Annular scanning complete polarization ground penetrating radar system carried on tunnel boring machine

Abstract

The invention relates to the technical field of tunnel construction equipment, and discloses an annular scanning complete polarization ground penetrating radar system carried on a TBM (Tunnel Boring Machine), and the system comprises a control unit which is disposed in a TBM control room and is used for transmitting a control signal and receiving and storing measurement data; the fully-polarized ground penetrating radar antenna array is mounted in a gap between cutter spokes and is used for transmitting and receiving electromagnetic waves; each group comprises two transmitting antennas and two receiving antennas; the two transmitting antennas transmit horizontally polarized electromagnetic waves and vertically polarized electromagnetic waves respectively, the two receiving antennas receive horizontally polarized echoes and vertically polarized echoes respectively, and a complete 2 * 2 scattering matrix of a front annular area is obtained by rotating the fully polarized antenna array through the cutterhead to complete a measurement period. The multi-polarization radar antenna is adopted, the scattering characteristic information of the target body can be comprehensively obtained by transmitting and receiving electromagnetic wave signals in multiple polarization states, and more comprehensive information can be provided for target recognition under complex geological conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel construction equipment, and in particular to a ring-scanning full-polarization ground penetrating radar system mounted on a tunnel boring machine. Background Art

[0002] A tunnel boring machine (TBM) is an intelligent tunnel construction equipment integrating multiple systems such as machinery, electricity, hydraulics, sensing and control. It has the ability of multi-functional collaborative operations such as rock mass fragmentation, muck transportation, segment installation and real-time monitoring, and is especially suitable for the efficient and safe construction of large-section long tunnels under complex geological conditions. With the in-depth implementation of the "Transportation Power" strategy in China and the large-scale development of urban underground space, TBM technology has been successfully applied to major engineering fields such as railway and highway tunnels, water conservancy and hydropower tunnels, and urban utility tunnels, and has gradually become the preferred construction plan for the construction of deep-buried long tunnels. Under the background of new urbanization construction and infrastructure upgrading, in the face of increasingly strict construction safety standards and continuously rising labor costs, the limitations of the traditional drill and blast method in the construction of deep and long tunnels are becoming increasingly prominent, and the technical and economic advantages of the TBM method are becoming more and more significant.

[0003] However, TBM construction faces severe challenges in geological adaptability, and its core problem lies in the insufficient ability to perceive and make intelligent decisions on the adverse geological conditions in front of the tunnel face during the tunneling process. Engineering practice shows that when TBM encounters sub-meter-scale small-scale complex geological disasters, such as water-bearing fracture zones, broken soft interlayers, karst pipelines, etc., it is extremely easy to trigger major engineering accidents such as water and mud inrush and surrounding rock instability. Although the scale of such geological disaster bodies is limited, they often have the characteristics of strong concealment and high suddenness, and often have hydraulic or mechanical connections with deep-seated adverse geological bodies. Especially in complex geological environments such as high water pressure and high ground stress, it may induce chain engineering disasters, seriously threatening construction safety and project progress. Therefore, realizing the accurate identification and quantitative evaluation of sub-meter-scale small-scale complex geological disasters in front of the tunnel face during TBM tunneling is the key technical bottleneck for improving the geological adaptability of TBM.

[0004] At present, the advanced geological prediction technology system for TBM tunnels is not yet perfect, and there is an obvious gap in its technical maturity and reliability compared with traditional drill-and-blast tunnels. The existing technical methods are mainly divided into three categories: The first category is seismic detection technology based on elastic wave theory, including the HSP method (Horizontal Sound Profiling), the TRT method (Tunnel Reflection Tomography), and the ISIS system (Integrated Seismic Imaging System), etc. By optimizing the seismic source excitation method and signal processing algorithm, these methods have achieved the detection of large-scale geological anomalies;

[0005] Among them, the HSP method (Horizontal Sound Profiling) is a commonly used seismic wave advanced geological prediction technology in tunnel engineering, mainly used to detect the unfavorable geological structures in front of the tunnel face. The theoretical basis of the HSP method lies in the fact that the propagation characteristics of elastic waves in rock and soil masses (including parameters such as wave velocity and amplitude) are closely related to the physical properties (such as composition, density, and elastic modulus) and structural state of rock and soil masses. It is an advanced technology for TBM tunnels based on seismic exploration methods; The second category is the passive source monitoring technology based on the vibration signals during TBM tunneling, represented by the TSWD method (Tunnel Seismic While Drilling) and its derivative technologies. This technology inversely analyzes the geological conditions ahead by analyzing the characteristics of the vibration wave field generated by the cutter head breaking rock; The third category is the electrical prospecting technology based on the differences in electrical parameters, such as the BEAM system (Bore-tunneling Electrical Ahead Monitoring), three-dimensional focused induced polarization method, and transient electromagnetic method, etc., which have unique advantages in the detection of water-bearing structures.

