A tunnel supporting structure and a supporting method thereof under complex geological conditions

Abstract

The application relates to the technical field of tunnel construction, in particular to a tunnel supporting structure under complex geological conditions, which comprises a steel arch, the steel arch comprises a first steel plate and a second steel plate, the first steel plate is located above the second steel plate, a supporting shoe is arranged below the steel arch, the supporting shoe is movably arranged on the ground of the tunnel, a plurality of pressure-absorbing mechanisms are arranged between the first steel plate and the second steel plate, the pressure-absorbing mechanisms are used for absorbing and dispersing high kinetic energy generated instantaneously when rock burst occurs, the second steel plate and the supporting shoe are rotationally connected through a connecting piece, and a positioning mechanism is arranged between the first steel plate and the supporting shoe. The pressure-absorbing mechanism arranged between the first steel plate and the second steel plate can realize active shrinkage deformation to absorb and consume high kinetic energy generated by rock burst when the rock burst occurs, rigid damage is avoided, and the technical effect of continuous supporting is realized. The technical problem that the prior art lacks the effects of buffering and energy absorption and is prone to brittle damage or overall instability is solved.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, and in particular to a tunnel support structure and support method under complex geological conditions. Background Technology

[0002] In tunnel engineering, the complexity of geological conditions is one of the key factors affecting construction safety and structural stability. As underground engineering progresses to deeper levels, extreme geological conditions such as high ground stress, large deformations in soft rock, and rockbursts are becoming increasingly prominent, posing severe challenges to traditional tunnel support structures. Conventional steel arch support systems typically employ rigid connections or single elastic elements, making it difficult to simultaneously meet the dual requirements of flexible pressure relief and rigid load-bearing. In the initial stage of small deformation in the surrounding rock, excessive support stiffness can easily lead to stress concentration and induce surrounding rock failure. Furthermore, during rockbursts or sudden large deformations of the surrounding rock, if the support cannot absorb high kinetic energy or rapidly increase its load-bearing capacity, structural failure may occur, potentially even leading to catastrophic accidents.

[0003] Traditional tunnel support structures typically employ steel arch frames combined with anchor bolts and shotcrete. However, these rigid support systems often struggle to effectively absorb and disperse the high kinetic energy generated by rockbursts, making them prone to localized yielding, instability, or even complete failure. Furthermore, the connections between traditional steel arch frames and ground (or invert) support shoes are mostly fixed, lacking flexibility and prone to loosening after impact, leading to reduced support effectiveness. Therefore, a new type of tunnel support structure capable of adapting to complex geological conditions such as rockbursts is urgently needed.

[0004] A search revealed Chinese patent CN112780300B, which discloses a high-pressure-bearing tunnel support structure. The structure includes an arched tunnel comprising an arch crown, left arch waist, right arch waist, left arch foot, and right arch foot. Multiple circular holes are evenly distributed on the sidewalls of the arched tunnel. Support chambers communicating with these circular holes are located within the sidewalls of the arched tunnel. Support reinforcing bars are inserted into the circular holes, with one end extending into the support chamber. A reinforcement mechanism is provided on the outside of the support reinforcing bars within the support chamber. This invention, by providing a reinforcement mechanism on the outside of the support reinforcing bars within the support chamber, not only enhances the strength of the reinforcing bars but also effectively drains high-pressure water, allowing the high-pressure water and its potential energy to dissipate outwards, preventing damage to the support system. Furthermore, the arc-shaped members and arc-shaped steel mesh can cover the arch crown, left arch waist, right arch waist, left arch foot, and right arch foot of the arched tunnel, ensuring effective support for the overall structure of the arched tunnel.

[0005] While the aforementioned existing technologies can support the surrounding rock of tunnels, the rigid support suffers from excessive rigidity due to the enormous energy generated instantaneously during rock bursts, leading to stress concentration and a lack of buffering and energy absorption effects. This makes it prone to brittle failure or overall instability. Summary of the Invention

[0006] To address the problems existing in the prior art, this application provides a tunnel support structure under complex geological conditions. The aim is to change the traditional approach of simply increasing the strength and stiffness of materials to resist rockburst impact, and instead use a set of pressure release and release mechanisms to mechanically link and actively absorb, disperse, and buffer the instantaneous high kinetic energy of rockburst, and automatically restore the support function after the impact.

