Tunnel expansion section construction supporting structure and construction method

Abstract

The invention discloses a tunnel expansion section construction supporting structure and a construction method, and relates to the technical field of tunnel supporting structures.The tunnel expansion section construction supporting structure comprises a supporting frame, supporting bases are rotationally installed on the two sides of the supporting frame, and a supporting plate is fixedly installed at the top of the supporting frame; a connecting plate is jointly installed between the supporting plate and the top of the supporting frame in a sliding mode. The device further comprises a limiting assembly and a driving assembly. The problems that in an existing construction mode, dismantling and rebuilding procedures are independent, construction links are increased, the construction period is tedious, and efficiency is low are solved; and secondly, in the window period before the primary support is dismantled and the secondary lining is built, the tunnel surrounding rock loses the temporary support, the stability can be obviously reduced, collapse or excessive deformation is extremely prone to occurring, and therefore the problems of personnel injury, equipment damage and construction period delay are caused.

Description

Technical Field

[0001] This invention relates to the field of tunnel support structure technology, and in particular to a support structure and construction method for tunnel widening sections. Background Technology

[0002] Support during tunnel expansion is a crucial step in ensuring construction safety and tunnel stability. The purpose of support is to control the deformation of the surrounding rock and prevent the tunnel from collapsing during construction. Support measures typically include two stages: initial support and secondary lining.

[0003] In existing technologies, although initial support is provided using steel arch frames and secondary lining is done with reinforced concrete to support and protect the tunnel, the initial support needs to be dismantled before secondary lining can be installed, followed by reinforcement and concrete pouring. This "dismantle before build" approach has many drawbacks:

[0004] First, the demolition and reconstruction processes are independent of each other, which increases the number of construction steps, resulting in a complicated construction period and low efficiency.

[0005] Secondly, during the gap period before the removal of the initial support and the construction of the secondary lining, the surrounding rock of the tunnel loses its temporary support, and its stability will decrease significantly. It is very easy for it to collapse or deform excessively, which will cause problems such as personnel injury, equipment damage and project delays.

[0006] Therefore, how to optimize the construction process, reduce the time of unsupported exposure of the surrounding rock, and improve the efficiency and safety of secondary lining construction has become a technical problem that urgently needs to be solved in this field.

[0007] Based on this, the present invention proposes a support structure and construction method for tunnel enlargement section. Summary of the Invention

[0008] The purpose of this invention is to provide a support structure and construction method for tunnel widening sections, so as to solve the problems mentioned in the background art, reduce construction steps, and improve construction efficiency.

[0009] The technical solution of the present invention is: a construction support structure for a tunnel expansion section, including a support frame, with support seats rotatably installed on both sides of the support frame, a support plate fixedly installed on the top of the support frame, and a connecting plate slidably installed between the support plate and the top of the support frame, and also including a limiting component and a driving component.

[0010] The limiting components are installed on the support frame and the support plate.

[0011] The limiting component includes a pair of first fixing blocks and a second fixing block. The pair of first fixing blocks are symmetrically fixedly installed on the support frame, and the second fixing block is fixedly installed on the bottom of the support plate.

[0012] The drive assembly includes a mounting plate, a barrier plate, and a push plate. The mounting plate is fixedly mounted on the top of the support frame, the barrier plate slides through the mounting plate, and the push plate is fixedly mounted on the end of the barrier plate.

[0013] Preferably, each of the first fixing blocks has a groove inside, a limit block is slidably installed inside the groove, a return spring is fixedly connected between the limit block and the inner wall of the groove, and the inner side of the limit block has an inclined surface.

[0014] Preferably, a circular disk is eccentrically mounted on one side of the second fixing block, a limiting crank is fixedly mounted on the circular disk, a limiting slot is provided on the support plate, and the limiting crank and the limiting slot are engaged with each other.

[0015] Preferably, a fixing sleeve is fixedly installed on one side of the second fixing block, a telescopic rod is slidably installed inside the fixing sleeve, a drive plate is fixedly installed at the end of the telescopic rod, and the drive plate is fixedly connected to the connecting plate.

