Geological prediction system, method, shield machine and electrode array

Abstract

The present disclosure provides a geological prediction system, a method and a shield machine, which relate to the technical field of geological exploration. The electrode array includes: a cutter head configured to cooperate with a return electrode to establish an alternating electric field; a plurality of electrode assemblies, each of which including: a first electrode configured to output current towards a tunnel face of a construction tunnel; a second electrode arranged around a periphery of the first electrode; a third electrode arranged around a periphery of the second electrode, where the first electrode, the second electrode, the third electrode, and the cutter head are insulated from each other.

Description

Geological prediction systems, methods, tunnel boring machines and electrode systems

[0001] Cross-references to related applications

[0002] This application is based on and claims priority to CN application number 202411687600.X, filed on November 25, 2024, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure relates to the field of geological exploration technology, and in particular to a geological prediction system, method, tunnel boring machine and electrode system. Background Technology

[0004] With the increase in large-scale infrastructure projects in municipal engineering, transportation, and mining in China, and the improvement of infrastructure standards, underground construction projects account for an increasingly higher proportion of infrastructure projects. Underground construction is characterized by high risk factors and stringent requirements for equipment stability and technical safety. During underground construction, encountering water-bearing structures such as fracture zones, karst caves, and underground rivers often leads to sudden water inrushes, causing equipment damage, project delays, and even serious accidents such as casualties. To avoid these accidents, advanced geological forecasting methods are typically used to explore the geological conditions ahead of the tunnel face, and reasonable construction plans and handling measures are formulated in advance based on the measurement and evaluation analysis results. Summary of the Invention

[0005] According to one aspect of this disclosure, an electrode system for a geological prediction system is proposed, comprising: a cutterhead configured to cooperate with a return electrode to construct an alternating electric field; and a plurality of electrode assemblies, each of the plurality of electrode assemblies comprising: a first electrode configured to output current toward the working face of a construction tunnel; a second electrode disposed around the outer periphery of the first electrode; and a third electrode disposed around the outer periphery of the second electrode, wherein the first electrode, the second electrode, the third electrode, and the cutterhead are insulated from each other.

[0006] In some embodiments, the supply current to the first electrode is adjusted to make the second and third electrodes at the same potential.

[0007] In some embodiments, a plurality of electrode assemblies are disposed on one side of the center of the cutter head and arranged sequentially along the radial direction of the cutter head.

[0008] In some embodiments, the number of multiple electrode assemblies is determined based on the cutter head size.

[0009] In some embodiments, the cutter head has the same polarity as the first electrode and the opposite polarity to the return electrode.

[0010] According to another aspect of this disclosure, a geological prediction system is also proposed, comprising: the aforementioned electrode system; a transmitting system configured to provide excitation signals to the cutterhead and the return electrode; a focusing system corresponding to each electrode assembly configured to acquire a potential difference signal between a second electrode and a third electrode, and adjust the supply current of a first electrode based on the potential difference signal; and a measuring system corresponding to each electrode assembly configured to determine apparent resistivity based on a voltage signal between a third electrode and a reference electrode, and a current signal output by the first electrode, and determine geological information of the construction tunnel based on the apparent resistivity.

[0011] In some embodiments, the focusing system is configured to reduce the supply current of the first electrode when the potential of the second electrode is higher than the potential of the third electrode, and to increase the supply current of the first electrode when the potential of the second electrode is lower than the potential of the third electrode.

[0012] In some embodiments, the focusing system includes: an amplification circuit configured to amplify a potential difference signal to obtain a first signal; a notch filter circuit configured to notch the first signal to obtain a second signal; a first filter circuit configured to bandpass filter the second signal to obtain a third signal; a proportional-integral-derivative (PID) control circuit configured to PID adjust the third signal to obtain a fourth signal; and a first power amplifier circuit configured to amplify the fourth signal to generate a fifth signal and input the fifth signal to the first electrode to adjust the supply current of the first electrode.

[0013] In some embodiments, the excitation signal is a sine wave signal, and the transmitting system includes: a host computer configured to control the transmitting host to transmit the sine wave signal at predetermined time intervals; and a transmitting host configured to generate the sine wave signal and send the sine wave signal to the cutter head and the return electrode.

