Underground space TBM tunneling direction transient electromagnetic advanced detection device and method

Abstract

The invention discloses an underground space TBM tunneling direction transient electromagnetic advanced detection device and method, a motor is used as a magnetic core, so that electromagnetic signals can be enhanced, two transmitting coils and a receiving coil are arranged at the same time, and the two transmitting coils are respectively connected with equal and opposite currents to form transmitting sources with mutually offset magnetic fields, so that the electromagnetic signals can be enhanced. A pure secondary field response signal is generated at the position of the receiving coil; according to the mode, transient electromagnetic tunnel advanced geological forecast detection can be carried out in the tunneling direction of the TBM in the underground space, the detection precision is high, and no blind area exists in the detection range; in addition, in the detection process, no matter whether the tunneling direction is deflected or not, the front of the initial tunneling horizontal direction can be detected all the time, so that the advanced detection stability is guaranteed, whether the tunneling direction is deflected or not can be monitored in real time by processing electromagnetic data in the detection process, deflection angle information is judged, and the detection accuracy is improved. And then the TBM is guided to adjust the tunneling posture, and the tunneling efficiency is guaranteed.

Description

Technical Field

[0001] The invention relates to a transient electromagnetic advance detection device and method for underground space TBM excavation direction, belonging to the technical field of geological exploration. Background Art

[0002] Tunnel transient electromagnetic method for advanced geological prediction generally uses magnetic sources and electrical sources. The traditional working mode of electrical sources is long offset transient electromagnetic method (LOTEM), which uses several kilometers of grounded wires to transmit current underground and observe electromagnetic field responses within an offset range greater than 3 to 6 times the detection depth. Compared with magnetic sources, the construction is cumbersome, and the electrical sources are laid on the side walls on both sides of the tunnel, so the observation space for advanced detection is very small. In addition, the basic theory of electrical source transient electromagnetic method is based on horizontal electric dipoles, but in actual production, the transmitting source is often a long grounded wire. With the realization of short offset observation methods, the size of the transmitting source cannot be ignored, but due to site conditions, the transmitting source may not be laid horizontally and straightly. This change in source morphology will inevitably affect the response at the receiving point and ultimately affect the accuracy of data interpretation.

[0003] Magnetic source TEM uses an ungrounded loop as the transmitting source and measures the magnetic field or its time derivative inside or outside the frame. Due to the advantages of no need for grounded transmission, strong high-resistance penetration ability, high coupling with anomalies, and convenient construction, various devices of magnetic source TEM have become the main working form of advanced geological prediction using the tunnel transient electromagnetic method.

[0004] However, in the specific tunnel construction, the traditional tunnel transient electromagnetic method advanced geological prediction device generally adopts a coaxial dipole device. During TEM detection, the instrument receiving coil is arranged 5m behind the face, and the prediction range is 20 to 100m in front of the receiving coil. Due to the characteristics of the transient electromagnetic method itself, the range from the receiving coil to 20m in front of it is a detection blind area, and it is interfered by metal tools in the tunnel, so the TEM prediction results are different from the actual situation. In addition, in the tunnel construction of the tunnel boring machine (TBM), the traditional transient electromagnetic device form is limited by the TBM machinery. This large machine occupies most of the construction space behind the tunnel face, making it impossible to lay out the advanced detection line, excitation device and receiving sensor on the side wall of the tunnel face. In addition, the observation space of advanced geological prediction is very small, and it is difficult to establish an observation mode that is sensitive to the geophysical response of the adverse geological body in front of the tunnel face. In addition, the TBM machine is generally in a horizontal straight line during the excavation process, but when excavating rocks of different hardness, disturbances will occur due to uneven force, which will cause its excavation direction to deviate. The current method of monitoring deflection is relatively lagging, and it is impossible to determine the deflection in time after the deflection occurs. Ultimately, the deflection cannot be corrected in time, reducing the excavation work efficiency.

[0005] Therefore, how to provide a method that can not only perform transient electromagnetic tunnel advanced geological prediction detection on the TBM excavation direction of underground space, but also have high detection accuracy, and at the same time be able to monitor in real time whether the TBM excavation direction is deflected, so as to facilitate timely correction of the excavation direction and ensure the efficiency of excavation, is the research direction of this industry. Summary of the invention

[0006] In view of the problems existing in the above-mentioned prior art, the present invention provides a device and method for transient electromagnetic advance detection of the TBM excavation direction in an underground space, which can not only perform transient electromagnetic tunnel advance geological forecast detection on the TBM excavation direction in the underground space, but also has high detection accuracy. At the same time, it can monitor in real time whether the TBM excavation direction is deflected, so as to facilitate timely correction of the excavation direction and ensure the excavation efficiency.