[0007] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows: This application provides a tunnel support structure under complex geological conditions, including a steel arch frame, the steel arch frame comprising a first steel plate and a second steel plate, the first steel plate being located above the second steel plate; it also includes a support shoe disposed below the steel arch frame, the support shoe being movably disposed on the tunnel surface; a plurality of pressure-releasing mechanisms are spaced apart between the first steel plate and the second steel plate, the pressure-releasing mechanisms being used to absorb the high kinetic energy instantaneously generated during dispersed rock bursts; the second steel plate and the support shoe are rotatably connected by a connector, and a positioning mechanism is provided between the first steel plate and the support shoe, the positioning mechanism being used to restrict and lock the connector.

[0008] Further, the pressure-releasing mechanism includes a mounting plate connected to the inner side of the first steel plate and a mounting platform connected to the outer side of the second steel plate. A guide platform is slidably mounted on the mounting platform. A trigger rod is connected between the guide platform and the mounting plate. A pressure plate is connected to the trigger rod. A first disc spring is provided between the pressure plate and the mounting plate, and the first disc spring is sleeved on the trigger rod. Multiple support columns are provided below the pressure plate. Each support column passes through the mounting platform. The guide platform, the mounting platform, and the support columns are connected by a locking pin.

[0009] Furthermore, the technical solution includes multiple clearance grooves running through the mounting platform, and multiple locking grooves also being provided on the mounting platform; multiple guide grooves are provided on the guide platform, and the guide grooves, locking grooves, and clearance grooves are positioned correspondingly; the locking pin slides through the mounting platform and the support column, with one end of the locking pin located in the guide groove and the other end located in the locking groove.

[0010] Furthermore, a torsion spring is fitted onto the locking pin, and the end of the torsion spring is connected to the support column.

[0011] In a further embodiment of the technical solution, the connector includes a support rod fixedly connected to the end of the second steel plate, and a connecting rod fixedly connected to the support rod; the connecting rod is provided with a locking hole.

[0012] Further, the positioning mechanism includes a screw rotatably connected to a connecting rod. The screw passes through a support shoe and is connected to a hydraulic cylinder. One end of the hydraulic cylinder is connected to a hydraulic push rod, and the other end is connected to a locking rod. The locking rod mates with a locking hole. A support plate and a connecting plate are connected to the hydraulic push rod. The connecting plate is connected to a first steel plate. A second disc spring is provided between the support plate and the connecting plate, and the second disc spring is sleeved on the outside of the hydraulic push rod.

[0013] Furthermore, the technical solution includes multiple anchor holes through the first steel plate, the second steel plate, and the support shoe. These anchor holes are used to insert anchor rods and anchor them into the surrounding rock.

[0014] Furthermore, this application provides an operation method for tunnel support structures under complex geological conditions, comprising the following steps: The steel arch frame is installed and temporarily locked to the support shoe using connectors; The moving support shoe synchronously drives the steel arch frame to move, adjusting the relative position of the steel arch frame and the surrounding rock. After the position is adjusted, the positioning mechanism and the connecting parts work together to complete the complete locking of the steel arch frame and the support shoe. The surrounding rock is supported by steel arch frames, support boots, and pressure-releasing mechanisms installed on the steel arch frames.

[0015] Furthermore, this application provides an operation method for tunnel support structures under complex geological conditions, which further includes the following steps: When the surrounding rock bursts or undergoes sudden large deformation, it impacts the steel arch frame. The impact pressure release mechanism of the steel arch frame contracts to absorb and disperse the impact pressure. Once the pressure returns to normal, the pressure release and retraction mechanism should automatically reset to support the surrounding rock.

