Underground cave safety distributed optical fiber monitoring device

Abstract

The utility model discloses an underground cave safety distribution type optical fiber monitoring device which comprises an underground integration part and an overground integration part, and the top of the underground integration part is provided with a photoelectric composite cable connected with the overground integration part. The underground integrated part comprises an instrument body, an azimuth instrument, a bottom acoustic ranging probe, a stabilized voltage supply, a gyroscope, an acoustic velocity calibration device, an optical fiber and a sonar transmitting probe; according to the utility model, through the spiral winding layout of the optical fiber, sound wave vibration information from all directions can be captured in an omnibearing and dead-angle-free manner, detailed data can be provided for underground detection, the underground integrated part of the device is composed of a plurality of mutually independent and modularized units, and a user can carry out real-time measurement according to the requirements of specific measurement tasks. The section number or the length of the instrument can be flexibly adjusted, and the instrument can adapt to both small-sized and large-sized underground cavities.

Description

Technical Field

[0001] The utility model relates to the technical field of underground cave monitoring, and specifically relates to a distributed optical fiber monitoring device for underground cave safety. Background Technique

[0002] At present, China is actively promoting the construction of underground energy storage reservoirs. These energy storage reservoirs mainly use underground caves to store energy substances such as petroleum, natural gas, hydrogen, compressed air, and carbon dioxide, as well as scarce strategic resources such as helium. The purpose of underground energy storage reservoirs is to ensure the stable supply of energy, improve the utilization efficiency of clean energy, reduce carbon dioxide emissions, and at the same time ensure the safety of strategic materials;

[0003] In China, the main types of underground caves include depleted oil and gas reservoirs, aquifers, salt caverns, and mine tunnels. These five cave structures are complex and are the main objects used in the construction of domestic energy storage reservoirs. Due to the complexity of these structures, it is particularly important to implement a real-time underground cave safety monitoring system during the construction and operation periods;

[0004] In the safety monitoring of underground caves, although the traditional acoustic vibration analyzer method is widely used, it still faces many challenges. This method relies on arranging a sensor array on the cave surface to capture and analyze the acoustic signals caused by structural vibration or leakage, so as to locate the problem area and trigger an early warning;

[0005] However, the complex environment of underground caves limits the effectiveness of this method. Specifically, the underground cave structure often undergoes small deformations, and internal events such as inner wall shedding, microseisms, and micro-leakages inevitably occur. The vibration signals generated by these processes are often extremely weak, and due to the long propagation distance, the signals have been greatly attenuated when reaching the ground surface and are almost imperceptible. Coupled with the noise interference of the ground environment, it is difficult for traditional acoustic vibration analyzers to accurately capture and analyze the weak signal changes from the cave interior, thereby affecting the ability to monitor, make decisions, and analyze the changes in the cave environment in a timely manner;

[0006] In addition, this technology also faces problems such as sensors being vulnerable to electromagnetic interference, complex signal processing being difficult, high long-term installation and maintenance costs, and expensive high-performance sensors. These factors jointly restrict the effectiveness and popularity of traditional acoustic vibration analyzers in underground cave safety monitoring, making ground staff likely to face the dilemma of insufficient information and lagging decisions during the monitoring process. Content of the Utility Model

[0007] The purpose of the utility model is to provide a distributed optical fiber monitoring device for underground cave safety to solve the problems presented in the above background technique.

[0008] To achieve the above object, the utility model provides the following technical solution: An underground cave safety distributed optical fiber monitoring device, comprising an underground integrated part and a ground integrated part. An optoelectronic composite cable connected to the ground integrated part is arranged at the top of the underground integrated part. The underground integrated part includes an instrument body, an azimuth instrument, a bottom acoustic ranging probe, a regulated power supply, a gyroscope, a sound velocity calibration device, an optical fiber, and a sonar transmitting probe;

[0009] A plurality of groups of sonar transmitting probe units are arranged at the top of the instrument body. Three sonar transmitting probes are evenly arranged on the outer side of the sonar transmitting probe unit. An optical fiber connected to the optoelectronic composite cable is arranged on the outer sides of the instrument body and the sonar transmitting probe unit. The azimuth instrument, the regulated power supply, the gyroscope, and the sound velocity calibration device are respectively arranged in the instrument body from bottom to top. The bottom acoustic ranging probe is arranged at the bottom of the instrument body.