[0014] In some embodiments, the transmitting host includes: a control unit configured to generate multiple unipolar square wave signals, perform digital-to-analog conversion on the multiple unipolar square wave signals to generate multiple adjustable analog signals, and send the multiple unipolar square wave signals and the multiple adjustable analog signals to a programmable chopper circuit; a programmable chopper circuit configured to chop the multiple unipolar square wave signals and the multiple adjustable analog signals into bipolar square wave signals; a second filtering circuit configured to perform bandpass filtering on the bipolar square wave signals to obtain a sine wave signal; and a second power amplifier circuit configured to amplify the power of the sine wave signal and input the amplified sine wave signal to the cutter head and the return electrode.

[0015] In some embodiments, the measurement system includes: a signal conditioning and data acquisition circuit configured to condition and acquire a voltage signal between a third electrode and a reference electrode, and a current signal output from a first electrode; a calibration circuit configured to generate a calibration signal and input the calibration signal to the signal conditioning and data acquisition circuit to calibrate the signal conditioning and data acquisition circuit; an acquisition control circuit configured to control the signal conditioning and data acquisition circuit to perform data acquisition and signal conditioning, and to control the calibration circuit to calibrate the signal conditioning and data acquisition circuit; and a computer configured to send control commands to the acquisition control circuit, and to determine the apparent resistivity based on the voltage signal between the third electrode and the reference electrode, and the current signal output from the first electrode, and to determine the geological information of the construction tunnel based on the apparent resistivity.

[0016] In some embodiments, the measurement system further includes a power supply circuit configured to provide power to the signal conditioning and data acquisition circuit, the calibration circuit, the acquisition control circuit, and the computer.

[0017] According to another aspect of this disclosure, a tunnel boring machine is also proposed, including the aforementioned electrode system or geological prediction system for a geological prediction system.

[0018] According to another aspect of this disclosure, a geological prediction method based on the above-described geological prediction system is also proposed, comprising: providing an excitation signal to the cutterhead and the return electrode through a transmission system; acquiring a potential difference signal between a second electrode and a third electrode in an electrode assembly corresponding to each focusing system through each focusing system, and adjusting the power supply current of the first electrode according to the potential difference signal; acquiring a voltage signal between a third electrode and a reference electrode in an electrode assembly corresponding to each measurement system, and a current signal output by the first electrode through each measurement system, determining the apparent resistivity according to the voltage signal and the current signal, and determining the geological information of the construction tunnel according to the apparent resistivity.

[0019] In some embodiments, adjusting the supply current of the first electrode according to the potential difference signal includes: reducing the supply current of the first electrode when the potential of the second electrode is higher than the potential of the third electrode; and increasing the supply current of the first electrode when the potential of the second electrode is lower than the potential of the third electrode.

[0020] Other features and advantages of this disclosure will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0021] The accompanying drawings, which form part of this specification, illustrate embodiments of this disclosure and, together with the specification, serve to explain the principles of this disclosure.

[0022] This disclosure will become clearer with reference to the accompanying drawings and the following detailed description, wherein:

[0023] Figure 1 is a schematic diagram of the structure of some embodiments of the electrode system disclosed herein;

[0024] Figure 2 is a schematic diagram of the structure of some embodiments of the geological prediction system of this disclosure;

[0025] Figure 3 is a schematic diagram of some embodiments of the focused current field of this disclosure;

[0026] Figure 4 is a schematic diagram of the structure of some embodiments of the focusing system of this disclosure;

[0027] Figure 5 is a schematic diagram of the structure of some embodiments of the transmitter host of this disclosure;

[0028] Figure 6 is a schematic diagram of the structure of some embodiments of the measurement system of this disclosure;

[0029] Figure 7 is a flowchart illustrating some embodiments of the geological prediction method of this disclosure. Detailed Implementation

[0030] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present disclosure.

[0031] At the same time, it should be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn according to actual scale.

[0032] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this disclosure or its application or use.

[0033] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0034] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0035] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0036] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0037] In recent years, the number of large-diameter tunnels in China has gradually increased, and the commonly used geological forecast results cannot meet the needs of large-diameter tunnels for detailed evaluation of the tunnel face.

