CN111751892A - Mine transient electromagnetic detection method based on bipolar current with 100% duty ratio - Google Patents

Mine transient electromagnetic detection method based on bipolar current with 100% duty ratio Download PDF

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CN111751892A
CN111751892A CN202010564135.6A CN202010564135A CN111751892A CN 111751892 A CN111751892 A CN 111751892A CN 202010564135 A CN202010564135 A CN 202010564135A CN 111751892 A CN111751892 A CN 111751892A
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current
antenna
secondary field
square wave
transceiver
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许洋铖
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Chongqing University
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01VGEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V3/00Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
    • G01V3/18Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation specially adapted for well-logging
    • G01V3/26Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation specially adapted for well-logging operating with magnetic or electric fields produced or modified either by the surrounding earth formation or by the detecting device
    • G01V3/28Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation specially adapted for well-logging operating with magnetic or electric fields produced or modified either by the surrounding earth formation or by the detecting device using induction coils

Abstract

The invention discloses a mine transient electromagnetic detection device based on bipolar current with a duty ratio of 100%, and provides a method for exciting a secondary field by using bipolar square waves with a duty ratio of 100%, so that the signal intensity of the secondary field is improved by 1 time under the condition of not increasing the transmitting magnetic moment and the effective area of a receiving antenna. Because of no turn-off interval, the superposition times are increased by 1 time in the same detection time, and the signal-to-noise ratio of the secondary field is improved to
Figure DDA0002547172240000011
And the detection accuracy and efficiency are improved. Meanwhile, the characteristic that the change rate of the primary field is 0 in the current stabilization period is utilized, and the magnetic induction coil or the magnetic induction probe is adopted to output the induced voltage of the secondary field, so that the extraction of the secondary field in the total field in the current emission period is realized. Has great practical application significance.