[0006] When elastic waves propagate in rock mass media, if they encounter geological interfaces with different wave impedances (such as the interfaces between unfavorable geological bodies such as faults, fracture zones, or karst caves and intact surrounding rocks), a significant wave field energy redistribution phenomenon will occur: Part of the wave field energy is reflected at the interface according to Snell's law, forming a reflected wave signal that can be captured by the receiver; Another part of the energy penetrates the interface to generate a refracted wave and continues to propagate in the adjacent medium. Engineering practice shows that the wave impedance of common unfavorable geological bodies is usually reduced by 30%-70% compared with intact rock masses. This significant wave impedance difference provides an ideal physical premise for seismic wave reflection method detection;

[0007] In the application of tunnel engineering, the HSP method arranges a high-sensitivity three-component geophone array on the side wall behind the shield machine (such as Figure 2As shown by R1-R6, the system collects the reflected wave signals from the front of the heading face. The core of this method lies in:

[0008] (1) Signal identification: Based on the time history difference characteristics between the reflected wave and the direct wave, the effective reflected signals are extracted through the cross-correlation algorithm;

[0009] (2) Location principle: According to the travel time of the reflected wave and the known wave velocity, the offset imaging technology is adopted to determine the spatial position of the bad geological body;

[0010] (3) Attribute analysis: The engineering characteristics of the geological anomaly body are evaluated through the amplitude, frequency and attenuation characteristics of the reflected wave.

[0011] This advanced detection technology based on the elastic wave reflection principle can effectively identify the bad geological bodies within the range of 20 - 100 m in front of the heading face. Its detection accuracy decreases with the increase of distance, and the positioning error can be controlled within ±3 m within 50 m. Especially in the TBM construction environment, by optimizing the sensor layout scheme and developing special signal processing algorithms, the HSP method has developed into an important advanced geological prediction means suitable for the characteristics of mechanical tunneling;

[0012] However, the advanced detection methods based on the seismic wave reflection principle such as HSP have the following key technical bottlenecks in engineering applications:

[0013] (1) Resolution limitation problem:

[0014] Restricted by the inherent physical properties of seismic waves, there is a theoretical limit that is difficult to break through in its detection resolution. The main frequency range of the excited seismic wave is only 100 - 200 Hz, and this frequency band range is restricted by the dual constraints of the seismic source energy and the formation attenuation effect. At the same time, the longitudinal wave velocity range of common surrounding rocks is 1000 - 3000 m / s (typical range from sedimentary rocks to igneous rocks). According to the wave equation λ = v / f, the actual detection wavelength reaches the order of 5 - 30 m. According to the Rayleigh criterion δ = λ / 4, the theoretical resolution is only 1.25 - 7.5 m. This physical nature limitation causes traditional seismic methods to be completely unable to identify micro-scale geological anomaly bodies such as sub-meter (<1 m) water-bearing fracture networks and dissolution pipes, and these concealed structures are precisely the key disaster-causing factors for inducing major engineering disasters such as water inrush and mud inrush.

[0015] (2) Difficulty in identifying water-bearing structures:

[0016] There are fundamental technical obstacles in the identification of water-bearing structures. In terms of wave impedance characteristics, there is an overlapping area of more than 60% between the longitudinal wave velocity range (1500 - 2500 m / s) of water-saturated rock masses and intact surrounding rocks, resulting in extremely weak reflection energy. Through the calculation of the reflection coefficient formula R = (ρ2v2 - ρ1v1) / (ρ2v2 + ρ1v1), it can be known that the reflection coefficients of typical water-bearing fractures are generally less than 0.1. Such weak reflection signals make it difficult for conventional interpretation methods based on amplitude changes to effectively distinguish water-bearing anomalies from low-wave-velocity rock masses, and serious interpretation ambiguities will occur under complex hydrogeological conditions, seriously affecting the accurate identification of water-bearing structures.