[0038] This disclosure provides a geological prediction system, method, and electrode system applicable to large-diameter slurry shield tunneling machines. This allows the emitted current on the electrodes to flow perpendicularly into the strata in front of the cutterhead, enabling more accurate, effective, and precise detection of the geological conditions of the strata to be excavated. Specific embodiments will be used as examples to illustrate the solution of this disclosure.

[0039] Figure 1 is a schematic diagram of the structure of some embodiments of the electrode system disclosed herein. The electrode system 1 includes a cutter head 11 and a plurality of electrode assemblies 12.

[0040] The cutterhead 11 is a cutting disc with multiple feed slots, located at the front of the tunnel boring machine, used for cutting soil. The cutterhead 11 is configured to cooperate with a return electrode to create an alternating electric field; the cutterhead can function as an electrode, for example, as electrode A1.

[0041] Each of the plurality of electrode assemblies 12 includes a first electrode A0, a second electrode M1, and a third electrode M2. The first electrode A0 is configured to output current toward the working face of the tunnel; the second electrode M1 is disposed around the outer periphery of the first electrode; the third electrode M2 ​​is disposed around the outer periphery of the second electrode, wherein the first electrode A0, the second electrode M1, the third electrode M2, and the cutterhead 11 are insulated from each other. When the cutterhead 11 is used as an electrode, it has the same polarity as the first electrode A0.

[0042] The first electrode A0, the second electrode M1, and the third electrode M2 ​​are made of metal materials such as stainless steel and copper, and the insulating material between the electrodes is made of high-strength insulating material such as PEEK and fiberglass.

[0043] In the above embodiment, the cutter head 11 serves as electrode A1, and the current output by it surrounds the current output by the first electrode A0, so that the current output by the first electrode A0 will not cross the second electrode M1 and the third electrode M2 ​​and flow into the outside. This allows the current output by the first electrode to flow into the strata perpendicularly to the working face, which is convenient for subsequent geological exploration of the strata.

[0044] In some embodiments, the supply current of the first electrode A0 is adjusted according to the potential difference signal between the second electrode M1 and the third electrode M2. For example, the supply current of the first electrode A0 is adjusted so that the second electrode M1 and the third electrode M2 ​​are at the same potential.

[0045] The second electrode M1 and the third electrode M2 ​​are at the same potential, meaning there is no potential difference between them. According to Ohm's law, no current flows between them, causing the current output from the first electrode A0 to flow perpendicularly into the ground face. Using this inflowing current signal, a detailed assessment of the ground ahead of the tunnel face can be made, providing more accurate anomaly information for on-site construction and significantly reducing the risks of tunnel construction.

[0046] In some embodiments, a plurality of electrode assemblies 12 are disposed on one side of the center of the cutter head 11 and arranged sequentially along the radial direction of the cutter head 11. For example, starting from the center of the cutter head 11, a plurality of electrode assemblies 12 are arranged at different radii along the radial direction of the cutter head 11. Holes can be made at different radii to install the electrode assemblies 12.

[0047] In this embodiment, multiple electrode assemblies are arranged at different radial positions on the cutterhead, covering the radial direction of the cutterhead. When the cutterhead rotates, the electrode assemblies scan the formation on the circumference and cover the tunnel face on the circumference. In addition, the electrode assemblies are located on one side of the cutterhead, which can save the number of electrode assemblies while covering the geological prediction of the entire tunnel face, and facilitates installation.

[0048] In some embodiments, the number of electrode assemblies is determined based on the cutterhead size. The cutterhead size varies considerably among different types of tunnel boring machines, and the number of electrode assemblies can be determined according to the diameter of the cutterhead used in actual construction. To ensure a certain level of measurement accuracy, generally, the larger the cutterhead, the more electrode assemblies are arranged radially along it.

[0049] Figure 2 is a schematic diagram of the structure of some embodiments of the geological prediction system disclosed herein. The geological prediction system can be applied to equipment such as earth pressure shield tunneling machines and slurry shield tunneling machines. The geological prediction system includes the electrode system 1 in the above embodiments, the transmitting system 2, the focusing system 3 corresponding to each electrode component, and the measuring system 4 corresponding to each electrode component.