Description

Mine transient electromagnetic detection method based on bipolar current with 100% duty ratio
Technical Field
The invention relates to the field of mine geophysical exploration, in particular to a mine transient electromagnetic detection method based on 100% duty ratio bipolar current.
Background
The transient electromagnetic method is a method of transmitting a primary pulse magnetic field to the underground by using an ungrounded return wire or a grounded wire source, and observing a secondary induced eddy current field caused in the underground medium by using a coil or a grounded electrode during the interval of the primary pulse magnetic field. The transient electromagnetic method comprises aviation, ground, ocean and mine transient electromagnetic methods according to application ranges, is widely applied to the field of water damage detection of the front part of the underground tunneling head, the roadway top and bottom plates, the working face top and bottom plates and the side wall of a coal mine, and is a time domain method.
The mine transient electromagnetic detection technology is mainly used for disaster-causing water body detection in underground engineering. The existing transient electromagnetic detection technology for underground engineering is based on 50% duty ratio bipolar current emission, and is large in energy consumption and low in efficiency.
Disclosure of Invention
The invention aims to solve the technical problem of providing a mine transient electromagnetic detection method and device based on 100% duty ratio bipolar current, wherein a secondary field is excited by adopting 100% duty ratio bipolar square waves, and the signal intensity of the secondary field is improved by 1 time under the conditions of not increasing the transmitting magnetic moment and the effective area of a receiving antenna. Because of no turn-off interval, the superposition times are increased by 1 time in the same detection time, and the signal-to-noise ratio of the secondary field is improved to
Figure BDA0002547172220000011
And the detection accuracy and efficiency are improved. Meanwhile, the characteristic that the change rate of the primary field is 0 in the current stabilization period is utilized, and the magnetic induction coil or the magnetic induction probe is adopted to output the induced voltage of the secondary field, so that the extraction of the secondary field in the total field in the current emission period is realized. Has great practical application significance.
In order to solve the problems, the technical scheme of the invention is that a mine transient electromagnetic detection method based on 100% duty ratio bipolar current comprises the following steps:
s1: initializing a system, and setting the emission current pulse width and the current superposition times of the transient electromagnetic instrument;
s2: when the antenna rotates or moves to an appointed measuring line and measuring point, the transmitting unit transmits a square wave current with the pulse width set in S1 through the transmitting antenna;
s3: after the square wave current is transmitted in the step S2, the transient electromagnetic instrument transmits the negative square wave current of the pulse width set in the step S1 through the transmitting unit and the transmitting antenna; meanwhile, the receiving antenna receives a secondary field signal induced by the front stratum and outputs a secondary field induction voltage to be fed back to the electromagnetic instrument for collection;
s4: after the negative square wave current is transmitted in the step S3, the electromagnetic instrument transmits the square wave current of the pulse width set in the step S1 through the transmitting antenna; meanwhile, the receiving antenna receives a secondary field signal induced by the front stratum and outputs a secondary field induction voltage to be fed back to the electromagnetic instrument for collection;
s5: the steps of S3 and S4 are repeatedly performed until the number of times of superimposition set in S1 is completed.
In the above scheme, taking the 20ms pulse width emission current and the superposition 16 times as an example, it is necessary to emit 20ms pulse width positive square wave current first in the 1 st emission period, then emit 20ms negative square wave current, and then continue the above operation in the second emission period, and measure 16 times in total.
As a preferable mode, in S3 and S4, there is no emission current off interval between the positive square wave emission circuit and the negative square wave emission current.
As a preferred scheme, the characteristic that the change rate of the primary field is 0 during the stable period of the emission current is utilized, and the magnetic induction coil or the magnetic induction probe is adopted to output the induced voltage of the secondary field, so that the extraction of the secondary field in the total field during the current emission period is realized.
The specific measurement method may be according to the detection flow chart provided in fig. 3.
A transient electromagnetic detection device based on bipolar current with 100% duty ratio comprises a transceiver and a transient electromagnetic instrument connected with the transceiver, wherein a host comprises a power supply, a control unit, a charging socket, a display screen, a transmitting unit, a receiving unit and an antenna socket; the antenna socket is movably connected with the receiving and transmitting device; the transceiver comprises a transceiver antenna, a transceiver coil or a probe, and the transceiver antenna comprises a transmitting antenna and a receiving antenna.
In the above scheme, the transceiver is used for sending and receiving signals, the transient electromagnetic instrument power supply is used for supplying power to the device, a corresponding control circuit is arranged in the control unit and used for transient electromagnetic transceiving control, the charging socket is used for charging the transient electromagnetic instrument, the display screen is used for man-machine interaction and achievement diagram display, the transmitting unit is used for transmitting 100% bipolar square waves, the receiving unit is used for signal acquisition, and the antenna socket is used for antenna connection.
In conclusion, the invention has the following beneficial effects:
