Railway tunnel intelligent detection method based on stress sensing rod

Abstract

The invention relates to an intelligent railway tunnel detection method based on a stress sensing rod, which is applied to the field of detection, and comprises the following steps of: embedding the stress sensing rod in surrounding rock, and detecting deformation of the surrounding rock in the vertical, transverse and longitudinal directions by using a detection unit, so as to analyze and obtain the release direction and deformation of stress; the stress sensing rod is filled with air, and the air is extruded by utilizing the extrusion effect when the stress sensing rod deforms, so that the indicating liquid is driven by the air to be extruded into a specified position, and the deformation amount of the surrounding rock can be known by observing the length of the indicating liquid, so that field maintenance personnel can visually express the deformation amount; and the visual expression form and the detection value of the detection unit can be mutually verified, so that the detection accuracy and stability are effectively improved, in addition, a corresponding support adjustment scheme can be provided for maintenance personnel according to the detection value, and the safety of the tunnel is effectively improved.

Description

Technical Field

[0001] A railway tunnel intelligent detection method based on a stress sensing rod according to the present invention, especially a railway tunnel intelligent detection method based on a stress sensing rod applied to the detection field. Background Art

[0002] Surrounding rock deformation refers to the changes in shape and volume of the rock mass around an underground cavity and the displacement of the cavity wall. It is the general term for rheology, creep, creep, displacement, settlement, and floor heave of the surrounding rock. Surrounding rock deformation has a significant impact on the safe operation of railway tunnels. Therefore, it is crucial to carry out deformation detection work during the excavation process.

[0003] Currently, there are many detection means for tunnel deformation, and numerous devices are used. For example, the patent with the application number CN202010530033.2 discloses a rock bolt for detection, and the patent with the application number CN202410749911.8 discloses a bolt for detecting large deformation of soft rock. However, after analysis, it is found that the bolts in the above two patents can only detect the deformation of the surrounding rock in the vertical direction. In combination with the actual situation, the deformation of the surrounding rock of railway tunnels is not only vertical but also includes lateral and longitudinal deformations. Obviously, the above two patents cannot achieve such technical effects.

[0004] Moreover, the existing detection methods detect the overall deformation of the tunnel. Not only are a large number of sensors required to be arranged and a large amount of manpower and material resources need to be invested, but also the key deformation areas cannot be accurately detected in all directions. As a result, a corresponding adjustment plan cannot be made during the later support adjustment, leading to more severe deformation. Summary of the Invention

[0005] Aiming at the above-mentioned existing technologies, the technical problem to be solved by the present invention is to conduct all-round detection in the key deformation areas and formulate a corresponding support adjustment plan according to the detection results.

[0006] To solve the above problems, the present invention provides a railway tunnel intelligent detection method based on a stress sensing rod, including the following detection steps: S1. Excavation and initial monitoring: Excavate the tunnel, install support for the deformed surrounding rock area. In the initial stage, due to the release of in-situ stress, the plastic deformation of the surrounding rock is large, and a total station is used to continuously detect the deformed area. S2. Drilling: Wait until the stress of the surrounding rock is balanced and the deformation speed decreases, entering the slow deformation period. Remove the total station, open a hole in the support directly below the deformed area, and use a drill rod to drill a detection hole with a diameter of 10 - 20 cm perpendicular to the ground into the surrounding rock. S3. Fixing the stress sensing rod: Insert the stress sensing rod into the detection hole so that its lower end is lower than the support, and use an inflation device to inflate it to make it expand and be stuck in the hole to complete the fixation. S4. Connection device startup detection: Connect the measurement box to the lower end of the stress sensing rod and fix it on the support. Ensure the insulation of the wires and the sealing of the channels. After connecting the measurement box to the background detection and management platform, start the detection; Among them, the stress sensing rod includes an elastic cylinder. An air storage cavity is provided in the middle of the inner wall of the elastic cylinder, and a plurality of installation cavities are distributed around the air storage cavity. A set of sensing chains is placed inside each installation cavity. The measurement box includes a protection box and a plurality of signal processors installed inside the protection box and respectively signal-connected to multiple sets of sensing chains. The signal processors are signal-connected to the background detection and management platform through a remote signal sending device.

