Stratification cavity detection device and system

Abstract

This invention proposes a ground cavity detection device and system. The detection device includes at least one set of transmitting and receiving devices installed on the inner side of the shield shell of a tunneling machine. Both the transmitting and receiving devices have hydraulic cylinders, connecting cylinders, and telescopic columns. The two ends of the connecting cylinder are connected to the hydraulic cylinder and the inner side of the shield shell, respectively. The end of the piston rod inside the hydraulic cylinder is located inside the connecting cylinder and connected to the telescopic column. The movement of the piston rod can drive the telescopic column to slide within the connecting cylinder, allowing the end of the telescopic column to extend outward or retract inward from the telescopic hole on the shield shell. The telescopic column of the transmitting device contains a sound wave transmitting module, and the telescopic column of the receiving device contains a sound wave receiving module. This invention overcomes the lack of a technical solution for detecting geology above the tunnel boring machine (TBM), achieving the purpose of detecting ground cavities. Based on the detection results, the TBM parameters can be adjusted in a timely manner to avoid the risk of ground collapse or subsidence, ensuring stable construction.

Description

Technical Field

[0001] This utility model relates to the field of tunneling geological exploration technology, and in particular to a stratum cavity detection device and system. Background Technology

[0002] The disturbance to the above-ground strata during tunnel boring machine (TBM) excavation is a critical issue that cannot be ignored in urban underground engineering. The dynamic construction process of the TBM—cutting the soil with its cutterhead, simultaneously grouting to fill voids, and assembling tunnel segments to form the tunnel structure—disrupts the original stress balance of the strata. Due to the combined effects of soil excavation unloading, incomplete grouting, groundwater seepage, and mechanical vibration, stress redistribution easily occurs within the strata, leading to compression, loosening, or localized loss of the above-ground soil. If the disturbance exceeds a controllable range, it may form hidden cavities below the surface. These cavities are difficult to detect initially but will expand over time due to continuous soil and water erosion, eventually causing secondary disasters such as surface subsidence, pipeline rupture, or settlement of surrounding buildings and structures. Therefore, systematic cavity detection above the ground during TBM construction is a core technical aspect for ensuring project safety and preventing urban public risks.

[0003] In recent years, with the development of science and technology, research on geological exploration during tunnel construction has gradually emerged. For example, Chinese invention patent application CN202311621154.8 describes an advanced geological exploration method and device mounted on an ultra-large diameter slurry shield tunneling machine. This method uses an advanced geological prediction system mounted on an ultra-large diameter slurry shield tunneling machine to obtain the target seismic wave signal fed back from the tunnel face. The secondary denoising signal is then identified through an adverse geological body identification model to obtain the geological type identification result corresponding to the secondary denoising signal.

[0004] Current technologies can predict and detect abnormal geological conditions in front of the tunnel boring machine (TBM), but lack detection of abnormal geological conditions above the strata during construction. During construction, abnormal geological conditions in front of and above the TBM can significantly affect the normal operation of the TBM. Therefore, it is necessary to design a system for detecting cavities above the tunnel strata. Utility Model Content

[0005] The purpose of this invention is to provide a ground cavity detection device and system to address the lack of technical solutions for detecting geology above tunnel boring machines in the existing technology. This system aims to detect ground cavities during tunneling and adjust tunneling parameters in a timely manner based on the detection results, thereby avoiding the risk of ground collapse or subsidence and ensuring stable construction.

[0006] The above-mentioned technical objectives of this utility model are mainly achieved through the following technical solutions.

[0007] On the one hand, this utility model provides a ground cavity detection device, which includes at least one set of transmitting and receiving devices installed on the inner side of the shield shell of a tunneling machine;

[0008] Both the transmitting device and the receiving device have a hydraulic cylinder, a connecting cylinder, and a telescopic column. The two ends of the connecting cylinder are respectively connected to the inner side of the hydraulic cylinder and the shield shell. The end of the piston rod in the hydraulic cylinder is located inside the connecting cylinder and connected to the telescopic column. The movement of the piston rod can drive the telescopic column to slide inside the connecting cylinder, so that the end of the telescopic column extends outward or retracts inward from the telescopic hole on the shield shell.

