A tunnel void detection device

Abstract

The application relates to the technical field of tunnel detection, in particular to a tunnel cavity detection device which comprises a holding mechanism, a knocking mechanism and a sound wave receiving mechanism are connected to the upper end of the holding mechanism, the knocking mechanism and the sound wave receiving mechanism are accommodated in a shell, one end of the shell is in an open state, one end of the knocking mechanism is connected with a displacement driving mechanism along the axial direction of the knocking mechanism, the other end of the knocking mechanism reciprocally displaces in the shell towards the port of the shell under the action of the displacement driving mechanism, a supporting mechanism is connected to the outside of the shell along the circumferential direction of the knocking mechanism, a sliding mechanism is arranged on the top of the supporting mechanism, the upper end surface of the sliding mechanism is located above the horizontal plane of the port of the shell, the lower end surface of the sliding mechanism is connected to the side wall of the shell through a plurality of elastic mechanisms, and the plurality of elastic mechanisms are arranged along the circumferential direction of the knocking mechanism. The application can effectively reduce the interference on sound wave receiving, improve the detection accuracy, and has the advantages of convenient operation, high detection accuracy, strong practicability and the like.

Description

Technical Field

[0001] This application relates to the field of tunnel inspection technology, and in particular to a tunnel cavity detection device. Background Technology

[0002] With the rapid development of my country's railway industry, railway tunnels, as a crucial component of railway lines, are of paramount importance for their safe operation. The lining structure of railway tunnels not only bears the pressure of the surrounding rock but also plays a decisive role in ensuring the stability and durability of the tunnel. However, due to the special and concealed nature of railway tunnels, it is difficult to detect and identify internal quality defects and problems in the lining structure in real time. Once defects such as voids, cavities, and cracks appear in the lining, they can potentially lead to serious accidents such as tunnel collapse and water leakage, posing a significant threat to railway operational safety. Therefore, regular comprehensive inspections of tunnels to promptly detect and address lining defects have become necessary measures to prevent accidents and ensure the safe operation of railways. Currently, methods for detecting voids in tunnel linings are mainly divided into two categories: destructive testing (DPT) and non-destructive testing (NDT). DPT requires localized damage to the tunnel lining structure, such as core drilling, which not only damages the integrity of the lining but also requires repair after testing, consuming significant manpower, resources, and time, thus limiting its practical application. In contrast, NDT, with its advantages of no damage to the lining structure and fast testing speed, is more widely used in the field of tunnel lining inspection. Among the many NDT methods, manually striking the tunnel walls with a testing device is a common approach. For example, the void detection device for conventional railway tunnels disclosed in patent publication CN222050081U involves an operator holding a hammer handle, using a sound wave sensor group on the hammer head to receive the sound waves generated by the strike, and then performing time-frequency analysis on the sound wave data through a processor module to convert it into a spectrum diagram to determine the internal condition of the lining. However, this traditional impact testing method has significant drawbacks: when a hammer strikes the concrete surface of the tunnel wall, it induces surface vibrations. These vibrations compress or stretch the air, generating sound waves. These sound waves propagate within the tunnel space, interfering with the effective sound waves required for testing and producing noise, severely affecting the accuracy of the test results. This interference is particularly pronounced in complex tunnel environments with numerous noise sources, making it difficult for inspectors to accurately determine whether voids exist inside the lining and their specific location and size, greatly reducing the reliability and accuracy of the test.

[0003] Therefore, there is an urgent need for a non-destructive testing device for tunnel lining voids that can effectively isolate environmental noise and impact vibration interference, improve the purity of sound wave signal acquisition, and achieve stable and efficient detection. Utility Model Content

[0004] The purpose of this application is to provide a tunnel cavity detection device to solve the problems of large detection noise interference and general accuracy of detection results in the prior art.

[0005] The embodiments of this application can be implemented through the following technical solutions: A tunnel cavity detection device includes a gripping mechanism, the upper end of which is connected to a striking mechanism and a sound wave receiving mechanism. The striking mechanism and the sound wave receiving mechanism are housed in a housing. One end of the housing is open along the axial direction of the striking mechanism. One end of the striking mechanism is connected to a displacement driving mechanism, and the other end moves back and forth toward its port within the housing under the action of the displacement driving mechanism. Along the circumference of the striking mechanism, a support mechanism is connected to the outside of the housing. A sliding mechanism is provided on the top of the support mechanism. The upper end face of the sliding mechanism is located at or above the horizontal plane where the port of the housing is located. The lower end face of the sliding mechanism is connected to the side wall of the housing through a plurality of elastic mechanisms. The plurality of elastic mechanisms are arranged along the circumferential direction of the striking mechanism.