[0016] Compared with the prior art, the beneficial effects of the present invention are: This invention employs a pressure-retracting mechanism between a first and second steel plate. When a rockburst occurs, the impact force first acts on the first steel plate, driving a trigger rod and a pressure plate to compress a first disc spring. The impact kinetic energy is converted into the elastic potential energy of the first disc spring. During this process, the trigger rod drives the locking pin to slide within the guide groove and locking groove to unlock the support column. This causes the support column to tilt along the relief groove under pressure, dispersing the vertical pressure to the tangential direction and providing support after deformation. After the pressure returns to normal, the torsion spring between the support column and the locking pin allows the support column to return to its vertical support state. The pressure-retracting mechanism can actively contract and deform to absorb and dissipate the high kinetic energy generated by the rockburst, avoiding rigid damage. After the impact, the first disc spring allows the structure to automatically reset, achieving the technical effect of continuous support.

[0017] This invention utilizes a second steel plate and a support shoe that are rotatably connected via a connector, allowing for fine-tuning of the steel arch frame's angle according to the surrounding rock contour during the initial installation phase. Combined with a positioning mechanism, a secure lock is achieved after adjustment. A screw in the internal positioning mechanism triggers a hydraulic cylinder to extend a hydraulic push rod, which in turn drives a locking rod to precisely insert into the locking hole of the connecting rod, ensuring the connector remains stable under dynamic loads and thus achieving overall stability of the steel arch frame.

[0018] The present invention incorporates a second disc spring in the positioning mechanism. When the first steel plate is subjected to a severe impact, the impact force is transmitted to the second disc spring through the connecting plate and hydraulic push rod, forming a secondary buffer path to further disperse energy and protect the structural integrity of the connecting parts and support shoes. Furthermore, the greater the impact force on the first steel plate, the more stable the locking between the locking rod and the locking hole, thus ensuring the long-term stability of the steel arch frame. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a perspective view of the overall structure of the present invention; Figure 2 For the present invention Figure 1 Vertical sectional view; Figure 3 This is a diagram showing the connection relationship between the support boot and the positioning mechanism of the present invention; Figure 4 This is a three-dimensional structural view of the first steel plate of the present invention; Figure 5 This is a diagram showing the connection relationship between the first steel plate and the pressure-releasing mechanism of the present invention; Figure 6 This is a diagram showing the connection relationship between the second steel plate and the pressure-releasing mechanism of the present invention; Figure 7 For the present invention Figure 6 The main view; Figure 8 This is a three-dimensional structural view of the second steel plate of the present invention; Figure 9 This is a schematic diagram of the structure of the pressure-releasing mechanism of the present invention; Figure 10 For the present invention Figure 9 Vertical sectional view; Figure 11 For the present invention Figure 9 A three-dimensional image; Figure 12 This is a schematic diagram of the state of the pressure-bearing mechanism of the present invention after being compressed; Figure 13 This is a diagram showing the positional relationship between the mounting platform and the guide platform of this invention; Figure 14 For the present invention Figure 13 A three-dimensional view viewed from below; Figure 15 For the present invention Figure 13 The main view; Figure 16 For the present invention Figure 15 Sectional view along the AA direction; Figure 17 For the present invention Figure 15 Sectional view along the BB direction; Figure 18 This diagram shows the connection relationship between the guide platform, support column, and locking pin of the present invention. Figure 19 For the present invention Figure 18 Sectional view along the CC direction; Figure 20 This is a three-dimensional structural view of the guide platform of the present invention; In the diagram: 1. Steel arch frame; 11. First steel plate; 12. Second steel plate; 2. Support shoe; 3. Pressure release mechanism; 31. Mounting plate; 32. Mounting platform; 33. Guide platform; 34. Trigger rod; 35. Pressure plate; 36. First disc spring; 37. Support column; 38. Locking pin; 39. Relief groove; 310. Locking groove; 311. Guide groove; 312. Torsion spring; 4. Connecting piece; 41. Support rod; 42. Connecting rod; 43. Locking hole; 5. Positioning mechanism; 51. Screw; 52. Hydraulic cylinder; 53. Hydraulic push rod; 54. Locking rod; 55. Support plate; 56. Connecting plate; 57. Second disc spring; 6. Anchor hole. Detailed Implementation

[0021] 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.