[0009] The transmitting device has a sound wave transmitting module inside its telescopic column, and the receiving device has a sound wave receiving module inside its telescopic column.

[0010] In a preferred embodiment of the present invention, the sound wave emitting module has a pneumatic striking device for generating sound wave signals, the pneumatic striking device comprising a cylinder and a striking plate arranged opposite to each other.

[0011] In a preferred embodiment of this utility model, a ball valve is provided between the connecting cylinder and the side wall of the shield shell. The two ends of the valve seat of the ball valve are respectively fixedly connected to the shield shell and the connecting cylinder by bolts. The telescopic column passes through the through hole in the ball valve.

[0012] In a preferred embodiment of this utility model, the circumferential gap between the telescopic column and the connecting cylinder, the circumferential gap between the telescopic column and the ball valve, and the circumferential gap between the telescopic column and the telescopic hole are all filled with sealing oil.

[0013] In a preferred embodiment of this utility model, the axis of the piston rod inside the cylinder, the axis of the connecting cylinder, the axis of the telescopic column, and the axis of the telescopic hole on the shield shell coincide.

[0014] In a preferred embodiment of this utility model, the axis of the telescopic column is perpendicular to the inner surface of the shield.

[0015] In a preferred embodiment of the present invention, a set of transmitting and receiving devices includes one transmitting device and two receiving devices disposed on both sides of the transmitting device.

[0016] In a preferred embodiment of this utility model, the transmitting device and the receiving device are arranged at intervals along the tunneling direction of the tunneling machine, and the distance between the transmitting device and the receiving device is 0.5m.

[0017] In a preferred embodiment of this utility model, when the piston rod of the hydraulic cylinder is in the extended state, the end of the telescopic column extends outward from the shield shell by a length greater than or equal to 5 cm.

[0018] In a preferred embodiment of this invention, the cylinder is provided with a displacement sensor for detecting the extension length of the piston rod.

[0019] On the other hand, this utility model provides a formation cavity detection system, which includes:

[0020] The aforementioned geological cavity detection device;

[0021] The acoustic wave emitting module has an acoustic wave emitter configured to emit output acoustic waves into the stratum above the shield of the tunneling machine, the acoustic waves being used to detect whether there are cavities in the stratum above the shield.

[0022] The acoustic wave receiving module has an acoustic wave receiver, which is configured to receive the reflected wave of the acoustic wave emitted by the acoustic wave transmitter after it has propagated through the stratum.

[0023] The controller is configured to adjust based on the initial arrival time T of the reflected wave. 测 The amplitude A of the reflected wave 测 The variance D of the reflected wave 测 To determine whether there are cavities in the strata above the shield.

[0024] In a preferred embodiment of this invention, the controller stores the arrival time T of the reflected wave of the current tunneling stratum in a cavity-free state. 原 The amplitude A of the reflected wave 原 The variance D of the reflected wave 原 ;

[0025] The controller is configured to when (T) 测 -T 原 >25%T 原 And A 测 <50%A 原 And D 测 >200% D 原 At that time, it was determined that there were cavities in the strata above the shield.

[0026] In a preferred embodiment of the present invention, the invention includes one acoustic wave transmitter and two acoustic wave receivers, wherein the two acoustic wave receivers are disposed on both sides of the acoustic wave transmitter, and the acoustic wave transmitter and the acoustic wave receivers are spaced apart along the tunneling direction of the tunneling machine, with a distance of 0.5m between the acoustic wave receivers and the acoustic wave transmitter.

[0027] In a preferred embodiment of this invention, the detection system further includes:

[0028] The display is configured to interact with the controller, display information processed by the controller in a graphical user interface, and send instructions to the controller.

[0029] The power amplifier box is configured to amplify the weak electrical signal transmitted from the controller to the acoustic transmitter;

[0030] The power supply is configured to supply power to the controller, the display, and the amplifier box.

[0031] Compared with the prior art, the technical solution of this utility model has the following features and advantages:

[0032] The ground cavity detection device and system described in this utility model can detect cavities in the ground and adjust the tunneling parameters in a timely manner based on the detection results to avoid the risk of ground collapse or subsidence and ensure stable construction.