[0006] Furthermore, the displacement driving mechanism is an electromagnetic driving module, which includes an electromagnet, an electromagnetic push rod, and an elastic component. The striking mechanism is coaxially connected to one end of the electromagnetic push rod, and the other end of the electromagnetic push rod passes through the central through hole of the electromagnet and is connected to the bottom of the outer shell. The electromagnet and the outer shell are fixedly connected by a positioning component. The elastic component is sleeved on the lower part of the electromagnetic push rod, and its two ends are respectively limited between the lower end face of the electromagnet and the bottom of the outer shell.

[0007] Furthermore, the elastic mechanism extends along the axial direction of the striking mechanism, one end of the elastic mechanism is fixedly connected to the support mechanism, and the other end is fixedly connected to the bracket of the outer shell, the bracket extending radially along the striking mechanism.

[0008] Furthermore, the support mechanism is sleeved on the outside of the outer shell, and the support mechanism is slidably connected to the outer shell.

[0009] Furthermore, the support mechanism is provided with a plurality of weight-reducing holes, which are arranged circumferentially along the striking mechanism.

[0010] Furthermore, the sliding mechanism includes a support groove and a ball bearing. The bottom of the support groove is connected to the top of the support mechanism, and the ball bearing is rotatably connected inside the support groove. Along the axial direction of the striking mechanism, the highest point of the ball bearing is higher than the opening of the groove surface of the support groove.

[0011] Furthermore, the number of sound wave receiving mechanisms is at least one, and at least one sound wave receiving mechanism is coaxially arranged with the striking mechanism. The acquisition end of the sound wave receiving mechanism is adjacent to the port of the housing, and the sound wave receiving mechanism is communicatively connected to the audio processing module.

[0012] Furthermore, the outer shell is rotatably connected to the gripping mechanism via a damping pivot. The gripping mechanism includes a rod and a hinge frame. Along the axial direction of the rod, the hinge frame is connected to the end of the rod. The hinge frame has a U-shaped symmetrical structure, with its two side arms corresponding to the connecting lugs at the bottom of the outer shell. The arms of the hinge frame and the connecting lugs are connected through the damping pivot.

[0013] Furthermore, the connecting ear plate and / or the two side arms of the hinge frame are provided with hinge holes arranged along the axial direction of the rod body.

[0014] Furthermore, the rod body includes at least two nested sleeves with successively decreasing diameters, the connection position of the at least two nested sleeves is adjustable along the axial direction, and the sidewalls of the two tubes are locked by mutually cooperating elastic locking pins and locking holes or mutually cooperating threads and threaded openings.

[0015] The tunnel cavity detection device provided in the embodiments of this application has at least the following beneficial effects: The striking mechanism and the displacement driving mechanism in this application are coaxially connected. The electromagnetic driving module can drive the striking mechanism to move back and forth stably, ensuring that the striking force and frequency are controllable. The sound wave receiving mechanism is housed in the shell and adjacent to the port. It works with the elastic mechanism to buffer the striking vibration and reduce interference, making the sound wave signal acquisition more accurate and improving the accuracy of cavity identification. It has the advantages of low detection noise interference and accurate detection results.

[0016] The outer shell and the gripping mechanism are rotatably connected via a damping shaft, allowing for flexible adjustment of the detection angle. This easily meets the detection needs of different parts such as tunnel arches and sidewalls. The support mechanism is equipped with an external sliding mechanism, whose ball bearings are higher than the outer shell port, facilitating smooth movement of the device along the lining surface. The support mechanism features circumferential weight-reducing holes, which reduce the weight of the device and the operational burden while ensuring structural strength. It balances mobility and support stability, meeting the detection needs of various scenarios. It has advantages such as convenient manufacturing, high flexibility, and strong practicality. Attached Figure Description

[0017] Figure 1 , Figure 2 These are schematic diagrams of the overall structure of the tunnel cavity detection device of this application from different perspectives; Figure 3 for Figure 1 A magnified view of a portion of point A in the middle; Figure 4This is a cross-sectional schematic diagram of the internal structural components of the shell in this application.

