the tunnel entrance. The substructure of the tunnel entrance is reinforced with anchor rods to reinforce the surrounding rock, with steel arches and high-toughness shotcrete used as the initial support layer, convex shell drainage panels as the seismic isolation layer, reinforced concrete as the secondary lining layer, and wide longitudinal expansion joints set to facilitate transitional connection with the ordinary tunnel lining. The tunnel body is reinforced with anchor rods to reinforce the surrounding rock in the affected section, with steel arches and high-toughness shotcrete used as the initial support layer, convex shell drainage panels as the seismic isolation layer, reinforced concrete as the secondary lining layer, and wide deformation joints set in the longitudinal direction; The tunnel transition section substructure is designed for expansion, with surrounding rock grouting and additional anchor bolts used to reinforce the surrounding rock. Steel arches and high-toughness shotcrete are used as the primary support layer, convex shell drainage panels and foam concrete are used as the seismic isolation layer, and steel corrugated plate lining is used as the secondary lining layer. Flexible connectors are used for longitudinal connections to reduce vibration damage to the tunnel structure caused by earthquakes. The core section structure of the tunnel body is designed for expansion, and advanced surrounding rock grouting is adopted and anchor rods are added to reinforce the surrounding rock. Steel arch frames and high-toughness shotcrete are used as the initial support layer, convex shell drainage boards and foam concrete are used as the seismic isolation layer, steel corrugated plate lining is used as the secondary lining layer, and flexible connectors are used for longitudinal connections to reduce the vibration damage to the tunnel structure caused by earthquakes.

2. The multi-stage seismic isolation structure for a tunnel crossing an active fault zone according to claim 1, characterized in that: The stiffness and thickness of the seismic isolation layer are determined with the goal of isolating earthquakes and waterproofing; the thickness of the steel corrugated plate lining is determined with the goal of stiffness and stability; the length and stiffness of the flexible connector are determined based on the fault displacement and predicted earthquake motion intensity.

3. A design method for a multi-stage seismic isolation structure of a tunnel crossing an active fault zone, characterized in that: The method is used to design a multi-stage seismic isolation structure for a tunnel according to any one of claims 1 to 2, wherein a portal seismic isolation structure and a tunnel body crushing zone seismic isolation structure are sequentially arranged in the longitudinal direction of the tunnel, wherein the portal seismic isolation structure and the tunnel body crushing zone seismic isolation structure each include multiple substructures, and each substructure adopts a multi-stage seismic isolation layer design on the tunnel cross section. The method comprises the following steps: For the portal seismic isolation structure, a portal extension substructure, a portal shallow buried substructure, and a portal influencing substructure are provided, wherein the portal extension substructure and the portal shallow buried substructure are based on steel corrugated plate lining, and the steel corrugated plates are longitudinally connected by flexible connectors, and the portal shallow buried substructure and the portal influencing substructure include a seismic isolation layer; For the seismic isolation structure of the broken zone of the tunnel body, the tunnel body influence section structure, the tunnel body transition section structure and the tunnel body core section structure are set up, wherein the tunnel body influence section structure, the tunnel body transition section structure and the tunnel body core section structure contain seismic isolation layers, the tunnel body transition section structure and the tunnel body core section structure are based on steel corrugated plate lining, and are designed for expansion, and the steel corrugated plates are connected longitudinally with flexible connectors.

4. A storage medium, characterized in that It contains a series of instructions for executing the method steps as claimed in claim 3.

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