[0017] (3) Lack of real-time detection ability:

[0018] This method has serious engineering applicability problems in the TBM construction environment and lacks real-time monitoring functions. The rotation of the TBM cutterhead (1 - 3 rpm) and the propulsion vibration (10 - 50 Hz) generate mechanical noise exceeding 90 dB, resulting in the measured signal-to-noise ratio (SNR) dropping below 1 and the effective signal annihilation rate being as high as 80%. Such a harsh construction environment makes the HSP method have to interrupt tunneling for detection. The single shutdown time usually takes 2 - 4 hours, and continuous monitoring during tunneling cannot be achieved at all. This characteristic of having to stop work leads to a complete lack of real-time early warning function for geological anomalies in front of the tunnel face, seriously restricting the timeliness of construction safety control.

[0019] In addition, ground-penetrating radar (GPR), as a non-destructive detection technology based on high-frequency electromagnetic waves, has become an important means for accurately detecting water-bearing abnormal bodies within 20 meters in tunnel engineering due to its sub-meter high resolution, strong sensitivity to water bodies, and real-time detection capabilities. Based on ground-penetrating radar technology, the Wei research team innovatively developed the prototype of TULIPS (Tunnel Look-ahead Imaging Prediction System). This system adopts an innovative design of collaborative detection with a multi-band ground-penetrating radar array. Specifically, the system integrates two groups of high-resolution antennas (No. 1: 360 - 1060 MHz, No. 2: 360 - 1300 MHz) and one group of low-frequency antennas (No. 3: 100 - 520 MHz). Through the optimized layout along the circumferential gradient radius of the TBM cutterhead, the three groups of antennas can achieve counterclockwise synchronous rotation scanning at a constant angular velocity of 0.5 rad / s during tunneling. During TBM tunneling, the three groups of antennas rotate and scan counterclockwise at a constant angular velocity, and multi-channel synchronous data acquisition is achieved through a high sampling frequency of 3.657 GHz ( Figure 3) Among them, the high-resolution antenna is responsible for sub-meter-level fine detection in the front close range, while the low-frequency antenna realizes the identification of geological structures at a relatively long distance in the front. Through the comprehensive application of advanced signal processing algorithms such as DC removal, time varying gain, and Back-projection imaging, the three groups of antennas work together to form a full-space, multi-scale detection ability from the near field to the far field, and accurate advanced prediction.

[0020] However, the above technologies have the following disadvantages when used:

[0021] (1) Problem of missing polarization information

[0022] This system uses linearly polarized waves for signal transmission and reception. Its single-polarization antenna cannot capture the polarization rotation information generated when electromagnetic waves interact with the target, resulting in partial loss of the reflected signal, which limits its detection accuracy and target recognition reliability under complex geological conditions.

[0023] (2) Insufficient anisotropy identification

[0024] For geological structures with obvious anisotropic characteristics (such as fracture-developed zones, layered rock masses, etc.), it is difficult for a single-polarization system to obtain complete dielectric property tensor information through electromagnetic waves of a single polarization mode, resulting in a relatively high misjudgment rate of the anisotropy coefficient and being difficult to completely describe complex geological structures under complex geological conditions.

[0025] These defects seriously restrict the applicability of traditional ground-penetrating radar in the complex geological environment of TBM tunnels, especially in identifying water-bearing fracture networks and determining the anisotropy of rock masses.

[0026] Therefore, the existing technologies generally have three major limitations: one is that it requires shutdown operations, seriously affecting construction efficiency; the second is the insufficient resolution ability for small-scale geological disaster bodies; and the third is the lack of real-time early warning ability. Summary of the Invention

[0027] The purpose of the present invention is to solve the problems existing in the prior art, and a ring-scanning full-polarization ground-penetrating radar system mounted on a tunnel boring machine is proposed. By innovating the sensor layout scheme and optimizing the signal acquisition system, high-precision identification and dynamic early warning of sub-meter-level small-scale complex geological disaster bodies in the near front (within 20 m) of the tunnel are realized.