[0033] The ground cavity detection device and system described in this utility model can measure the excavation gap of the shield shell, adjust the excavation gap in a timely manner within a reasonable range, avoid the risk of machine jamming during tunneling machine construction, and ensure smooth progress. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0035] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of this invention in any way. Furthermore, the shapes and proportions of the components in the drawings are merely illustrative to aid in understanding the invention and do not specifically limit the shapes and proportions of the components. Those skilled in the art, under the guidance of this invention, can select various possible shapes and proportions to implement this invention according to specific circumstances.

[0036] Figure 1 This is a schematic diagram of the structure of the stratum cavity detection device of this utility model in the extended state;

[0037] Figure 2 This is a schematic diagram of the structure of the formation cavity detection device of this utility model in the retracted state;

[0038] Figure 3 This is a schematic diagram of the structure of the formation cavity detection system described in this utility model;

[0039] Figure 4 The waveform diagram of the reflected wave received by the sound wave receiver when the sound wave emitted by the sound wave transmitter propagates inside the tube segment;

[0040] Figure 5 The waveform diagram of the reflected wave received by the sound wave receiver when the sound wave emitted by the sound wave transmitter propagates inside the cement column;

[0041] Figure 6 for Figure 4 Waveform of R2;

[0042] Figure 7 for Figure 6 The spectrum diagram corresponding to the waveform in the middle;

[0043] Figure 8 for Figure 5 Waveform of R2;

[0044] Figure 9 for Figure 8 The corresponding spectrum diagram.

[0045] Explanation of reference numerals in the attached figures:

[0046] 10. Launching device; 11. First hydraulic cylinder; 111. First piston rod; 12. First connecting cylinder; 13. First telescopic column; 14. First ball valve;

[0047] 20. Receiving device; 21. Second hydraulic cylinder; 211. Second piston rod; 22. Second connecting cylinder; 23. Second telescopic column; 24. Second ball valve;

[0048] 30. Shield shell; 31. Expansion port;

[0049] 40. Sound wave transmitter; 41. Sound wave receiver; 42. Controller; 43. Display; 44. Power amplifier box; 45. Power supply. Detailed Implementation

[0050] To enable those skilled in the art to better understand the technical solutions of this utility model, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this utility model.

[0051] It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0053] Implementation Method 1:

[0054] like Figure 1 and Figure 2 As shown, this utility model provides a ground cavity detection device, which includes at least one set of transmitting devices 10 and receiving devices 20 installed on the inner side of the shield shell 30 of a tunneling machine; both transmitting devices 10 and receiving devices 20 have hydraulic cylinders, connecting cylinders and telescopic columns. The two ends of the connecting cylinder are respectively connected to the hydraulic cylinder and the inner side of the shield shell 30. The end of the piston rod in the hydraulic cylinder is located in the connecting cylinder and connected to the telescopic column. The movement of the piston rod can drive the telescopic column to slide in the connecting cylinder, so that the end of the telescopic column extends outward or retracts inward from the telescopic hole 31 on the shield shell 30; wherein, the telescopic column of the transmitting device 10 is provided with a sound wave transmitting module, and the telescopic column of the receiving device 20 is provided with a sound wave receiving module.

[0055] The ground cavity detection device described in this utility model can detect cavities in the ground and adjust the tunneling parameters in a timely manner based on the detection results to avoid the risk of ground collapse or subsidence and ensure stable construction.

[0056] The following section will provide a detailed description of the specific structure of each part of the stratum cavity detection device described in this utility model, as well as the position and connection relationship between each part.

[0057] The detection device described in this utility model is installed on the inner side of the shield shell 30 and is used to detect the strata above the outer side of the shield shell 30. It uses acoustic detection to detect whether there are cavities above the strata after excavation, and then avoids surface collapse caused by excavation by sealing the cavities.

[0058] The detection device of this utility model has at least one set of transmitting devices 10 and receiving devices 20. One set of devices may have one transmitting device 10 and one receiving device 20, that is, a single transmitting and single receiving method is adopted; preferably, one set of devices may have one transmitting device 10 and multiple receiving devices 20, that is, a single transmitting and multiple receiving method is adopted; in a typical embodiment, two receiving devices 20 are respectively arranged on both sides of one transmitting device 10.