[0018] Numbers in the diagram 1-Holding mechanism; 11-Bar body; 12-Hinge frame; 2-Striking mechanism; 3-Sound wave receiving mechanism; 4-Outer shell; 41-Bracket; 42-Connecting ear plate; 43-Positioning component; 5-Displacement driving mechanism; 51-Electromagnet; 52-Electromagnetic push rod; 53-Elastic component; 6-Support mechanism; 61-Weight reduction hole; 7-Sliding mechanism; 71-Support groove; 72-Ball; 8-Elastic mechanism; 9-Damping shaft. Detailed Implementation

[0019] The present application will now be further described based on preferred embodiments and with reference to the accompanying drawings.

[0020] Furthermore, for ease of understanding, various components on the drawings have been enlarged or reduced, but this is not intended to limit the scope of protection of this application.

[0021] Singular forms of words also include plural meanings, and vice versa.

[0022] In the description of the embodiments of this application, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use, they are only for the convenience of describing this application 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, and therefore should not be construed as a limitation on this application. In addition, in the description of this application, in order to distinguish different units, the terms "first," "second," etc. are used in this specification, but these are not limited by the manufacturing order, nor should they be construed as indicating or implying relative importance. Their names may differ in the detailed description and claims of this application.

[0023] The vocabulary used in this specification is for illustrative purposes and is not intended to limit the scope of this application. It should also be noted that, unless otherwise expressly specified and limited, the terms "set," "connected," and "linked" 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 mechanical connection, a direct connection, or an indirect connection via an intermediate medium; or they can refer to the internal communication between two components. Those skilled in the art will understand the specific meaning of these terms in this application.

[0024] like Figures 1 to 3As shown, a tunnel cavity detection device includes a gripping mechanism 1. The upper end of the gripping mechanism 1 is connected to a striking mechanism 2 and a sound wave receiving mechanism 3. The striking mechanism 2 and the sound wave receiving mechanism 3 are housed in a housing 4. One end of the housing 4 is open. Along the axial direction of the striking mechanism 2, one end of the striking mechanism 2 is connected to a displacement driving mechanism 5. The other end moves back and forth within the housing 4 towards its port under the action of the displacement driving mechanism 5. This is used to strike the surface of the tunnel lining with stable force and frequency, exciting the internal structure of the lining to vibrate and generate characteristic sound waves. At the same time, the sealed space formed by the housing 4 isolates external interference, ensuring that the sound wave receiving mechanism 3 can accurately collect the characteristic sound wave signal indicating whether there is a cavity inside the lining.

[0025] In some preferred embodiments, a support mechanism 6 is connected to the outside of the housing 4 along the circumference of the striking mechanism 2. A sliding mechanism 7 is provided on the top of the support mechanism 6. The upper end face of the sliding mechanism 7 is located at or above the horizontal plane where the port of the housing 4 is located. When adjusting the detection position, the sliding mechanism 7 can reduce the frictional resistance between the housing 4 and the lining surface, making it easier for the operator to move the device flexibly.

[0026] In some preferred embodiments, the sliding mechanism 7 includes a support groove 71 and a ball bearing 72. The bottom of the support groove 71 is connected to the top of the support mechanism 6. The ball bearing 72 is rotatably connected to the inside of the support groove 71 via an annular limiting protrusion on the inner wall of the groove or a detachable end cap, ensuring that the ball bearing 72 can rotate flexibly in any direction while preventing it from falling out of the groove. Along the axial direction of the striking mechanism 2, the highest point of the ball bearing 72 is higher than the groove opening of the support groove 71. When the device is fastened to the tunnel lining surface, the ball bearing 72 can preferentially contact the lining surface, replacing the sliding friction between the support groove 71 and the lining with rolling friction, greatly reducing the resistance when the device moves. At the same time, it avoids the support groove 71 directly scraping the lining surface and causing damage, ensuring that the device can flexibly slide and adjust the detection position in different areas of the lining.

[0027] Furthermore, the lower end face of the sliding mechanism 7 is connected to the side wall of the outer shell 4 through several elastic mechanisms 8. The several elastic mechanisms 8 are arranged along the circumferential direction of the striking mechanism 2. The elastic mechanisms 8 are connected between the sliding mechanism 7 and the outer shell 4, and can serve as a vibration buffer layer. By stretching or deforming, they absorb part of the vibration energy, greatly weaken the intensity of vibration transmission to the outer shell 4, reduce the risk of resonance of the outer shell 4, and reduce the interference of "secondary noise" to the sound wave receiving mechanism 3 from the source.