[0028] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0029] A ring-scanning full-polarization ground-penetrating radar system mounted on a tunnel boring machine, comprising:

[0030] A control unit, deployed in the TBM control room, is used to transmit control signals and receive and store measurement data;

[0031] A full-polarization ground penetrating radar antenna array, installed in the spoke gaps of the cutter head, is used for electromagnetic wave transmission and reception;

[0032] Among them, each group includes two transmitting antennas and two receiving antennas;

[0033] Among them, the two transmitting antennas respectively transmit horizontally polarized electromagnetic waves and vertically polarized electromagnetic waves, and the two receiving antennas respectively receive horizontally polarized echoes and vertically polarized echoes. The full-polarization antenna array completes a measurement cycle through the rotation of the cutter head to obtain a complete 2×2 scattering matrix of the front annular area;

[0034] A data transmission system is used for data transmission between the control unit and the full-polarization antenna array.

[0035] Preferably, multiple sets of the full-polarization ground penetrating radar antenna arrays are provided, and are arranged in a gradient distribution along the radial direction of the cutter head, forming a concentric cylinder scanning architecture to complete the full-space coverage of the space in front of the tunnel.

[0036] Preferably, the full-polarization ground penetrating radar antenna array adopts a multi-layer composite wave-transparent protective cover design to prevent damage to the antenna during the operation of the TBM.

[0037] Preferably, the data transmission system includes:

[0038] A network analyzer, and the network analyzer is connected to:

[0039] A power amplifier, used to amplify the transmitted signal;

[0040] A switch controller, which responds to the control unit instruction to switch the polarization channel.

[0041] Preferably, the switch controller executes a four-polarization measurement timing sequence to sequentially complete:

[0042] S1, transmitting antenna 1 transmits an H-polarized wave, and receiving antenna 1 receives an HH-polarized signal;

[0043] S2, transmitting antenna 1 transmits an H-polarized wave, and receiving antenna 2 receives an HV-polarized signal;

[0044] S3, transmitting antenna 2 transmits a V-polarized wave, and receiving antenna 1 receives a VH-polarized signal;

[0045] S4, transmitting antenna 2 transmits a V-polarized wave, and receiving antenna 2 receives a VV-polarized signal;

[0046] Each measurement cycle is synchronized with the angular velocity of the cutter head rotation to generate a complete 2×2 scattering matrix.

[0047] Preferably, each group of the full-polarization ground penetrating radar antenna arrays is connected to a corresponding network analyzer through a double-layer shielded coaxial cable, and the network analyzer is connected to the control unit through an optical fiber acquisition card.

[0048] Preferably, the operating frequency band of the antennas of the full-polarization ground penetrating radar antenna array is set between 100 MHz and 1300 MHz.

[0049] Preferably, three sets of the full-polarization ground penetrating radar antenna arrays are provided and are arranged in a gradient distribution along the radial direction of the cutter head, and are respectively fixed at three measurement radius positions of 1 m, 1.8 m, and 2.5 m.

[0050] Preferably, the full-polarization ground penetrating radar antenna array adopts one of Vivaldi antennas, meandered line polarization antennas, and bow-tie antennas.

[0051] Preferably, three sets of the data transmission systems are provided and are respectively connected to the three sets of full-polarization ground penetrating radar antenna arrays.

[0052] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0053] The present invention adopts multiple polarization radar antennas. By transmitting and receiving electromagnetic wave signals of multiple polarization states, it can comprehensively obtain the scattering characteristic information of the target body, can provide more comprehensive information for target recognition under complex geological conditions, and break through to realize the full-polarization data acquisition during the TBM tunneling process; the recognition accuracy of geological anomalies is significantly improved through polarization feature analysis; real-time imaging is performed as the TBM operates, without affecting the normal tunneling operation of the TBM. Description of the Drawings

[0054] Figure 1 It is a schematic composition diagram of a ring-scanning full-polarization ground penetrating radar system carried on a tunnel boring machine proposed by the present invention;

[0055] Figure 2 It is a schematic diagram of the full-polarization ground penetrating radar antenna array of a ring-scanning full-polarization ground penetrating radar system carried on a tunnel boring machine proposed by the present invention;

[0056] Figure 3 It is a schematic diagram of the working mode of the full-polarization ground penetrating radar antenna array of a ring-scanning full-polarization ground penetrating radar system carried on a tunnel boring machine proposed by the present invention;

[0057] Figure 4 It is a schematic layout diagram of the full-polarization ground penetrating radar antenna array on the TBM cutter head.