[0050] The transmitting system 2 is configured to provide an excitation signal to the cutterhead 11 and the return electrode 5. For example, the excitation signal is a low-frequency sine wave signal of 10Hz to 1kHz, which establishes a stable alternating electric field in the strata surrounding the tunnel boring machine. The cutterhead 11 and the return electrode 5 have opposite polarities. The return electrode 5 forms a circuit with the cutterhead 11 and the first electrode A0, respectively.

[0051] The focusing system 3 corresponding to each electrode assembly is configured to acquire the potential difference signal between the second electrode M1 and the third electrode M2, and adjust the supply current of the first electrode A0 according to the potential difference signal. For example, by adjusting the supply current of the first electrode A0 so that the second electrode M1 and the third electrode M2 ​​are at the same position, under this condition, the current emitted by the first electrode A0 can flow into the formation perpendicular to the working face.

[0052] In some embodiments, different numbers of electrode assemblies can be arranged according to the diameter of the tunnel boring machine and the requirements for the accuracy of geological forecasting. As shown in Figure 3, this embodiment shows four sets of electrode assemblies, with the current beam 1210 of electrode assembly 121, the current beam 1220 of electrode assembly 122, the current beam 1230 of electrode assembly 123, and the current beam 1240 of electrode assembly 124 flowing vertically into the strata.

[0053] The measurement system 4 corresponding to each electrode assembly is configured to determine the apparent resistivity based on the voltage signal between the third electrode M2 ​​and the reference electrode 6, and the current signal output by the first electrode A0, and to determine the geological information of the construction tunnel based on the apparent resistivity.

[0054] For example, the voltage signal between the third electrode M2 ​​and the reference electrode 6, and the current signal output by the first electrode A0 are amplified, filtered, converted from analog to digital, and processed digitally to obtain the emission current I0 of each first electrode A0 and the potential Vm of each third electrode. Then, the apparent resistivity in front of each electrode assembly is calculated using the formula Ra=K*Vm / I0, where K is the electrode coefficient.

[0055] Different geological conditions often have different apparent resistivity, so changes in apparent resistivity can reflect changes in geological conditions. For example, if the strata have a high water content, the apparent resistivity is low; if the strata are mainly composed of rock, the apparent resistivity is high.

[0056] The measurement system 4 measures the voltage signal between the third electrode M2 ​​and the reference electrode 6, rather than the voltage signal between the first electrode A0 and the reference electrode 6. This allows for the measurement of the potential within the formation, reducing the influence of mud on the measurement and thus improving the accuracy of apparent resistivity calculation.

[0057] In the above embodiments, the geological prediction system, through the electrode system disclosed herein, and in conjunction with the transmission system, focusing system, and measurement system, enables current to flow vertically into the strata and calculate the apparent resistivity of the strata. This allows for more accurate, effective, and precise detection of the geological conditions of the strata to be excavated, providing more accurate anomaly information for on-site construction and greatly reducing the risks of tunnel construction.

[0058] In some embodiments, the return electrode 5 and the reference electrode 6 are generally served by ground anchors installed at a distance of about 200 meters from the tail of the tunnel boring machine.

[0059] In some embodiments, the number of electrode assemblies corresponds to the number of focusing systems 3 and measurement systems 4. As shown in Figure 3, if four electrode assemblies are provided, the geological prediction system includes four focusing systems and four measurement systems.

[0060] The following will describe the launching system, focusing system and measurement system of this disclosure in detail using specific embodiments as examples.

[0061] In some embodiments of this disclosure, the focusing system is generally installed in a waterproof and dustproof cavity near the electrode assembly, and each electrode assembly has its own independent focusing system. The focusing system is configured to reduce the supply current of the first electrode A0 when the potential of the second electrode M1 is higher than that of the third electrode M2, thereby reducing the potential difference between the second electrode M1 and the third electrode M2; and to increase the supply current of the first electrode when the potential of the second electrode M1 is lower than that of the third electrode M2, thereby reducing the potential difference between the second electrode M1 and the third electrode M2.

[0062] Through the above continuous adjustment, the potential difference between the second electrode M1 and the third electrode M2 ​​is made zero. Under this condition, the current emitted by the first electrode A0 can flow into the formation perpendicular to the working face.

[0063] As shown in Figure 4, which is a structural schematic diagram of some embodiments of the focusing system of this disclosure, the focusing system includes an amplification circuit 31, a notch filter circuit 32, a first filter circuit 33, a PID control circuit 34, and a first power amplifier circuit 35.