[0028] In some preferred embodiments, the elastic mechanism 8 extends along the axial direction of the striking mechanism 2, that is, in the same direction as the reciprocating direction of the striking mechanism 2 and perpendicular to the tunnel lining surface to be inspected. One end of the elastic mechanism 8 is fixedly connected to the support mechanism 6, and the other end is fixedly connected to the bracket 41 of the outer shell 4. The bracket 41 extends radially along the striking mechanism 2 and is used to buffer the reaction force vibration generated by the striking through the axial elastic deformation of the elastic mechanism 8. Combined with the design of several elastic mechanisms 8 evenly distributed around the circumference of the striking mechanism 2, the circumferential synergistic effect of multiple sets of elastic mechanisms is utilized to limit the radial displacement of the component through the lateral stiffness of each elastic mechanism, thereby indirectly achieving the isolation of secondary radial vibration during the striking process, and thus reducing interference to the signal collected by the sound wave receiving mechanism 3. Preferably, the elastic mechanism 8 is a shock-absorbing spring.

[0029] In some preferred embodiments, the support mechanism 6 is sleeved on the outside of the outer shell 4, and the support mechanism 6 is slidably connected to the outer shell 4. When the device is fastened to the lining surface, the axially extending elastic mechanism 8 can accurately compensate for the fitting gap between the outer shell 4 and the lining surface through its own expansion and contraction, ensuring that the sliding mechanism 7 located above the horizontal plane of the port of the outer shell 4 can be pressed down to be in the same horizontal plane as the port of the outer shell 4, thereby allowing the sealing gasket of the port of the outer shell 4 to fit tightly against the lining and maintain the sound insulation effect of the sealed space.

[0030] In some preferred embodiments, the support mechanism 6 is provided with a plurality of weight-reducing holes 61, which are arranged along the circumference of the striking mechanism 2 to reduce weight and alleviate fatigue caused by long-term operation.

[0031] In some preferred embodiments, the number of sound wave receiving mechanisms 3 is at least one, and at least one sound wave receiving mechanism 3 is coaxially arranged with the striking mechanism 2. The acquisition end of the sound wave receiving mechanism 3 is adjacent to the port of the outer shell 4. The sound wave receiving mechanism 3 is communicatively connected to an audio processing module. The audio processing module is used to process the audio acquired by the sound wave receiving mechanism 3 to obtain the sound wave of tunnel lining voids. Preferably, the sound wave receiving mechanism 3 is a microphone.

[0032] In some preferred embodiments, such as Figure 4As shown, the displacement driving mechanism 5 is an electromagnetic driving module. The displacement driving mechanism 5 includes an electromagnet 51, an electromagnetic push rod 52, and an elastic component 53. The striking mechanism 2 is coaxially connected to one end of the electromagnetic push rod 52. The other end of the electromagnetic push rod 52 passes through the central through hole of the electromagnet 51 and is connected to the bottom of the outer shell 4. The electromagnet 51 is fixedly connected to the outer shell 4 by a positioning member 43. Preferably, the positioning member 43 is a screw. The elastic component 53 is sleeved on the lower part of the electromagnetic push rod 52, and one end of the elastic component 53 is limited to the lower end face of the electromagnet 51, and the other end is limited to the annular limiting groove on the inner side of the bottom of the outer shell 4. This ensures that both ends of the elastic component 53 are respectively limited between the lower end face of the electromagnet 51 and the bottom of the outer shell 4, effectively preventing the elastic component 53 from moving axially or radially along the electromagnetic push rod 52, and allowing the elastic component 53 to be reset.

[0033] When the electromagnet 51 is energized, the electromagnetic attraction drives the armature to extend the electromagnetic push rod 52 towards the lining, and the striking mechanism 2 completes the striking action. At this time, the elastic component 53 is compressed and stores elastic potential energy. When the electromagnet 51 is de-energized, the electromagnetic attraction disappears, the elastic component 53 releases potential energy to push the electromagnetic push rod 52 to quickly reset, and drive the striking mechanism 2 back to the initial position. At the same time, it buffers the transmission of the striking reaction force to the bottom of the outer shell 4, reduces the interference of vibration on the signal collected by the sound wave receiving mechanism 3, and ensures the stability of the striking frequency and force.

