A tunnel complex surrounding rock section prestress horizontal buttress supporting method and device

Abstract

The application provides a tunnel complex surrounding rock section prestress horizontal bracing supporting method, which comprises a horizontal bracing, the horizontal bracing comprises bracing rods, gravity support rods and longitudinal connecting members, the bracing rods cross the tunnel section, the two ends are connected with pressure bearing steel plates in the two side walls of the lining, and the middle part is provided with an adjustable sleeve, and the dynamic active regulation and control of the prestress is realized by adjusting the length of the sleeve. The gravity support rods comprise two support columns, the top of the support columns is hinged with the top steel bars of the lining, the two sides of the support columns are connected with the bracing rods in a hinged mode, and a triangular structure is formed, which is used for providing gravity support for the horizontal bracing after the loss of the prestress. The longitudinal connecting members are arranged along the tunnel axis at a designed interval, and the pressure bearing steel plates of each section are connected into an integral supporting frame through the section steel. The application can effectively inhibit the deformation and cracking of the lining, has the advantages of convenient construction, high efficiency and strong adaptability, and is suitable for the reinforcement construction of various underground caverns such as V-class surrounding rock and fault fracture zone.

Description

Technical Field

[0001] This invention belongs to the field of water conservancy engineering technology, and specifically relates to a method and device for prestressed horizontal bracing support in complex surrounding rock sections of tunnels. Background Technology

[0002] Currently, when tunnels pass through complex surrounding rock sections, especially fault fracture zones, the fractured surrounding rock and poor self-bearing capacity in the fault area often cause the lining structure to bear significant asymmetric loads, which can easily lead to engineering problems such as lining cracking, excessive deformation, and even overall instability.

[0003] Traditional reinforcement methods typically involve increasing the lining cross-section, adding anchor bolts, or grouting. However, these methods have long construction cycles, require interrupting normal tunnel operation, and affect project benefits. They often require damaging the original lining structure for reinforcement, causing secondary damage to the original structure. At the same time, the above-mentioned reinforcement methods are mostly passive support, making it difficult to actively adjust the support force according to the deformation and stress changes of the surrounding rock. It is also difficult to monitor the stress and deformation state of the support structure and the surrounding rock in real time, making it difficult to detect hidden dangers in a timely manner.

[0004] It is evident that how to construct a prestressed horizontal bracing support method for complex surrounding rock sections of tunnels, providing active support for the tunnel lining, ensuring support effectiveness and lining stress safety, is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] To address the aforementioned technical problems, in a first aspect, the present invention provides a method for prestressed horizontal bracing support in complex surrounding rock sections of tunnels, wherein the complex surrounding rock section of the tunnel includes a main fault fault zone and a fault influence zone, and the method includes the following steps: Based on the width of the main fault zone and the fault influence zone, the tunnel diameter and the design head, determine the location and specifications of the pre-embedded pressure-bearing steel plate, horizontal bracing and longitudinal connecting components; During the construction and erection of the lining reinforcement, the welding of the pressure-bearing steel plate and the lining reinforcement is completed simultaneously, and longitudinal connecting components connected to several pressure-bearing steel plates are welded along the tunnel axis. Pour the lining concrete to ensure that the bearing steel plate is exposed and intact, and complete the curing to allow the lining to take shape and gradually reach the design strength. Horizontal bracing connected to several pressure-bearing steel plates is installed along the tunnel axis to test the overall structural stability of the testing device.

[0006] In the first aspect, each of the horizontal bracing members includes two bracing members connected by an adjusting sleeve. The other ends of the two bracing members are respectively connected to two pressure-bearing steel plates arranged opposite to each other in the left and right side walls of the lining. Adjacent pressure-bearing steel plates are welded together by longitudinal connecting members.

[0007] In the first aspect, the two supporting rods are threadedly connected to the adjusting sleeve, and the other ends of the two supporting rods are respectively threadedly connected to the corresponding bearing steel plates to adjust the prestress of the horizontal bracing by changing the tightness of the threads. The longitudinal connecting member is welded to the bearing steel plate.

[0008] In the first aspect, each horizontal brace also includes two support columns, one end of which is hinged to one of the two brace members respectively, and the other end of which is hinged to the top side of the lining to form a triangular truss structure in the middle of the horizontal brace.