[0016] Preferably, a second return spring is fixedly connected between the drive plate and the fixed sleeve, and a support slide rod is fixedly installed between the second fixed block and the support frame, with the drive plate and the support slide rod slidingly engaged.

[0017] Preferably, a connecting rod is fixedly installed on one side of the push plate, and the end of the connecting rod is slidably installed on the second fixed block, and a reset groove is provided at the end of the connecting rod.

[0018] Preferably, multiple support seats are rotatably installed at equal intervals at both ends of the support frame, a connecting groove is symmetrically opened on one side of the support frame, and a connecting block is symmetrically fixedly installed on the other side of the support frame. A connecting hole is opened on both the connecting groove and the connecting block, and a temporary support rod is provided at the bottom of the support seat.

[0019] Preferably, the support plate is provided with symmetrical guide grooves, and guide plates are fixedly installed on both sides of the connecting plate, with the guide plates and guide grooves slidingly engaged.

[0020] A construction method for a support structure in a tunnel widening section includes the following steps:

[0021] Step 1: Determine the number of support frames and temporary support rods based on the actual construction conditions of the tunnel expansion section.

[0022] Step 2: After the tunnel is enlarged and excavated, the support frame is evenly laid on the inner wall of the tunnel through connecting blocks and connecting grooves, and temporary support rods are installed through support seats to further improve the support effect of the support frame.

[0023] Step 3: When secondary lining is required, workers can insert steel bars into the support frame from one end of the tunnel wall, so that the steel bars extend beyond the first and second positioning blocks and reach one side of the second positioning block, and the steel bars are evenly distributed around the center of the tunnel by the guide block.

[0024] Step 4: When the worker inserts the steel bar, the steel bar pushes the push plate, which in turn moves the barrier plate away from the drive plate, so that the barrier plate no longer abuts against one side of the drive plate. At this time, the reset spring releases its elastic potential energy, and the elastic deformation pushes the drive plate to move. The drive plate then moves the connecting plate, so that the connecting plate moves into the adjacent support frame.

[0025] Step 5: When the drive plate moves the connecting plate, the drive plate abuts against the limiting block, and the inclined surface of the limiting block decomposes the thrust of the drive plate into a tangential force, thereby driving the limiting block to move closer to the first fixed block. At this time, the limiting block compresses the first reset spring, causing the first reset spring to undergo elastic deformation and accumulate elastic potential energy. When the connecting plate moves into the adjacent support frame, the first reset spring releases the elastic potential energy, undergoes elastic deformation, and pushes the limiting block to move away from the first fixed block, so that the straight part of the limiting block abuts against one side of the drive plate, hindering the movement of the drive plate.

[0026] Step 6: The push plate drives the connecting rod to move, and the end of the connecting rod pushes the disc to rotate. The disc drives the limiting crank to move, so that the limiting crank stops obstructing the movement of the connecting plate. At this time, the connecting rod continues to move, so that the reset groove moves to the bottom of the disc. The disc rotates and resets under the action of gravity, thereby driving the limiting crank to reset, so that the limiting crank abuts against one side of the connecting plate, obstructing the movement of the connecting plate.

[0027] Step 7: Workers remove the temporary support rods and spray concrete onto the support frame to complete the secondary lining of the tunnel support.

[0028] This invention provides an improved support structure and construction method for tunnel widening sections, which, compared with the prior art, has the following improvements and advantages:

[0029] Firstly, by setting a limiting component, this invention, compared to existing technologies, allows workers to insert reinforcing bars into the support frame before the initial support needs to be removed and the secondary lining needs to be built. The reinforcing bars pass through the first and second positioning blocks, and the driving component moves the connecting plate to the adjacent support frame. At this point, workers can remove the temporary support rods and spray concrete onto the support frame to complete the secondary lining. This avoids the need to remove the initial support, rebuild the reinforcing bars, and pour concrete before the secondary lining, which leads to a cumbersome construction period and low efficiency. It reduces the steps involved in building the support structure, improves the stability during tunnel construction, thereby increasing work efficiency and enhancing tunnel safety.