[0007] In the above railway tunnel deformation detection method, the deformation of the surrounding rock in the vertical, horizontal, and longitudinal directions is detected by the stress sensing rod that penetrates deep into the surrounding rock. The stress release direction and deformation amount of the surrounding rock are obtained by using the deformation of the stress sensing rod, which is convenient for maintenance personnel to deeply study and analyze the development trend of the surrounding rock deformation and provide support for the maintenance personnel to formulate a matching support adjustment plan.

[0008] As a further improvement of the present application, the sensing chain includes a plurality of detection units connected in series. Each detection unit includes a spherical base slidably connected to the installation cavity, a rotating ball movably hinged to the spherical base, a flexible film pressure sensor fixedly connected to the inner surface of the spherical base, a touch head fixedly connected directly below the rotating ball and matching the flexible film pressure sensor, and an elastic rotating rod fixedly connected directly above the rotating ball. Each elastic rotating rod is fixedly connected to the bottom of the spherical base above it.

[0009] As a further improvement of the present application, the flexible film pressure sensor is integrally divided into a plurality of equal parts, and coordinate information representing different directions, the depth of the surrounding rock, and the offset angle of the touch head relative to the center point of the flexible film pressure sensor is embedded in each equal part through the background detection and management platform.

[0010] As a supplement to the further improvement of the present application, the touch head is made of a smooth and friction-resistant material, and a elastic pad is also laid between the flexible film pressure sensor and the spherical base.

[0011] As a further improvement of the present application, a plurality of LED display signs are fixedly connected to the lower side wall of the protection box and distributed around, and are respectively electrically connected to the multiple signal processors. The displayed image of the LED display sign is an indicating arrow.

[0012] As another improvement of the present application, the lowermost detection unit in each sensing chain is fixedly connected to the inner wall of the installation cavity. The upper end of the elastic cylinder is fixedly connected with a flexible airbag communicating with the inside of the air storage cavity, and the upper end of the flexible airbag is fixedly connected with a pressing hemispherical body. The upper end of the rotating ball at the uppermost position in each sensing chain is fixedly connected with a rigid pressing rod, and the rigid pressing rod penetrates above the installation cavity and is fixedly connected with the pressing hemispherical body. An inductive displacement sensor is installed inside each rotating ball.

[0013] As a supplement to another improvement of the present application, multiple flexible film pressure sensors and inductive displacement sensors in the same sensing chain are all signal-connected to their corresponding signal processors in a parallel manner, and the detection object of the inductive displacement sensor is the spherical base located above it, and the spherical base is made of metal material.

[0014] As yet another improvement of the present application, the lower end of the elastic cylinder is also communicated with a one-way air valve, and a liquid storage tank is placed directly below the one-way air valve in the protection box. The liquid storage tank includes a quick connector matching the one-way air valve, a telescopic airbag communicated with the quick connector, and a liquid pushing plate fixedly connected to the lower end of the telescopic airbag and hermetically sliding-connected to the inner wall of the liquid storage tank. The space below the liquid pushing plate in the liquid storage tank is filled with an indicating liquid. A quantity display strip is fixedly connected to the lower side wall of the protection box, and the quantity display strip includes a sliding cavity communicated with the inside of the liquid storage tank and two measuring blocks hermetically sliding-connected inside the sliding cavity and connected by a return spring.

[0015] As a supplement to yet another improvement of the present application, the quantity display strip is made of a transparent material, and scale lines are engraved at the bottom of the quantity display strip. A fluorescent agent is also mixed in the indicating liquid, and the mixing ratio of the indicating liquid to the fluorescent agent is 2 - 5:1.