[0058] In the figure: 1. Control unit; 2. Network analyzer; 3. Power amplifier; 4. Switch controller; 5. Full-polarization ground-penetrating radar antenna array; 6. TBM cutter head. Detailed implementation manners

[0059] 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 of the embodiments.

[0060] As Figures 1 - 4 shown, based on the problems existing in the prior art, this embodiment proposes a ring-scanning full-polarization ground-penetrating radar system mounted on a tunnel boring machine, including:

[0061] A control unit 1, deployed in the TBM control room, for transmitting control signals and receiving and storing measurement data;

[0062] In this embodiment, the control unit 1 uses a PC host, equipped with a dual-port PCIe 4.0x8 storage interface, and forms a RAID 10 array through 8 NVMe SSDs, supporting hot plugging and online expansion. The continuous write speed is ≥6GB / s (4K random write 1MIOPS). At the same time, a supercapacitor power-off protection module is configured to ensure data integrity;

[0063] A full-polarization ground-penetrating radar antenna array 5, installed in the spoke gap of the cutter head through a rigid bracket, for electromagnetic wave transmission and reception;

[0064] Among them, each group includes two transmitting antennas and two receiving antennas;

[0065] Among them, the two transmitting antennas respectively transmit horizontally polarized electromagnetic waves and vertically polarized electromagnetic waves, and the two receiving antennas respectively receive horizontally polarized echoes and vertically polarized echoes. The full-polarization antenna array completes a measurement cycle through the rotation of the cutter head to obtain a complete 2×2 scattering matrix of the front annular area:

[0066]

[0067] The above process is controlled and completed by the switch controller 4. The switch controller 4 executes a four-polarization measurement timing sequence and sequentially completes:

[0068] S1. Transmitting antenna 1 transmits an H-polarized wave, and receiving antenna 1 receives an HH-polarized signal;

[0069] S2. Transmitting antenna 1 transmits an H-polarized wave, and receiving antenna 2 receives an HV-polarized signal;

[0070] S3. Transmitting antenna 2 transmits a V-polarized wave, and receiving antenna 1 receives a VH-polarized signal;

[0071] At S4, the transmitting antenna 2 transmits V-polarized waves, and the receiving antenna 2 receives VV-polarized signals;

[0072] Each measurement period is synchronized with the angular velocity of the cutter head rotation. As a preferred example of this embodiment, the angular velocity of the cutter head rotation is 0.5 rad / s, thereby generating a complete 2×2 scattering matrix;

[0073] A data transmission system is used for data transmission between the control unit 1 and the full-polarization antenna array.

[0074] Multiple sets of the full-polarization ground-penetrating radar antenna arrays 5 are provided and arranged in a gradient distribution along the radial direction of the cutter head, forming a concentric cylinder scanning architecture to complete the full-space coverage of the space in front of the tunnel. Different from the arrangement method carried on the rear of the tunnel in the prior art, in the present invention, the ground-penetrating radar antenna array is directly carried on the TBM cutter head 6, realizing continuous rotation scanning (rotation speed 0.5 rad / s), real-time data acquisition, and on-line data processing during tunneling, and solving the technical bottleneck that the traditional method must stop for detection.

[0075] As a preferred example of this embodiment, three sets of the full-polarization ground-penetrating radar antenna arrays 5 are provided and arranged in a gradient distribution along the radial direction of the cutter head, and are respectively fixed at three measurement radius positions of 1 m, 1.8 m, and 2.5 m;

[0076] Adopting the above structure settings brings the following outstanding effects:

[0077] (1) In terms of multi-radius collaborative detection, through the arrangement of antenna arrays with three measurement radii of 1 m, 1.8 m, and 2.5 m, a three-dimensional full coverage is formed in front as the TBM rotates. Compared with the single-antenna arrangement method, the detection blind area is effectively reduced, and through the cross-validation of multi-radius data, the problems of limited detection range and inaccurate positioning in the traditional method are effectively solved;

[0078] (2) In terms of full-polarization measurement ability, each group of antenna arrays measures through four polarization modes of HH, HV, VH, and VV of the system to obtain a complete 2×2 scattering matrix. Subsequently, through polarization analysis, the recognition accuracy of the system for structurally complex abnormal bodies such as water-containing fractures can be improved;

