Supporting method for unstable cavity collapse hole at top of tunnel

Abstract

This invention discloses a support method for unstable collapsed cavities at the top of a tunnel, belonging to the field of tunnel construction technology. The support method includes the following steps: S1: After discovering a collapsed cavity at the top of the tunnel, an initial support steel arch is erected at the top of the tunnel; S2: Anti-collapse support components are installed on the initial support steel arch, with a cave support component at the top of the anti-collapse support components; S3: The cave support components are adjusted to fit snugly against the collapsed cavity, and the cave support components are fixed; S4: The anti-collapse support components are removed, and an arched support fixed to the initial support steel arch is installed at the bottom of the collapsed cavity; S5: Initial shotcrete and secondary lining are carried out at the top of the tunnel; S6: The space between the initial support steel arch and the arched support is filled and sealed. Through this support method and the support structure used, the support structure and the collapsed cavity are closely integrated, jointly generating deformation, thereby improving the support effect, ensuring safe operation in the later stages, and the construction method is simple and does not affect the construction period.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, and in particular to a support method for unstable collapsed cavities at the top of a tunnel. Background Technology

[0002] The focus of highway and railway construction is gradually shifting to the highly developed karst mountainous areas of the west, posing significant challenges to geological surveying, construction safety, and the ecological environment. Karst is a very common geological phenomenon on Earth, occurring from high mountains to rocks thousands of meters deep in the Earth's crust. my country has a vast territory with significant differences in topography and landforms between east and west, resulting in highly complex regional geological conditions, among which karst geology is a typical example of complex geological features. my country is one of the countries with the widest distribution of karst geology in the world, with soluble rock strata covering one-third of its land area.

[0003] Early treatment of karst tunnels often employed a "drainage" method, primarily involving the construction of drainage tunnels, ditches, pipes, seepage trenches, open channels, culverts, or auxiliary pilot tunnels to intercept and drain groundwater. However, tunnels constructed mainly for drainage can introduce numerous geological hazards and quality problems during operation. For cavities and collapses encountered during tunnel excavation, current support methods, primarily concrete retaining walls or shotcrete and anchor systems, are insufficient to achieve the desired support effect under such complex geological conditions. This is mainly because the support structure is not tightly integrated with the karst cave and cannot deform together. Therefore, determining the timing and appropriate solutions for handling geological hazards during karst tunnel excavation has become a pressing issue that needs to be addressed in karst tunnel excavation. Summary of the Invention

[0004] To address the aforementioned problems, this invention aims to provide a support method for unstable collapsed cavities at the top of tunnels. This support method enables the support structure to be tightly integrated with the collapsed cavity, causing them to deform together, thereby improving the support effect, ensuring safe operation in the later stages, and the construction method is simple and does not affect the construction period.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for supporting unstable collapsed cavities in the roof of a tunnel, characterized by comprising the following steps:

[0007] S1: After discovering a collapsed cavity at the top of the tunnel, an initial support steel arch is erected at the top of the tunnel.

[0008] S2: Install anti-collapse support components on the initial steel arch frame;

[0009] S3: Install the karst cave support component on top of the anti-collapse support component, adjust the karst cave support component to fit the collapsed cavity, and then fix the karst cave support component.

[0010] S4: Remove the anti-collapse support components and install an arch support at the bottom of the collapsed cavity, fixing the arch support to the initial support steel arch frame;

[0011] S5: Initial spraying and secondary lining construction at the top of the tunnel;

[0012] S6: After the secondary lining template is removed and the curing strength reaches the design requirements, the space between the initial support steel arch frame and the arch support is filled and sealed.

[0013] Furthermore, the anti-collapse support component includes an inverted C-shaped locking block, the top of the initial support steel arch frame is locked inside the inverted C-shaped locking block, and a movement limiting component is provided between the inverted C-shaped locking block and the initial support steel arch frame; two sets of gear assemblies are installed on the top of the inverted C-shaped locking block, and each set of gear assemblies is movably connected to a support arm for fixing the cave support component.

[0014] Furthermore, the movable limiting component includes a roller installed on the top of the inner sidewall of the inverted C-shaped block, a limiting rack slidably connected to the bottom of the inverted C-shaped block, and a limiting gear rotatably installed inside the inverted C-shaped block, which meshes with the limiting rack.