[0007] In order to achieve the above-mentioned object, the technical solution adopted by the present invention is: a transient electromagnetic advance detection device for the TBM excavation direction in an underground space, comprising a transmitting coil, a receiving coil, a transient electromagnetic transceiver and a data processing terminal;

[0008] There are two transmitting coils, both of which are wound around the outer circumference of the oil cylinder and are separated by a certain distance; the receiving coil is wound around the outer circumference of the motor in the middle of the oil cylinder, so that the motor serves as the magnetic core of the receiving coil; the transient electromagnetic transceiver is connected to the transmitting coil and the receiving coil respectively, so as to make the electromagnetic signal excited by the transmitting coil pass through the blade opening of the cutter disc after being enhanced by the magnetic core, and obtain the electromagnetic signal received by the receiving coil;

[0009] The data processing terminal communicates wirelessly with the transient electromagnetic transceiver device and is used to receive electromagnetic data fed back by the transient electromagnetic transceiver device for analysis and processing to determine whether there is an abnormal body.

[0010] Furthermore, the two transmitting coils are parallel and coaxial with the same number of turns, and equal and opposite currents are respectively passed through the two transmitting coils to form a transmitting source whose magnetic fields cancel each other out, and generate a pure secondary field response signal at the position of the receiving coil.

[0011] Furthermore, the receiving coil and the transmitting coil are parallel and coaxial to each other, and the axes of the transmitting coil and the receiving coil are coaxial with the cutter head axis of the TBM machine.

[0012] Furthermore, the data processing terminal is a tablet computer.

[0013] The working method of the above-mentioned underground space TBM excavation direction transient electromagnetic advance detection device comprises the following specific steps:

[0014] Step 1: TBM excavation and transient electromagnetic advance detection: Install the transient electromagnetic advance detection device in the TBM, then start the transient electromagnetic advance detection device to transmit and receive electromagnetic data, and transmit it to the data processing terminal;

[0015] Step 2: Determine the abnormal body: After processing the feedback electromagnetic data, the data processing terminal determines the geological conditions within a certain range ahead. If there is no abnormal body within the range, the TBM machine will continue to advance and enter step 3; if there is, the TBM machine will stop advancing and re-plan the route or take other measures;

[0016] Step 3: Monitoring and adjusting the excavation direction deflection: During the excavation process of the TBM, the rock mass hardness will cause disturbances, which will lead to the deflection of the excavation direction. The data processing terminal continuously receives electromagnetic data. The transient response of the center of the transmitting coil is set as B z , its time rate of change is The specific formula is:

[0017]

[0018] Where I is the transmitting current, ρ is the apparent resistivity of the half space, a is the radius of the transmitting coil, μ is the magnetic permeability of the current geology, and T is the time, starting from the time the current is turned off. is the error function;

[0019] When the TBM is disturbed during the excavation process, causing the excavation direction to deflect, the transmitting coil and the receiving coil in the horizontal xy plane are deflected. The roll angle of degrees, the transmitting coil and the receiving coil are deflected by an inclination of η degrees in the vertical zy plane; then the horizontal component of the transient electromagnetic response at the center of the transmitting coil After the following decomposition:

[0020]

[0021] The above formula can make a certain component always point to the horizontal direction of the TBM machine's excavation, thereby realizing horizontal advance detection that is not deflected by the excavation direction; and the track map wirelessly transmitted by the transient electromagnetic transceiver equipment to the data processing terminal is drawn in real time, so as to monitor the deflection information of the excavation direction in real time during the excavation process, and then guide the TBM machine to adjust the excavation posture.

[0022] The principle of the present invention for realizing advanced detection is: the propagation of the electromagnetic field conforms to the Maxwell equations, assuming divB = 0; for the inside of the magnetic core in the coil, the relationship between the magnetic field intensity H, the magnetic flux density B and the magnetization intensity M is given by the following formula:

[0023]

[0024] We calculate the divergence on both sides of formula (1) using the following relationship:

[0025]

[0026] In formula (2), J is the magnetic polarization intensity; the magnetic polarization intensity represents the vector sum of the magnetic dipole moments within the magnetic material; the electromagnetic boundary conditions force B to be continuous in the direction perpendicular to the boundary and the tangential component of H to be continuous at the boundary between media with different electromagnetic properties; for isotropic ferromagnetic media, the following equation represents the magnetic flux in the receiver:

[0027] B R =μ0H R +D f J T +J T (3)

[0028] It can be seen from formula (3) that the magnetic induction intensity B of the receiving coil is R From three parts: the induced magnetic field of the receiving coil (μ0H R )、Demagnetization field (D f J T ) and the magnetic polarization field of the ferrite core (J T ); therefore, from the configuration representation of the ferrite core transmitting and receiving coil mutual inductance analytical expression, it can be concluded that placing the cylindrical ferrite core in the receiving coil will magnetize the core, and then the magnetic flux passing through the receiving coil will increase, so the electromagnetic signal will be enhanced.