[0016] In summary, by burying stress sensing rods inside the surrounding rock, using the detection units to detect the deformation of the surrounding rock in the vertical, horizontal, and longitudinal directions, thereby analyzing and obtaining the stress release direction and deformation amount, and by filling air inside the stress sensing rods, using the extrusion effect when the stress sensing rods deform to squeeze out the air, and then letting the air drive the indicating liquid to be squeezed into the specified position, the deformation amount of the surrounding rock can be known by observing the length of the indicating liquid, so as to give an intuitive expression to the on-site maintenance personnel, and this intuitive expression form can be mutually verified with the detection values of the detection units, thereby effectively improving the accuracy and stability of the detection. In addition, according to the detection values, a corresponding support adjustment plan can be provided for the maintenance personnel, effectively improving the safety of the tunnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is the flowchart of the detection method for the first embodiment of the present application; Figure 2 It is the prior art solution diagram for the first embodiment of the present application; Figure 3 This is the technical solution diagram of the first implementation mode of the present application; Figure 4 This is the front sectional view of the stress sensing rod and the measuring box of the second implementation mode of the present application; Figure 5 This is the three-dimensional exploded view of the sensing chain of the first implementation mode of the present application; Figure 6 This is the front sectional view of the detection unit of the first implementation mode of the present application; Figure 7 This is the state diagram of the detection unit of the first implementation mode of the present application during measurement; Figure 8 This is the state diagram of the sensing chain of the first implementation mode of the present application when detecting lateral and vertical deformations; Figure 9 This is the front sectional view of the digital display bar of the second implementation mode of the present application.

[0018] Description of the reference numerals in the figure: 1 Elastic cylinder, 101 Air storage cavity, 102 Installation cavity, 2 Sensing chain, 3 Protection box, 4 Signal processor, 5 Spherical base, 501 Elastic pad, 6 Rotating ball, 601 Inductive displacement sensor, 7 Flexible thin-film pressure sensor, 8 Touch pressure head, 9 Elastic rotating rod, 10 Pressing hemispherical head, 11 Flexible airbag, 12 Rigid pressing rod, 13 LED display board, 14 One-way air valve, 15 Liquid storage tank, 16 Quick connector, 17 Telescopic airbag, 18 Liquid pushing plate, 19 Digital display bar, 1901 Sliding cavity, 20 Measuring block. Specific implementation mode

[0019] The following will make a detailed description of the two implementation modes of the present application in conjunction with the accompanying drawings.