[0015] Furthermore, each gear assembly includes a gear shaft, on which a large gear and a small gear are coaxially fixed, and each of the large gear and the small gear is meshed with the support arm.

[0016] Furthermore, the cave support assembly includes a tarpaulin and a steel mesh, and the steel mesh is detachably connected to the support arm via a connector.

[0017] Furthermore, the connector includes two spring steel plates symmetrically fixed to the top of the support arm, and two adjusting screws inserted into the reinforcing mesh. Each of the two adjusting screws has a limiting groove matching the spring steel plate on the side close to each other, and the middle parts of the two adjusting screws are connected by a first fixing component; the tops of the two adjusting screws are connected by a second fixing component.

[0018] Furthermore, the first fixing component includes an adjusting nut sleeved on each of the adjusting screws, a limiting ring plate fixed at the top and bottom outer edges of each adjusting nut, and a ring of teeth on the outer side wall of each adjusting nut located between the two limiting ring plates. A driving internal gear is sleeved on both adjusting nuts, and the driving internal gear is meshed with the teeth on the two adjusting nuts.

[0019] Furthermore, the second fixing component includes a fixing plate, the tops of both adjusting screws penetrate the fixing plate, each adjusting screw has a limiting nut at its top, and each limiting nut has a baffle fixed at its top.

[0020] Furthermore, during the initial spraying and secondary lining construction in step S5, grouting ports are reserved. In step S6, grouting pipes are inserted at the grouting ports to fill and seal the grouting area between the initial support steel arch frame and the arch support.

[0021] The beneficial effects of this invention are:

[0022] 1. The support method of this invention, after discovering a collapsed cavity at the top of the tunnel, uses a karst cave support component to support the collapsed cavity. The height of the karst cave support component can be adjusted to ensure that the tarpaulin is tightly integrated with the top of the karst cave, causing deformation together and thus improving the support effect. Then, based on the setting of the arch support, tunnel construction can be carried out while supporting the collapsed cavity, avoiding the need to treat the karst cave before construction in existing support methods, thereby shortening the construction period. After the tunnel secondary lining construction is completed, grouting is performed on the grouting area between the initial support steel arch frame and the arch support to ensure the safety of tunnel operation in the later stage. The support construction method is simple and does not affect the construction period.

[0023] 2. The anti-collapse support component in this invention can be quickly moved and adjusted on the initial support steel arch frame via rollers. The interaction of the limiting rack and limiting gear can fix the anti-collapse support component to the initial support steel arch frame, preventing the position of the anti-collapse support component from shifting when the height of the karst cave support component is adjusted. Through the cooperation between the large and small gears and the support arm, the stable raising and lowering of the karst cave support component can be achieved, improving stability. The tarpaulin in the karst cave support component can fit tightly against the top of the collapsed cavity, and the steel mesh can prevent falling rocks from the top of the collapsed cavity from posing a danger to construction personnel.

[0024] 3. In this invention, the reinforcing mesh and the support arm are detachably connected via connectors. When installing the cave support assembly, the reinforcing mesh is installed on top of the support arm via the connectors. At this time, it is only necessary to insert the spring steel plate into the corresponding limiting groove. Then, two adjusting screws are inserted into the reinforcing mesh, and the tops of the two adjusting screws are fixed above the reinforcing mesh by the fixing plate and the limiting nut. The fixing plate can increase the contact area with the reinforcing mesh and improve the fixing effect. Then, the internal gear is rotated from below the reinforcing mesh to adjust the height of the two adjusting nuts, firmly locking the reinforcing mesh between the fixing plate and the two adjusting nuts, quickly achieving the fixing between the reinforcing mesh and the support arm. When disassembling the anti-collapse support assembly, the support arm is moved downward by the large gear and the small gear, pulling the spring steel plate out of the limiting groove, which quickly achieves the separation between the support arm and the reinforcing mesh. The connector and the reinforcing mesh remain on top of the collapsed cavity. The anti-collapse support assembly can be reused, has low cost, and does not require manual entry into the collapsed cavity to disassemble the reinforcing mesh and the support arm, greatly reducing the difficulty of construction work and improving construction efficiency. Attached Figure Description

[0025] Figure 1 This is a flowchart of the support method in Embodiment 1 of the present invention.