[0059] Specifically, such as Figure 1 and Figure 2 As shown, the launching device 10 includes a first hydraulic cylinder 11, a first connecting cylinder 12, and a first telescopic column 13. The two ends of the first connecting cylinder 12 are connected to the first hydraulic cylinder 11 and the inner side of the shield shell 30, respectively. The end of the first piston rod 111 inside the first hydraulic cylinder 11 is located inside the first connecting cylinder 12 and connected to the first telescopic column 13. The first piston rod 111 and the first telescopic column 13 are fixedly connected by a threaded connection, thus enabling the first piston rod 111 to drive the first telescopic column 13 to perform telescopic movements. The first connecting cylinder 12 is sleeved on the outer periphery of the first telescopic column 13, allowing the first telescopic column 13 to telescopically extend relative to the first connecting cylinder 12. A telescopic hole 31 is provided on the shield shell 30 at a position corresponding to the first telescopic column 13. The telescopic hole 31 is a through hole connecting the internal space of the shield shell 30 to the external soil layer. Under the action of the first piston rod 111, the first telescopic column 13 slides within the first connecting cylinder 12, causing the end of the first telescopic column 13 to extend outward or retract inward from the telescopic hole 31 on the shield shell 30.

[0060] Furthermore, the first telescopic column 13 of the transmitting device 10 is equipped with a sound wave emitting module, which can generate sound waves through vibration. When the first telescopic column 13 is in the extended state, that is, when the end of the first telescopic column 13 extends out of the telescopic hole 31 on the shield shell 30, the sound wave emitting module is activated to emit sound waves into the strata outside the shield shell 30. Here, the sound wave emitting module is a device that can generate sound through vibration, and no specific limitation is made here.

[0061] Specifically, such as Figure 1 and Figure 2As shown, the receiving device 20 includes a second hydraulic cylinder 21, a second connecting cylinder 22, and a second telescopic column 23. The two ends of the second connecting cylinder 22 are connected to the second hydraulic cylinder 21 and the inner side of the shield shell 30, respectively. The end of the second piston rod 211 inside the second hydraulic cylinder 21 is located inside the second connecting cylinder 22 and connected to the second telescopic column 23. The second piston rod 211 and the second telescopic column 23 are fixedly connected by a threaded connection, thus enabling the second piston rod 211 to drive the second telescopic column 23 to perform telescopic movements. The second connecting cylinder 22 is sleeved on the outer periphery of the second telescopic column 23, allowing the second telescopic column 23 to telescopically move relative to the second connecting cylinder 22. A telescopic hole 31 is provided on the shield shell 30 at a position corresponding to the second telescopic column 23. The telescopic hole 31 is a through hole connecting the internal space of the shield shell 30 and the external soil layer. Under the drive of the second piston rod 211, the second telescopic column 23 slides within the second connecting cylinder 22, causing the end of the second telescopic column 23 to extend outward or retract inward from the telescopic hole 31 on the shield shell 30.

[0062] Furthermore, the second telescopic column 23 of the receiving device 20 is equipped with a sound wave receiving module, which is a sound wave sensor that can receive sound wave signals. When the second telescopic column 23 is in the extended state, that is, when the end of the second telescopic column 23 extends out of the telescopic hole 31 on the shield shell 30, the sound wave receiving module is activated to receive sound waves in the strata outside the shield shell 30.

[0063] The following will further explain the structure and technical effects of the preferred embodiment of the stratum cavity detection device of this utility model.

[0064] According to one embodiment of this utility model, the acoustic wave emitting module has a pneumatic striking device for generating acoustic wave signals. The pneumatic striking device includes a cylinder and a striking plate (not shown) arranged opposite each other. A pre-drilled air pipe hole is provided on the first cylinder 11, through which an air pipe on the cylinder passes, and the air pipe is connected to an air source to provide power for the cylinder's movement. When the first telescopic column 13 is in the extended state, and geological exploration is required, the cylinder is controlled to strike the striking plate. The striking plate vibrates, generating acoustic waves that propagate into the strata in a fixed direction.