[0020] The first implementation mode: As Figure 1 shown, it includes the following detection steps: S1. Excavation and initial monitoring: Excavate the tunnel, and install support on the deformed surrounding rock part (at the initial stage of excavation, the prior art uses bolts to fix unstable rock blocks or soil layers on stable rock masses to prevent collapse or landslide, while in this implementation mode, support is used to reinforce the surrounding rock, and the support is an arched steel structure). In the initial stage, due to the release of in-situ stress, the plastic deformation of the surrounding rock is large, and a total station is used to continuously detect the deformed part; S2. Drilling: Wait until the stress of the surrounding rock is balanced and the deformation speed decreases, enter the slow deformation period, remove the total station, open a hole in the support directly below the deformed part, and use a drill rod to drill a detection hole with a diameter of 10 - 20 cm and perpendicular to the ground into the surrounding rock; S3. Fix the stress sensing rod: Insert the stress sensing rod into the detection hole, make its lower end lower than the support, and use an inflation device to inflate it to make it expand and be stuck in the hole to complete the fixation; It should be noted that when inflating the stress sensing rod, the inflation pressure is determined according to the diameters of the on-site stress sensing rod and the detection hole, and inflation is carried out until the stress sensing rod expands and can be firmly clamped with the detection hole; S4. Connection device startup detection: As Figure 3 shown, connect the measurement box to the lower end of the stress sensing rod and fix it on the support, do a good job in wire insulation and channel sealing, and start the detection after connecting the measurement box to the background detection management platform; It should be noted that in order to make the stress sensing rod match the detection hole, the diameter of the stress sensing rod is also 10 - 20 cm, and compared with the prior art, as Figure 2 、 3 shown, only one stress sensing rod needs to be arranged in the key monitoring area for this detection method; Among them, as Figure 4 shown, the stress sensing rod includes an elastic cylinder 1 (preferably made of polyurethane elastic material, and other materials can also be selected according to actual needs). An air storage cavity 101 is arranged in the middle of the inner wall of the elastic cylinder 1, and a plurality of installation cavities 102 are distributed around the air storage cavity 101. A set of sensing chains 2 are placed inside each installation cavity 102. The measurement box includes a protection box 3 and a plurality of signal processors 4 installed inside the protection box 3 and respectively signal-connected to the multiple sets of sensing chains 2. The signal processor 4 is signal-connected to the background detection management platform through a remote signal sending device. The specific connection structure and working principle of this part are well-known technologies for those skilled in the relevant fields and will not be described in detail here; The sensing chain 2 includes a plurality of detection units connected in series. As Figure 5 、 6 shown, each detection unit includes a spherical base 5 slidably connected to the installation cavity 102, a rotating ball 6 movably hinged to the spherical base 5, a flexible film pressure sensor 7 fixedly connected to the inner surface of the spherical base 5 (the specific model is selected according to actual needs and will not be described in detail here), a touch pressure head 8 fixedly connected directly below the rotating ball 6 and matching the flexible film pressure sensor 7, and an elastic rotating rod 9 fixedly connected directly above the rotating ball 6 (preferably made of rubber material, and other materials can also be selected according to actual needs). And each elastic rotating rod 9 is fixedly connected to the bottom of the spherical base 5 above it. After the detection unit is squeezed by the surrounding rock deformation, it will bend in the direction of stress release. At this time, the rotation of the rotating ball 6 in the spherical base 5 will cause the touch pressure head 8 to deviate relative to the center point of the flexible film pressure sensor 7, so that the direction of the surrounding rock deformation can be detected. Moreover, the rotating ball 6 can rotate 360° relative to the spherical base 5, so the deformation detection of the surrounding rock in the horizontal and vertical directions can be realized; As Figure 5As shown in the figure, the flexible film pressure sensor 7 is integrally divided into multiple equal-area regions, and coordinate information representing different directions, surrounding rock depths, and the offset angle of the touch head 8 relative to the center point of the flexible film pressure sensor 7 is embedded in each equal-area region through a background detection and management platform (the specific embedding method and working principle are well-known technologies to those skilled in the relevant art and will not be described in detail here). After the rotating ball 6 rotates relative to the spherical base 5, the touch head 8 offsets from the center point of the flexible film pressure sensor 7 to any one of the equal-area regions of the flexible film pressure sensor 7. Then, the touch head 8 generates a pressure electrical signal in this area, and this electrical signal includes information such as the depth of the detection unit in the surrounding rock, the direction of bending of the detection unit affected by stress release, and the offset angle of the touch head 8 relative to the center point of the flexible film pressure sensor 7. The background detection and management platform can obtain the direction of stress release based on the bending direction of the detection unit, and can obtain the displacement amount during the deformation of the surrounding rock based on the offset angle of the touch head 8 relative to the center point of the flexible film pressure sensor 7. Therefore, the specific parameters of the deformation of the surrounding rock can be detected through the detection unit, which is convenient for maintenance personnel to conduct in-depth research and analysis. The touch head 8 is made of a smooth and friction-resistant material. A elastic pad 501 is also laid between the flexible film pressure sensor 7 and the spherical base 5. In order to extend the service life of the touch head 8, a smooth and wear-resistant material is used. In order to enable the touch head 8 to generate a pressure signal on the flexible film pressure sensor 7, the elastic force of the elastic pad 501 is used to press the flexible film pressure sensor 7 against the touch head 8, effectively avoiding the generation of invalid electrical signals; As Figure 4 shown in the figure, the lowermost detection unit in each group of sensing chains 2 is fixedly connected to the inner wall of the installation cavity 102. The upper end of the elastic cylinder 1 is fixedly connected to a flexible airbag 11 that communicates with the inside of the air storage cavity 101, and the upper end of the flexible airbag 11 is fixedly connected to a top pressure hemisphere 10. The upper end of the rotating ball 6 located at the uppermost part of each group of sensing chains 2 is fixedly connected to a rigid pressure rod 12, and the rigid pressure rod 12 penetrates above the installation cavity 102 and is fixedly connected to the top pressure hemisphere 10. An inductive displacement sensor 601 is installed inside each rotating ball 6. The top pressure hemisphere 10 can press the detection unit downward through the rigid pressure rod 12, and the distance between adjacent two detection units is shortened. At this time, the inductive displacement sensor 601 detects the change in the distance between the two detection units, thereby realizing the detection of the surrounding rock in the vertical direction, and the detection value of the inductive displacement sensor 601 can reflect the vertical deformation amount of the surrounding rock; Multiple flexible film pressure sensors 7 and inductive displacement sensors 601 in the same set of sensing chains 2 are all connected to their corresponding signal processors 4 in parallel. The detection object of the inductive displacement sensor 601 is the spherical base 5 above it. The spherical base 5 is made of metal. The working principle of the inductive displacement sensor 601 is that when the object to be measured approaches or moves away from the coil, the inductance value of the coil will change, and the effect is best when the object to be measured is metal. Therefore, the spherical base 5 is made of metal, and the displacement of the spherical base 5 detected by the inductive displacement sensor 601 can reflect the surrounding rock deformation amount; This implementation method realizes the detection of the deformation of the surrounding rock in the vertical, horizontal and longitudinal directions. It can not only detect the direction of the deformation, but also detect the corresponding deformation amount, which is convenient for maintenance personnel to deeply study and analyze the development trend of the surrounding rock deformation, and provide support for the maintenance personnel to provide a matching support adjustment plan.