[0026] Figure 2 This is a schematic diagram of the location of the collapsed cavity in Embodiment 1 of the present invention.

[0027] Figure 3 This is a schematic diagram of the overall structure of the support structure in Embodiment 1 of the present invention.

[0028] Figure 4 This is a schematic diagram of the anti-collapse support component structure in Embodiment 1 of the present invention.

[0029] Figure 5 This is a schematic diagram of the gear assembly structure in Embodiment 1 of the present invention.

[0030] Figure 6 This is a schematic diagram of the limiting rack and limiting gear structure in Embodiment 1 of the present invention.

[0031] Figure 7 This is a schematic diagram of the cave support component structure in Embodiment 1 of the present invention.

[0032] Figure 8 This is a schematic diagram of the initial spraying and secondary lining structure in Embodiment 1 of the present invention.

[0033] Figure 9 This is a schematic diagram of the grouting pipe structure in Embodiment 1 of the present invention.

[0034] Figure 10 This is a schematic diagram of the detachable connection structure between the support arm and the steel mesh in Embodiment 2 of the present invention.

[0035] Figure 11 This is a front view of the connector structure in Embodiment 2 of the present invention.

[0036] Figure 12 For the present invention Figure 11 Enlarged view of a portion of the structure in section A.

[0037] Figure 13 This is a schematic diagram of the top structure of the support arm in Embodiment 2 of the present invention.

[0038] Figure 14 This is a schematic diagram of the first fixed component structure in Embodiment 2 of the present invention.

[0039] Figure 15 For the present invention Figure 14 Schematic diagram of cross-sectional structure in the middle BB direction.

[0040] Figure 16 This is a top view of the adjusting nut structure in Embodiment 2 of the present invention.

[0041] Figure 17 This is a cross-sectional view of the internal gear structure in Embodiment 2 of the present invention.

[0042] Figure 18 This is a cross-sectional view of the fixed plate structure in Embodiment 2 of the present invention.

[0043] Figure 19 This is a cross-sectional view of the limiting nut and baffle structure in Embodiment 2 of the present invention.

[0044] The components are as follows: 1-Initial steel arch frame, 101-Anchor bolt, 2-Anti-collapse support component, 201-Inverted C-shaped locking block, 202-Gear assembly, 2021-Gear shaft, 2022-Large gear, 2023-Small gear, 203-Support arm, 204-Roller, 205-Limiting rack, 2051-Extrusion plate, 206-Limiting gear, 207-Mounting plate, 208-Mounting block, 3-Cave support component, 301-Tannel cloth, 302-Steel mesh, 4-Arch support, 5-Initial spraying and secondary lining, 6-Support. Steel plate, 7-grouting pipe, 701-pipe body, 702-elastic plate, 8-grouting area, 9-connector, 901-spring steel sheet, 902-adjusting screw, 903-limiting groove, 904-adjusting nut, 905-limiting ring plate, 906-tooth, 907-drive internal gear, 908-fixed plate, 9081-through hole, 909-limiting nut, 910-baffle, 911-installation groove, 912-spring, 913-limiting ball, 914-operating outer ring, 100-tunnel, 200-collapsed cavity. Detailed Implementation

[0045] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0046] Example 1:

[0047] See attached document Figure 1-9 A method for supporting unstable collapsed cavities at the top of a tunnel includes the following steps:

[0048] S1: After discovering a collapsed cavity 200 at the top of tunnel 100, an initial support steel arch frame 1 was erected at the top of tunnel 100, as shown in the attached diagram. Figure 2-3 As shown, the initial support steel arch 1 matches the shape of the tunnel, and the initial support steel arch 1 is an I-beam. The initial support steel arch 1 is fixed by the locking foot anchor rod 101.