[0022] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "front end", "rear end", "inner side", "outer side", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0023] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0024] Example 1 Reference Figure 1-8 As shown, the present invention provides a tunnel support structure under complex geological conditions, including a steel arch frame 1. The steel arch frame 1 is a double-layer structure, specifically including a first steel plate 11 and a second steel plate 12. The first steel plate 11 is located above the second steel plate 12, that is, the first steel plate 11 is closer to the surrounding rock. The structure also includes a support shoe 2 disposed below the steel arch frame 1. The support shoe 2 is movably disposed on the tunnel floor and can slide along the ground to adjust its position.

[0025] Specifically, refer to Figure 3 As shown, the support shoe 2 consists of two parts: a support block and two sets of rollers located at the bottom of the support block. The rollers facilitate the movement of the support shoe 2, which drives the steel arch frame 1 within the tunnel.

[0026] In this embodiment, refer to Figure 5 As shown, both the first steel plate 11 and the second steel plate 12 are arched structures, and the first steel plate 11 has an installation groove on its inner side, while the second steel plate 12 is partially fixedly fitted into the installation groove on the first steel plate 11.

[0027] To cope with rockburst impact, multiple pressure-retracting mechanisms 3 are provided at intervals between the first steel plate 11 and the second steel plate 12. Specifically, the pressure-retracting mechanism 3 is located in the mounting groove opened on the first steel plate 11.

[0028] In this embodiment, refer to Figure 9-20 As shown, the pressure-releasing mechanism 3 includes a mounting plate 31 fixedly connected to the inner side of the first steel plate 11, and a mounting platform 32 fixedly connected to the outer side of the second steel plate 12. A guide platform 33 is slidably disposed on the mounting platform 32. A trigger rod 34 is connected between the guide platform 33 and the mounting plate 31, and a pressure plate 35 is fixedly connected to the trigger rod 34. A first disc spring 36 is disposed between the pressure plate 35 and the mounting plate 31, and the first disc spring 36 is sleeved on the outside of the trigger rod 34.

[0029] In detail, the mounting plate 31 has an arc-shaped plate structure and is attached to the inner side of the first steel plate 11. The mounting platform 32 has a "T"-shaped structure and a circular groove is provided in the mounting platform 32 for the guide platform 33 to slide. The guide platform 33 has a frustum structure that is smaller at the top and larger at the bottom.

[0030] As an example, the first disc spring 36 in this application has variable stiffness mechanical characteristics. Its initial stiffness is low, about 40 kN / mm, which allows the surrounding rock to obtain flexible pressure relief under small deformation and avoids stress concentration. Its end stiffness is high, about 400 kN / mm, which limits excessive deformation.

[0031] Furthermore, multiple support columns 37 are provided below the pressure plate 35, with the upper ends of the support columns 37 abutting against the pressure plate 35. Each support column 37 passes through the mounting platform 32. The guide platform 33, the mounting platform 32, and the support columns 37 are connected by locking pins 38. When a rock eruption occurs, the first steel plate 11 is pressed, causing the mounting plate 31 to compress the first disc spring 36 and deform. The first disc spring 36 absorbs part of the kinetic energy. Simultaneously, the first steel plate 11 is pressed, pushing the trigger rod 34 and causing the support columns 37 to move downward through the pressure plate 35.