[0009] Secondly, the present invention provides a prestressed horizontal bracing support device for a tunnel with complex surrounding rock sections. The support device is installed within the lining of the tunnel. The complex surrounding rock section includes a main fault fault zone and a fault influence zone. The support device comprises: Several pre-embedded pressure-bearing steel plates are symmetrically pre-embedded in the left and right side walls of the lining along the tunnel axis. Several horizontal braces are arranged at intervals along the tunnel axis, and the two ends of the several horizontal braces are respectively connected to two pressure-bearing steel plates arranged opposite to each other in the left and right side walls of the lining. Several longitudinal connecting members are provided, and each pair of adjacent pressure-bearing steel plates is connected by longitudinal connecting members.

[0010] Secondly, each of the horizontal bracing members includes two bracing rods, which are connected by an adjusting sleeve. The other ends of the two bracing rods are respectively connected to two pressure-bearing steel plates arranged opposite to each other in the left and right side walls of the lining.

[0011] Secondly, both of the supporting rods are threadedly connected to the adjusting sleeve, and the other ends of the two supporting rods are respectively threadedly connected to the corresponding pressure-bearing steel plates. The longitudinal connecting member is welded to the pressure-bearing steel plate so as to adjust the prestress of the horizontal supporting rod by changing the tightness of the threads.

[0012] Secondly, each of the horizontal bracing members further includes two support columns, one end of which is respectively hinged to the two bracing members, and the other end of which is hinged to the top side of the lining, so as to form a triangular truss structure in the middle of the horizontal bracing member.

[0013] Beneficial effects: This invention proposes a prestressed horizontal bracing support method for complex surrounding rock sections of tunnels. In the early stages of lining, the pre-embedded positions and specifications of the bearing steel plates are determined based on the width of the main fault fault zone and the fault influence zone, the tunnel diameter, and the design head. Then, during the lining pouring process, the bearing steel plates are installed according to the pre-embedded positions. After the lining is formed and reaches its design strength, horizontal bracing support devices connected to several bearing steel plates are installed along the tunnel axis at designed intervals. This invention effectively suppresses lining deformation and cracking, and has the advantages of convenient construction, high efficiency, and strong adaptability. It is suitable for the reinforcement construction of various underground caverns, including those in Class V surrounding rock and fault fracture zones.

[0014] Therefore, a prestressed horizontal bracing support method for complex surrounding rock sections of tunnels is constructed to achieve effective support for the tunnel lining. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this specification or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a flowchart of the method for prestressed horizontal bracing support in complex surrounding rock sections of tunnels, as described in this embodiment of the invention. Figure 2 This is a layout diagram of the pressure-bearing steel plate, horizontal bracing support device, and longitudinal connecting components in an embodiment of the present invention; Figure 3 This is a force diagram of the horizontal bracing support device in an embodiment of the present invention; Attached image description: 1. Lining; 2. Bearing steel plate; 3. Support rods; 4. Adjusting sleeves; 5. Longitudinal connecting components; 6. Support columns; 7. Hinge joints; Detailed Implementation

[0017] The technical solutions of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0018] Furthermore, in the embodiments of this specification, when a component is referred to as being "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is considered to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. When a component is considered to be "set on" another component, it can be directly set on the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in the embodiments of this specification are for illustrative purposes only and are not intended to limit the invention.

[0019] Example 1: like Figure 1-2 As shown in the figure, this embodiment provides a prestressed horizontal bracing support method for a tunnel with complex surrounding rock. The complex surrounding rock section of the tunnel includes a fault main fault zone (muddy) and a fault influence zone (fractured rock mass). The method includes the following steps: determining the pre-embedded position and specifications of the pressure-bearing steel plate 2 according to the width of the fault main fault zone and the fault influence zone, the diameter of the tunnel, and the design head; installing the pressure-bearing steel plate 2 according to the pre-embedded position during the lining 1 pouring process; and after the lining 1 is formed and reaches the design strength, setting up a horizontal bracing support device connected to several pressure-bearing steel plates 2 along the tunnel axis.