[0010] Preferably, the outer diameter of the sonar transmitting probe unit is 100 mm and the length is 80 mm, which is smaller than the size of 114.3 mm of the smallest known traditional underground cave shaft.

[0011] Preferably, the shapes of the instrument body and the sonar transmitting probe unit are cylindrical, which can easily adapt to various specifications of shafts, ensuring a wide range of applications.

[0012] Preferably, the optical fiber is spirally wound around the outer side of the instrument body, which can capture subtle acoustic vibration signals.

[0013] Preferably, the instrument body and the sonar transmitting probe unit are made of titanium alloy, endowing them with excellent strength, corrosion resistance, and high-temperature resistance characteristics.

[0014] Preferably, the optical fiber is a special optical fiber, enabling this instrument to have high performance while also having extremely high cost performance.

[0015] Compared with the prior art, the beneficial effects of the utility model are:

[0016] 1. Through the spiral winding layout of the optical fiber, this device ensures that acoustic vibration information from all directions can be captured comprehensively and without dead angles, and can provide detailed data for underground detection;

[0017] 2. The slender design of this device is highly versatile and can easily adapt to various specifications of shafts, ensuring a wide range of applications;

[0018] 3. The underground integrated part of this device consists of multiple independent and modular units. Users can flexibly adjust the number of instrument sections or the length according to the requirements of specific measurement tasks, and it can adapt to both small and large underground cavities;

[0019] 4. The device combines distributed fiber optic acoustic sensor technology and can identify and locate the three most common problems during the cavity formation and maintenance of underground caves: leakage, inner wall shedding, and cavity deformation, so as to quickly take corresponding measures to ensure the integrity and safety of the cave structure;

[0020] 5. The device can obtain rich parameter information inside the cavity. Through the multiple scattering effects of distributed optical fibers - Rayleigh scattering, Raman scattering, and Brillouin scattering, it can obtain the structure inside the underground cave cavity, the internal environment temperature of the cavity, and the pressure inside the cavity;

[0021] 6. The core sensor of the device - a highly resistant special optical fiber - has an extremely low unit cost, only about ten yuan per meter in length. This price advantage enables this instrument to have extremely high cost performance while maintaining high performance;

[0022] 7. Compared with traditional electronic instruments, the device is free from the bondage of electromagnetic interference, ensuring the purity and efficiency of data transmission;

[0023] 8. The device has extremely high sensitivity, excellent high temperature, high pressure, and corrosion resistance, perfectly meeting the requirements of the complex and changeable detection environment of underground cave cavities, laying a solid foundation for accurate and reliable underground detection work. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic structural diagram of the present utility model;

[0025] Figure 2 is a perspective view of the underground integrated part of the present utility model;

[0026] Figure 3 is a top view of the sonar transmitting probe unit of the present utility model;

[0027] Figure 4 is a perspective view of the sonar transmitting probe unit of the present utility model;

[0028] Figure 5 is a wiring schematic diagram of the optical fiber of the present utility model.

[0029] In the figure: 1. Underground integrated part; 2. Optoelectronic composite cable; 3. Above-ground integrated part; 4. Instrument body; 5. Azimuth instrument; 6. Bottom acoustic ranging probe; 7. Voltage stabilizing power supply; 8. Gyroscope; 9. Sound velocity calibration device; 10. Optical fiber; 11. Sonar transmitting probe; 12. Sonar transmitting probe unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0031] Please refer to Figures 1-5 , an embodiment provided by the present invention: an underground cave safety distributed optical fiber monitoring device, including an underground integrated part 1 and an above-ground integrated part 3. A fiber optic composite cable 2 connected to the above-ground integrated part 3 is provided at the top of the underground integrated part 1. The underground integrated part 1 includes an instrument body 4, a direction finder 5, a bottom acoustic ranging probe 6, a regulated power supply 7, a gyroscope 8, a sound velocity calibration device 9, an optical fiber 10, and a sonar transmitting probe 11;