[0030] Secondly, this invention, by setting a limiting component, allows the connecting plate to move into the adjacent support frame under the drive of the second return spring and the drive plate. The return spring releases its elastic potential energy to push the limiting block, causing it to abut against one side of the drive plate, thus limiting the drive plate. Simultaneously, under the action of the drive component, the movement of the connecting rod causes the disc to rotate eccentrically, moving the limiting crank rod into the limiting slot on the support plate. This further limits and fixes the connecting plate, preventing it from shifting towards the support plate after moving into the adjacent support frame. This would reduce the connection effect between adjacent support frames, leading to decreased stability of the support structure and increased construction risks. The invention enhances the connection effect between support frames and improves the stability of the support structure. Attached Figure Description

[0031] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the overall three-dimensional structure of the present invention;

[0033] Figure 2 This is a schematic diagram of the splicing structure of the support frame provided by the present invention;

[0034] Figure 3 A schematic diagram of the support frame structure provided by the present invention;

[0035] Figure 4 This is a schematic diagram of the limiting component structure provided by the present invention;

[0036] Figure 5 Provided by the present invention Figure 4Enlarged structural diagram at point A in the diagram;

[0037] Figure 6 This is a schematic diagram of the drive component structure provided by the present invention;

[0038] Figure 7 This is a schematic diagram of the connecting plate and support plate structure provided by the present invention.

[0039] Figure label:

[0040] 1. Support frame; 2. Connecting groove; 3. Connecting block; 4. Support base; 5. First positioning block; 6. Second positioning block; 7. Guide block; 8. Support plate; 9. Connecting plate; 10. Guide groove; 11. Guide plate; 12. Limiting slot; 13. Support slide rod; 14. First fixing block; 15. Limiting block; 16. Slide groove; 17. Return spring one; 18. Mounting plate; 19. Push plate; 20. Barrier plate; 21. Second fixing block; 22. Circular disc; 23. Limiting crank rod; 24. Connecting rod; 25. Return groove; 26. Fixing sleeve; 27. Telescopic rod; 28. Return spring two; 29. ​​Drive plate; 30. Temporary support rod. Detailed Implementation

[0041] The present invention will now be described in detail, and the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] This invention provides an improved support structure and construction method for tunnel widening sections. The technical solution of this invention is as follows:

[0043] Example 1

[0044] like Figures 1 to 7 As shown in the figure, this embodiment of the invention provides a support structure for the construction of a tunnel expansion section, including a support frame 1, with support seats 4 rotatably mounted on both sides of the support frame 1, and a support plate 8 fixedly mounted on the top of the support frame 1. A connecting plate 9 is slidably mounted between the support plate 8 and the top of the support frame 1. The structure also includes a limiting component and a driving component. The support frame 1 can be made of high-strength steel to ensure sufficient load-bearing capacity. The rotatable connection of the support seats 4 allows for fine-tuning according to the unevenness of the ground, ensuring stable support.

[0045] Limiting components are installed on the support frame 1 and the support plate 8.

[0046] The limiting assembly includes a pair of first fixing blocks 14 and a second fixing block 21. The pair of first fixing blocks 14 are symmetrically fixed on the support frame 1, and the second fixing block 21 is fixedly installed on the bottom of the support plate 8. The limiting assembly can precisely control the movement of the connecting plate 9 from multiple directions, providing a structural basis for subsequent locking.

[0047] The drive assembly includes a mounting plate 18, a barrier plate 20, and a push plate 19. The mounting plate 18 is fixedly mounted on the top of the support frame 1. The barrier plate 20 slides through the mounting plate 18. The push plate 19 is fixedly mounted on the end of the barrier plate 20. The mounting plate 18 provides guidance for the sliding of the barrier plate 20, ensuring its smooth movement. As a directly force-bearing component, the push plate 19 can be optimized in size and shape according to the diameter of the reinforcing bar to ensure effective pushing of the inserted reinforcing bar.

[0048] Furthermore, each first fixing block 14 has a groove 16 inside, and a limit block 15 is slidably installed inside the groove 16. A return spring 17 is fixedly connected between the limit block 15 and the inner wall of the groove 16. The inner side of the limit block 15 has an inclined surface. The angle design of this inclined surface is crucial. It is necessary to ensure that when the drive plate 29 is pressed, it can generate a sufficient component force to push the limit block 15 back, while ensuring that in the locked state, the flat surface of the limit block 15 can provide sufficient resistance to prevent the drive plate 29 from retracting.