[0034] In some preferred embodiments, the electromagnet 51 establishes a signal and power connection with the control module via wires. The control module can output PWM signals with different duty cycles. The equivalent voltage input to the electromagnet 51 is controlled by adjusting the duty cycle of the PWM signal. The electromagnetic attraction generated by the electromagnet 51 is positively correlated with the square of the input voltage. An increase in voltage will cause the coil inside the electromagnet 51 to generate a stronger magnetic field, which in turn will generate a greater attraction to the armature of the electromagnetic push rod 52, causing the electromagnetic push rod 52 to drive the striking mechanism 2 to move towards the lining surface with a greater thrust, ultimately increasing the striking force. Conversely, by reducing the PWM duty cycle, the voltage is reduced, weakening the electromagnetic attraction and the push rod thrust, thus reducing the striking force. In this way, the control module can precisely adjust the duty cycle of the PWM signal to achieve stepless control of the striking force of the striking mechanism 2, adapting to the detection needs of tunnel linings of different thicknesses and strengths, and avoiding damage to the lining due to excessive force or failure to excite effective characteristic sound waves due to insufficient force.

[0035] In some preferred embodiments, the outer shell 4 is rotatably connected to the gripping mechanism 1 via a damping pivot 9. The gripping mechanism 1 includes a rod 11 and a hinge frame 12. The rod 11 is coaxially arranged with the striking mechanism 2. Along the axial direction of the rod 11, the hinge frame 12 is connected to the end of the rod 11. The hinge frame 12 has a U-shaped symmetrical structure, with its two side arms corresponding to the connecting ear plates 42 at the bottom of the outer shell 4. The arms of the hinge frame 12 and the connecting ear plates 42 are connected through the damping pivot 9. The damping pivot 9 can enable the outer shell 4 to rotate at multiple angles relative to the gripping mechanism 1 when the operator applies external force, and can lock the current angle through its own damping force after the external force is removed, preventing the outer shell 4 from shifting due to gravity or vibration. This ensures that when the device detects different inclined surfaces of the tunnel lining, the open end of the outer shell 4 can still fit tightly against the part to be detected, while allowing the operator to adjust the gripping posture according to the detection position, reducing the labor intensity of long-term operation.

[0036] In some preferred embodiments, in order to achieve the hinge position being set along the axial direction of the striking mechanism 2, the connecting ear plate 42 and / or the two side arms of the hinge frame 12 are provided with hinge holes arranged along the axial direction of the rod 11.

[0037] In some preferred embodiments, the rod 11 is a telescopic and adjustable multi-segment sleeve structure, specifically including at least two nested sleeves with successively decreasing diameters. The connection position of the at least two nested sleeves is adjustable along the axial direction. The side walls of the two tubes are locked by a locking structure, so that the telescopic range of the rod 11 can be set according to the needs of the tunnel inspection scenario. The outer wall of its grip section is wrapped with a non-slip rubber sleeve and has finger-shaped grooves, which not only ensures the convenience of telescopic adjustment and the structural stability after locking, but also improves the comfort of the operator holding it for a long time, and is suitable for inspection operations at different height positions such as tunnel arch, side wall, and invert arch.

[0038] The locking structure consists of mutually cooperating elastic locking pins and locking holes or threads and threaded openings. When using mutually cooperating elastic locking pins and locking holes, the outer tube sidewall is provided with an elastic locking element, and the inner tube is provided with multiple locking holes spaced axially at corresponding positions. When adjusting the length of the rod, pressing the locking element disengages it from the current locking hole. After pulling the inner tube to the required length, the locking element is engaged with the corresponding locking hole under the action of the spring to achieve positioning. When using mutually cooperating threads and threaded openings for locking, the outer wall of the inner tube is provided with an external thread, and the inner wall of the end of the outer tube is provided with a matching internal thread. By rotating the inner tube, the threaded pair rotates relative to each other to achieve length extension and retraction. After reaching the desired position, the self-locking characteristic of the thread completes the locking. The structure is stable and can achieve stepless adjustment.