[0049] S2: Install anti-collapse support component 2 on the initial support steel arch frame 1;

[0050] Specifically, the anti-collapse support component 2 is as shown in the attached figure. Figure 4-6 As shown, the system includes an inverted C-shaped locking block 201 with an open bottom. The top horizontal section of the I-shaped structure of the initial support steel arch 1 is locked in the inverted C-shaped locking block 201. A moving limiting assembly is provided between the inverted C-shaped locking block 201 and the initial support steel arch 1. The moving limiting assembly includes a roller 204 installed on the top of the inner wall of the inverted C-shaped locking block 201. The roller 204 allows the entire anti-collapse support assembly 2 to move on the initial support steel arch 1. A limiting rack 205 is slidably connected to the bottom of the inverted C-shaped locking block 201. The limiting rack 205 is arranged vertically, and the bottom of the inverted C-shaped locking block 201 has an opening that matches the limiting rack 205. The matching limiting groove ensures that the limiting rack 205 can only move up and down in the vertical direction; the inverted C-shaped locking block 201 has a limiting gear 206 rotatably installed inside, which meshes with the limiting rack 205. By rotating the limiting gear 206, the limiting rack 205 can be driven to move up and down. The top of the limiting rack 205 is fixed with a pressing plate 2051. When the limiting rack 205 moves upward until the pressing plate 2051 contacts the bottom surface of the top of the I-shaped structure of the initial support steel arch frame 1 and generates pressure, the anti-collapse support component can be limited to prevent it from moving; there are at least two rollers 204 and at least two moving limiting components, which are symmetrically distributed on both sides of the vertical section of the I-shaped structure of the initial support steel arch frame 1.

[0051] Furthermore, the top of the inverted C-shaped locking block 201 is fixedly connected to a mounting block 208 via two mounting plates 207. Two sets of gear assemblies 202 are installed within the mounting block 208, symmetrically arranged. Each set of gear assemblies 202 includes a gear shaft 2021, on which a large gear 2022 and a small gear 2023 are coaxially fixed. Rotating the gear shaft 2021 drives the large gear 2022 and small gear 2023 to rotate synchronously. Each large gear 2022... Both the large gear 2022 and the small gear 2023 are fitted with support arms 203. Each support arm 203 is a long rod structure with toothed grooves. The grooves on the support arm 203 mesh with the corresponding large gear 2022 or small gear 2023. The mounting block 208 has a movable through hole that matches the support arm 203, thereby limiting the movement direction of the support arm 203. By rotating the large gear 2022 and the small gear 2023, the support arm 203 can be moved up and down, thus adjusting its height. It should be noted that the rotation of the gear shaft 2021 is driven by a motor, which is not shown in the figure.

[0052] The inverted C-shaped locking block 201 in the anti-collapse support component 2 is locked onto the top of the I-shaped structure of the primary support steel arch frame 1. The anti-collapse support component 2 is pushed to the design position by the roller 204. The limiting gear 206 is rotated and the height of the limiting rack 205 is adjusted so that the extrusion plate 2051 contacts the top and bottom surfaces of the I-shaped structure of the primary support steel arch frame 1, thereby limiting the position of the anti-collapse support component 2.

[0053] S3: Install the cave support component 3 on the top of the anti-collapse support component 2, adjust the cave support component 3 to fit with the collapsed cavity 200, and then fix the cave support component 3.

[0054] Specifically, the cave support assembly 3 is as shown in the attached figure. Figure 7 As shown, the structure includes a tarpaulin 301 and a reinforcing mesh 302. The tarpaulin 301 covers the reinforcing mesh 302, and the top of the reinforcing mesh 302 is detachably connected to the support arm 203. First, the tarpaulin 301 is placed on top of the reinforcing mesh 302, and the middle part of the reinforcing mesh 302 is installed on top of the support arm 203. Then, both ends of the integral structure formed by the tarpaulin 301 and the reinforcing mesh 302 are fixed to the initial support steel arch 1, and the two ends of the integral structure formed by the tarpaulin 301 and the reinforcing mesh 302 correspond to the edges of the collapsed cavity 200.

[0055] In this step, rotating the gear shaft 2021 drives the large gear 2022 and the small gear 2023 to rotate, thereby adjusting the height of the support arm 203 and adjusting the height of the middle part of the steel mesh 302 and the tarpaulin 301, so that the tarpaulin 301 can fit against the top surface of the collapsed cavity 200, improving the support effect; then, the cave support component 3 can be fixed to the top of the collapsed cavity 200 by installing anchor rods, and the steel mesh 302 can play a protective role, preventing the rock blocks on the top of the collapsed cavity 200 from falling into the construction area.

[0056] S4: Remove the anti-collapse support component 2 and install an arch support 4 at the bottom of the collapsed cavity 200. The arch support 4 is fixed to the initial support steel arch frame 1.