[0032] Multiple groups of sonar transmitting probe units 12 are provided at the top of the instrument body 4. The instrument body 4 and the sonar transmitting probe units 12 are cylindrical in shape, which can easily adapt to various specifications of wellbores, ensuring a wide range of applications. Three groups of sonar transmitting probes 11 are evenly arranged on the outer side of the sonar transmitting probe units 12. An optical fiber 10 connected to the fiber optic composite cable 2 is provided on the outer sides of the instrument body 4 and the sonar transmitting probe units 12. The optical fiber 10 is spirally wound around the outer side of the instrument body 4, and its distribution rule is to rotate and rise from the bottom to the right. It can capture subtle acoustic vibration signals and analyze them using advanced signal processing algorithms, so as to quickly and accurately judge the type and location of events. The optical fiber 10 is a high-tolerance special optical fiber, and its unit cost is extremely low, only about ten yuan per meter. This price advantage enables this instrument to have extremely high cost performance while maintaining high performance. Inside the instrument body 4, a direction finder 5, a regulated power supply 7, a gyroscope 8, and a sound velocity calibration device 9 are arranged from bottom to top in sequence. A bottom acoustic ranging probe 6 is provided at the bottom of the instrument body 4.

[0033] The instrument body 4 and the sonar transmitting probe units 12 are made of titanium alloy material. Combined with the special optical fiber wound on the surface, it not only endows them with excellent strength, corrosion resistance, and high-temperature resistance characteristics, but also ensures their reliable operation and long-term stability in extremely complex environments such as underground caves.

[0034] The above-ground integrated part 3, as the core control and processing center, is mainly responsible for data processing, image generation, and sending and receiving of instructions. Its core components include a main control system, an imaging system, a level conversion module, a fiber optic composite cable depth control unit, an optical pulse generator, a circulator, and an optoelectronic conversion device, which work together to ensure the accurate processing and transmission of information;

[0035] The main control system is responsible for issuing instructions to control the lowering and operation of the underground instrument through the optical and electrical composite cable, supporting two working modes: automatic and manual. In the manual mode, the operator can, according to needs, especially for the upper area of the cavity where shedding, tiny gas leakage and deformation are likely to occur, precisely control the instrument to be lowered to the specified depth to achieve customized and all-weather monitoring tasks. If the automatic mode is selected, the system will automatically adjust the lifting of the instrument to comprehensively monitor the state of the entire cavity.

[0036] The device can freely control the length of the instrument according to the actual size of the measured cavity, that is, the number of sonar emission probe units 12. There are 3 sonar emission probes 11 outside the sonar emission probe unit 12, ensuring coverage in all 360° directions. The overall external diameter of the sonar emission probe unit 12 is 100 mm, which is smaller than the size of the smallest known traditional underground cave shaft of 114.3 mm. The length is set to 80 mm. There is a highly sealed thread built into the interface of the sonar emission probe unit 12 for connection. The sonar emission probe unit 12 incorporates an electro-acoustic conversion circuit and a control interface.

[0037] For the monitoring of cavity deformation, we refer to advanced sonar detection technology, actively emit sound waves and receive the signals reflected back by the distributed fiber optic sensor, and carefully analyze the characteristic changes in these sound wave data to accurately judge whether there is a tiny deformation on the inner wall of the cavity. Secondly, we use the difference in the sound wave transmission time to calculate the distance change between the probe and the cavity, and then evaluate whether the inner wall of the cavity has undergone significant morphological adjustment. Given the possible complex medium environment inside the cavity, such as brine or gas, etc., these media have different degrees of influence on the sound wave propagation speed. Therefore, strict sound speed calibration must be carried out before detection to ensure the accuracy of the measurement results. To cope with the influence of various media inside the cavity on the sound wave propagation characteristics, we have integrated a sound wave frequency adjustment function at the control end of the sonar probe. This design allows us to flexibly adjust the frequency of the emitted sound wave according to the actual composition of the medium inside the cavity, thereby optimizing the sound wave propagation effect and detection sensitivity to ensure high-quality detection data can be obtained under different medium conditions.