[0032] To ensure reliable guidance of the locking pin 38, the mounting platform 32 is provided with multiple clearance grooves 39 and multiple locking grooves 310. The guide platform 33 is provided with multiple guide grooves 311, and the guide grooves 311, locking grooves 310, and clearance grooves 39 are positioned correspondingly. The locking pin 38 slides through the mounting platform 32 and the support column 37, with one end located in the guide groove 311 and the other end located in the locking groove 310. When the trigger rod 34 moves downward, the locking pin 38 slides upward along the guide groove 311. Since the bottom surface of the guide groove 311 is wedge-shaped, the locking pin 38 disengages from the locking groove 310 at the other end during the sliding process, thereby releasing the restriction on the support column 37. This causes the support column 37 to tilt along the clearance groove 39 under the push of the pressure plate 35, thereby dispersing the vertical pressure to the tangential direction of the support column 37, thus dispersing the stress and also providing support.

[0033] As an example, the clearance groove 39 is a rounded rectangular structure, the locking groove 310 is a cuboid structure, the guide groove 311 is a "T" shaped structure, and the locking pin 38 has cuboid structures at both ends and a cylindrical structure in the middle.

[0034] Furthermore, a torsion spring 312 is fitted onto the locking pin 38, and the end of the torsion spring 312 is connected to the support column 37 to provide a restoring torsional force. After the rock burst ends and the pressure returns to normal, the torsion spring 312 between the support column 37 and the locking pin 38 can restore the support column 37 to a vertical support state.

[0035] Example 2 Based on Example 1, referring to Figure 8 As shown, in order to facilitate the adjustment of the angle of the steel arch frame 1 and make it fit the surrounding rock better, a connecting piece 4 is provided between the second steel plate 12 and the support shoe 2.

[0036] In this embodiment, the connector 4 includes a support rod 41 fixedly connected to the end of the second steel plate 12, and a connecting rod 42 fixedly connected to the support rod 41. The connecting rod 42 is provided with a locking hole 43.

[0037] Furthermore, a positioning mechanism 5 is provided between the first steel plate 11 and the support shoe 2 to restrict and lock the connecting piece 4.

[0038] For details, refer to Figure 2-3 , Figure 6-7 As shown, the positioning mechanism 5 includes a screw 51 rotatably connected to the connecting rod 42. The screw 51 passes through the support shoe 2 and is connected to a hydraulic cylinder 52. One end of the hydraulic cylinder 52 is connected to a hydraulic push rod 53, and the other end is connected to a locking rod 54. The locking rod 54 engages with a locking hole 43. A support plate 55 and a connecting plate 56 are connected to the hydraulic push rod 53, and the connecting plate 56 is connected to the first steel plate 11. A second disc spring 57 is provided between the support plate 55 and the connecting plate 56, and the second disc spring 57 is sleeved on the outside of the hydraulic push rod 53. When the first steel plate 11 is impacted, the force is transmitted to the second disc spring 57 through the connecting plate 56 and the hydraulic push rod 53, forming a secondary buffer.

[0039] As an example, the head end of the locking rod 54 is tapered, which makes the first steel plate 11 more subjected to impact force, thereby pushing the locking rod 54 into the locking hole 43 more, making the locking more secure.

[0040] It should be noted that the second disc spring 57 has the same variable stiffness mechanical characteristics as the first disc spring 36.

[0041] Furthermore, to enhance the overall support anchoring capacity, multiple anchor holes 6 are provided through the first steel plate 11, the second steel plate 12, and the support shoe 2 for inserting anchor rods and anchoring the anchor rods into the surrounding rock.

[0042] It should be noted that the hydraulic cylinder 52 and hydraulic push rod 53 mentioned above are all existing mature components. The specific model can be selected according to actual needs, and the inventor can purchase them on the market.

[0043] Specific application examples The following describes the specific application process of a tunnel support structure under complex geological conditions in the tunnel support process under complex geological conditions of high ground stress and frequent rock bursts, in conjunction with Embodiment 1 and Embodiment 2.

[0044] In tunnel construction, especially under complex geological conditions of high ground stress and frequent rockbursts, controlling the stability of the surrounding rock is a key technical challenge. Rockburst is a dynamic instability phenomenon characterized by its suddenness and large energy release, posing a serious threat to the safety of construction equipment and personnel.