[0057] Disassemble the steel mesh 302 from the support arm 203, rotate the limiting gear 206 in the opposite direction to disengage the limiting rack 205 from the initial support steel arch frame 1, and then remove the anti-collapse support component 2 to the next section.

[0058] An arch support 4 that matches the bottom of the collapsed cavity 200 is prefabricated. The arch support 4 is welded and fixed to the top of the primary support steel arch frame 1 by multiple column-shaped support steel plates 6. A certain height is provided between the primary support steel arch frame 1 and the arch support 4 to form a grouting zone 8.

[0059] S5: Initial shotcreting and secondary lining 5 construction on the top of tunnel 100, as shown in the attached document. Figure 8 As shown;

[0060] The construction of the initial shotcrete and the secondary lining 5 adopts the existing technology. First, the initial shotcrete operation is carried out and grouting ports are reserved. Then, the secondary lining is constructed, and grouting ports are also reserved at the corresponding positions.

[0061] S6: After the secondary lining template is removed and the curing strength reaches the design requirements, the space between the initial support steel arch frame 1 and the arch support 4 is filled and sealed.

[0062] A grouting pipe 7 is inserted at the grouting port, and one end of the grouting pipe 7 is inserted into the grouting area 8 to fill and seal the grouting area 8 between the initial support steel arch frame 1 and the arch support 4.

[0063] The grouting pipe 7 is as shown in the attached figure. Figure 9 As shown, the device includes a pipe body 701, with an elastic plate 702 fixed to the outer periphery of the pipe body 701. One end of the elastic plate 702 is fixedly connected to the pipe body 701, and the other end of the pipe body 701 is inclined outward. When the grouting pipe 7 is inserted, the pipe body 701 and the elastic plate 702 can be inserted into the grouting port together by squeezing the elastic plate 702, so that the elastic plate 702 is located in the grouting zone 8. At this time, the end of the elastic plate 702 that is not connected to the pipe body 701 is located outside the grouting port. Pulling the grouting pipe 7 outward can be limited by the elastic plate 701 to prevent the grouting pipe 7 from falling outward.

[0064] Example 2:

[0065] Based on Embodiment 1, Embodiment 2 provides a detachable connection method between the reinforcing mesh 302 and the support arm 203. Specifically, the reinforcing mesh 302 and the support arm 203 are detachably connected via a connector 9, as shown in the attached figure. Figure 10-19 As shown.

[0066] More specifically, the connector 9 includes two spring steel plates 901 symmetrically fixed to the top of the support arm 203. Both spring steel plates 901 are arc-shaped when not under external force, and can deform along the arc-shaped structure when under external force. The connector 9 also includes two adjusting screws 902 inserted into the reinforcing mesh 302. Since the reinforcing mesh 302 is a mesh structure, the two adjusting screws 902 can pass through the mesh openings of the reinforcing mesh 302. Each of the two adjusting screws 902 has a limiting groove 903 on its side that is close to the other, matching the spring steel plates 901, thus securing the two spring steel plates. The steel plates 901 are inserted into the corresponding limiting grooves 903 to connect the support arm 203 with the two adjusting screws 902. When the support arm 203 moves upward, the adjustment screws 902 move upward synchronously through the cooperation of the spring steel plates 901 and the limiting grooves 903. The spring steel plates 901 will not bend upward and detach from the adjusting screws 902. When the support arm 203 moves downward, with the adjusting screws 902 fixed, the support arm 203 pulls the spring steel plates 901 downward, and the spring steel plates 901 can disengage from the limiting grooves 903, realizing the rapid disengagement of the support arm 203 from the adjusting screws 902.

[0067] To improve the stability of the spring steel sheet 901 in the limiting groove 903 without affecting its disengagement, mounting grooves 911 are symmetrically provided on both sides of each limiting groove 903. Multiple springs 912 are installed in each mounting groove 911, and each spring 912 has a limiting ball 913 at its end. When the spring 912 is in equilibrium, a portion of the limiting ball 913 is located in the limiting groove 903. When the spring steel sheet 901 is inserted into the limiting groove 903, the spring 912 is compressed, and the spring steel sheet 901 is pressed between the two sets of limiting balls 913. Due to the mutual force of the two sets of springs 912, the spring steel sheet 901 is more stably fixed in the limiting groove 903. Furthermore, when the support arm 203 moves downward, the limiting balls 913 do not affect the disengagement of the spring steel sheet 901.