[0079] (3) In terms of real-time detection, through the continuous measurement of three groups of antenna arrays and the cutter head rotation scanning mechanism, continuous detection synchronized with the TBM tunneling is realized. The data processing delay is controlled within 3 s. With the 10 Gbps optical fiber transmission system, the three-dimensional geological model in front can be updated in real time (update frequency ≥ 0.2 Hz), solving the problem that the traditional advanced geological prediction lags behind the tunneling progress;

[0080] Compared with the prior art, the present invention can comprehensively obtain the scattering characteristic information of the target by transmitting and receiving electromagnetic wave signals of multiple polarization states, can provide more comprehensive information for target recognition under complex geological conditions, and breakthroughly realizes the acquisition of full-polarization data during the TBM tunneling process; the recognition accuracy of geological anomalies is significantly improved through polarization feature analysis; real-time imaging is performed as the TBM operates, without affecting the normal tunneling operation of the TBM.

[0081] In this embodiment, the full-polarization ground-penetrating radar antenna array 5 adopts a multi-layer composite wave-transparent protective cover design to prevent damage to the antenna during the TBM operation;

[0082] As a preferred example of this embodiment, the multi-layer composite wave-transparent protective cover is composed of a silicon nitride ceramic layer (2 mm), a polytetrafluoroethylene buffer layer (1.5 mm), and an epoxy resin sealing layer (0.5 mm) stacked in sequence.

[0083] In this embodiment, the data transmission system includes:

[0084] A network analyzer 2, and the network analyzer 2 is connected to:

[0085] A power amplifier 3 for amplifying the signal of the emission control unit 1;

[0086] A switch controller 4 for switching the polarization channels in response to the instructions of the control unit 1;

[0087] Each group of the full-polarization ground-penetrating radar antenna arrays 5 is connected to the corresponding network analyzer 2 through a double-shielded coaxial cable. After collecting data, the data is transmitted to the network analyzer 2. The cable impedance is 50 Ω, and the transmission bandwidth is 0.1 - 1.5 GHz. The network analyzer 2 is connected to the control unit 1 through an optical fiber acquisition card. As a preferred example of this embodiment, the network analyzer 2 is connected to the PC host through a PCIe 3.0 x8 optical fiber acquisition card (10 Gbps). Each unit is configured with a dual SFP+ redundant link. The industrial computer integrates a PTP-1588v2 synchronization card (OCXO clock source, time deviation ≤ 100 ns), and uses a customized UDP protocol to transmit compressed data with time stamps and CRC checks.

[0088] In this embodiment, the operating frequency band of the antennas of the full-polarization ground-penetrating radar antenna array 5 is set between 100 MHz and 1300 MHz. As a preferred example of this embodiment, a 400 MHz main frequency antenna array is adopted. Based on the propagation speed of electromagnetic waves in rock and soil media (0.1 - 0.15 m / ns), the theoretical wavelength range is 0.25 - 0.375 m. Through the back-projection algorithm, the system can achieve a spatial resolution of 0.1 - 0.3 m, which is about 20 times higher than the prior art of 1.25 - 7.5 m, meeting the accurate recognition requirements of sub-meter geological anomalies.

[0089] The full-polarization ground-penetrating radar antenna array 5 adopts one of Vivaldi antennas, meandering line polarization antennas, and bow-tie antennas. Each group of antennas has the ability to independently measure any polarization mode (HH, HV, VH, VV).

[0090] Adopting a Vivaldi antenna array can achieve higher polarization purity (cross-polarization ratio ≥ 35 dB).

[0091] Using a meandering line polarization antenna can enhance the low-frequency detection performance through a three-dimensional structure.

[0092] However, due to the limited layout space in front of the TBM cutterhead 6, as a preferred example of this embodiment, in this embodiment, a flat bow-tie antenna is adopted.

[0093] In this embodiment, three groups of data transmission systems are provided and are respectively connected to the three groups of full-polarization ground-penetrating radar antenna arrays 5.

[0094] In addition, based on the dielectric constant difference principle (ε_water = 81, ε_rock = 4 - 12), through the reflection coefficient formula R = (√ε1 - √ε2) / (√ε1 + √ε2), it can be calculated that the reflection coefficient of the water-rock interface reaches 0.6 - 0.7, which is more than 6 times higher than the seismic wave reflection coefficient (<0.1). Therefore, compared with the prior art, the detection method of the present invention can more easily detect water-containing structures.