[0021] The second implementation method: Although the first implementation method can detect the direction and amount of deformation, it mainly relies on electrical signal detection, and there may be deficiencies in the reliability and working stability of electrical signal detection. Therefore, on the basis that the rest of this implementation method is the same as the first implementation method, a structure that can intuitively express the surrounding rock deformation amount is additionally provided. It can not only provide technical support for the support adjustment plan for on-site maintenance personnel, but also form a mutual verification mechanism with the electrical signal detection method, effectively improving the accuracy of detection. The specific structure is as follows: As Figure 4 shown, a plurality of LED display boards 13 distributed in a ring and respectively electrically connected to a plurality of signal processors 4 are fixedly connected to the lower side wall of the protection box 3. The displayed image of the LED display board 13 is an indicating arrow. After the background detection and management platform analyzes the detection value of the detection unit to obtain the direction of the surrounding rock deformation, it controls the LED display board 13 to display the indicating arrow in the corresponding direction. In this way, the staff on-site for maintenance can intuitively know the direction of the next support adjustment, effectively improving the accuracy of the support adjustment; As Figure 4 、 9As shown in the figure, a one-way air valve 14 is also connected to the lower end of the elastic cylinder 1. A liquid storage tank 15 is placed directly below the one-way air valve 14 in the protection box 3. The liquid storage tank 15 includes a quick connector 16 that matches the one-way air valve 14, a telescopic airbag 17 connected to the quick connector 16, and a liquid pushing plate 18 fixedly connected to the lower end of the telescopic airbag 17 and hermetically slidingly connected to the inner wall of the liquid storage tank 15. The specific connection structure and working principle of the one-way air valve 14 and the quick connector 16 are well-known technologies to those skilled in the relevant art and will not be described in detail here. The space in the liquid storage tank 15 below the liquid pushing plate 18 is filled with an indicating liquid. A quantity display strip 19 is fixedly connected to the lower side wall of the protection box 3. The quantity display strip 19 includes a sliding cavity 1901 communicating with the inside of the liquid storage tank 15, and two measuring blocks 20 hermetically slidingly connected inside the sliding cavity 1901 and connected by a return spring. The quantity display strip 19 is made of a transparent material, and scale lines are engraved at the bottom of the quantity display strip 19. The indicating liquid is also mixed with a fluorescent agent, and the mixing ratio of the indicating liquid to the fluorescent agent is 2 - 5:1. Since the light in the tunnel is relatively dim and the line of sight is not very good, the addition of the fluorescent agent to the indicating liquid is used to improve the display effect. As Figure 9 shown, whether the elastic cylinder 1 is subjected to vertical deformation, lateral and longitudinal deformation extrusion of the surrounding rock, the pre-filled air inside can be squeezed into the telescopic airbag 17. After the telescopic airbag 17 is filled with external air, it expands downward accordingly, and then squeezes the indicating liquid into the quantity display strip 19 to move the measuring blocks 20. In this way, the distance between the two measuring blocks 20 can reflect the deformation amount of the surrounding rock, thus giving the on-site maintenance personnel an intuitive expression form, effectively improving the interaction between people and equipment. At the same time, the intuitive expression of the deformation amount and the detection unit form a mutual verification mechanism. When there is a difference between the two, it can be known that there is a problem with one of them, so as to troubleshoot in time and effectively improve the accuracy of detection.