[0065] According to one embodiment of the present invention, such as Figure 1 and Figure 2 As shown, a first ball valve 14 is provided between the first connecting cylinder 12 and the side wall of the shield shell 30. The two ends of the valve seat of the first ball valve 14 are fixedly connected to the shield shell 30 and the first connecting cylinder 12 by bolts, respectively. The first telescopic column 13 passes through the through hole in the first ball valve 14. A second ball valve 24 is provided between the second connecting cylinder 22 and the side wall of the shield shell 30. The two ends of the valve seat of the second ball valve 24 are fixedly connected to the shield shell 30 and the second connecting cylinder 22 by bolts, respectively. The second telescopic column 23 passes through the through hole in the second ball valve 24.

[0066] The first ball valve 14 and the second ball valve 24 are used to replace the first telescopic column 13 and the second telescopic column 23 under pressure. That is, the ball valve is temporarily closed for short-term sealing when the telescopic column is replaced. At the same time, the telescopic hole 31 on the shield shell 30 can be sealed after the telescopic column is removed to prevent soil from the outside of the shield shell 30 from entering the tunneling machine. That is, the ball valve is closed after the telescopic column is removed to maintain a long-term sealing.

[0067] According to one embodiment of this utility model, the circumferential gaps between the first telescopic column 13 and the first connecting cylinder 12, the circumferential gaps between the first telescopic column 13 and the first ball valve 14, and the circumferential gaps between the first telescopic column 13 and the telescopic hole 31 are all filled with sealing oil; the circumferential gaps between the second telescopic column 23 and the second connecting cylinder 22, the circumferential gaps between the second telescopic column 23 and the second ball valve 24, and the circumferential gaps between the second telescopic column 23 and the telescopic hole 31 are all filled with sealing oil. The sealing oil ensures the pressure resistance of the transmitting device 10 and the receiving device 20 while achieving a seal, preventing impurities outside the shield shell 30 from entering the transmitting device 10 and the receiving device 20 and causing equipment malfunctions.

[0068] According to one embodiment of the present invention, such as Figure 1 and Figure 2 As shown, the axes of the first piston rod 111, the first connecting cylinder 12, the first telescopic column 13, and the telescopic hole 31 on the shield shell 30 in the first cylinder 11 coincide; preferably, the axis of the first telescopic column 13 is perpendicular to the inner surface of the shield shell 30; the axes of the second piston rod 211, the second connecting cylinder 22, the second telescopic column 23, and the telescopic hole 31 on the shield shell 30 in the second cylinder 21 coincide; preferably, the axis of the second telescopic column 23 is perpendicular to the inner surface of the shield shell 30.

[0069] According to one embodiment of the present invention, the transmitting device 10 and the receiving device 20 are arranged at intervals along the tunneling direction of the tunneling machine, and the distance between the transmitting device 10 and the receiving device 20 is 0.5m.

[0070] According to one embodiment of the present invention, the length of the ends of the first telescopic column 13 and the second telescopic column 23 extending outward from the shield shell 30 is greater than or equal to 5 cm.

[0071] According to one embodiment of this utility model, a displacement sensor is provided on the first hydraulic cylinder 11 for detecting the extension length of the first piston rod 111, or a displacement sensor is provided on the second hydraulic cylinder 21 for detecting the extension length of the second piston rod 211. By detecting the extension length of the piston rod through the displacement sensor, the excavation gap of the shield shell 30 can be measured, and the excavation gap can be adjusted in a timely manner to keep it within a reasonable range, thereby avoiding the risk of jamming during tunneling machine construction and ensuring smooth advancement.

[0072] Implementation Method Two:

[0073] like Figure 3 As shown, this utility model also provides a ground cavity detection system, which includes the ground cavity detection device described in Embodiment 1, a sound wave transmitter 40 in the sound wave transmitting module, a sound wave receiver 41 in the sound wave receiving module, and a controller 42; wherein, the sound wave transmitter 40 is configured to emit sound waves into the ground above the shield 30 of the tunnel boring machine, and the sound waves are used to detect whether there are cavities in the ground above the shield 30; the sound wave receiver 41 is configured to receive the reflected waves of the sound waves emitted by the sound wave transmitter 40 after propagating through the ground; the controller 42 is configured to detect the initial arrival time T of the reflected waves. 测 The amplitude A of the reflected wave 测 The variance D of the reflected wave 测 To determine whether there are cavities in the strata above shield 30.