[0095] The above is only the preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. An annular scanning full-polarization ground penetrating radar system mounted on a tunnel boring machine, characterized in that: Comprising: A control unit (1), deployed in the TBM control room, for transmitting control signals and receiving and storing measurement data; A full-polarization ground-penetrating radar antenna array (5), installed in the spoke gaps of the cutterhead, for electromagnetic wave transmission and reception; Each group includes two transmitting antennas and two receiving antennas; Among them, the two transmitting antennas respectively transmit horizontally polarized electromagnetic waves and vertically polarized electromagnetic waves, and the two receiving antennas respectively receive horizontally polarized echoes and vertically polarized echoes. The full-polarization antenna array completes a measurement cycle through the rotation of the cutterhead to obtain a complete 2×2 scattering matrix of the front annular area; A data transmission system for data transmission between the control unit (1) and the full-polarization antenna array.

2. The annular scanning full-polarization ground penetrating radar system mounted on a tunnel boring machine according to claim 1, characterized in that: Multiple sets of the full-polarization ground-penetrating radar antenna arrays (5) are provided and are arranged in a gradient along the radial direction of the cutterhead to form a concentric cylindrical scanning architecture to complete the full-space coverage of the space in front of the tunnel.

3. The annular scanning full-polarization ground penetrating radar system mounted on a tunnel boring machine according to claim 1, wherein: The full-polarization ground-penetrating radar antenna array (5) adopts a multi-layer composite wave-transmitting protective cover design to prevent damage to the antenna during the operation of the TBM.

4. The annular scanning full-polarization ground penetrating radar system mounted on a tunnel boring machine according to claim 2, characterized in that: The data transmission system includes: A network analyzer (2), and the network analyzer (2) is connected to: A power amplifier (3) for amplifying the transmitted signal; A switch controller (4) that switches the polarization channel in response to the instructions of the control unit (1).

5. The annular scanning full-polarization ground penetrating radar system mounted on a tunnel boring machine according to claim 4, characterized in that: The switch controller (4) executes a four-polarization measurement timing sequence and sequentially completes: S1, the transmitting antenna 1 transmits an H-polarized wave, and the receiving antenna 1 receives an HH-polarized signal; S2, the transmitting antenna 1 transmits an H-polarized wave, and the receiving antenna 2 receives an HV-polarized signal; S3, the transmitting antenna 2 transmits a V-polarized wave, and the receiving antenna 1 receives a VH-polarized signal; S4, the transmitting antenna 2 transmits a V-polarized wave, and the receiving antenna 2 receives a VV-polarized signal; Each measurement cycle is synchronized with the rotation angular velocity of the cutterhead to generate a complete 2×2 scattering matrix.

6. The annular scanning full-polarization ground penetrating radar system mounted on a tunnel boring machine according to claim 4, characterized in that: Each group of the full-polarization ground-penetrating radar antenna arrays (5) is connected to the corresponding network analyzer (2) through a double-shielded coaxial cable, and the network analyzer (2) is connected to the control unit (1) through an optical fiber acquisition card.

7. The annular scanning full-polarization ground penetrating radar system mounted on a tunnel boring machine according to claim 1, characterized in that: The operating frequency band of the antennas of the full-polarization ground-penetrating radar antenna array (5) is set between 100 MHz and 1300 MHz.

8. An annular scanning full-polarization ground penetrating radar system mounted on a tunnel boring machine according to claim 2, characterized in that: Three sets of the full-polarization ground-penetrating radar antenna arrays (5) are provided and are arranged in a gradient along the radial direction of the cutterhead, and are respectively fixed at three measurement radius positions of 1 m, 1.8 m, and 2.5 m.

9. The annular scanning full-polarization ground penetrating radar system mounted on a tunnel boring machine according to claim 1, characterized in that: The full-polarization ground-penetrating radar antenna array (5) adopts one of a Vivaldi antenna, a meandered-line polarization antenna, and a bow-tie antenna.

10. A circular scanning full-polarization ground penetrating radar system mounted on a tunnel boring machine according to claim 8, characterized in that: Three sets of the data transmission systems are provided and are respectively connected to the three sets of full-polarization ground-penetrating radar antenna arrays (5).

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