[0045] Traditional tunnel support structures typically employ steel arch frames combined with anchor bolts and shotcrete. However, these rigid support systems often struggle to effectively absorb and disperse the high kinetic energy generated by rockbursts, making them prone to localized yielding, instability, or even complete failure.

[0046] Based on this, this application provides a tunnel support structure under complex geological conditions. In specific use: the steel arch frame 1 is hoisted into place, and the second steel plate 12 is temporarily rotated and connected to the support shoe 2 by the screws 51 in the connector 4.

[0047] Pushing or pulling the support shoe 2 moves it along the tunnel floor, thereby moving the entire steel arch frame 1 and adjusting the first steel plate 11 to achieve the optimal fit with the surrounding rock contour. After the position is confirmed, the screw 51 in the inward positioning mechanism 5 triggers the hydraulic cylinder 52 to drive the hydraulic push rod 53 to extend towards the locking rod 54, so that the locking rod 54 inserts into the locking hole 43 on the connecting rod 42, completing the complete locking of the steel arch frame 1 and the support shoe 2. Subsequently, anchor rods are driven into each anchor hole 6 and grout is injected to anchor the entire support structure in the surrounding rock.

[0048] Under normal working conditions without rock bursts, the steel arch frame 1, the support shoe 2, and the anchor bolts work together to provide a stable radial constraint force on the surrounding rock.

[0049] Under normal support conditions, the two ends of the locking pin 38 are respectively engaged in the guide groove 311 and the locking groove 310, the support column 37 is locked, and the first disc spring 36 is in a pre-compressed state.

[0050] When a rockburst or sudden large deformation of the surrounding rock occurs, such as when the impact load exceeds 500 kN, the surrounding rock violently impacts the first steel plate 11, pushing the mounting plate 31 and the trigger rod 34 downward. The mounting plate 31 then compresses the first disc spring 36 downward, and the impact kinetic energy is converted into the elastic potential energy of the first disc spring 36, which in turn drives the support column 37 to move downward synchronously.

[0051] As the trigger rod 34 moves downward, it causes the locking pin 38 to slide upward within the guide groove 311, thereby releasing the restriction of the locking groove 310 on the locking pin 38. Simultaneously, the pressure plate 35 pushes the support column 37 to overcome the torque of the torsion spring 312 and tilt along the relief groove 39, which can effectively prevent stress concentration and decompose the vertical pressure to the tangential direction of the support column 37, thereby achieving stress dispersion.

[0052] At the same time, some of the impact force is transmitted to the connecting plate 56 through the first steel plate 11. The connecting plate 56 compresses the second disc spring 57 and pushes the hydraulic push rod 53 to form a secondary buffer path, further dispersing the energy and protecting the structural integrity of the connecting piece 4 and the support shoe 2.

[0053] When the rockburst pressure disappears, the first disc spring 36 releases its potential energy, pushing the trigger rod 34 and the pressure plate 35 to reset upwards. The locking pin 38 slides downwards along the guide groove 311 and slides into the locking groove 310 to lock. The support column 37 deflects and resets to the initial vertical support state under the action of the torsion spring 312. Simultaneously, the second disc spring 57 resets, and the entire structure re-tightens against the surrounding rock to achieve continuous and effective support.

[0054] It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of this invention, and these should also be considered within the scope of protection of this invention. These modifications and improvements will not affect the effectiveness of the invention or the practicality of the patent. The scope of protection claimed in this application shall be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A tunnel support structure under complex geological conditions, comprising a steel arch frame (1), characterized in that: The steel arch frame (1) includes a first steel plate (11) and a second steel plate (12), with the first steel plate (11) located above the second steel plate (12); It also includes a support shoe (2) installed below the steel arch frame (1), the support shoe (2) being movably installed on the tunnel floor; Multiple pressure-retracting mechanisms (3) are provided at intervals between the first steel plate (11) and the second steel plate (12). The pressure-retracting mechanisms (3) are used to absorb the high kinetic energy generated instantaneously when the dispersed rock burst occurs. The second steel plate (12) is rotatably connected to the support shoe (2) via a connector (4). A positioning mechanism (5) is provided between the first steel plate (11) and the support shoe (2). The positioning mechanism (5) is used to restrict and lock the connector (4).