[0020] Specifically, Embodiment 1 of the present invention proposes a prestressed horizontal bracing support method for complex surrounding rock sections of tunnels. First, based on the width of the main fault fault zone and the fault influence zone, the diameter of the tunnel, and the design head, the position and specifications of the pre-embedded pressure-bearing steel plate 2 and the horizontal bracing support device are determined. Then, during the construction and erection of the lining reinforcement, the pressure-bearing steel plate 2 is installed according to the pre-embedded position. The lining concrete is poured to ensure that the pressure-bearing steel plate 2 is exposed and intact, and curing is completed to allow the lining to take shape and gradually reach the design strength. After the lining 1 is formed and reaches the design strength, the horizontal bracing support device is installed and firmly connected to the pressure-bearing steel plate 2. The overall structural stability of the device is tested, and controllable prestress is applied to the lining 1 through the adjustable horizontal bracing support device to achieve a balance of the surrounding rock pressure in the fault zone.

[0021] It should be noted that the method of this application is particularly applicable to the permanent reinforcement of large-diameter tunnels with a width of ≥5m and a water head of ≥100m and an inner diameter of ≥8m under adverse geological conditions; it is not applicable to scenarios where the main fault zone is extremely unstable and the lining 1 has already experienced large-area cracking and collapse (in such scenarios, prestress control cannot reverse the risk of collapse).

[0022] In some possible implementations, the horizontal bracing support device includes several horizontal braces, which are spaced apart along the tunnel axis. Each horizontal brace includes two bracing rods 3, which are connected by an adjusting sleeve 4. The outer ends of the two bracing rods 3 are respectively connected to two pressure-bearing steel plates 2 arranged opposite to each other in the left and right side walls of the lining 1.

[0023] Specifically, see Figure 2 As shown, the horizontal bracing support device includes several horizontal braces, which are arranged at design intervals along the tunnel axis to form multiple active lateral supports covering the main fault zone. Adjacent bearing steel plates 2 are connected by longitudinal connecting members 5 to connect the multiple horizontal braces into a whole, forming a complete spatial rigid support system covering the fracture zone. Compared with single or multiple independently set support devices, this significantly improves the deformation resistance and load resistance of the fracture zone support, effectively disperses local concentrated forces, and enhances the overall stability and deformation resistance of the support system. As an feasible approach, the longitudinal connecting members 5 are made of steel sections arranged along the tunnel axis and are reliably connected to the bearing steel plates 2 by double-sided welding or high-strength bolts to ensure that the strength of the connection is not lower than the strength of the member itself. Each horizontal brace includes two bracing members 3, and the two bracing members 3 are connected by an adjusting sleeve 4. The outer ends of the two bracing members 3 are connected to two pressure-bearing steel plates 2 that are embedded in the left and right side walls of the lining 1. By adjusting the sleeve 4, the total length of the horizontal brace can be changed, thereby applying or releasing prestress to the lining 1 to achieve active support.

[0024] In some possible implementations, the two bracing members 3 are threadedly connected to the adjusting sleeve 4, the outer ends of the two bracing members 3 are respectively threadedly connected to the corresponding bearing steel plates 2, and the longitudinal connecting member 5 is welded to the bearing steel plates 2 so as to adjust the prestress of the horizontal bracing by changing the tightness of the threads.

[0025] Specifically, the two supporting rods 3 are threadedly connected to the adjusting sleeve 4. The inner walls of both ends of the adjusting sleeve 4 are machined with internal threads of opposite directions, one end being a positive thread and the other end being a negative thread, which are respectively matched and connected to the external threads of the two supporting rods 3. The outer ends of the two supporting rods 3 are respectively threadedly connected to the corresponding bearing steel plates 2. In this way, by rotating the adjusting sleeve 4, the total length of the horizontal support can be changed, thereby applying or releasing prestress to the lining 1 and realizing active support.

[0026] In some possible implementations, each horizontal brace also includes two support columns 6, one end of which is hinged to the two brace members 3 respectively, and the other end of which is hinged to the top side of the lining 1, so as to form a triangular truss structure in the middle of the horizontal brace.