[0049] Furthermore, a disc 22 is eccentrically mounted on one side of the second fixing block 21. A limiting crank 23 is fixedly mounted on the disc 22. A limiting slot 12 is provided on the support plate 8. The limiting crank 23 and the limiting slot 12 are engaged with each other. The eccentric mounting design allows the rotation of the disc 22 to be converted into a large-amplitude swing of the limiting crank 23, thereby blocking or releasing the connecting plate 9. The shape of the limiting slot 12 matches the end of the limiting crank 23 to ensure a firm engagement.

[0050] Furthermore, a fixing sleeve 26 is fixedly installed on one side of the second fixing block 21. A telescopic rod 27 is slidably installed inside the fixing sleeve 26. A drive plate 29 is fixedly installed at the end of the telescopic rod 27. The drive plate 29 is fixedly connected to the connecting plate 9. The combination of the fixing sleeve 26 and the telescopic rod 27 provides guidance and support for the movement of the drive plate 29, making its movement path more precise. The fixed connection between the telescopic rod 27 and the drive plate 29 ensures the directness of power transmission.

[0051] Furthermore, a second return spring 28 is fixedly connected between the drive plate 29 and the fixed sleeve 26, and a support slide rod 13 is fixedly installed between the second fixed block 21 and the support frame 1. The drive plate 29 and the support slide rod 13 slide against each other, and the second return spring 28 provides the power source for the movement of the drive plate 29. The support slide rod 13 further enhances the stability of the drive plate 29 when sliding, preventing it from deflecting or getting stuck.

[0052] Furthermore, a connecting rod 24 is fixedly installed on one side of the push plate 19. The end of the connecting rod 24 is slidably installed on the second fixed block 21. A reset groove 25 is provided at the end of the connecting rod 24. The function of the reset groove 25 is to provide space for the rotary disk 22 to reset, so as to realize the continuous movement of the connecting rod 24 and the intermittent drive of the rotary disk 22. This is the key structure for realizing automatic sequential control.

[0053] Furthermore, multiple support seats 4 are rotatably installed at equal intervals at both ends of the support frame 1. A connecting groove 2 is symmetrically opened on one side of the support frame 1, and a connecting block 3 is symmetrically fixedly installed on the other side. Connecting holes are provided on both the connecting groove 2 and the connecting block 3. A temporary support rod 30 is provided at the bottom of the support seat 4. The design of the connecting groove 2, connecting block 3, and their connecting holes allows multiple support frames 1 to be quickly and accurately assembled into a whole, forming a continuous support system. The temporary support rod 30 can be a hydraulic prop or an adjustable-length mechanical prop for easy installation and disassembly.

[0054] Furthermore, guide grooves 10 are symmetrically provided on the support plate 8, and guide plates 11 are fixedly installed on both sides of the connecting plate 9. The guide plates 11 and guide grooves 10 slide together. The guide structure can effectively restrict the degree of freedom of the connecting plate 9, so that it can only slide in a predetermined direction, thereby improving the reliability of the action.

[0055] Example 2

[0056] A construction method for a support structure in a tunnel widening section includes the following steps:

[0057] Step 1: Determine the quantity of support frame 1 and temporary support rod 30 based on the actual construction conditions of the tunnel expansion section.

[0058] Step 2: After the tunnel is enlarged and excavated, the support frame 1 is evenly laid on the inner wall of the tunnel through the connecting block 3 and the connecting groove 2, and the temporary support rod 30 is installed through the support seat 4 to further improve the support effect of the support frame 1.

[0059] Step 3: When secondary lining is required, workers can insert steel bars into the support frame 1 from one end of the tunnel wall, so that the steel bars exceed the first positioning block 5 and the second positioning block 6 and extend to one side of the second positioning block 6, and the steel bars are evenly distributed around the center of the tunnel by the guide block 7.

[0060] Step 4: When the worker inserts the steel bar, the steel bar pushes the push plate 19, and the push plate 19 drives the barrier plate 20 to move away from the drive plate 29, so that the barrier plate 20 no longer abuts against one side of the drive plate 29. At this time, the reset spring 28 releases its elastic potential energy and undergoes elastic deformation to push the drive plate 29 to move. The drive plate 29 then drives the connecting plate 9 to move, so that the connecting plate 9 moves into the adjacent support frame 1.