2. The tunnel support structure under complex geological conditions according to claim 1, characterized in that: The pressure-retracting mechanism (3) includes a mounting plate (31) connected to the inner side of the first steel plate (11) and a mounting platform (32) connected to the outer side of the second steel plate (12). A guide platform (33) is slidably provided on the mounting platform (32). A trigger rod (34) is connected between the guide platform (33) and the mounting plate (31). A pressure plate (35) is connected to the trigger rod (34). A first disc spring (36) is provided between the pressure plate (35) and the mounting plate (31). The first disc spring (36) is sleeved on the trigger rod (34). Multiple support columns (37) are provided below the pressure plate (35), and each support column (37) passes through the mounting platform (32). The guide platform (33), the mounting platform (32) and the support column (37) are connected by a locking pin (38).

3. The tunnel support structure under complex geological conditions according to claim 2, characterized in that: The mounting platform (32) is provided with multiple clearance grooves (39) and multiple locking grooves (310). The guide platform (33) is provided with a plurality of guide grooves (311), and the guide grooves (311), locking grooves (310) and clearance grooves (39) are positioned correspondingly; The locking pin (38) slides through the mounting platform (32) and the support column (37). One end of the locking pin (38) is located in the guide groove (311), and the other end is located in the locking groove (310).

4. The tunnel support structure under complex geological conditions according to claim 3, characterized in that: A torsion spring (312) is fitted on the locking pin (38), and the end of the torsion spring (312) is connected to the support column (37).

5. A tunnel support structure under complex geological conditions according to claim 1 or 4, characterized in that: The connector (4) includes a support rod (41) fixedly connected to the end of the second steel plate (12), and a connecting rod (42) fixedly connected to the support rod (41). The connecting rod (42) has a locking hole (43).

6. A tunnel support structure under complex geological conditions according to claim 5, characterized in that: The positioning mechanism (5) includes a screw (51) rotatably connected to the connecting rod (42). The screw (51) passes through the support shoe (2) and is connected to a hydraulic cylinder (52). One end of the hydraulic cylinder (52) is connected to a hydraulic push rod (53), and the other end is connected to a locking rod (54). The locking rod (54) is engaged with the locking hole (43), and the hydraulic push rod (53) is connected to a support plate (55) and a connecting plate (56), and the connecting plate (56) is connected to the first steel plate (11). A second disc spring (57) is provided between the support plate (55) and the connecting plate (56), and the second disc spring (57) is sleeved on the outside of the hydraulic push rod (53).

7. A tunnel support structure under complex geological conditions according to claim 6, characterized in that: Multiple anchor holes (6) are provided through the first steel plate (11), the second steel plate (12), and the support shoe (2). The anchor holes (6) are used to insert anchor rods and anchor the anchor rods in the surrounding rock.

8. The support method for a tunnel support structure under complex geological conditions according to claim 1, characterized in that, Includes the following steps: The steel arch frame (1) is installed and temporarily locked to the support shoe (2) by the connector (4); The moving support shoe (2) synchronously drives the steel arch frame (1) to move, and adjusts the relative position of the steel arch frame (1) and the surrounding rock. After the position is adjusted, the positioning mechanism (5) and the connecting piece (4) work together to complete the complete locking of the steel arch frame (1) and the support shoe (2). The support of the surrounding rock is achieved by the steel arch frame (1), the support shoe (2) and the pressure release mechanism (3) set on the steel arch frame (1).

9. A support method for a tunnel support structure under complex geological conditions according to claim 8, characterized in that, It also includes the following steps: When the surrounding rock bursts or undergoes sudden large deformation, it impacts the steel arch frame (1). The impact pressure on the steel arch frame (1) is reduced by the pressure-reducing mechanism (3), which absorbs and disperses the impact pressure. After the pressure returns to normal, the pressure release mechanism (3) should automatically reset to achieve support for the surrounding rock.

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