[0064] The amplifier circuit 31 is configured to amplify the potential difference signal between the potential of the second electrode M1 and the third electrode M2 ​​to obtain the first signal.

[0065] The notch filter circuit 32 is configured to notch the first signal to obtain the second signal. For example, the notch filter circuit can notch power frequency interference signals in the first signal to reduce power frequency interference signals.

[0066] The first filter circuit 33 is configured to perform bandpass filtering on the second signal to obtain the third signal. For example, the first filter circuit is a bandpass filter circuit that attenuates out-of-band interference signals and reduces interference signals outside the frequency range of the useful signal.

[0067] The PID control circuit 34 is configured to perform PID (Proportional-Integral-Differential) adjustment on the third signal to obtain the fourth signal. For example, the PID control circuit processes the useful signal to control the supply current of the first electrode.

[0068] The first power amplifier circuit 35 is configured to amplify the fourth signal to generate a fifth signal and input the fifth signal to the first electrode A0 to adjust the supply current of the first electrode A0.

[0069] Initially, the second electrode M1 and the third electrode M2 ​​are typically at different potentials, with a potential difference signal existing between them. This potential difference signal serves as the input to the focusing system. The focusing system, through a series of signal conditioning and PID control adjustments, controls the magnitude of the power supply current to the first electrode A0. Through continuous adjustment, the potential difference between the second electrode M1 and the third electrode M2 ​​is made zero. Under this condition, the current emitted by the first electrode A0 can flow into the formation perpendicularly to the working face.

[0070] In some embodiments of this disclosure, the launching system is typically placed in a relatively enclosed environment such as a main control room or a PLC (Programmable Logic Controller) room. The launching system includes a host computer and a launching host. The host computer is configured to control the launching host to emit sinusoidal signals at predetermined time intervals. For example, software installed on the host computer controls the launching host to emit sinusoidal signals at certain time intervals, supplying them to the cutterhead and return electrodes. The launching host is configured to generate sinusoidal signals and send them to the cutterhead and return electrodes, thereby establishing a stable electric field in the strata surrounding the tunnel boring machine.

[0071] As shown in Figure 5, which is a schematic diagram of the structure of some embodiments of the transmitter host disclosed herein, the transmitter host includes a control unit 21, a programmable chopper circuit 22, a second filter circuit 23, and a second power amplifier circuit 24.

[0072] The control unit 21 is configured to generate multiple unipolar square wave signals of specific frequencies, perform digital-to-analog conversion on the multiple unipolar square wave signals to generate multiple adjustable analog signals, and send the multiple unipolar square wave signals and the multiple adjustable analog signals to a programmable chopper circuit. The control unit 21 is, for example, an MCU (Microcontroller Unit) / FPGA (Field Programmable Gate Array) unit that can generate multiple unipolar square wave signals of specific frequencies, generate multiple adjustable analog signals through a digital-to-analog converter, and output the unipolar square wave signals and adjustable analog signals to the programmable chopper unit.

[0073] The programmable chopper circuit 22 is configured to chop multiple unipolar square wave signals and multiple adjustable analog signals into bipolar square wave signals. For example, the programmable chopper unit chops unipolar square wave signals and adjustable analog signals generated by the MCU / FPGA unit into amplitude-adjustable bipolar square wave signals.

[0074] The second filter circuit 23 is configured to perform bandpass filtering on the bipolar square wave signal to obtain a sine wave signal. For example, the second filter circuit performs bandpass filtering on the bipolar square wave signal to smooth the square wave and obtain an amplitude-adjustable sine wave signal.

[0075] The second power amplifier circuit 24 is configured to amplify the power of the sine wave signal and input the amplified sine wave signal to the cutter head and the return electrode.

[0076] In the above embodiment, the transmitting system provides multi-frequency sinusoidal signals to the cutterhead and return electrode to establish a stable electric field in the strata around the tunnel boring machine. Then, by adjusting the supply current of the first electrode, the potential difference between the second and third electrodes approaches zero. On the one hand, the cutterhead current surrounds the output current of the first electrode, preventing the current of the first electrode from flowing out through the second and third electrodes. On the other hand, the potential difference between the second and third electrodes is zero, so that the output current of the first electrode flows into the strata perpendicular to the tunnel face, thereby improving the accuracy of subsequent geological prediction.