[0074] The ground cavity detection system described in this utility model can detect cavities in the ground and adjust the tunneling parameters in a timely manner based on the detection results, so as to avoid the risk of ground collapse or subsidence and ensure stable construction.

[0075] Specifically, the geological cavity detection device has been described in detail in Implementation Method 1, and will not be repeated here.

[0076] like Figure 3 As shown, the sound wave transmitter 40 can convert electrical signals into sound wave signals, and it can generate sound waves by pneumatic percussion. The sound wave receiver 41 is a sound wave sensor or receiving sensor, which can sense sound wave signals and convert them into electrical signals.

[0077] If there are cavities (filled with air or water) in the formation, the sound waves emitted by the sound wave transmitter 40 will affect the sound waves when they pass through the cavities, thereby causing changes in the waveform and spectral characteristics of the sound waves. After receiving the sound wave signal (converted electrical signal) fed back by the sound wave receiver 41, the controller 42 analyzes the corresponding sound wave signal and can determine whether there are cavities in the formation based on the corresponding characteristics.

[0078] In an optional embodiment, the presence of cavities in the formation is determined by comparative analysis.

[0079] Specifically, the controller 42 stores the first arrival time T of the reflected wave in the current tunneling stratum under conditions without cavities. 原 The amplitude A of the reflected wave 原 The variance D of the reflected wave 原That is, under the same detection conditions, the sound wave transmitter 40 and sound wave receiver 41 described above are used to detect strata without cavities, and the first arrival time T of the reflected wave in the normal strata is obtained in advance. 原 The amplitude A of the reflected wave 原 The variance D of the reflected wave 原 And store it in controller 42.

[0080] After receiving the acoustic wave signal during the actual detection process, the controller 42 obtains the initial arrival time T of the reflected wave from it. 测 The amplitude A of the reflected wave 测 The variance D of the reflected wave 测 And compare it with the pre-stored data for analysis. If (T) 测 -T 原 >25%T 原 And A 测 <50%A 原 And D 测 >200% D 原 If the above conditions are not met simultaneously, it can be determined that there are cavities in the strata above the shield 30; if the above conditions are not met simultaneously, it is determined that there are no cavities in the detected strata.

[0081] The technical basis for comparing and judging based on the initial arrival time T, amplitude A, and variance D of the reflected wave is as follows:

[0082] (1) Delay effect of reflected waves caused by cavities: When cavities are located in the path of sound wave propagation, the arrival time T of reflected waves is significantly delayed compared to the surrounding strata due to the reduced wave velocity (air filling) or detour (the path may be extended when filled with water).

[0083] The first arrival time T of the reflected wave refers to the moment when the sound wave first arrives at the sound wave receiver 41. The first arrival time T is one of the most basic and critical pieces of information in applications such as acoustic ranging, positioning, and velocity analysis.

[0084] Three sound wave receivers 41 (R1, R2, R5) were used to experimentally test the propagation of sound waves within the tunnel segment. R1, R2, and R5 were installed along the length of the tunnel segment, with R1 and R2 spaced 0.5 meters apart and R2 and R5 spaced 1 meter apart. The tunnel segment was struck with a hammer at a distance of 0.5 meters from R5. The sound wave signals generated by the hammer strike were received by the three sound wave receivers 41. Figure 4As shown, the arrival times of the first wave of the sound waves received by R1, R2, and R5 are 0.00832s, 0.00816s, and 0.00808s, respectively. Based on the distance, the propagation speed of the sound wave is calculated as: 1 / (0.00832-0.00816) = 6250m / s, 0.5 / (0.00816-0.00808) = 6250m / s, which means the wave speed of the sound wave inside the tube segment is 6250m / s.