the invention utilizes bipolar square waves on the rising edgeAnd the falling edge both generate the secondary field: at the falling edge of the positive emission current, the induced voltage excited by the secondary field in the stratum in the receiving antenna is V1On the rising edge of the negative emission current, the induced voltage excited by the secondary field in the stratum in the receiving antenna is V2And the positive and negative emitting current periods have no intermission period, so that the secondary field induction voltage in the receiving coil is V in the positive and negative current switching period1+V2=2V1=2V2Thus, the secondary field signal is increased by a factor of 1. Meanwhile, due to the 100% duty ratio, in the same detection time, the emission times are 2 times of the emission times of the 50% duty ratio, and therefore the superposition times are 2 times of the superposition times of the 50% duty ratio. According to the relationship between the superposition times and the signal-to-noise ratio:
Figure BDA0002547172220000031
thus, it is possible to provide
Figure BDA0002547172220000041
Therefore, the total secondary field signal-to-noise ratio is improved to
Figure BDA0002547172220000042
And (4) doubling. The accuracy and the efficiency of detection are improved. Meanwhile, the characteristic that the change rate of the primary field is 0 in the current stabilization period is utilized, and the magnetic induction coil or the magnetic induction probe is adopted to output the induced voltage of the secondary field, so that the extraction of the secondary field in the total field in the current emission period is realized. Has great practical application significance.
The scheme innovatively utilizes the characteristic that bipolar square waves can generate secondary fields at the rising edge and the falling edge, adopts 100% duty ratio bipolar current for emission, and improves the accuracy and the efficiency of detection.
Drawings
Fig. 1 is a schematic structural diagram of a mine transient electromagnetic detection device based on 100% duty ratio bipolar current.
Fig. 2 is a diagram of a 100% bipolar square wave emission current.
FIG. 3 is a flow chart of a mine transient electromagnetic detection method based on bipolar current with 100% duty cycle according to the present invention.
Reference numerals: 1. a transient electromagnetic instrument host; 2. a transceiver device; 3. a control unit; 4. a charging socket; 5. a display screen; 6. a transmitting unit; 7. a receiving unit; 8. an antenna socket; 9. a power source; 10. a positive square wave emission current; 11. a negative square wave emission current; 12. positively turning off the secondary field induction voltage; 13. the negative turns off the secondary field induced voltage.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
Example 1, shown in conjunction with figure 3:
a mine transient electromagnetic detection method of bipolar current with 100% duty ratio comprises the following steps:
s1: initializing a system, and setting the emission current pulse width and the current superposition times of the transient electromagnetic instrument;
s2: when the antenna rotates or moves to the agreed survey line and survey point, the transmitting unit 6 transmits a square wave current of the pulse width set in S1 through the transmitting antenna;
s3: after the transmission of the square wave current in S2 is completed, the electromagnetic instrument transmits the negative square wave current of the pulse width set in S1 through the transmission unit 6; meanwhile, the receiving antenna receives a secondary field signal induced by the front stratum and outputs a secondary field induction voltage to be fed back to the electromagnetic instrument for collection;
s4: after the negative square wave current is transmitted in the step S3, the electromagnetic instrument transmits the square wave current of the pulse width set in the step S1 through the transmitting antenna; meanwhile, the receiving antenna receives a secondary field signal induced by the front stratum and outputs a secondary field induction voltage to be fed back to the electromagnetic instrument for collection;
s5: the steps of S3 and S4 are repeatedly performed until the number of times of superimposition set in S1 is completed.
In the above embodiment, taking the 20ms pulse width emission current and the superposition 16 times as an example, it is necessary to emit 20ms pulse width positive square wave current, then 20ms negative square wave current in the 1 st emission period, and then continue the above operation in the second emission period, and measure 16 times in total.
As a preferred embodiment, in S3 and S4, there is no emission current off interval between the square wave emission circuit and the negative square wave emission current.
As a preferred embodiment, the characteristic that the change rate of the primary field is 0 during the stable period of the emission current is utilized, and the magnetic induction coil or the magnetic induction probe is adopted to output the induced voltage of the secondary field, so that the extraction of the secondary field in the total field during the current emission period is realized. In the preferred embodiment, the characteristic that the change rate of the primary field is 0 during the stable period of the emission current is utilized, and the magnetic induction coil or the magnetic induction probe is adopted to output the induced voltage of the secondary field, so that the extraction of the secondary field in the total field during the current emission period is realized.
The specific measurement method may be according to the detection flow chart provided in fig. 3.
Example 2, shown in conjunction with figures 1 and 2:
a transient electromagnetic detection device based on 100% duty ratio bipolar current comprises a transceiver 2 and a transient electromagnetic instrument connected with the transceiver 2, wherein a host comprises a power supply 9, a control unit 3, a charging socket 4, a display screen 5, a transmitting unit 6, a receiving unit 7 and an antenna socket 8; the antenna socket 8 is movably connected with the transceiver 2; the transceiver 2 comprises a transceiver antenna, a transceiver coil or a probe, and the transceiver antenna comprises a transmitting antenna and a receiving antenna.
In the above embodiment, the transceiver is used for sending and receiving signals, the transient electromagnetic instrument power supply is used for supplying power to the device, the control unit is internally provided with a corresponding control circuit for transient electromagnetic transceiver control, the charging socket is used for charging the transient electromagnetic instrument, the display screen is used for man-machine interaction and achievement diagram display, the transmitting unit is used for transmitting 100% bipolar square waves, the receiving unit is used for signal acquisition, and the antenna socket is used for antenna connection.
The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present invention.

