A tunnel geological disaster advance prediction method and system based on a quadrature field source

Abstract

This invention belongs to the field of geophysical exploration technology and provides a method and system for advanced prediction of tunnel geological hazards based on orthogonal field sources. It constructs two sets of high-order pseudo-random signals, deploys orthogonal field sources, and each field source emits different sets of high-order pseudo-random signals. Two sets of orthogonal observation points are set up at the tunnel face and on the tunnel floor within a set distance. The two field sources are simultaneously excited, and the two sets of observation points observe and collect received signals for a set duration. Based on the frequency components of the emitted high-order pseudo-random signals, the electromagnetic field data of the corresponding field source is extracted. Based on the electromagnetic field data, the apparent resistivity of the single-component electric field and the Carnia apparent resistivity are calculated to obtain the detection results. This invention can realize the detection of geological conditions at tunnel construction sites.

Description

Technical Field

[0001] This invention belongs to the field of geophysical exploration technology, specifically relating to a method and system for predicting tunnel geological hazards based on orthogonal field sources. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] With the rapid and large-scale construction of infrastructure projects such as high-speed railways, highways, and urban rail transit, the number of long tunnels is also increasing. However, the geographical environment of some areas is mostly mountainous and hilly, and the terrain in most areas is complex, which brings great difficulties and risks to tunnel construction. Ensuring safe, rapid, and efficient tunnel construction is of paramount importance in current tunnel construction. Therefore, it is essential to conduct advanced geological forecasting for tunnels.

[0004] Advanced pseudo-random signal customization technology can transmit a set of multi-frequency signals at once, with up to 81 frequencies, enabling high-resolution detection of targets and possessing the potential for advanced detection and prediction of geological conditions near tunnel faces in the near-field (transmitter-receiver distance of approximately 1 km). Meanwhile, previous single-source transmission modes have a certain signal "zero-value zone," which significantly limits the observation range. Therefore, it is necessary to increase the number of field sources to expand the signal coverage. Summary of the Invention

[0005] To address the aforementioned problems, this invention proposes a method and system for advanced prediction of tunnel geological hazards based on orthogonal field sources. Starting from the field source setup and observation method of the artificial source frequency domain electromagnetic method, this invention constructs an artificial source electromagnetic tunnel advanced geological prediction method based on high-order pseudo-random signals by deploying near-field dual field sources and orthogonal observation components outside the tunnel. This method successfully obtains high-quality artificial source electromagnetic data to reflect the geological conditions at the tunnel construction site.

[0006] According to some embodiments, the present invention adopts the following technical solution:

[0007] A method for predicting tunnel geological hazards based on orthogonal field sources includes the following steps:

[0008] Two sets of high-order pseudo-random signals are constructed, and orthogonal field sources are deployed outside the tunnel. The field sources emit different sets of high-order pseudo-random signals respectively.

[0009] Two sets of orthogonal observation points are set up at the tunnel face and on the tunnel floor within a set distance. Two field sources are excited at the same time. The two sets of observation points observe and collect the received signals for a set time. Based on the frequency components of the transmitted high-order pseudo-random signals, the electromagnetic field data of the corresponding field source is extracted.

[0010] Based on the electromagnetic field data, the apparent resistivity of the single-component electric field and the apparent resistivity of the Carnia field are calculated to obtain the detection results.

[0011] As an alternative implementation method, the transmission and reception distances of the orthogonal field sources are all above the set value.

[0012] As an alternative implementation, the main frequencies of the high-order pseudo-random signals from the two field sources do not overlap and are excited at different frequencies, and are simultaneously transmitted under the control of a dual-channel signal transmitter and signal transmission controller.

[0013] As an alternative implementation, the two field sources are orthogonal field sources with equal pole spacing.

[0014] As an alternative implementation, the tunnel face is used as the primary observation location, and the observation points on the tunnel face are used to observe the two parallel electric field components and the vertical magnetic component.

[0015] As an alternative implementation, the base plate serves as a reference observation position, and the observation points on the base plate are used to observe the horizontal orthogonal electric field component E. x E y and horizontal orthogonal magnetic component H x H y .

[0016] As a further step, the magnetic component H x H y Perpendicular to the electric field component E y E x .

[0017] As a further step, the electromagnetic components of each set of observation points are arranged orthogonally.

[0018] As an alternative implementation method, based on two sets of orthogonal electromagnetic field components obtained from the observation points at the tunnel face, the single-component apparent resistivity and the Carnia apparent resistivity are calculated respectively, thereby realizing the advanced prediction of geological hazards near the tunnel face. The advanced prediction results are verified by using the detection results of the observation points at the tunnel floor as a reference.