[0085] Three acoustic receivers 41 (R1, R2, R5) were used to experimentally test the propagation of sound waves within the cement. R1, R2, and R5 were installed along the length of the tunnel segment on the grouting cement, with R1 and R2 spaced 1 meter apart, and R2 and R5 spaced 1 meter apart. The tunnel segment was struck with a hammer at a distance of 0.5 meters from R5. The three acoustic receivers 41 were used to receive the sound wave signals generated by the hammer strike. Figure 5 As shown, the arrival times of the first wave of the sound waves received by R1, R2, and R5 are 0.01112s, 0.01168s, and 0.01216s, respectively. Based on the distance, the propagation speed of the sound wave is calculated as: 1 / (0.01168-0.01112)=1786m / s, 1 / (0.01216-0.01168)=2083m / s, which means the wave speed of the sound wave within the cement is 2083m / s.

[0086] The comparison shows that the propagation speed of sound waves in cement differs from that in tunnel lining segments.

[0087] (2) Amplitude reduction caused by cavities: Cavities scatter and absorb sound waves, resulting in a significant reduction in the amplitude of reflected waves (especially when air fills the cavities).

[0088] according to Figure 4 and Figure 5 As shown, the amplitude A of the reflected waves is different in different strata.

[0089] (3) Increased spectral variance D caused by voids: Due to scattering, reflection and other effects, the acoustic signal in the void region oscillates more violently, and the variance D of the corresponding spectrum of the waveform increases significantly.

[0090] like Figure 6 and Figure 7 As shown, these are the waveforms detected by R2 and their corresponding spectra in the segment test data; Figure 8 and Figure 9 As shown, these are the waveforms and corresponding spectra detected by R2 in the cement test data. (The text abruptly ends here.) Figure 7 and Figure 9 The comparison shows that the spectral variance D of the reflected waves from different strata is different.

[0091] The following will further explain the structure and technical effects of the preferred embodiment of the formation cavity detection system of this utility model.

[0092] According to one embodiment of the present invention, such as Figure 3 As shown, the detection system includes a sound wave transmitter 40 and two sound wave receivers 41. The two sound wave receivers 41 are arranged on both sides of the sound wave transmitter 40. The sound wave transmitter 40 and the sound wave receivers 41 are spaced apart along the tunneling direction of the tunneling machine, and the distance between the sound wave receivers 41 and the sound wave transmitter 40 is 0.5m.

[0093] According to one embodiment of the present invention, such as Figure 3 As shown, the detection system also includes a display 43, a power amplifier box 44, and a power supply 45; wherein, the display 43 is configured to interact with the controller 42, display the information processed by the controller 42 in a graphical user interface and send instructions to the controller 42; the power amplifier box 44 is configured to amplify the weak electrical signal transmitted by the controller 42 to the sound wave transmitter 40; and the power supply 45 is configured to supply power to the controller 42, the display 43, and the power amplifier box 44.

[0094] Specifically, such as Figure 3 As shown, power supply 45 is responsible for powering the entire system. Power supply 45 is electrically connected to controller 42, display 43 and power amplifier box 44. Power amplifier box 44 is located between controller 42 and sound wave transmitter 40 and is used to amplify the weak electrical signal from controller 42. Display 43 is a human-computer interaction device. It is electrically connected to controller 42. Display 43 can display the processed detection results to the operator and transmit the control commands issued by the operator to controller 42 so that the entire system can work in the same planned control unit.

[0095] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this utility model. It should be understood that the above descriptions are merely specific embodiments of this utility model and are not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. A device for detecting cavities in a formation, characterized in that, Includes at least one set of launching devices (10) and receiving devices (20) installed on the inner side of the shield (30) of the tunneling machine; Both the launching device (10) and the receiving device (20) have a hydraulic cylinder, a connecting cylinder and a telescopic column. The two ends of the connecting cylinder are connected to the inner side of the hydraulic cylinder and the shield (30) respectively. The end of the piston rod in the hydraulic cylinder is located in the connecting cylinder and connected to the telescopic column. The movement of the piston rod can drive the telescopic column to slide in the connecting cylinder so that the end of the telescopic column extends outward or retracts inward from the telescopic hole (31) on the shield (30). The transmitting device (10) has a sound wave transmitting module inside its telescopic column, and the receiving device (20) has a sound wave receiving module inside its telescopic column.