[0027] Specifically, each horizontal brace also includes two support columns 6. The two support columns 6 are hinged to the brace members 3 and the top of the lining 1, forming a deformable adaptive triangular truss structure. By setting the triangular truss structure, the two support columns 6 are hinged to the horizontal brace and the top of the lining 1, which can effectively suppress the vertical deformation of the horizontal brace and improve the stiffness and stability of the horizontal brace in the vertical plane.

[0028] Example 2: This invention provides a prestressed horizontal bracing support device for complex surrounding rock sections of tunnels.

[0029] Since Embodiment 2 and Embodiment 1 are embodiments under the same inventive concept, and the device structure in Embodiment 2 is exactly the same as that in Embodiment 1, the structure in Embodiment 2 that is substantially the same as that in Embodiment 1 will not be described in detail. For the parts not described in detail, please refer to Embodiment 1.

[0030] A brief explanation of the working mechanism and bearing capacity of the horizontal bracing of lining 1: The core advantage of this system is that it addresses the problem of lining 1 being damaged by direct compression of surrounding rock pressure in fault zones. By setting up prestressed horizontal bracing inside the tunnel to form a rigid support system, the system effectively transfers and bears the surrounding rock pressure from lining 1 to the horizontal bracing.

[0031] During construction, the pre-embedded pressure-bearing steel plate 2 and the secondary lining 1 form an integral load-bearing structure. After the horizontal bracing is subjected to controllable prestress through the central adjusting sleeve 4, it is reliably connected to the pressure-bearing steel plate 2. When the surrounding rock in the fault zone exerts compressive pressure on the lining 1, the horizontal bracing forms a reverse support force directly against the lining 1 by means of the pre-stressed material. The surrounding rock pressure that was originally borne by the lining 1 alone is transmitted to the horizontal bracing through the force diffusion effect of the bearing steel plate 2. Then, through the longitudinal connecting member 5, the local bearing capacity of the single horizontal bracing is transformed into the overall bearing capacity of the spatial support system, so that the surrounding rock pressure is mainly borne by the horizontal bracing system, which greatly reduces the load on the lining 1 and fundamentally avoids the compression, deformation and cracking damage of the lining 1 caused by the surrounding rock pressure.

[0032] Meanwhile, the triangular steel column hinged structure strengthens the vertical stability of the horizontal bracing, ensuring that the horizontal bracing always maintains a stable top-support state. The entire system takes load transfer as its core logic, completely changing the unfavorable stress state of the traditional lining 1 bearing the surrounding rock pressure alone, and significantly improving the load-bearing capacity and safety of the prestressed cross-section lining 1 in the fault fracture zone of the tunnel.

[0033] Explanation of the working mechanism and load-bearing mechanism of the support device In response to the problem that direct compression of the surrounding rock pressure in the fault zone can easily lead to damage to the lining 1, the core advantage of the support device in this application is that by setting up a horizontal bracing support device inside the tunnel to form a spatial rigid support system, the surrounding rock pressure can be effectively transferred and borne by the horizontal bracing support device.

[0034] Specifically, during the construction phase, a pressure-bearing steel plate 2 is pre-embedded, forming an integral load-bearing structure with the lining 1 during casting. Horizontal bracing is subjected to controllable prestress through an adjusting sleeve 4 located in the middle, and both ends of the horizontal bracing are reliably connected to the pre-embedded pressure-bearing steel plate 2, forming active support for the lining 1. When the surrounding rock in the fault zone exerts compressive pressure on the lining 1, the horizontal bracing, relying on the pre-set prestress, forms a reverse support force, directly supporting the lining 1 to balance the external load. The surrounding rock pressure originally borne solely by the lining 1 is evenly transmitted to the horizontal bracing through the force diffusion effect of the pressure-bearing steel plate 2. Furthermore, the longitudinal connecting component 5 transforms the local bearing capacity of each horizontal bracing into the overall bearing capacity of the spatial support system, ensuring that the surrounding rock pressure is mainly borne by the support device. This significantly reduces the load on the lining 1, fundamentally preventing the compression, deformation, and cracking damage to the lining 1 caused by the surrounding rock pressure. At the same time, the triangular truss structure formed by the support columns 6 effectively enhances the stability of the horizontal bracing in the vertical plane, ensuring that the horizontal bracing always maintains a reliable top support state.