[0019] A tunnel geological hazard prediction system based on orthogonal field sources includes:

[0020] Orthogonal field sources are used to transmit two pre-constructed sets of high-order pseudo-random signals respectively;

[0021] Orthogonal observation points are set up at the tunnel face and on the tunnel floor within a set distance. After two field sources are excited at the same time, the two sets of observation points observe and collect the received signals for a set time. Based on the frequency components of the transmitted high-order pseudo-random signal, the electromagnetic field data of the corresponding field source is extracted.

[0022] The calculation unit is used to calculate the apparent resistivity of the single-component electric field and the apparent resistivity of the Carnia field based on the electromagnetic field data, and obtain the detection results.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. This invention provides advanced geological prediction information for tunnels by deploying orthogonal dual-field sources with the same transmit and receive distance (source points coincide) outside the tunnel and obtaining high-resolution geological exploration data near the tunnel face based on near-field detection characteristics.

[0025] 2. This invention employs two sets of receiving points deployed within the survey area for separate observation. The electromagnetic components of each set of receiving points are orthogonally arranged. Based on the frequency components of the transmitted high-order pseudo-random signal, the received data of the corresponding field source can be extracted, which greatly improves the efficiency of dual-source observation.

[0026] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0027] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0028] Figure 1 This is a schematic diagram of the time-domain sequence of a 50A signal in a high-order pseudo-random signal from an orthogonal field source according to one embodiment.

[0029] Figure 2 This is a schematic diagram of the spectrum of a 50A signal in a high-order pseudo-random signal from an orthogonal field source according to one embodiment.

[0030] Figure 3 This is a schematic diagram of the time-domain sequence of a 50B signal in a high-order pseudo-random signal from an orthogonal field source according to one embodiment.

[0031] Figure 4 This is a schematic diagram of the spectrum of a 50B signal in a high-order pseudo-random signal from an orthogonal field source according to one embodiment.

[0032] Figure 5 This is a diagram illustrating the system's field operation mode in one embodiment.

[0033] Figure 6 This is a diagram showing the apparent resistivity of a single component electric field at the face of a tunnel according to one embodiment. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0035] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, 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.

[0036] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0037] Where there is no conflict, the embodiments and features described in this application may be combined with each other.

[0038] Example 1

[0039] This embodiment discloses a method and system for predicting advanced geological hazards in electromagnetic tunnels based on high-order pseudo-random signals using dual orthogonal staggered-frequency artificial sources, including the following steps:

[0040] Step 1: Based on the construction method of high-order pseudo-random signals, construct the high-order pseudo-random signals used for the equidistant orthogonal field source; the signals used for the orthogonal field source are 50A (50 frequencies, fundamental frequency 2.0Hz, frequency range 2.0Hz~7168Hz) and 50B (50 frequencies, fundamental frequency 2.4Hz, frequency range 2.4Hz~8601.6Hz). All frequencies contained in the signals used for the orthogonal field source do not overlap and are excited at different frequencies.

[0041] Construct one set of signals as a 50A signal, such as Figure 1 As shown, this is a time-domain sequence, such as... Figure 2 The image shows the spectrum, where circles (○) represent exploration frequencies. A 5th-order, 50-frequency signal was used, spanning the frequency band from 2.0 to 7168 Hz, comprising a total of 50 frequencies. Its frequency components are shown in Table 1.

[0042] Table 1

[0043]

[0044] Construct one set of signals as 50B signals, such as Figure 3 , Figure 4 As shown, a 5th-order, 50-frequency signal is used, with a frequency band of 2.4–8601.6 Hz, totaling 50 frequencies. Its frequency components are shown in Table 2.

[0045] Table 2

[0046]

[0047] Step 2: Deploy the orthogonal field source at a distance of 1km from the receiver, connect it to the signal transmitter via an external power supply, connect the copper electrodes with long wires, and use the signal transmission controller to transmit signals. A1B1 transmits a 50A signal, and A2B2 transmits a 50B signal.

[0048] like Figure 5 As shown, a set of orthogonal field sources with equal pole spacing are deployed. Field source A1B1 emits as follows: Figure 1 , Figure 2 The signal shown is emitted by field source A2B2 as follows: Figure 3 and Figure 4 The signal shown typically has a transmission and reception distance greater than 1km, and the wire source is typically 0.5km to 2km long.

[0049] In some embodiments, the two field source points coincide, and a long wire is used to ground the field source. The field source is deployed in a place with a large transmit-receive distance (such as more than 1 km). If the tunnel is long enough, the field source can also be deployed inside the tunnel and connected to the signal transmitter through an external power supply. The signal controller transmits the frequency error signal.