[0061] Step 5: When the drive plate 29 moves the connecting plate 9, the drive plate 29 abuts against the limiting block 15, and the inclined surface of the limiting block 15 decomposes the thrust of the drive plate 29 into a tangential force, thereby driving the limiting block 15 to move closer to the first fixed block 14. At this time, the limiting block 15 squeezes the return spring 17, causing the return spring 17 to undergo elastic deformation and accumulate elastic potential energy. When the connecting plate 9 moves into the adjacent support frame 1, the return spring 17 releases its elastic potential energy and undergoes elastic deformation, pushing the limiting block 15 to move away from the first fixed block 14, so that the straight part of the limiting block 15 abuts against one side of the drive plate 29, hindering the movement of the drive plate 29.

[0062] Step 6: The push plate 19 drives the connecting rod 24 to move. The end of the connecting rod 24 pushes the disc 22 to rotate. The disc 22 drives the limiting crank 23 to move, so that the limiting crank 23 stops obstructing the movement of the connecting plate 9. At this time, the connecting rod 24 continues to move, so that the reset groove 25 moves to the bottom of the disc 22. The disc 22 rotates and resets under the action of gravity, thereby driving the limiting crank 23 to reset, so that the limiting crank 23 abuts against one side of the connecting plate 9, obstructing the movement of the connecting plate 9.

[0063] Step 7: The workers remove the temporary support rods 30 and spray concrete onto the support frame 1 to complete the secondary lining of the tunnel support.

[0064] The specific working principle is as follows: First, the initial installation of the support structure is carried out. After the excavation of the tunnel widening section is completed, the required number of support frames 1 and temporary support rods 30 are determined according to design requirements and actual site conditions. Workers hoist multiple support frames 1 into position sequentially, and interlock them with the connecting slots 2 of adjacent frames via connecting blocks 3 on one side. Bolts or pins are then driven into the connecting holes for fixation, thus evenly laying several support frames 1 along the tunnel axial direction to form a continuous initial support ring. Subsequently, the support seats 4, which are rotated and installed on both sides of the support frame 1, are adjusted to a suitable angle, and temporary support rods 30 are installed at their bottom. The other end of the temporary support rod 30 is firmly pressed against the ground or base, and by applying pre-tension, it provides stable support to the support frame 1, ensuring its stability during subsequent construction.

[0065] When secondary lining construction is required, this invention enters the automatic linkage operation stage. Workers begin inserting the designed reinforcing bars one by one into the support frame 1, starting from one end of the tunnel inner wall. The reinforcing bars first pass through the first positioning block 5 and the second positioning block 6, and under the guidance of the guide block 7, are accurately and evenly distributed around the center of the tunnel, laying the foundation for subsequent binding and concrete pouring. As the reinforcing bars continue to be inserted and press against the push plate 19, the drive assembly is triggered. The thrust of the reinforcing bars forces the push plate 19 to move away from the drive plate 29, and the barrier plate 20, fixedly connected to it, slides synchronously on the mounting plate 18. When the barrier plate 20 completely releases its contact constraint on the drive plate 29, the previously compressed return spring 28 instantly releases its elastic potential energy, undergoes elastic deformation, and pushes the drive plate 29 along the support slide rod 13 away from the fixed sleeve 26.

[0066] The movement of the drive plate 29 directly drives the connecting plate 9 fixedly connected to it. The connecting plate 9, through the guide plates 11 on both sides and the guide grooves 10 on the support plate 8, smoothly slides out from the top of the current support frame 1 and moves into the adjacent support frame 1, thereby establishing a temporary mechanical connection between two adjacent support units. During the extension of the connecting plate 9, the drive plate 29 will come into contact with the limiting block 15 slidably installed in the first fixing block 14. Since the inner side of the limiting block 15 has an inclined surface, the thrust of the drive plate 29 is decomposed into a tangential component, which overcomes the elastic force of the return spring 17 and pushes the limiting block 15 into the slide groove 16, causing the return spring 17 to accumulate elastic potential energy. When the connecting plate 9 is fully extended into the adjacent support frame 1 and reaches the predetermined position, the drive plate 29 just passes the limiting block 15. At this time, the reset spring 17 releases its elastic potential energy, pushing the limit block 15 to reset away from the first fixed block 14, so that the flat part of the limit block 15 tightly abuts against one side of the drive plate 29, thereby forming the first lock on the drive plate 29 and preventing it from accidentally retracting along with the connecting plate 9.