[0077] In some embodiments of this disclosure, the measurement system is configured to detect a voltage signal between a third electrode and a reference electrode, and a current signal output by a first electrode, and to determine the apparent resistivity based on the voltage signal between the third electrode and the reference electrode, and the current signal output by the first electrode, and to determine the geological information of the construction tunnel based on the apparent resistivity.

[0078] As shown in Figure 6, which is a schematic diagram of the structure of some embodiments of the measurement system of this disclosure, the measurement system includes a signal conditioning and data acquisition circuit 41, a calibration circuit 42, an acquisition control circuit 43, and a computer 44.

[0079] The signal conditioning and data acquisition circuit 41 is configured to condition and acquire the voltage signal between the third electrode M2 ​​and the reference electrode, as well as the current signal output from the first electrode A0. For example, it amplifies, filters, and performs A / D conversion on the voltage signal between the third electrode M2 ​​and the reference electrode, as well as the current signal output from the first electrode A0, to facilitate subsequent acquisition.

[0080] The calibration circuit 42 is configured to generate a calibration signal and input the calibration signal to the signal conditioning and data acquisition circuit to calibrate the signal conditioning and data acquisition circuit. For example, the calibration circuit is responsible for generating the calibration signal. When the measurement system is in calibration mode, the calibration signal serves as the input to the signal conditioning and data acquisition circuit. Under the control of the control acquisition circuit, the signal conditioning and data acquisition circuit is calibrated, that is, the input-output relationship of the signal conditioning data and the acquisition circuit is determined, thereby improving the accuracy of the measurement system.

[0081] The acquisition control circuit 43 is configured to control the signal conditioning and data acquisition circuit to perform data acquisition and signal conditioning, and to control the calibration circuit to calibrate the signal conditioning and data acquisition circuit. For example, the acquisition control circuit is the control center of data acquisition, responsible for generating synchronous trigger signals and signals such as operating mode and gain control, controlling the signal conditioning and data acquisition circuit to complete data acquisition and signal conditioning according to the computer's control commands, and calibrating the signal conditioning and data acquisition circuit.

[0082] Computer 44 is configured to send control commands to the acquisition and control circuit, and to determine the apparent resistivity based on the voltage signal between the third electrode and the reference electrode, and the current signal output by the first electrode, and to determine the geological information of the tunnel under construction based on the apparent resistivity. For example, the computer is responsible for the human-computer interface and command forwarding, and is equipped with a web server and an FTP (File Transfer Protocol) server. Users can access the web page provided by the web server through terminals such as mobile phones, tablets, and laptops via wireless or wired means, and set relevant parameters of the geological prediction system through the web page, thereby controlling the data acquisition mode and acquisition time, etc.

[0083] In some embodiments, the measurement system further includes a power supply circuit 45 configured to provide power to the signal conditioning and data acquisition circuit, calibration circuit, acquisition control circuit, and computer. For example, the power supply circuit provides DC power of different voltages and powers to the various circuit modules to maintain their normal operation.

[0084] In the above embodiments, the apparent resistivity is determined based on the voltage signal between the third electrode and the reference electrode, and the current signal output by the first electrode. The geological information of the tunnel under construction is predicted based on the apparent resistivity, thereby enabling a detailed evaluation of the tunnel face.

[0085] The geological prediction system described above can realize focused scanning electrical resistivity tomography (SEP) advanced geological prediction. For example, Figure 7 is a schematic flowchart of some embodiments of the geological prediction method disclosed herein, which includes steps S71-S73.

[0086] In step S71, an excitation signal is provided to the cutterhead and return electrode via the transmitting system. This excitation signal, for example, is a sine wave signal, which can establish a stable electric field in the strata surrounding the tunnel boring machine.

[0087] In step S72, the potential difference signal between the second electrode and the third electrode in the electrode assembly corresponding to each focusing system is obtained through each focusing system, and the power supply current of the first electrode is adjusted according to the potential difference signal.

[0088] In some embodiments, when the potential of the second electrode is higher than that of the third electrode, the supply current of the first electrode is reduced, thereby reducing the potential difference between the second and third electrodes; and when the potential of the second electrode is lower than that of the third electrode, the supply current of the first electrode is increased, thereby reducing the potential difference between the second and third electrodes. This allows the output current of the first electrode to flow into the formation perpendicular to the working face.