[0050] Step 3: Simultaneously excite orthogonal field sources and set up two sets of receiving points in the test area (granite) for observation. The electromagnetic components of each set of receiving points are orthogonally arranged. Based on the frequency components of the emitted high-order pseudo-random signal, the received data of the corresponding field source can be extracted.

[0051] In some embodiments, two sets of observation points can be set up at the tunnel face and the adjacent tunnel floor, with the tunnel face as the primary observation location and the floor as the reference observation location. Two parallel components of the electric field (E) are observed at the tunnel face. x1 E x2 ) and vertical magnetic component (H) z ), Observation of horizontal orthogonal electric field components (E) on the base plate x E y ) and horizontal orthogonal magnetic components (H x H y perpendicular to E y E x By setting up the above measurement points, two sets of orthogonal electromagnetic component measurement points are formed. Measurements are taken at the tunnel face and base plate, and received signals are collected for a certain duration. Based on the frequency components of the transmitted high-order pseudo-random signal, the received data of the corresponding field source can be extracted.

[0052] Step 4, as follows Figure 6 As shown, when the transmit / receive distance meets the near-area condition, 10 3 The high-frequency range of Hz can effectively obtain shallow geological information of the survey area, and clearly has the ability to predict the geological conditions of tunnels in advance.

[0053] With a transmit / receive distance of 1km, the 50-frequency wave can reflect the geological conditions near the tunnel face. Based on electromagnetic field observation data, the apparent resistivity of the single-component electric field and the apparent resistivity of the Cania are calculated. The detection effect is analyzed through the calculation results, and the effective frequency range that can be used for tunnel advanced geological prediction is further obtained.

[0054] Orthogonal electromagnetic field components are simultaneously deployed at the tunnel face and floor, and two parallel electric field components (E0) are deployed at the tunnel face. x1 E x2 ) and vertical magnetic field component H z (Orthogonal to the two electric field components, normally "x, y, z" are labels from a horizontal plane perspective, but since the tunnel face itself is vertical, H here...) z For E x In other words, it is equivalent to H y ), and horizontal orthogonal electric field components (E) are arranged on the base plate. x E y ) and horizontal orthogonal magnetic components (H x H y perpendicular to E y E x By setting up the aforementioned measuring points, electromagnetic field observation data of the tunnel face and the base plate orthogonally can be obtained simultaneously. According to the formula for calculating the single-component apparent resistivity of the wide-area electromagnetic method, substituting E into the value of the tunnel face... x1 E x2 The single-component apparent resistivity calculation result is obtained, and the tunnel floor is substituted into E. x E y The observed values ​​yielded the single-component apparent resistivity calculation results. Based on the Carnia formula for apparent resistivity, the values ​​were substituted into E at the working face. x1 E x2 With H z (for E) x In other words, it is equivalent to H y Substitute E into the tunnel floor slab respectively x H y，以 and E y H x The observation data yielded the apparent resistivity calculation results of Kania. Both apparent resistivity results can reflect the geological conditions near the tunnel face. Theoretically, the apparent resistivity should have a certain degree of similarity in shape. Therefore, by taking the tunnel face as the main factor and the bottom plate as a reference, information on geological hazards affecting tunnel construction can be obtained, and thus, advance prediction of tunnel geological hazards can be carried out.

[0055] Copper electrodes were inserted through holes drilled in the test area, fixed with wet soil to increase conductivity, and magnetic rods were placed as required. A signal receiver was connected to measure the received signals for a certain acquisition time. After data denoising and normalization, the apparent resistivity of the single-component electric field and the apparent resistivity of the Carnia were finally calculated. The apparent resistivity of the single-component electric field and the apparent resistivity of the Carnia were calculated using two sets of orthogonal electromagnetic field components at the tunnel face. This was used for advanced prediction of geological hazards near the tunnel face, and the results were verified using the detection results of the tunnel floor as a reference.

[0056] In this embodiment, the process of calculating the apparent resistivity of a single-component electric field includes: ρ a = ;

[0057] In the formula, ;

[0058] ;

[0059] = ;

[0060] ; k = ;

[0061] in, For device coefficients, dL For the source polar distance, To measure the electrode distance, The voltage value at the observation point. The electric field strength at the observation point, I The induced current intensity, r For transmit and receive distance, φ To observe the azimuth angle, ω It is angular frequency. ω = 2 f , σ For the earth's electrical conductivity, μ Permeability in free space μ = μ 0 = 4 ×10 -7 , i It is a unit imaginary number.

