A rectangular cross-section tunnel supporting structure and a supporting method capable of realizing synchronous push-piling

Abstract

The application discloses a rectangular cross-section tunnel supporting structure and a supporting method, wherein a hydraulic cylinder assembly is fixedly connected to an extensible supporting body, a hydraulic control system is used for controlling the piston rod movement of the hydraulic cylinder assembly; the piston rod is fixedly connected to the supporting body, and the end of the piston rod is in contact with one side of a shield head; a hinge fixing device is used for fixing the unfolded supporting body; the supporting body is composed of multiple arch structure units which are sequentially connected along the tunnel axis, and the front end is close to the tunnel face; each arch structure unit comprises mutually parallel and coaxial outermost planes, middle layer planes and innermost planes which are sequentially arranged, and the outermost planes are located at the front end; for the two adjacent arch structure units, the innermost plane at the front end simultaneously serves as the outermost plane at the rear end. The application realizes synchronous pushing and splicing, and has high automatic splicing degree.

Description

Technical Field

[0001] This invention relates to the field of tunnel support, and in particular to a rectangular cross-section tunnel support structure and support method that enables simultaneous assembly and disassembly. Background Technology

[0002] The complex and variable geological conditions traversing urban and intercity transportation tunnels place higher demands on construction safety and efficiency. In particular, the timely and stable formation of tunnel support structures during tunnel excavation plays a crucial role in improving construction safety and efficiency. Current segment construction systems still require manual segment identification, gripping, positioning, assembly, and bolting, making automated assembly difficult. While CRCC Heavy Industry has proposed an automatic segment identification and gripping method, which mechanizes the gripping and positioning of segments, the assembly process still requires multiple workers. Bouygues of France designed the Atlas automatic segment assembly machine, using industrial robots for pin positioning and connection; however, its system is overly complex and space-consuming, unsuitable for mechanized construction in confined underground spaces. Therefore, there is an urgent need to develop new tunnel support structures with features such as simultaneous pushing and assembling and timely support. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention proposes a rectangular cross-section tunnel support structure and support method that enables simultaneous assembly and disassembly.

[0004] The specific technical solution is as follows:

[0005] A rectangular cross-section tunnel support structure capable of synchronous excavation and assembly includes: a support body, a hydraulic cylinder assembly, a hydraulic control system, a hinge fixing device, and a shield head; the support body is telescopic, the hydraulic cylinder assembly is fixedly connected to the support body, and the hydraulic control system is used to control the movement of the piston rod of the hydraulic cylinder assembly; the piston rod is fixedly connected to the support body, and its end contacts one side of the shield head, the other side of the shield head faces the tunnel face, and is used for excavation; the hinge fixing device is used to fix the support body when it is extended to its limit;

[0006] The support structure is composed of multiple arch frame structural units connected sequentially along the tunnel axis, with the arch frame structural unit closest to the tunnel face being the front end; each arch frame structural unit includes an outermost plane, an intermediate layer plane, and an innermost plane arranged in parallel and coaxial order, with the outermost plane close to the tunnel face; for two adjacent arch frame structural units, the innermost plane of the front arch frame structural unit also serves as the outermost plane of the rear arch frame structural unit.

[0007] The outermost plane, the middle layer plane, and the innermost plane each include four support rods and four composite ball hinges. Each support rod's two ends are respectively rolled to two composite ball hinges. The four support rods and composite ball hinges form a closed rectangle. The outermost plane and the innermost plane have identical structures. The length of the horizontal support rod along the central axis of the middle layer plane is the same as the length of the vertical support rod along the central axis of the outermost plane, and the length of the vertical support rod along the central axis of the middle layer plane is the same as the length of the horizontal support rod along the central axis of the outermost plane. The positions of the composite ball hinges on the outermost plane and the middle layer plane correspond one-to-one and are rolled to each other via the support rods. The positions of the composite ball hinges on the middle layer plane and the innermost plane also correspond one-to-one and are rolled to each other via the support rods.