[0089] In step S73, the voltage signal between the third electrode and the reference electrode in the electrode assembly corresponding to each measurement system and the current signal output by the first electrode are acquired through each measurement system. The apparent resistivity is determined based on the voltage signal and the current signal, and the geological information of the construction tunnel is determined based on the apparent resistivity.

[0090] For example, the apparent resistivity in front of the electrode assembly can be calculated using the formula Ra = K * Vm / I0, where K is the electrode coefficient, Vm is the voltage signal between the third electrode and the reference electrode, and I0 is the current signal output by the first electrode. Apparent resistivity often varies under different geological conditions, thus changes in apparent resistivity can reflect changes in geological conditions. For instance, if the strata have a high water content, the apparent resistivity is low; if the strata are mainly composed of rock, the apparent resistivity is high.

[0091] In the above embodiments, since the current signal flowing out of the first electrode can flow into the stratum perpendicularly to the tunnel face, and the voltage signal between the third electrode and the reference electrode is used to measure the internal points of the stratum, the influence of mud on the measurement can be reduced, thereby making the calculation of apparent resistivity more accurate, and thus enabling a fine evaluation of the stratum in front of the tunnel face of a large-diameter slurry shield machine.

[0092] In some embodiments, a tunnel boring machine is protected, which includes the electrode system or geological prediction system described above for a geological prediction system.

[0093] The tunnel boring machine (TBM) could be an earth pressure shield machine or a slurry shield machine.

[0094] This tunnel boring machine can use the current signal flowing vertically into the strata to make a detailed evaluation of the strata in front of the tunnel face, providing more accurate anomaly information for on-site construction and greatly reducing the risks of tunnel construction.

[0095] This concludes the detailed description of the present disclosure. To avoid obscuring the concept of the disclosure, some details known in the art have not been described. Those skilled in the art will fully understand how to implement the technical solutions disclosed herein based on the above description.

[0096] The methods and apparatus of this disclosure may be implemented in many ways. For example, they may be implemented by software, hardware, firmware, or any combination of software, hardware, and firmware. The above-described order of steps for the methods is for illustrative purposes only, and the steps of the methods of this disclosure are not limited to the order specifically described above unless otherwise specifically stated. Furthermore, in some embodiments, this disclosure may also be implemented as a program recorded on a recording medium, the program including machine-readable instructions for implementing the methods according to this disclosure. Thus, this disclosure also covers recording media storing programs for performing the methods according to this disclosure.

[0097] While specific embodiments of this disclosure have been described in detail by way of example, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of this disclosure. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of this disclosure. The scope of this disclosure is defined by the appended claims.

Claims

1. An electrode system for a geological prediction system, comprising: The cutter head is configured to work with the return electrode to create an alternating electric field. ； Multiple electrode assemblies, each of the multiple electrode assemblies comprising: The first electrode is configured to output current toward the working face of the tunnel under construction. The second electrode is disposed around the outer periphery of the first electrode; The third electrode is disposed around the outer periphery of the second electrode, wherein... The first electrode, the second electrode, the third electrode, and the cutter head are insulated from each other.

2. The electrode system according to claim 1, wherein, The power supply current of the first electrode is adjusted to make the second electrode and the third electrode have the same potential.

3. The electrode system according to claim 1 or 2, wherein, The plurality of electrode assemblies are disposed on one side of the center of the cutter head and arranged sequentially along the radial direction of the cutter head.

4. The electrode system according to any one of claims 1 to 3, wherein, The number of the plurality of electrode assemblies is determined according to the size of the cutter head.

5. The electrode system according to any one of claims 1 to 4, wherein, The cutter head has the same polarity as the first electrode and the opposite polarity to the return electrode.

6. A geological prediction system, comprising: The electrode system according to any one of claims 1 to 5; The launching system is configured to provide excitation signals to the cutter head and the return electrode; The focusing system corresponding to each electrode assembly is configured to acquire the potential difference signal between the second electrode and the third electrode, and adjust the supply current of the first electrode according to the potential difference signal; as well as The measurement system corresponding to each electrode assembly is configured to determine the apparent resistivity based on the voltage signal between the third electrode and the reference electrode and the current signal output by the first electrode, and to determine the geological information of the construction tunnel based on the apparent resistivity.