[0029] Compared with the prior art, the present invention utilizes the above principle and uses the motor as the magnetic core, thereby enhancing the received electromagnetic signal, and simultaneously arranges two transmitting coils and one receiving coil, and the two transmitting coils are respectively fed with equal and opposite currents to form a transmitting source in which the magnetic fields cancel each other out, and a pure secondary field response signal is generated at the position of the receiving coil; this method can not only perform transient electromagnetic tunnel advance geological prediction detection on the TBM excavation direction of the underground space, but also has high detection accuracy, and there is no blind spot within the detection range; in addition, during the detection process, the present invention can always detect the front of the initial excavation horizontal direction regardless of whether the excavation direction is deflected, thereby ensuring the stability of the advance detection, and during the detection process, the electromagnetic data is processed to monitor in real time whether the excavation direction is deflected, and to judge the deflection angle information, thereby guiding the TBM machine to adjust the excavation posture to ensure the excavation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0031] Figure 2 It is a schematic diagram of monitoring the deflection of the excavation direction in the present invention.

[0032] In the figure: 1-oil cylinder, 2-motor, 3-blade edge, 4-transmitting coil, 5-transient electromagnetic transceiver, 6-receiving coil, 7-knife disc. DETAILED DESCRIPTION

[0033] The present invention will be further described below.

[0034] like Figure 1 As shown, a transient electromagnetic advance detection device for the excavation direction of a TBM in an underground space comprises a transmitting coil 4, a receiving coil 6, a transient electromagnetic transceiver 5 and a data processing terminal;

[0035] There are two transmitting coils 4, both of which are wound on the outer circumference of the oil cylinder 1 and are at a distance from each other; the receiving coil 6 is wound on the outer circumference of the motor 2 in the middle of the oil cylinder 1, so that the motor 2 serves as the magnetic core of the receiving coil 6; the transient electromagnetic transceiver is connected to the transmitting coil 4 and the receiving coil 6 respectively, and is used to make the transmitting coil 4 excite the electromagnetic signal to pass through the blade opening of the cutter head, and obtain the electromagnetic signal received by the receiving coil 6 after the magnetic core is increased; the two transmitting coils 4 are parallel to each other and coaxial and have the same number of turns, and the two transmitting coils 4 are respectively passed with equal and opposite currents to form a transmitting source with mutually canceling magnetic fields, and a pure secondary field response signal is generated at the position of the receiving coil 6. The receiving coil 6 is parallel to the transmitting coil 4 and coaxial, and the axes of the transmitting coil 4 and the receiving coil 6 are coaxial with the axis of the cutter head of the TBM machine.

[0036] The data processing terminal communicates wirelessly with the transient electromagnetic transceiver 5 and is used to receive electromagnetic data fed back by the transient electromagnetic transceiver 5 for analysis and processing to determine whether there is an abnormal body; the data processing terminal is a tablet computer.

[0037] The working method of the above-mentioned underground space TBM excavation direction transient electromagnetic advance detection device comprises the following specific steps:

[0038] Step 1: TBM excavation and transient electromagnetic advance detection: Install the transient electromagnetic advance detection device in the TBM, then start the transient electromagnetic advance detection device to transmit and receive electromagnetic data, and transmit it to the data processing terminal;

[0039] Step 2: Determine the abnormal body: After processing the feedback electromagnetic data, the data processing terminal determines the geological conditions within a certain range ahead. If there is no abnormal body within the range, the TBM machine will continue to advance and enter step 3; if there is, the TBM machine will stop advancing and re-plan the route or take other measures;

[0040] Step 3: Monitoring and adjusting the excavation direction deflection: During the excavation process of the TBM, the rock mass hardness may cause disturbances, which may lead to the deflection of the excavation direction. Figure 2 As shown, the data processing terminal continuously receives electromagnetic data. Assume that the transient response of the center of the transmitting coil is B z , its time rate of change is The specific formula is:

[0041]