[0008] Furthermore, the hydraulic cylinder assembly includes: a hydraulic cylinder, a fixed plate, a piston rod, a threaded rod, and a nut; the hydraulic cylinder is fixedly connected to a support rod horizontally aligned with the center axis of the outermost plane of the foremost arch frame structural unit in its fully deployed state via the fixed plate; the threaded rod is fixedly connected to two opposing support rods in the outermost plane of the arch frame structural unit closest to the tunnel face via the nut; one end of the piston rod is installed inside the hydraulic cylinder, and the other end passes through the threaded rod and is fixedly connected to it, with its end contacting the shield head.

[0009] Furthermore, the bottom of the fixing plate is fixedly connected to the hydraulic cylinder, and the top is designed with an opening and closing structure, which is detachably connected to the support rod by a nut; the opening and closing structure of the fixing plate is provided with a through hole, the diameter of which is adapted to the support rod.

[0010] Furthermore, the hydraulic control system includes an oil tank and multiple control units. Each control unit includes a three-position four-way directional valve and two hydraulic locks. The three-position four-way directional valve includes a pressure port P, a return port T, an output port A, and an output port B. Output port A is connected to the rodless chamber of the hydraulic cylinder via a hydraulic lock, and output port B is connected to the rod chamber of the hydraulic cylinder via a hydraulic lock. The oil tank is connected to the pressure port P of the three-position four-way directional valve of each control unit, simultaneously supplying pressurized oil to multiple hydraulic cylinders. The three-position four-way directional valve controls the direction of oil flow by changing the relative position between the valve core and the valve body, connecting or closing the oil circuit, thereby changing the working state of the hydraulic cylinder. The hydraulic lock is used to fix the oil pressure difference between the two chambers of the hydraulic cylinder, thereby fixing the position of the piston rod.

[0011] Furthermore, the support rod includes a middle support rod section and hemispheres fixed to both ends of the support rod section; the support rod is manufactured as a single piece, or the support rod section and the hemispheres are manufactured separately and then fixed together.

[0012] Furthermore, the material of the support rod is selected from any one of steel pipe, I-beam, channel steel and corrugated steel.

[0013] Furthermore, the composite ball hinge is a cube with a ball pit on each of the four adjacent sides, and only two of the four sides are opposite each other. The ball pits and the support rod are interference-fitted to achieve a rolling connection.

[0014] Furthermore, the horizontally oriented support rod with the outermost and innermost planes below it, along with the two composite ball hinges connected to its two ends, are in contact with the ground, while the remaining composite ball hinges and support rods are all above the ground.

[0015] Furthermore, the arch frame structure unit is a central axis symmetric structure.

[0016] A method for supporting rectangular cross-section tunnels that enables simultaneous assembly and disassembly, based on the aforementioned support structure for rectangular cross-section tunnels that enables simultaneous assembly and disassembly, includes the following steps:

[0017] Step 1: Prefabricate the arch frame structure units in the factory and transport them to the location in the tunnel that requires support;

[0018] Step 2: Connect the arch frame structure unit in the contracted state to the arch frame structure unit that has been deployed at the tunnel face.

[0019] Step 3: Fix the hydraulic cylinder to the unfolded arch structure unit at the tunnel face using a fixing plate, and fix the piston rod to the arch structure unit in the retracted state through a threaded rod and nut, and make the piston rod contact the shield head to provide support for the forward excavation of the shield head;

[0020] Step 4: The hydraulic control system enables the synchronous movement of multiple piston rods, allowing the shield head to advance forward while deploying the newly added arch structure unit until the shield head advances the distance to the maximum deployment limit of the arch structure unit.

[0021] Step 5: Secure the unfolded arch frame structure unit using hinge fixing devices;

[0022] Step Six: Repeat steps two through five until the total tunnel excavation distance meets the construction design requirements.

[0023] The beneficial effects of this invention are:

[0024] (1) The present invention achieves the simultaneous push and splicing by connecting the piston cylinder assembly with the support body and the shield head, thereby providing support for the forward excavation of the shield head and enabling the support body to unfold. This structural design solves the problems of low efficiency and difficult construction of traditional segment support automated assembly, and has the advantages of simple on-site construction process and high degree of automated assembly.

[0025] (2) The rectangular cross-section tunnel support structure proposed in this invention can realize synchronous splicing and assembly. It only requires multiple hydraulic cylinders to realize integrated support operation and construction, which greatly improves the construction efficiency of tunnel engineering. Attached Figure Description

[0026] Figure 1 This is an overall schematic diagram of a rectangular cross-section tunnel support structure that can be synchronously assembled in an embodiment of the present invention.