[0068] The two adjusting screws 902 are connected at their middle parts by a first fixing component, which connects the two adjusting screws 902 to form an integral structure. The tops of the two adjusting screws 902 are connected by a second fixing component. In use, the steel mesh 302 is locked between the first fixing component and the second fixing component, thereby fixing the entire connector 9 and the steel mesh 302 together.

[0069] The first fixing assembly includes adjusting nuts 904 sleeved on each adjusting screw 902. Each adjusting nut 904 has a limiting ring plate 905 fixed at its top and bottom outer edges. Each adjusting nut 904 has a ring of teeth 906 on its outer side wall between the two limiting ring plates 905. A driving internal gear 907 is sleeved on both adjusting nuts 904. The driving internal gear 907 meshes with the teeth 906 on the two adjusting nuts 904. The driving internal gear 907 is located at the limiting ring at the top of the two adjusting screws 902. Between plate 905 and bottom limiting ring plate 905, the drive internal gear 907 is prevented from disengaging from the adjusting nut 902. Rotating the drive internal gear 907 causes the teeth 906 on the outer wall of the adjusting nut 904 to mesh, thus rotating the adjusting nut 904 on the adjusting screw 902. Simultaneously, the drive internal gear 907 moves up and down with the adjusting nut 904. This ensures overall synchronicity between the drive internal gear 907 and the two adjusting screws 902, achieving synchronous lifting and lowering of the two adjusting nuts 904 on the two adjusting screws 902. To facilitate rotation of the drive internal gear 907, an operating outer ring 914 with a regular hexagonal outer edge is fixed around the outer circumference of the drive internal gear 907. The operating outer ring 914 and the drive internal gear 907 are an integral structure; rotation of the operating outer ring 914 allows rotation of the drive internal gear 907.

[0070] The second fixing component includes a fixing plate 908, with the tops of both adjusting screws 902 penetrating the fixing plate 908. The fixing plate 908 has through holes 9081 for the two adjusting screws 902 to pass through. Each adjusting screw 902 has a limiting nut 909 at its top, and each limiting nut 909 has a baffle 910 fixed to its top. The limiting nut 909 and the baffle 910 are an integral structure, capable of pressing the fixing plate 908 tightly against the top of the reinforcing mesh 302. The baffle 910 increases the contact area between the limiting nut 909 and the tarpaulin 302, preventing damage to the tarpaulin 301 above the reinforcing mesh 302 after the tops of the adjusting screws 902 penetrate the adjusting screws. The fixing plate 908 increases the contact area between the limiting nut 909 and the reinforcing mesh 302, improving the fixing effect.

[0071] The working principle of the connector 9 in this embodiment is as follows: When the connector 9 in this embodiment is used, the two adjusting screws 902 with the first fixing component are first connected to the support arm 203, and the two spring steel plates 901 are inserted into the limiting grooves 903 of the adjusting screws 902. At this time, the spring steel plates 901 squeeze the springs 912, so that they are squeezed between the two sets of limiting balls 913. Due to the force of the two sets of springs 912 approaching each other, the spring steel plates 901 can be more stably fixed in the limiting grooves 903.

[0072] Then, insert the two adjusting screws 902 into the mesh of the steel mesh 302, clamp the fixing plate 908 onto the two adjusting screws 902, and tighten the limiting nut 909 and the baffle 910 at the top of the adjusting screws 902 so that the bottom of the limiting nut 909 is in contact with the fixing plate 908 and the fixing plate 908 is in contact with the steel mesh 302.

[0073] Finally, rotate the outer ring 914 to rotate the drive gear 907. The rotation of the drive gear 907 causes the adjusting nut 904 to rotate on the adjusting screw 902, thereby moving the entire first fixing component upward on the two adjusting screws 902 until the first fixing component is in contact with the bottom of the steel mesh 302, and the steel mesh 302 is fixed between the first fixing component and the second fixing component.