2. The geological cavity detection device according to claim 1, characterized in that, The acoustic wave emitting module has a pneumatic striking device for generating acoustic wave signals, the pneumatic striking device including a cylinder and a striking plate arranged opposite each other.

3. The geological cavity detection device according to claim 1, characterized in that, A ball valve is provided between the connecting cylinder and the side wall of the shield (30). The two ends of the valve seat of the ball valve are fixedly connected to the shield (30) and the connecting cylinder by bolts, respectively. The telescopic column passes through the through hole in the ball valve.

4. The geological cavity detection device according to claim 3, characterized in that, The circumferential gap between the telescopic column and the connecting cylinder, the circumferential gap between the telescopic column and the ball valve, and the circumferential gap between the telescopic column and the telescopic hole (31) are all filled with sealing oil.

5. The geological cavity detection device according to claim 1, characterized in that, The axes of the piston rod, the connecting cylinder, the telescopic column, and the telescopic hole (31) on the shield (30) in the cylinder coincide.

6. The formation cavity detection device according to claim 5, characterized in that, The axis of the telescopic column is perpendicular to the inner side of the shield (30).

7. The geological cavity detection device according to claim 1, characterized in that, A set of transmitting devices (10) and receiving devices (20) includes one transmitting device (10) and two receiving devices (20) respectively disposed on both sides of the transmitting device (10).

8. The geological cavity detection device according to claim 7, characterized in that, The transmitting device (10) and the receiving device (20) are arranged at intervals along the tunneling direction of the tunneling machine, and the distance between the transmitting device (10) and the receiving device (20) is 0.5m.

9. The geological cavity detection device according to claim 1, characterized in that, When the piston rod of the hydraulic cylinder is in the extended state, the end of the telescopic column extends outward from the shield shell (30) by a length greater than or equal to 5 cm.

10. The geological cavity detection device according to claim 1, characterized in that, The hydraulic cylinder is equipped with a displacement sensor for detecting the extension length of the piston rod.

11. A system for detecting cavities in a formation, characterized in that, include: The geological cavity detection device according to any one of claims 1-10; The acoustic wave emitting module has an acoustic wave emitter (40) configured to emit output acoustic waves into the stratum above the shield (30) of the tunneling machine, the acoustic waves being used to detect whether there are cavities in the stratum above the shield (30). The acoustic wave receiving module has an acoustic wave receiver (41), which is configured to receive the reflected wave of the acoustic wave emitted by the acoustic wave transmitter (40) after it has propagated through the stratum. The controller (42) is configured to adjust the time of arrival T of the reflected wave according to the initial arrival time T. 测 The amplitude A of the reflected wave 测 The variance D of the reflected wave 测 To determine whether there are cavities in the strata above the shield (30).

12. The formation cavity detection system according to claim 11, characterized in that, The controller (42) stores the arrival time T of the reflected wave of the current tunneling stratum in a cavity-free state. 原 The amplitude A of the reflected wave 原 The variance D of the reflected wave 原 ; The controller (42) is configured to when (T 测 -T 原 >25%T 原 And A 测 <50%A 原 And D 测 When the original value is >200%, it is determined that there are cavities in the strata above the shield (30).

13. The formation cavity detection system according to claim 11, characterized in that, It includes one acoustic transmitter (40) and two acoustic receivers (41), wherein the two acoustic receivers (41) are respectively disposed on both sides of the acoustic transmitter (40), the acoustic transmitter (40) and the acoustic receivers (41) are disposed at intervals along the tunneling direction of the tunneling machine, and the distance between the acoustic receivers (41) and the acoustic transmitter (40) is 0.5m.

14. The formation cavity detection system according to claim 11, characterized in that, Also includes: The display (43) is configured to interact with the controller (42) to display information processed by the controller (42) in a graphical user interface and to send instructions to the controller (42); The power amplifier box (44) is configured to amplify the weak electrical signal transmitted by the controller (42) to the acoustic transmitter (40); The power supply (45) is configured to supply power to the controller (42), the display (43) and the amplifier box (44).

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