[0035] Therefore, the support device in this application takes load transfer as its core logic, which avoids the unfavorable stress state of the traditional lining 1 bearing the surrounding rock pressure alone, and improves the load resistance and structural safety of the prestressed cross-section lining 1 in the complex surrounding rock section of the tunnel.

[0036] See Figure 3 As shown, the force transmission path is as follows: First, the surrounding rock deforms, generating compressive stress on the lining 1 pointing towards the center of the tunnel. This is the original driving force of the entire system. Subsequently, the lining 1 transmits the compressive stress it bears to the horizontal bracing through the bearing steel plate 2, so that the two ends of the horizontal bracing are subjected to horizontal forces from the lining 1. Finally, the prestress applied to the two ends of the horizontal bracing and the supporting force generated by the triangular truss structure set in the middle of the horizontal bracing together form an outward reaction force, which counteracts the horizontal force from the lining 1. Thus, a complete force balance closed loop is formed: "surrounding rock pressure → lining 1 → horizontal bracing → prestress reaction force → lining 1 → surrounding rock".

[0037] Example 3: This embodiment provides a specific parametric design example based on the above embodiment one, which serves as an exemplary illustration of the specific implementation of the method of the present invention under specific engineering conditions.

[0038] This example focuses on a large fault section of a hydraulic tunnel as the reinforcement target. The main fault zone is 8m wide, and the surrounding rock stability is poor. The surrounding rock pressure coefficient λ is 0.8, the tunnel diameter D is 10m (inner diameter), the design head h = 120m, and the safety factor K = 1.2. These parameters conform to the typical working conditions of a large fault section in a hydraulic tunnel.

[0039] I. Parameter Design of Horizontal Support System Q355B high-strength steel is selected for the struts 3, the bearing steel plate 2, and the longitudinal connecting members 5. It has excellent tensile and compressive strength and can adapt to the stress requirements under high water head and high surrounding rock pressure conditions. Moreover, the uniform material of each component is conducive to ensuring the stress coordination of the overall structure.

[0040] The main body of the strut member 3 is made of H-beam steel H350×175×7×11, with specific dimensional parameters as follows: section height 350mm; flange width 175mm; web thickness 7mm; flange thickness 11mm.

[0041] An M30 high-strength bolt sleeve is fixed to the center of the support member 3 using a full-circumference bevel welding process. The bolt sleeve is welded integrally with the entire end face of the H-beam to ensure uniform transmission of prestress and avoid local stress concentration. The bolt sleeve is compatible with the bolt holes on the bearing steel plate 2 to ensure that the connection strength is consistent with the main component and facilitates prestress adjustment.

[0042] II. Parameter Design of Embedded Pressure-Bearing Steel Plate 2 The pressure-bearing steel plate 2 is made of Q355B high-strength steel, which is consistent with the material of the support rod 3 and the longitudinal connecting member 5 to ensure the overall stress coordination.

[0043] The dimensions of the bearing steel plate 2 are selected as follows: plane size 400mm×400mm, plate thickness 20mm, to provide sufficient bearing area and bending thickness, effectively resist local bending deformation caused by the prestress of the horizontal bracing, and evenly distribute the concentrated force to the concrete of lining 1 to prevent local crushing of lining 1.

[0044] III. Parameter Design of Longitudinal Connection Component 5 The longitudinal connecting member 5 is made of channel steel 20a, with the following specific dimensional parameters: section height 200mm; flange width 73mm; web thickness 7mm; and average flange thickness 11.4mm.

[0045] IV. Determining the Quantity and Location of Deployment To fully cover the fault fracture zone and ensure that the support system is embedded in the stable surrounding rock, a horizontal bracing support device with a total length of 12m is installed, extending 2m to each end of the fault main fault zone (i.e., the fault influence zone) on the basis of a width of 8m.

[0046] Several horizontal bracings are evenly arranged at 1.5m intervals along the tunnel axis, with a total of 9 horizontal bracings; correspondingly, a set of pressure-bearing steel plates 2 is set every 1.5m along the tunnel axis, wherein each set includes two steel plates arranged opposite each other on the left and right side walls of the lining 1, for a total of 18 pressure-bearing steel plates 2.