7. The geological prediction system according to claim 6, wherein, The focusing system is configured to reduce the supply current of the first electrode when the potential of the second electrode is higher than the potential of the third electrode, and to increase the supply current of the first electrode when the potential of the second electrode is lower than the potential of the third electrode.

8. The geological prediction system according to claim 6 or 7, wherein, The focusing system includes: An amplifier circuit is configured to amplify the potential difference signal to obtain a first signal; A notch filter circuit is configured to notch filter the first signal to obtain a second signal; The first filtering circuit is configured to perform bandpass filtering on the second signal to obtain the third signal; A proportional-integral-derivative (PID) control circuit is configured to perform PID adjustment on the third signal to obtain a fourth signal. The first power amplifier circuit is configured to amplify the fourth signal to generate a fifth signal and input the fifth signal to the first electrode to adjust the power supply current of the first electrode.

9. The geological prediction system according to any one of claims 6 to 8, wherein, The excitation signal is a sinusoidal signal, and the transmitting system includes: The host computer is configured to control the transmitter to transmit sinusoidal signals at predetermined time intervals. The transmitting host is configured to generate the sinusoidal signal and send the sinusoidal signal to the cutter head and the return electrode.

10. The geological prediction system according to claim 9, wherein, The transmitting host includes: The control unit is configured to generate multiple unipolar square wave signals, perform digital-to-analog conversion on the multiple unipolar square wave signals to generate multiple adjustable analog signals, and send the multiple unipolar square wave signals and the multiple adjustable analog signals to a programmable chopper circuit. The programmable chopper circuit is configured to chop the multiple unipolar square wave signals and the multiple adjustable analog signals into bipolar square wave signals. The second filtering circuit is configured to perform bandpass filtering on the bipolar square wave signal to obtain a sine wave signal. The second power amplifier circuit is configured to amplify the power of the sinusoidal signal and input the amplified sinusoidal signal to the cutter head and the return electrode.

11. The geological prediction system according to any one of claims 6 to 10, wherein, The measurement system includes: The signal conditioning and data acquisition circuit is configured to condition and acquire the voltage signal between the third electrode and the reference electrode, as well as the current signal output by the first electrode. A calibration circuit is configured to generate a calibration signal and input the calibration signal to the signal conditioning and data acquisition circuit to calibrate the signal conditioning and data acquisition circuit. The acquisition control circuit is configured to control the signal conditioning and data acquisition circuit to perform data acquisition and signal conditioning, and to control the calibration circuit to calibrate the signal conditioning and data acquisition circuit; The computer is configured to send control commands to the acquisition control circuit, and to determine the apparent resistivity based on the voltage signal between the third electrode and the reference electrode and the current signal output by the first electrode, and to determine the geological information of the construction tunnel based on the apparent resistivity.

12. The geological prediction system according to claim 11, wherein, The measurement system also includes: The power supply circuit is configured to provide power to the signal conditioning and data acquisition circuit, the calibration circuit, the acquisition control circuit, and the computer.

13. A tunnel boring machine, comprising: The electrode system according to any one of claims 1 to 5; or The geological prediction system according to any one of claims 6 to 12.

14. A geological prediction method based on the geological prediction system according to any one of claims 6 to 12, comprising: The firing system provides excitation signals to the cutter head and the return electrode. The potential difference signal between the second electrode and the third electrode in the electrode assembly corresponding to each focusing system is obtained through each focusing system, and the power supply current of the first electrode is adjusted according to the potential difference signal. The voltage signal between the third electrode and the reference electrode in the electrode assembly corresponding to each measurement system and the current signal output by the first electrode are acquired by each measurement system. The apparent resistivity is determined based on the voltage signal and the current signal, and the geological information of the construction tunnel is determined based on the apparent resistivity.

15. The geological prediction method according to claim 14, wherein, Adjusting the supply current of the first electrode according to the potential difference signal includes: When the potential of the second electrode is higher than the potential of the third electrode, reduce the supply current to the first electrode; and When the potential of the second electrode is lower than that of the third electrode, the supply current of the first electrode is increased.