[0039] The specific embodiments of this application have been described in detail above. For those skilled in the art, several improvements and modifications can be made to this application without departing from the principle of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A tunnel cavity detection device, comprising a gripping mechanism (1), wherein the upper end of the gripping mechanism (1) is connected to a striking mechanism (2) and a sound wave receiving mechanism (3), characterized in that: The striking mechanism (2) and the sound wave receiving mechanism (3) are housed in the housing (4). One end of the housing (4) is open. Along the axial direction of the striking mechanism (2), one end of the striking mechanism (2) is connected to the displacement driving mechanism (5), and the other end moves back and forth toward its port in the housing (4) under the action of the displacement driving mechanism (5). Along the circumference of the striking mechanism (2), a support mechanism (6) is connected to the outside of the outer shell (4). A sliding mechanism (7) is provided on the top of the support mechanism (6). The upper end face of the sliding mechanism (7) is located at or above the horizontal plane where the port of the outer shell (4) is located. The lower end face of the sliding mechanism (7) is connected to the side wall of the outer shell (4) through several elastic mechanisms (8). Several elastic mechanisms (8) are arranged along the circumferential direction of the striking mechanism (2).

2. The tunnel cavity detection device according to claim 1, characterized in that: The displacement driving mechanism (5) is an electromagnetic driving module. The displacement driving mechanism (5) includes an electromagnet (51), an electromagnetic push rod (52), and an elastic component (53). The striking mechanism (2) is coaxially connected to one end of the electromagnetic push rod (52). The other end of the electromagnetic push rod (52) passes through the central through hole of the electromagnet (51) and is connected to the bottom of the outer shell (4). The electromagnet (51) and the outer shell (4) are fixedly connected by a positioning component (43). The elastic component (53) is sleeved on the lower part of the electromagnetic push rod (52), and its two ends are respectively limited between the lower end face of the electromagnet (51) and the bottom of the outer shell (4).

3. The tunnel cavity detection device according to claim 1, characterized in that: The elastic mechanism (8) extends along the axial direction of the striking mechanism (2). One end of the elastic mechanism (8) is fixedly connected to the support mechanism (6), and the other end is fixedly connected to the bracket (41) of the outer shell (4). The bracket (41) extends radially along the striking mechanism (2).

4. The tunnel cavity detection device according to claim 1, characterized in that: The support mechanism (6) is sleeved on the outside of the outer shell (4), and the support mechanism (6) is slidably connected to the outer shell (4).

5. The tunnel cavity detection device according to claim 1, characterized in that: The support mechanism (6) is provided with a plurality of weight-reducing holes (61), which are arranged along the circumference of the striking mechanism (2).

6. The tunnel cavity detection device according to claim 1, characterized in that: The sliding mechanism (7) includes a support groove (71) and a ball (72). The bottom of the support groove (71) is connected to the top of the support mechanism (6). The ball (72) is rotatably connected inside the support groove (71). Along the axial direction of the striking mechanism (2), the highest point of the ball (72) is higher than the groove opening of the support groove (71).

7. The tunnel cavity detection device according to claim 1, characterized in that: The number of sound wave receiving mechanisms (3) is at least one, and at least one of the sound wave receiving mechanisms (3) is arranged coaxially with the striking mechanism (2). The acquisition end of the sound wave receiving mechanism (3) is adjacent to the port of the outer shell (4), and the sound wave receiving mechanism (3) is communicatively connected to the audio processing module.

8. The tunnel cavity detection device according to claim 1, characterized in that: The outer shell (4) is rotatably connected to the gripping mechanism (1) via a damping pivot (9). The gripping mechanism (1) includes a rod (11) and a hinge frame (12). Along the axial direction of the rod (11), the hinge frame (12) is connected to the end of the rod (11). The hinge frame (12) has a U-shaped symmetrical structure, with its two side arms corresponding to the connecting ear plate (42) at the bottom of the outer shell (4). The arms of the hinge frame (12) and the connecting ear plate (42) are connected through the damping pivot (9).

9. The tunnel cavity detection device according to claim 8, characterized in that: The connecting ear plate (42) and / or the two side arms of the hinge frame (12) are provided with hinge holes arranged along the axial direction of the rod (11).

10. The tunnel cavity detection device according to claim 9, characterized in that: The rod (11) includes at least two nested sleeves with successively decreasing diameters. The connection position of the at least two nested sleeves is adjustable along the axial direction. The sidewalls of the two tubes are locked by mutually cooperating elastic locking pins and locking holes or mutually cooperating threads and threaded openings.

Images