[0047] Furthermore, given the tunnel diameter of 10m, in order to effectively resist water pressure and surrounding rock deformation, the horizontal bracing should be positioned at the height of the lining 1 where the stress is most unfavorable and the deformation is greatest, i.e., 3m above the tunnel centerline, or 8m from the tunnel bottom. Therefore, in this embodiment, the vertical placement height of the pressure-bearing steel plate 2 is determined to be 8m from the tunnel bottom.

[0048] Finally, it should be noted that the above embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the scope of the technology disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention. All should be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

[0049] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. Other modifications can be made by those skilled in the art. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for prestressed horizontal bracing support in a tunnel with complex surrounding rock, wherein the complex surrounding rock section of the tunnel includes a main fault fault zone and a fault influence zone, characterized in that, The method includes the following steps: Based on the width of the main fault zone and the fault influence zone, the tunnel diameter and the design head, determine the location and specifications of the pre-embedded pressure-bearing steel plate, horizontal bracing and longitudinal connecting components; During the construction and erection of the lining reinforcement, the welding of the pressure-bearing steel plate and the lining reinforcement is completed simultaneously, and longitudinal connecting components connected to several pressure-bearing steel plates are welded along the tunnel axis. Pour the lining concrete to ensure that the bearing steel plate is exposed and intact, and complete the curing to allow the lining to take shape and gradually reach the design strength. Horizontal bracing connected to several pressure-bearing steel plates is installed along the tunnel axis to test the overall structural stability of the testing device.

2. The prestressed horizontal bracing support method for complex surrounding rock sections of tunnels according to claim 1, characterized in that: Each of the horizontal bracing members includes two bracing members, which are connected by an adjusting sleeve. The other ends of the two bracing members are respectively connected to two pressure-bearing steel plates arranged opposite each other in the left and right side walls of the lining. Two adjacent pressure-bearing steel plates on the same side are connected by a longitudinal connecting member.

3. The prestressed horizontal bracing support method for complex surrounding rock sections of tunnels according to claim 2, characterized in that: The two supporting rods are threadedly connected to the adjusting sleeve, and the other ends of the two supporting rods are respectively threadedly connected to the corresponding bearing steel plates. The longitudinal connecting member is welded to the bearing steel plate so as to adjust the prestress of the horizontal supporting rod by changing the tightness of the threads.

4. The prestressed horizontal bracing support method for complex surrounding rock sections of tunnels according to claim 3, characterized in that: Each horizontal brace also includes two support columns, one end of which is hinged to one of the two brace members respectively, and the other end of which is hinged to the top side of the lining to form a triangular truss structure in the middle of the horizontal brace.

5. A prestressed horizontal bracing support device for a tunnel in a complex surrounding rock section, the support device being installed within the tunnel lining, the complex surrounding rock section comprising a main fault fault zone and a fault influence zone, characterized in that... The support device includes: Several pre-embedded pressure-bearing steel plates are symmetrically pre-embedded in the left and right side walls of the lining along the tunnel axis. Several horizontal braces are arranged at intervals along the tunnel axis, and the two ends of the several horizontal braces are respectively connected to two pressure-bearing steel plates arranged opposite to each other in the left and right side walls of the lining. Several longitudinal connecting members are provided, and each pair of adjacent pressure-bearing steel plates is connected by longitudinal connecting members.

6. The prestressed horizontal bracing support device for complex surrounding rock sections of tunnels according to claim 5, characterized in that: Each of the horizontal braces includes two bracing members connected by an adjusting sleeve.

7. The prestressed horizontal bracing support device for complex surrounding rock sections of tunnels according to claim 6, characterized in that: Both of the aforementioned support rods are threadedly connected to the adjusting sleeve, and the other ends of the two support rods are respectively threadedly connected to the corresponding bearing steel plates, so as to adjust the prestress of the horizontal support by changing the tightness of the threads. The longitudinal connecting member is welded to the bearing steel plate.

8. The prestressed horizontal bracing support device for complex surrounding rock sections of tunnels according to claim 7, characterized in that: Each of the horizontal bracing members also includes two support columns, one end of which is hinged to one of the two bracing members respectively, and the other end of which is hinged to the top side of the lining to form a triangular truss structure in the middle of the horizontal bracing member.

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