[0022] It should be added that the detection methods of the stress sensing rod and the measuring box in step S4 are as follows: S41. Lateral and longitudinal deformation monitoring: As Figure 7 、 8 shown, when the surrounding rock deforms laterally and longitudinally, it will cause the stress sensing rod to bend, and the sensing chain 2 will bend accordingly. Multiple detection units in the same group will bend to different degrees and generate electrical signals. The position where the electrical signal is generated is determined by the position of the touch head 8 on the flexible film pressure sensor 7, representing the stress direction. The signal processor 4 transmits the electrical signal to the background detection management platform. The platform analyzes the electrical signals of the same group and multiple groups, selects the maximum offset angle as the detection value, and analyzes the stress release direction and the deformation amount of the surrounding rock based on this to guide the on-site maintenance personnel to adjust the support plan; S42. Vertical direction deformation monitoring: As Figure 8As shown, when the surrounding rock deforms vertically, the lower pressing top pressure hemisphere 10 presses down the sensing chain 2 through the rigid pressing rod 12, causing the spherical base 5 to move. The measured value of the inductive displacement sensor 601 changes and sends out an electrical signal. The electrical signal is the difference before and after the movement of the spherical base 5, representing the deformation amount in the vertical direction. The background detection and management platform compares the differences of the same group and multiple groups, selects the maximum difference as the detection value, and the maintenance personnel adjust the support accordingly. S43. On-site visual inspection method: In addition to obtaining the support adjustment plan from the background, on-site maintenance personnel can also conduct on-site visual inspection. The background controls the LED display board 13 to display the stress release direction indication arrow according to the detection value. After the stress sensing rod is squeezed, the gas is squeezed into the telescopic airbag 17 to make it expand, and the indicating liquid is squeezed into the quantity display bar 19 to push the measuring block 20 to move. The distance between the measuring blocks 20 corresponds to the deformation amount of the surrounding rock, and the same applies to the vertical direction.

[0023] In addition, it should be additionally noted that after the stress sensing rod completes the detection task, in the principle of saving, the measuring box can be disassembled from the support, and then the air inside the stress sensing rod can be released completely through the one-way air valve 14, so that the stress sensing rod can be taken out and reused, saving costs.

[0024] Combined with the current actual requirements, the above implementation method adopted by this application, the protection scope is not limited to this. Within the scope of knowledge possessed by those skilled in the art, various changes made without departing from the concept of this application still fall within the protection scope of the present invention.

Claims

1. A railway tunnel intelligent detection method based on a stress sensing rod, characterized in that: The following detection steps are included: S1. Excavation and initial monitoring: During tunnel excavation, support is set up for the deformed surrounding rock. In the initial stage, due to the release of in-situ stress, the surrounding rock undergoes large plastic deformation, and the deformed parts are continuously monitored using a total station. S2, drilling: wait until the surrounding rock stress is balanced, the deformation speed is reduced, and it enters the slow deformation period, remove the total station, support the opening directly below the deformation part, and use the drill rod to drill a 10-20cm diameter detection hole vertical to the ground into the surrounding rock; S3. Fix the stress sensing rod: insert the stress sensing rod into the detection hole so that its lower end is lower than the support, and use the inflatable device to inflate it so that it expands and gets stuck in the hole to complete the fixation; S4. Connect the equipment and start the test: Connect the measuring box to the lower end of the stress sensing rod and fix it on the support, make sure the wire insulation and channel sealing are done well, connect the measuring box to the background test management platform and start the test; The stress sensing rod comprises an elastic cylinder (1), the inner wall of the elastic cylinder (1) is provided with an air storage cavity (101) located in the middle thereof, and a plurality of mounting cavities (102) distributed around the air storage cavity (101), a group of sensing chains (2) are placed inside each of the mounting cavities (102), the measuring box comprises a protection box (3), and a plurality of signal processors (4) mounted inside the protection box (3) and respectively connected to the signals of the plurality of sensing chains (2), and the signal processors (4) are connected to the backend detection management platform through a remote signal sending device.