[0062] The apparent resistivity of Cania is calculated as follows:

[0063] ρ = 2 or ρ = 2 ;

[0064] ω It is angular frequency. μ E is the free space permeability. x E y These are the observed horizontal orthogonal electric field components at the observation point on the base plate, H. x H y These are the horizontal orthogonal magnetic components of the observation point on the base plate.

[0065] Example 2

[0066] A tunnel geological hazard prediction system based on orthogonal field sources includes:

[0067] An orthogonal dual-field source outside the tunnel is used to transmit two pre-constructed sets of high-order pseudo-random signals respectively;

[0068] Orthogonal observation points are set up at the tunnel face and on the tunnel floor within a set distance. After two field sources are excited at the same time, the two sets of observation points observe and collect the received signals for a set time. Based on the frequency components of the transmitted high-order pseudo-random signal, the electromagnetic field data of the corresponding field source is extracted.

[0069] The calculation unit is used to calculate the apparent resistivity of the single-component electric field and the apparent resistivity of the Carnia field based on the electromagnetic field data, and obtain the detection results.

[0070] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of one or more computer-usable storage media (including, but not limited to, disk storage, etc.) containing computer-usable program code. CD - ROM It takes the form of a computer program product implemented on (such as optical memory, etc.).

[0071] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0072] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0073] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0074] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art without creative effort within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for predicting tunnel geological hazards based on orthogonal field sources, characterized in that, Includes the following steps: Two sets of high-order pseudo-random signals are constructed, and orthogonal dual field sources are deployed outside the tunnel. The field sources emit different sets of high-order pseudo-random signals respectively. Two sets of orthogonal observation points were set up at the tunnel face and on the tunnel floor within a set distance. Two field sources were simultaneously excited, and the two sets of observation points observed and collected the received signals for a set duration. Based on the frequency components of the transmitted high-order pseudo-random signals, the electromagnetic field data of the corresponding field sources were extracted. The tunnel face served as the primary observation position, and the observation points on the tunnel face were used to observe the two parallel electric field components and the vertical magnetic component. The tunnel floor served as the reference observation position, and the observation points on the floor were used to observe the horizontal orthogonal electric field component E. x E y and horizontal orthogonal magnetic component H x H y ; Magnetic component H x H y Perpendicular to the electric field component E y E x ; Based on the electromagnetic field data, the apparent resistivity of the single-component electric field and the apparent resistivity of the Carnia were calculated, with the face of the tunnel as the main focus and the results of the base plate as a reference, to obtain the detection results.

2. The method for advanced prediction of tunnel geological hazards based on orthogonal field sources as described in claim 1, characterized in that, The transmit and receive distances of the orthogonal field sources are all above the set values.

3. The method for advanced prediction of tunnel geological hazards based on orthogonal field sources as described in claim 1, characterized in that, The two field sources are orthogonal field sources with equal polarity outside the tunnel.

4. The method for advanced prediction of tunnel geological hazards based on orthogonal field sources as described in claim 1, characterized in that, The electromagnetic components of each set of observation points are arranged orthogonally.

5. The method for advanced prediction of tunnel geological hazards based on orthogonal field sources as described in claim 1, characterized in that, Based on two sets of orthogonal electromagnetic field components obtained from observation points at the tunnel face, the single-component apparent resistivity and Carnia apparent resistivity are calculated respectively, enabling advanced prediction of geological hazards near the tunnel face. The advanced prediction results are verified by using the detection results from observation points on the tunnel floor as a reference.

6. A tunnel geological hazard prediction system based on orthogonal field sources, characterized in that, include: An orthogonal dual-field source outside the tunnel is used to transmit two pre-constructed sets of high-order pseudo-random signals respectively; Orthogonal observation points are deployed at the tunnel face and on the tunnel floor within a set distance. After simultaneously exciting two field sources, the two sets of observation points observe and collect the received signals for a set duration. Based on the frequency components of the transmitted high-order pseudo-random signals, the electromagnetic field data of the corresponding field source is extracted. The tunnel face serves as the primary observation location, with observation points there used to observe the two parallel electric field components and the vertical magnetic component. The tunnel floor serves as the reference observation location, with observation points on the floor used to observe the horizontal orthogonal electric field component E. x E y and horizontal orthogonal magnetic component H x H y ; Magnetic component H x H y Perpendicular to the electric field component E y E x ; The calculation unit is used to calculate the apparent resistivity of the single-component electric field and the apparent resistivity of the Carnia field based on the electromagnetic field data, with the results from the working face as the main focus and the results from the base plate as a reference, to obtain the detection results.

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