[0027] Figure 2 This is a schematic diagram of the support rod in an embodiment of the present invention.

[0028] Figure 3 This is a schematic diagram of the structure in an embodiment of the present invention, showing the hydraulic cylinder mounted on the support body via a fixing plate.

[0029] Figure 4 This is a schematic diagram illustrating the working principle of the hydraulic control system in an embodiment of the present invention.

[0030] Figure 5 This is a flowchart of a rectangular cross-section tunnel support method that enables synchronous assembly in an embodiment of the present invention.

[0031] In the diagram, support rod 1, support rod section 1-1, hemisphere 1-2, composite ball hinge 2, hydraulic cylinder assembly 3, hydraulic cylinder 3-1, fixing plate 3-2, threaded rod 3-3, nut 3-4, piston rod 3-5, hydraulic control system 4, three-position four-way directional valve 4-1, oil tank 4-2, hydraulic lock 4-3, hinge fixing device 5, and shield head 6. Detailed Implementation

[0032] The present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments. The objectives and effects of the present invention will become clearer as a result. The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0033] like Figure 1As shown, a rectangular cross-section tunnel support structure capable of synchronous excavation and assembly includes: a support body, a hydraulic cylinder assembly 3, a hydraulic control system 4, a hinge fixing device 5, and a shield head 6. The hydraulic cylinder assembly 3 includes: a hydraulic cylinder 3-1, a fixing plate 3-2, a threaded rod 3-3, a nut 3-4, and a piston rod 3-5. The hydraulic cylinder assembly 3 is fixed to the support body. The piston rod 3-5 of the hydraulic cylinder assembly 3 contacts one side of the shield head 6. The movement of the piston rod 3-5 provides support for the forward excavation of the shield head 6, simultaneously driving the support body to unfold, achieving synchronous excavation and assembly. The other side of the shield head 6 faces the tunnel face and is used for breaking ground and excavating the tunnel. The hydraulic control system 4 is connected to the hydraulic cylinder 3-1 and is used to control the movement of the piston rod 3-5, thereby synchronously controlling the forward excavation of the shield head 6 and the unfolding of the support body. The hinge fixing device 5 is used to fix the support body when it is unfolded to its limit.

[0034] The support structure is a three-dimensional structure composed of multiple repeating arch frame structural units, arranged sequentially along the tunnel axis. Each arch frame structural unit is a centrally symmetrical structure, comprising: an outermost plane, an intermediate plane, and an innermost plane. These three planes are parallel and coaxially arranged, with the outermost plane closest to the tunnel face. The outermost plane includes four support rods 1 and four composite ball hinges 2. Each support rod 1 has two ends that are rolled to two composite ball hinges 2, forming a closed rectangle. The innermost plane has the same structure as the outermost plane, also including four support rods 1 and four composite ball hinges 2, forming a closed rectangle. The intermediate layer plane also includes four support rods 1 and four composite ball hinges 2. The support rods 1 and composite ball hinges 2 form a closed square. The length of the horizontal support rod 1 along the central axis of the intermediate layer plane is the same as the length of the vertical support rod 1 along the central axis of the outermost plane, and the length of the vertical support rod 1 along the central axis of the intermediate layer plane is the same as the length of the horizontal support rod 1 along the central axis of the outermost plane. In this embodiment, the top and bottom edges of the outermost and innermost planes are the shorter sides, and the left and right edges are the longer sides; correspondingly, the top and bottom edges of the intermediate layer plane are the longer sides, and the left and right edges are the shorter sides.

[0035] Four composite ball hinges 2 located on the outermost plane correspond one-to-one with four composite ball hinges 2 located on the middle layer plane, and are connected by four support rods 1. Similarly, four composite ball hinges 2 located on the middle layer plane correspond one-to-one with four composite ball hinges 2 located on the innermost plane, and are also connected by four support rods 1. In summary, an arch frame structural unit includes a total of twenty support rods 1 and twelve composite ball hinges 2. Among them, the horizontal support rods 1 located below the outermost and innermost planes, and the two composite ball hinges 2 connected to their ends, are in contact with the ground, while the remaining composite ball hinges 2 and support rods 1 are all located above the ground.