[0042] Where I is the transmitting current, ρ is the apparent resistivity of the half space, a is the radius of the transmitting coil, and μ is the magnetic permeability of the current geology (approximately 4π×10 －7 H / m), T is the time, starting from the time when the current is turned off, is the error function;

[0043] When the TBM is disturbed during the excavation process, causing the excavation direction to deflect, the transmitting coil and the receiving coil in the horizontal xy plane are deflected. The roll angle of degrees, the transmitting coil and the receiving coil are deflected by an inclination of η degrees in the vertical zy plane; then the horizontal component of the transient electromagnetic response at the center of the transmitting coil After the following decomposition:

[0044]

[0045] The above formula can make a certain component always face the horizontal direction of the TBM machine excavation, thereby realizing horizontal advance detection that is not deflected by the excavation direction; and the track map wirelessly transmitted to the data processing terminal by the transient electromagnetic transceiver 5 is drawn in real time, so as to monitor the deflection information of the excavation direction in real time during the excavation process, and then guide the TBM machine to adjust the excavation posture.

[0046] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A transient electromagnetic advance detection device for underground space TBM excavation direction, characterized in that: It includes a transmitting coil, a receiving coil, a transient electromagnetic transceiver and a data processing terminal; There are two transmitting coils, both of which are wound around the outer circumference of the oil cylinder and are separated by a certain distance; the receiving coil is wound around the outer circumference of the motor in the middle of the oil cylinder, so that the motor serves as the magnetic core of the receiving coil; the transient electromagnetic transceiver is respectively connected to the transmitting coil and the receiving coil, so as to make the electromagnetic signal excited by the transmitting coil pass through the blade opening of the cutter disc, and obtain the electromagnetic signal received by the receiving coil after being enhanced by the magnetic core; The data processing terminal communicates wirelessly with the transient electromagnetic transceiver device and is used to receive electromagnetic data fed back by the transient electromagnetic transceiver device for analysis and processing to determine whether there is an abnormal body.

2. According to claim 1, the underground space TBM excavation direction transient electromagnetic advance detection device is characterized in that: The two transmitting coils are parallel and coaxial with the same number of turns, and equal and opposite currents are respectively passed into the two transmitting coils to form a transmitting source whose magnetic fields cancel each other out, and generate a pure secondary field response signal at the position of the receiving coil.

3. According to claim 1, the underground space TBM excavation direction transient electromagnetic advance detection device is characterized in that: The receiving coil and the transmitting coil are parallel and coaxial to each other, and the axes of the transmitting coil and the receiving coil are coaxial with the cutter head axis of the TBM machine.

4. According to claim 1, the underground space TBM excavation direction transient electromagnetic advance detection device is characterized in that: The data processing terminal is a tablet computer.

5. A working method of the underground space TBM excavation direction transient electromagnetic advance detection device according to any one of claims 1 to 4, characterized in that: The specific steps are: Step 1: TBM excavation and transient electromagnetic advance detection: Install the transient electromagnetic advance detection device in the TBM, then start the transient electromagnetic advance detection device to transmit and receive electromagnetic data, and transmit it to the data processing terminal; Step 2: Determine the abnormal body: After processing the feedback electromagnetic data, the data processing terminal determines the geological conditions within a certain range ahead. If there is no abnormal body within the range, the TBM machine will continue to advance and enter step 3; if there is, the TBM machine will stop advancing and re-plan the route or take other measures; Step 3: Monitoring and adjusting the excavation direction deflection: During the excavation process of the TBM, the rock mass hardness will cause disturbances, which will lead to the deflection of the excavation direction. The data processing terminal continuously receives electromagnetic data. The transient response of the center of the transmitting coil is set as B z , its time rate of change is The specific formula is: Where I is the transmitting current, ρ is the apparent resistivity of the half space, a is the radius of the transmitting coil, μ is the magnetic permeability of the current geology, and T is the time, starting from the time the current is turned off. is the error function; When the TBM is disturbed during the excavation process, causing the excavation direction to deflect, the transmitting coil and the receiving coil in the horizontal xy plane are deflected. The roll angle of degrees, the transmitting coil and the receiving coil are deflected by an inclination of η degrees in the vertical zy plane; then the horizontal component of the transient electromagnetic response at the center of the transmitting coil After the following decomposition: The above formula can make a certain component always point to the horizontal direction of the TBM machine's excavation, thereby realizing horizontal advance detection that is not deflected by the excavation direction; and the track map wirelessly transmitted by the transient electromagnetic transceiver equipment to the data processing terminal is drawn in real time, so as to monitor the deflection information of the excavation direction in real time during the excavation process, and then guide the TBM machine to adjust the excavation posture.

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