阅读说明：本技术 基于100%占空比双极性电流的矿井瞬变电磁探测方法 (Mine transient electromagnetic detection method based on bipolar current with 100% duty ratio ) 是由 许洋铖 于 2020-06-19 设计创作，主要内容包括：本发明公开了一种基于100％占空比双极性电流的矿井瞬变电磁探测装置,提出采用占空比100％的双极性方波来激发二次场,在不增加发射磁矩、接收天线有效面积的情况下将二次场信号强度提高了1倍。由于没有关断间歇,在相同探测时间内叠加次数增加了1倍,二次场信噪比提高至<Image he="76" wi="98" file="DDA0002547172240000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>倍,提高了探测的准确率和效率。同时,利用一次场在电流稳定期间变化率为0的特点,采用磁感应线圈或磁感应探头输出二次场感应电压,实现了电流发射期间总场中二次场的提取。具有重大实际应用意义。(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 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.)

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.

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 toAnd 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:thus, it is possible to provideTherefore, the total secondary field signal-to-noise ratio is improved to

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.