[0036] like Figure 2 As shown, each support rod 1 includes a central support segment 1-1 and hemispheres 1-2 fixed to both ends of the support segment 1-1. The support rod 1 can be manufactured as a single piece, or the support segment 1-1 and the hemispheres 1-2 can be manufactured separately and then fixed together. The support rod 1 can be any one of steel pipe, I-beam, channel steel, and corrugated steel; in this embodiment, steel pipe is selected.

[0037] The composite ball hinge 2 has a cubic configuration, with a ball-shaped recess on each of its four adjacent sides. Only two of the four sides are opposite each other. The radius of the ball-shaped recess is slightly larger than the radius of the hemisphere 1-2 of the support rod 1. The rolling connection between the support rod 1 and the composite ball hinge 2 is achieved by embedding the hemisphere 1-2 of the support rod 1 into the ball-shaped recess. Compared with existing ball hinge designs, the advantage of this cubic configuration design of the composite ball hinge 2 is that it can simultaneously achieve up to four rolling connection constraints. In this embodiment of the invention, up to four support rods 1 can achieve rolling connection constraints.

[0038] Repeat this arch frame structure unit along the tunnel axis, denoting the direction closest to the tunnel face as the front end. Between two adjacent arch frame structure units, the innermost plane of the front arch frame structure unit coincides with the outermost plane of the rear arch frame structure unit, meaning that adjacent arch frame structure units share four composite ball hinges 2 and four support rods 1. For example... Figure 1 As shown, the arch frame structure unit closest to the tunnel face is in a retracted state, waiting to be unfolded by the hydraulic cylinder assembly 3; while the remaining arch frame structure units are in a fully unfolded state and are axially fixed by the hinge fixing device 5.

[0039] The hydraulic cylinder assembly 3 is equipped with multiple corresponding hydraulic cylinders 3-1 and piston rods 3-5 to ensure that the support force provided to the shield head 6 by the movement of the piston rods 3-5 is sufficiently large and uniform. In this embodiment, four corresponding hydraulic cylinders 3-1 and piston rods 3-5 are provided. Two hydraulic cylinders 3-1 are fixedly connected to the horizontal support rod 1 located at the top of the outermost plane of the foremost arch frame structure unit in the fully deployed state through fixing plates 3-2. The other two hydraulic cylinders 3-1 are fixedly connected to the horizontal support rod 1 located at the bottom of the outermost plane of the foremost arch frame structure unit in the fully deployed state through fixing plates 3-2. The threaded rod 3-3 is fixedly connected to the two horizontal support rods 1 in the outermost plane of the arch frame structure unit closest to the tunnel face through nuts 3-4, and the axis of the threaded rod 3-3 is vertical. One end of the piston rod 3-5 is installed in the hydraulic cylinder 3-1, and the other end passes through the threaded rod 3-3 and is fixedly connected to the threaded rod 3-3. This design enables the arch frame structure unit to be deployed through the transmission of force when the piston rod 3-5 moves.

[0040] like Figure 3As shown, the bottom of the fixing plate 3-2 is fixedly connected to the hydraulic cylinder 3-1, and the top is designed with an opening and closing structure, which allows for detachable connection to the support rod 1 via a nut. A through hole is provided at the opening and closing structure of the fixing plate 3-2, and the diameter of the through hole is adapted to the support rod 1. When the fixing plate 3-2 is closed, the hydraulic cylinder 3-1 can be fixedly connected to the corresponding support rod 1; when it is opened, the hydraulic cylinder 3-1 can be detached from the support rod 1. This design facilitates the disassembly and assembly of the hydraulic cylinder assembly 3 when adding new arch frame structural units in practical applications.