2. The intelligent detection method for railway tunnels based on stress sensing rods according to claim 1 is characterized in that: The sensing chain (2) comprises a plurality of detection units connected in series, each of the detection units comprising a spherical base (5) slidably connected to the mounting cavity (102), a follow-up ball (6) movably hinged to the spherical base (5), a flexible film pressure sensor (7) fixedly connected to the inner surface of the spherical base (5), a touch pressure head (8) fixedly connected to the bottom of the follow-up ball (6) and matching the flexible film pressure sensor (7), and an elastic follow-up rod (9) fixedly connected to the top of the follow-up ball (6), and each elastic follow-up rod (9) is fixedly connected to the bottom of the spherical base (5) above it.

3. The intelligent detection method for railway tunnels based on stress sensing rods according to claim 2 is characterized in that: The flexible film pressure sensor (7) is divided into a plurality of equally divided areas as a whole, and coordinate information representing different directions, surrounding rock depths, and offset angles of the pressure head (8) relative to the center point of the flexible film pressure sensor (7) is embedded in each equally divided area through a background detection management platform.

4. The intelligent detection method for railway tunnels based on stress sensing rods according to claim 2 is characterized in that: The touch pressure head (8) is made of a smooth, friction-resistant material, and an elastic pad (501) is provided between the flexible film pressure sensor (7) and the spherical base (5).

5. The intelligent detection method for railway tunnels based on stress sensing rods according to claim 2 is characterized in that: A plurality of LED display boards (13) which are distributed around and electrically connected to a plurality of signal processors (4) are fixedly connected to the side wall at the lower end of the protection box (3), and the images displayed on the LED display boards (13) are indicating arrows.

6. The intelligent detection method for railway tunnels based on stress sensing rods according to claim 2 is characterized in that: The detection unit at the bottom of each set of sensing chains (2) is fixedly connected to the inner wall of the installation cavity (102); the upper end of the elastic cylinder (1) is fixedly connected to a flexible air bag (11) that is in communication with the interior of the air storage cavity (101); the upper end of the flexible air bag (11) is fixedly connected to a top pressure hemisphere (10); the upper end of the follow-up ball (6) at the top of each set of sensing chains (2) is fixedly connected to a rigid pressure rod (12); the rigid pressure rod (12) passes through the top of the installation cavity (102) and is fixedly connected to the top pressure hemisphere (10); and each follow-up ball (6) is installed with an inductive displacement sensor (601) inside.

7. The intelligent detection method for railway tunnels based on stress sensing rods according to claim 6 is characterized in that: The plurality of flexible film pressure sensors (7) and inductive displacement sensors (601) in the same set of sensing chains (2) are all connected in parallel to the corresponding signal processors (4) for signal transmission, and the detection object of the inductive displacement sensor (601) is the spherical base (5) located above it, and the spherical base (5) is made of metal.

8. The intelligent detection method for railway tunnels based on stress sensing rods according to claim 1 is characterized in that: The lower end of the elastic cylinder (1) is also connected to a one-way air valve (14), and a liquid storage box (15) is placed on the protective box (3) directly below the one-way air valve (14). The liquid storage box (15) comprises a quick connector (16) matching the one-way air valve (14), a telescopic air bag (17) connected to the quick connector (16), and a liquid pushing plate (18) fixedly connected to the lower end of the telescopic air bag (17) and sealingly slidably connected to the inner wall of the liquid storage box (15). The space below the liquid pushing plate (18) of the liquid storage box (15) is filled with an indicator liquid. The lower end side wall of the protective box (3) is fixedly connected to a volume display strip (19), and the volume display strip (19) comprises a sliding cavity (1901) connected to the inside of the liquid storage box (15), and two measuring blocks (20) sealedly slidably connected to the inside of the sliding cavity (1901) and connected via a return spring.

9. The intelligent detection method for railway tunnels based on stress sensing rods according to claim 8 is characterized in that: The indicator strip (19) is made of a transparent material, and a scale line is engraved on the bottom of the indicator strip (19). The indicator liquid is also mixed with a fluorescent agent, and the mixing ratio of the indicator liquid to the fluorescent agent is 2-5:1.

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