[0074] When disassembling the anti-collapse support component 2, rotating the gear shaft 2021 drives the large gear 2022 and the small gear 2023 to rotate, adjusting the height of the support arm 203 downwards. As the support arm 203 moves downwards, it pulls the spring steel plate 901, allowing the spring steel plate 901 to disengage from the limiting groove 903. This enables the support arm 203 to quickly disengage from the adjusting screw 902. The adjusting screw 902, the first fixing component, and the second fixing component remain at the top of the collapsed cavity along with the reinforcing mesh 302.

[0075] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for supporting unstable collapsed cavities at the top of a tunnel, characterized in that, Includes the following steps, S1: After discovering the collapsed cavity (200) at the top of the tunnel (100), a preliminary support steel arch frame (1) was erected at the top of the tunnel (100). S2: Install anti-collapse support components (2) on the initial support steel arch frame (1); S3: Install the cave support component (3) on the top of the anti-collapse support component (2), adjust the cave support component (3) to fit with the collapsed cavity (200), and then fix the cave support component (3); S4: Remove the anti-collapse support assembly (2) and set an arch support (4) at the bottom of the collapsed cavity (200), and fix the arch support (4) to the initial support steel arch frame (1); S5: Perform initial spraying and secondary lining (5) construction on the top of the tunnel (100); S6: When the secondary lining template is removed and the curing strength reaches the design requirements, the space between the initial support steel arch frame (1) and the arch support (4) is filled and sealed. The anti-collapse support component (2) includes an inverted C-shaped locking block (201), the top of the primary support steel arch frame (1) is locked in the inverted C-shaped locking block (201), and a moving limiting component is provided between the inverted C-shaped locking block (201) and the primary support steel arch frame (1); two sets of gear assemblies (202) are installed on the top of the inverted C-shaped locking block (201), and each set of gear assemblies (202) is movably connected to a support arm (203) for fixing the cave support component (3). The movable limiting component includes a roller (204) installed on the top of the inner side wall of the inverted C-shaped block (201), a limiting rack (205) slidably connected to the bottom of the inverted C-shaped block (201), and a limiting gear (206) rotatably installed inside the inverted C-shaped block (201) and meshing with the limiting rack (205).

2. The support method for unstable collapsed cavities at the top of a tunnel according to claim 1, characterized in that: Each gear assembly (202) includes a gear shaft (2021), on which a large gear (2022) and a small gear (2023) are coaxially fixed, and each of the large gear (2022) and the small gear (2023) is meshed with a support arm (203).

3. The support method for unstable collapsed cavities at the top of a tunnel according to claim 2, characterized in that: The cave support assembly (3) includes a tarpaulin (301) and a steel mesh (302), and the steel mesh (302) is detachably connected to the support arm (203) via a connector (9).

4. The support method for unstable collapsed cavities at the top of a tunnel according to claim 3, characterized in that: The connector (9) includes two spring steel plates (901) symmetrically fixed to the top of the support arm (203) and two adjusting screws (902) inserted into the steel mesh (302). Each of the two adjusting screws (902) has a limiting groove (903) matching the spring steel plate (901) on the side close to each other. The middle parts of the two adjusting screws (902) are connected by a first fixing component. The tops of the two adjusting screws (902) are connected by a second fixing component.

5. The support method for unstable collapsed cavities at the top of a tunnel according to claim 4, characterized in that: The first fixing component includes an adjusting nut (904) sleeved on each of the adjusting screws (902). Each adjusting nut (904) has a limiting ring plate (905) fixed at the top and bottom outer edges. Each adjusting nut (904) has a ring of teeth (906) on the outer side wall between the two limiting ring plates (905). A driving internal gear (907) is sleeved on the two adjusting nuts (904). The driving internal gear (907) and the teeth (906) on the two adjusting nuts (904) are meshed.

6. The support method for unstable collapsed cavities at the top of a tunnel according to claim 5, characterized in that: The second fixing component includes a fixing plate (908), the tops of the two adjusting screws (902) both penetrate the fixing plate (908), the top of each adjusting screw (902) is provided with a limiting nut (909), and the top of each limiting nut (909) is fixed with a baffle (910).

7. The support method for unstable collapsed cavities at the top of a tunnel according to claim 1, characterized in that: In step S5, grouting ports are reserved during the initial spraying and secondary lining (5) construction. In step S6, grouting pipes (7) are inserted at the grouting ports to fill and seal the grouting area (8) between the initial support steel arch frame (1) and the arch support (4).

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