[0041] The hydraulic control system 4 is used to control the synchronous movement of the four piston rods 3-5. For example... Figure 4 As shown, the hydraulic control system 4 includes an oil tank 4-2 and four control units, with each control unit corresponding to one of the four hydraulic cylinders 3-1. Each control unit includes a three-position four-way directional valve 4-1 and two hydraulic locks 4-3. The three-position four-way directional valve 4-1 includes a pressure port P, a return port T, an output port A, and an output port B; output port A is connected to the rodless chamber of hydraulic cylinder 3-1 via hydraulic locks 4-3, and output port B is connected to the rod chamber of hydraulic cylinder 3-1 via hydraulic locks 4-3. The oil tank 4-2 is connected to the pressure port P of the three-position four-way directional valves 4-1 of the four control units, and simultaneously supplies pressurized oil to the four hydraulic cylinders 3-1. The three-position four-way directional valves 4-1 control the direction of oil flow by changing the relative position between the valve core and the valve body, thus opening or closing the oil circuit and changing the working state of the four hydraulic cylinders 3-1. Hydraulic lock 4-3 is used to fix the oil pressure difference between the two chambers of hydraulic cylinder 3-1, thereby fixing the position of piston rod 3-5, so that the rectangular cross-section tunnel support structure can be fixed at the designated position when folded or unfolded.

[0042] like Figure 5 As shown, based on the above-mentioned rectangular cross-section tunnel support structure that enables synchronous assembly, a method for supporting rectangular cross-section tunnels that enables synchronous assembly is proposed, specifically including the following steps:

[0043] Step 1: The arch frame structure units of the rectangular cross-section tunnel support structure designed in this invention, which can be synchronously assembled, are prefabricated in the factory and transported by truck to the location in the tunnel that requires support.

[0044] Step 2: Connect the arch frame structure unit in the contracted state to the arch frame structure unit that has been deployed at the tunnel face.

[0045] Step 3: Fix the hydraulic cylinder 3-1 to the unfolded arch structure unit at the tunnel face using the fixing plate 3-2. Connect the piston rod 3-5 to the arch structure unit in the retracted state through the threaded rod 3-3 and nut 3-4, and make the piston rod 3-5 contact the shield head 6 to provide support for the forward excavation of the shield head 6.

[0046] Step 4: The hydraulic control system 4 enables the synchronous movement of multiple piston rods 3-5, allowing the shield head 6 to advance forward while deploying the newly added arch frame structure unit, until the shield head 6 advances the distance to the limit of the arch frame structure unit's deployment.

[0047] Step 5: Secure the unfolded arch frame structure unit using hinge fixing device 5.

[0048] Step Six: Repeat steps two through five until the total tunnel excavation distance meets the construction design requirements.

[0049] It will be understood by those skilled in the art that the above descriptions are merely preferred examples of the invention and are not intended to limit the invention. Although the invention has been described in detail with reference to the foregoing examples, those skilled in the art can still modify the technical solutions described in the foregoing examples or make equivalent substitutions for some of the technical features. All modifications and equivalent substitutions made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A rectangular cross-section tunnel support structure capable of synchronous push-jacking, characterized by, include: The support structure comprises a support body, a hydraulic cylinder assembly, a hydraulic control system, a hinge fixing device, and a shield head. The support body is telescopic, the hydraulic cylinder assembly is fixedly connected to the support body, and the hydraulic control system controls the movement of the piston rod of the hydraulic cylinder assembly. The piston rod is fixedly connected to the support body, and its end contacts one side of the shield head, the other side of which faces the tunnel face for excavation. The hinge fixing device is used to fix the support body when it is extended to its limit. The support structure is composed of multiple arch frame structural units connected sequentially along the tunnel axis, with the arch frame structural unit closest to the tunnel face being the front end; each arch frame structural unit includes an outermost plane, an intermediate layer plane, and an innermost plane arranged in parallel and coaxial order, with the outermost plane close to the tunnel face; for two adjacent arch frame structural units, the innermost plane of the front arch frame structural unit also serves as the outermost plane of the rear arch frame structural unit. The outermost plane, the middle layer plane, and the innermost plane each include four support rods and four composite ball hinges. Each support rod's two ends are respectively rolled to two composite ball hinges. The four support rods and composite ball hinges form a closed rectangle. The outermost plane and the innermost plane have identical structures. The length of the horizontal support rod along the central axis of the middle layer plane is the same as the length of the vertical support rod along the central axis of the outermost plane, and the length of the vertical support rod along the central axis of the middle layer plane is the same as the length of the horizontal support rod along the central axis of the outermost plane. The positions of the composite ball hinges on the outermost plane and the middle layer plane correspond one-to-one and are rolled to each other via the support rods. The positions of the composite ball hinges on the middle layer plane and the innermost plane also correspond one-to-one and are rolled to each other via the support rods.