[0067] Simultaneously, in the initial stage of the push plate 19 being pushed by the reinforcing bars, the connecting rod 24 fixedly mounted on its side also moves. The end of the connecting rod 24 first contacts the disc 22 eccentrically mounted on the second fixed block 21 and pushes it to rotate. The rotation of the disc 22 causes the limiting crank 23 fixed on it to swing synchronously, causing the limiting crank 23 to disengage from the limiting slot 12, releasing the initial limitation on the connecting plate 9 and clearing the way for the extension of the connecting plate 9. As the push plate 19 continues to move, the connecting rod 24 continues to advance. When the reset slot 25 at its end moves directly below the disc 22, the disc 22 loses the support of the connecting rod 24 and rotates in the opposite direction and resets under its own gravity. This reset action causes the limiting crank 23 to swing again, causing it to re-enter the limiting slot 12 on the support plate 8. At this time, the reset limiting crank 23 is exactly abutting against one side of the fully extended connecting plate 9, forming a second lock on the position of the connecting plate 9. Thus, through the double locking of the limiting block 15 and the limiting crank 23, the connecting plate 9 is firmly fixed in the extended state, tightly connecting the two adjacent support frames 1 into a whole.

[0068] Finally, after confirming that all connecting plates 9 are reliably locked, workers can safely remove the temporary support rods 30. Since adjacent support frames 1 are connected by the connecting plates 9 to form an integral structure, the stability of the entire support system is not reduced by the removal of the temporary support rods 30. Subsequently, workers can spray concrete onto the support frames 1 and the inserted steel mesh to pour the secondary lining. After the concrete solidifies, it forms a high-strength, permanent composite lining together with the built-in steel reinforcement and support frames 1, thus efficiently and safely completing all support work for the tunnel enlargement section.

[0069] The foregoing description enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A support structure for the construction of a tunnel widening section, comprising a support frame (1), wherein support seats (4) are rotatably installed on both sides of the support frame (1), characterized in that: A support plate (8) is fixedly installed on the top of the support frame (1), and a connecting plate (9) is slidably installed between the support plate (8) and the top of the support frame (1). The structure also includes: Limiting components are provided on the support frame (1) and the support plate (8); The limiting component includes a pair of first fixing blocks (14) and a second fixing block (21). The pair of first fixing blocks (14) are symmetrically fixed on the support frame (1), and the second fixing block (21) is fixed on the bottom of the support plate (8). The drive assembly includes a mounting plate (18), a barrier plate (20), and a push plate (19). The mounting plate (18) is fixedly mounted on the top of the support frame (1), the barrier plate (20) slides through the mounting plate (18), and the push plate (19) is fixedly mounted on the end of the barrier plate (20).

2. The tunnel enlargement section construction support structure according to claim 1, characterized in that: Each of the first fixing blocks (14) has a sliding groove (16) inside, and a limiting block (15) is slidably installed inside the sliding groove (16). A reset spring (17) is fixedly connected between the limiting block (15) and the inner wall of the sliding groove (16). The inner side of the limiting block (15) is provided with an inclined surface.

3. The tunnel enlargement section construction support structure according to claim 1, characterized in that: A circular disc (22) is eccentrically mounted on one side of the second fixed block (21). A limiting crank (23) is fixedly mounted on the circular disc (22). A limiting slot (12) is opened on the support plate (8). The limiting crank (23) and the limiting slot (12) are engaged with each other.

4. The tunnel enlargement section construction support structure according to claim 1, characterized in that: A fixing sleeve (26) is fixedly installed on one side of the second fixing block (21). A telescopic rod (27) is slidably installed inside the fixing sleeve (26). A drive plate (29) is fixedly installed at the end of the telescopic rod (27). The drive plate (29) is fixedly connected to the connecting plate (9).