[0038] For the two specific events of cavity shedding and micro-leakage, we have developed a unique sound signal recognition technology. These two events will generate their own unique sound signal characteristics when they occur. Through the fiber optic network spirally wound on the surface of the instrument, we can capture these subtle sound vibration signals and analyze them using advanced signal processing algorithms to quickly and accurately judge the type of the event and its occurrence location.

[0039] Working principle: When in use, the device lowers the underground integrated part 1 into the underground cave through the ground integrated part 3, and gradually activates each functional module through the optical and electrical composite cable 2. First, the regulated power supply 7 is started to ensure a stable power supply for all modules. Subsequently, the azimuth instrument 5 is activated to accurately position the direction of the instrument. Then, the gyroscope 8 is enabled to maintain the stability of the instrument's attitude. Subsequently, the sound velocity calibration device 9 is activated to improve the accuracy of the measurement data. After that, the bottom acoustic ranging probe 6 is activated to prevent the instrument from being damaged due to collision. Finally, the sonar transmitting probe 11 is started to prepare for acoustic detection.

[0040] As each module is successively started, the helically wound optical fiber 10 begins to capture sound vibration signals from all directions. These signals are converted into data and efficiently transmitted through the optical and electrical composite cable 2 to the ground integrated part 3 for real-time imaging processing and in-depth analysis, thereby achieving a comprehensive and accurate monitoring of the underground environment.

[0041] For those skilled in the art, it is obvious that the present utility model is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present utility model. Therefore, in any regard, the embodiments should be regarded as exemplary and non-limiting. The scope of the present utility model is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be encompassed within the present utility model. Any reference signs in the claims should not be construed as limiting the claimed rights.

[0042] In the description of the present utility model, unless otherwise specified, the meaning of "a plurality of" is two or more; the orientation or positional relationships indicated by terms such as "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present utility model. In addition, terms such as "first", "second", "third", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0043] In the description of the present utility model, it should be noted that unless otherwise clearly specified and defined, the terms "connected" and "coupled" should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

Claims

1. An underground cave safety distributed optical fiber monitoring device, comprising an underground integrated part (1) and an above-ground integrated part (3), wherein the top of the underground integrated part (1) is provided with an optical-electric composite cable (2) connected to the above-ground integrated part (3), characterized in that: The underground integrated part (1) comprises an instrument body (4), a azimuth meter (5), a bottom acoustic wave ranging probe (6), a voltage-stabilized power supply (7), a gyroscope (8), a sound velocity calibration device (9), an optical fiber (10) and a sonar transmitting probe (11); A plurality of groups of sonar transmitting probe units (12) are arranged on the top of the instrument body (4), three groups of sonar transmitting probes (11) are evenly arranged on the outside of the sonar transmitting probe units (12), optical fibers (10) connected to the photoelectric composite cable (2) are arranged on the outside of the instrument body (4) and the sonar transmitting probe units (12), a azimuth meter (5), a voltage-stabilized power supply (7), a gyroscope (8) and a sound velocity calibration device (9) are arranged from bottom to top inside the instrument body (4), and a bottom acoustic wave ranging probe (6) is arranged at the bottom of the instrument body (4).

2. The underground cave safety distributed optical fiber monitoring device according to claim 1, characterized in that: The sonar transmitting probe unit (12) has an outer diameter of 100 mm and a length of 80 mm.

3. The underground cave safety distributed optical fiber monitoring device according to claim 1, characterized in that: The instrument body (4) and the sonar transmitting probe unit (12) are cylindrical in shape.

4. The underground cave safety distributed optical fiber monitoring device according to claim 3, characterized in that: The optical fiber (10) is spirally wound on the outside of the instrument body (4).

5. The underground cave safety distributed optical fiber monitoring device according to claim 1, characterized in that: The instrument body (4) and the sonar transmitting probe unit (12) are made of titanium alloy.

6. The underground cave safety distributed optical fiber monitoring device according to claim 1, characterized in that: The optical fiber (10) is a special optical fiber.

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