2. The rectangular cross-section tunnel support structure capable of synchronous assembly as described in claim 1, characterized in that, The hydraulic cylinder assembly includes: a hydraulic cylinder, a fixed plate, a piston rod, a threaded rod, and a nut; the hydraulic cylinder is fixedly connected to a support rod horizontally along the center axis of the outermost plane of the foremost arch frame structure unit in its fully deployed state via the fixed plate; the threaded rod is fixedly connected to two opposing support rods in the outermost plane of the arch frame structure unit closest to the tunnel face via the nut; one end of the piston rod is installed inside the hydraulic cylinder, and the other end passes through the threaded rod and is fixedly connected to it, with its end contacting the shield head.

3. The rectangular cross-section tunnel support structure capable of synchronous assembly as described in claim 2, characterized in that, The bottom of the fixing plate is fixedly connected to the hydraulic cylinder, and the top is designed with an opening and closing structure, which is detachably connected to the support rod by a nut; the opening and closing structure of the fixing plate has a through hole with a diameter that matches the support rod.

4. The rectangular cross-section tunnel support structure capable of synchronous assembly as described in claim 2, characterized in that, The hydraulic control system includes an oil tank and multiple control units. Each control unit includes a three-position four-way directional valve and two hydraulic locks. The three-position four-way directional valve includes a pressure port P, a return port T, an output port A, and an output port B. Output port A is connected to the rodless chamber of the hydraulic cylinder via a hydraulic lock, and output port B is connected to the rod chamber of the hydraulic cylinder via a hydraulic lock. The oil tank is connected to the pressure port P of the three-position four-way directional valve of each control unit, simultaneously supplying pressurized oil to multiple hydraulic cylinders. The three-position four-way directional valve controls the direction of oil flow by changing the relative position between the valve core and the valve body, connecting or closing the oil circuit, thereby changing the working state of the hydraulic cylinder. The hydraulic lock is used to fix the oil pressure difference between the two chambers of the hydraulic cylinder, thereby fixing the position of the piston rod.

5. The rectangular cross-section tunnel support structure capable of synchronous assembly as described in claim 1, characterized in that, The support rod includes a middle support section and hemispheres fixed to both ends of the support section; the support rod is manufactured as a single piece, or the support section and hemispheres are manufactured separately and then fixed together.

6. The rectangular cross-section tunnel support structure capable of synchronous assembly according to claim 1, characterized in that, The material of the support rod is selected from any one of steel pipe, I-beam, channel steel and corrugated steel.

7. The rectangular cross-section tunnel support structure capable of synchronous assembly as described in claim 1, characterized in that, The composite ball hinge has a cubic configuration, with a ball pit on each of the four adjacent sides, and only two of the four sides are opposite each other. The ball pits and the support rod are interference-fitted to achieve a rolling connection.

8. The rectangular cross-section tunnel support structure capable of synchronous assembly according to claim 1, characterized in that, The horizontal support rod with the outermost and innermost planes below it, and the two composite ball hinges connected to its two ends, are in contact with the ground. The remaining composite ball hinges and support rods are all above the ground.

9. The rectangular cross-section tunnel support structure capable of synchronous assembly according to claim 1, characterized in that, The arch frame structure unit is a central axis symmetric structure.

10. A method for supporting rectangular cross-section tunnels capable of synchronous assembly, implemented based on the rectangular cross-section tunnel support structure capable of synchronous assembly as described in any one of claims 2-4, characterized in that, Includes the following steps: Step 1: Prefabricate the arch frame structure units in the factory and transport them to the location in the tunnel that requires support; Step 2: Connect the arch frame structure unit in the contracted state to the arch frame structure unit that has been deployed at the tunnel face. Step 3: Fix the hydraulic cylinder to the unfolded arch structure unit at the tunnel face using a fixing plate, and fix the piston rod to the arch structure unit in the retracted state through a threaded rod and nut, and make the piston rod contact the shield head to provide support for the forward excavation of the shield head; Step 4: The hydraulic control system enables the synchronous movement of multiple piston rods, allowing the shield head to advance forward while deploying the newly added arch structure unit until the shield head advances the distance to the maximum deployment limit of the arch structure unit. Step 5: Secure the unfolded arch frame structure unit using hinge fixing devices; Step Six: Repeat steps two through five until the total tunnel excavation distance meets the construction design requirements.

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