5. The tunnel enlargement section construction support structure according to claim 4, characterized in that: A reset spring (28) is fixedly connected between the drive plate (29) and the fixed sleeve (26), and a support slide rod (13) is fixedly installed between the second fixed block (21) and the support frame (1). The drive plate (29) and the support slide rod (13) are in sliding cooperation.

6. The tunnel enlargement section construction support structure according to claim 1, characterized in that: A connecting rod (24) is fixedly installed on one side of the push plate (19). The end of the connecting rod (24) is slidably installed on the second fixed block (21). A reset groove (25) is opened at the end of the connecting rod (24).

7. The tunnel enlargement section construction support structure according to claim 1, characterized in that: Multiple support seats (4) are rotatably installed at equal intervals at both ends of the support frame (1). A connecting groove (2) is symmetrically opened on one side of the support frame (1), and a connecting block (3) is symmetrically fixedly installed on the other side of the support frame (1). A connecting hole is opened on both the connecting groove (2) and the connecting block (3). A temporary support rod (30) is provided at the bottom of the support seat (4).

8. The tunnel enlargement section construction support structure according to claim 1, characterized in that: The support plate (8) is symmetrically provided with guide grooves (10), and guide plates (11) are fixedly installed on both sides of the connecting plate (9). The guide plates (11) and guide grooves (10) slide together.

9. A construction method for a tunnel enlargement section support structure, applicable to the tunnel enlargement section support structure as described in any one of claims 1-8, characterized in that: Includes the following steps: Step 1: Determine the quantity of support frame (1) and temporary support rod (30) based on the actual construction conditions of the tunnel expansion section; Step 2: After the tunnel is enlarged and excavated, the support frame (1) is evenly laid on the inner wall of the tunnel through the connecting block (3) and the connecting groove (2), and temporary support rods (6) are installed through the support seat (4) to further improve the support effect of the support frame (1). Step 3: When secondary lining is required, workers can insert steel bars into the support frame (1) from one end of the tunnel wall, so that the steel bars exceed the first positioning block (5) and the second positioning block (6) and extend to one side of the second positioning block (6), and the steel bars are evenly distributed around the center of the tunnel through the guide block (7). Step 4: When the worker inserts the steel bar, the steel bar pushes the push plate (19), and the push plate (19) drives the barrier plate (20) to move away from the drive plate (29), so that the barrier plate (20) no longer abuts against one side of the drive plate (29). At this time, the reset spring 2 (28) releases elastic potential energy and undergoes elastic deformation to push the drive plate (29) to move. The drive plate (29) then drives the connecting plate (9) to move, so that the connecting plate (9) moves into the adjacent support frame (1). Step 5: When the drive plate (29) drives the connecting plate (9) to move, the drive plate (29) abuts against the limiting block (15), and the inclined surface of the limiting block (15) decomposes the thrust of the drive plate (29) into a tangential force, thereby driving the limiting block (15) to move closer to the first fixed block (14). At this time, the limiting block (15) squeezes the first reset spring (17), causing the first reset spring (17) to undergo elastic deformation, accumulating elastic potential energy. When the connecting plate (9) moves into the adjacent support frame (1), the first reset spring (17) releases elastic potential energy, undergoes elastic deformation, and pushes the limiting block (15) to move away from the first fixed block (14), so that the straight part of the limiting block (15) abuts against one side of the drive plate (29), hindering the movement of the drive plate (29). Step 6: The push plate (19) drives the connecting rod (24) to move. The end of the connecting rod (24) pushes the disc (22) to rotate. The disc (22) drives the limiting crank (23) to move, so that the limiting crank (23) stops obstructing the movement of the connecting plate (9). At this time, the connecting rod (24) continues to move, so that the reset groove (25) moves to the bottom of the disc (22). The disc (22) rotates and resets under the action of gravity, thereby driving the limiting crank (23) to reset, so that the limiting crank (23) abuts against one side of the connecting plate (9) and obstructs the movement of the connecting plate (9). Step 7: The staff removes the temporary support rods (30) and sprays concrete onto the support frame (1) to complete the secondary lining of the tunnel support.

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