Claims (4)

1. A mine transient electromagnetic detection method based on bipolar current with a duty ratio of 100% is characterized by comprising the following steps:
s1: initializing a system, and setting emission current pulse width and superposition times;
s2: when the antenna rotates or moves to an appointed measuring line and measuring point, the electromagnetic instrument transmits square wave current with the pulse width set in S1 to the transmitting antenna;
s3: after the transmission of the square wave current in the step S2 is completed, the electromagnetic instrument transmits the negative square wave current of the pulse width set in the step S1 to the transmitting antenna; meanwhile, the receiving antenna receives a secondary field signal induced by the front stratum and outputs a secondary field induction voltage to be fed back to the electromagnetic instrument for collection;
s4: after the negative square wave current is transmitted in the step S3, the electromagnetic instrument transmits the square wave current of the pulse width set in the step S1 to the transmitting antenna; meanwhile, the receiving antenna receives a secondary field signal induced by the front stratum and outputs a secondary field induction voltage to be fed back to the electromagnetic instrument for collection;
s5: the steps S3 to S4 continue until the number of times of superimposition set in S1 is completed.
2. The method for transient electromagnetic detection based on bipolar current with 100% duty cycle of claim 1, wherein in the S3 and S4, there is no emission current off interval period between the positive square wave emission current and the negative square wave emission current.
3. The transient electromagnetic detection method based on the bipolar current with the duty ratio of 100% according to claim 1 or 2, characterized in that the extraction of the secondary field in the total field during the current emission period is realized by utilizing the characteristic that the change rate of the primary field during the emission current stabilization period is 0 and outputting the induced voltage of the secondary field by adopting a magnetic induction coil or a magnetic induction probe.
4. A transient electromagnetic detection technology and device based on bipolar current with 100% duty ratio is characterized by comprising a transceiver (2) and a transient electromagnetic instrument connected with the transceiver (2), wherein a host comprises a power supply (9), a control unit (3), a charging socket (4), a display screen (5), a transmitting unit (6), a receiving unit (7) and an antenna socket (8); the antenna socket (8) is movably connected with the transceiver (2); the transceiver (2) comprises a transceiver antenna, a transceiver coil or a probe, and the transceiver antenna comprises a transmitting antenna and a receiving antenna.
CN202010564135.6A 2020-06-19 2020-06-19 Mine transient electromagnetic detection method based on bipolar current with 100% duty ratio Pending CN111751892A (en)

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CN112379450A (en) * 2020-10-30 2021-02-19 中国石油天然气集团有限公司 Signal-to-noise ratio obtaining method and device for time-frequency electromagnetic square wave signal
CN112612061A (en) * 2020-11-25 2021-04-06 重庆大学 Host-free mining intrinsic safety type transient electromagnetic detection device, method and system
CN114047550A (en) * 2021-09-27 2022-02-15 中国地质科学院地球物理地球化学勘查研究所 Differential waveform transient electromagnetic measurement method for suppressing slow polarization effect
CN114089424A (en) * 2021-11-02 2022-02-25 武汉船舶通信研究所(中国船舶重工集团公司第七二二研究所) Portable shallow transient electromagnetic detection device

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112379450A (en) * 2020-10-30 2021-02-19 中国石油天然气集团有限公司 Signal-to-noise ratio obtaining method and device for time-frequency electromagnetic square wave signal
CN112612061A (en) * 2020-11-25 2021-04-06 重庆大学 Host-free mining intrinsic safety type transient electromagnetic detection device, method and system
CN112612061B (en) * 2020-11-25 2024-03-22 重庆大学 Main-machine-free mining intrinsic safety type transient electromagnetic detection device, method and system
CN114047550A (en) * 2021-09-27 2022-02-15 中国地质科学院地球物理地球化学勘查研究所 Differential waveform transient electromagnetic measurement method for suppressing slow polarization effect
CN114047550B (en) * 2021-09-27 2023-07-07 中国地质科学院地球物理地球化学勘查研究所 Differential waveform transient electromagnetic measurement method for suppressing slow polarization effect
CN114089424A (en) * 2021-11-02 2022-02-25 武汉船舶通信研究所(中国船舶重工集团公司第七二二研究所) Portable shallow transient electromagnetic detection device

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Application publication date: 20201009