Transient electromagnetic space perspective device and method in underground coal mine

Abstract

The present invention relates to a transient electromagnetic space perspective device and method in a coal mine underground hole, which can avoid the interference of metal bodies in the mine, solve the shallow detection blind area, obtain geological information within the entire transient electromagnetic detection range, form a perspective of the entire detection area, and be used in the field of geophysical exploration technology. The device includes a transmitting device and a receiving device for receiving the signal sent by the transmitting device; the transmitting device has a cylindrical shell I, one end of the cylindrical shell I is connected to a conical cover body I, and the other end is coaxially connected to a propulsion rod I; a wheel shaft perpendicular to the axial direction of the cylindrical shell is provided in the cylindrical shell I, and a first coil is provided on the wheel shaft; the receiving device has a cylindrical shell II, one end of the cylindrical shell II is connected to a conical cover body II, and the other end is coaxially connected to a propulsion rod II; a magnetic core probe is provided in the cylindrical shell II, and the magnetic core probe is connected to a connecting piece, and the connecting piece can be installed on the propulsion rod II by rotating around the axis of the cylindrical shell II through a rotating driving mechanism.

Description

Technical Field

[0001] The present invention relates to a transient electromagnetic space perspective device and method in a coal mine underground hole, which is applicable to the field of geophysical exploration technology. Background Art

[0002] In recent years, with the impending depletion of shallow coal resources, coal mining has gradually moved to deeper depths. However, the resulting complex geological conditions have greatly increased the difficulty of mining. In particular, hidden geological structures such as faults, sinkholes and fissure development zones are major hidden dangers of water inrush accidents. How to accurately identify and locate these hidden geological structures and know their water-rich properties in advance is the key to safe and efficient mining in coal mines.

[0003] The main methods for detecting geological structures in coal mines are drilling and geophysical detection. Among them, the drilling method is the most direct and effective, but it has the disadvantages of high construction cost and low efficiency, and it is only a "one-sided view". After the structure conducts water, its resistivity becomes significantly lower than that of the surrounding rock, showing low-resistance anomaly characteristics, which provides a detection basis for the application of geophysical methods based on resistivity differences. Geophysical methods have fast detection speed and low cost, especially mine transient electromagnetic method, which has the advantages of sensitivity to low-resistance anomalies and high resolution, and is widely used in exploring coal mine geological structures and their water-rich properties.

[0004] The mine transient electromagnetic method transmits an electromagnetic field to the coal seam head or roof and floor by powering the transmitting coil. After the current is turned off, the geological body in the coal seam or surrounding rock is stimulated to produce a secondary eddy current field, which contains rich geological information. The secondary field response value is obtained by the receiving coil, and its attenuation law over time is analyzed to achieve the purpose of detecting hidden geological bodies. Conventional mine transient electromagnetic methods are seriously affected by metal interference such as mining machines, anchor bolts, anchor nets and hydraulic supports because they complete transmission and reception in the tunnel. The collected secondary field data is easily distorted, which brings great difficulties to the interpretation of the data, and the existing interference suppression methods have general processing effects.

[0005] The mine transient electromagnetic method uses a multi-turn small loop device for transmission and reception. The self-inductance and mutual inductance between the loops will generate an inductive electromotive force, which will prolong the shutdown time and lead to a shallow detection blind area. Many scholars have conducted in-depth research on the inductance theory of multi-turn small loops, but none of them have proposed an ideal correction method. Or they simply discard early data and do not perform shallow geological interpretation. In addition, the multi-solution nature of the mine transient electromagnetic method makes it difficult to accurately locate geological anomalies.

[0006] In response to the above difficulties, some scholars have considered improving the construction method of transient electromagnetic method in mines, such as transmitting in mine tunnels and receiving in boreholes; completing transmission and reception in boreholes.

[0007] The Chinese invention patent with the patent publication number CN106970424A discloses a device and method for transient electromagnetic superposition advance detection of underground tunnels in coal mines. It uses a small wire frame with a side length of no more than 5m and a number of turns of no less than 10 turns, which is placed vertically at the borehole mouth of the underground borehole to transmit transient electromagnetic waveforms, rotate the outer transmitting frame, and use a probe in the hole to receive multiple components of the magnetic field. However, the device uses the hole mouth to transmit, which is inevitably affected by metal interference, and the mutual inductance of the coil near the hole mouth causes a detection blind spot. In addition, the tunnel space limits the size of the transmitting wire frame, and the underground explosion-proof requirements have limited transmission power. This results in the receiving signal becoming weaker and weaker as the distance from the receiving wire frame to the hole mouth gradually increases, and it is impossible to obtain geological anomaly information near the hole mouth and deep in the borehole, and the utilization rate of the borehole is insufficient.

[0008] The Chinese invention patent with the patent publication number CN10327858A discloses a multi-component transient electromagnetic method in underground coal mine boreholes. The measurement uses a dual transmitting coil in the borehole to receive radial component signals in six directions, realizing excitation and reception in the borehole. However, the device also cannot solve the mutual inductance problem between the transmitting and receiving wireframes, cannot perform geological interpretation of shallow detection blind areas, and cannot accurately locate geological anomalies. The electromagnetic wave CT perspective technology transmits electromagnetic waves in one side tunnel and receives them in the other measuring tunnel to observe whether there are perspective anomalies to obtain the distribution of geological bodies in the working face, but it cannot identify the water-richness of geological anomalies. If the width of the working face exceeds its limited penetration depth, no signal will be received in the tunnel, and the geological conditions in front cannot be detected.

[0009] The main defects of the existing technology are that the blind area of ​​mine transient electromagnetic method causes shallow information loss, and the current technical means are difficult to accurately locate geological anomalies. Therefore, how to obtain geological information within the entire detection range and realize the tracking, identification and high-precision positioning of geological structures are technical problems that urgently need to be solved. Summary of the invention

[0010] The technical problem to be solved by the present invention is: in view of the above-mentioned problems, a transient electromagnetic spatial perspective device and method are provided in a coal mine underground hole to avoid interference from metal bodies in the mine, solve the shallow detection blind area, obtain geological information within the entire transient electromagnetic detection range, and form a perspective of the entire detection area.

[0011] The technical solution adopted by the present invention is: a transient electromagnetic space perspective device in a hole in a coal mine, characterized by: comprising a transmitting device and a receiving device for receiving the signal sent by the transmitting device;

[0012] The launching device comprises a cylindrical shell I, one end of which is connected to a conical cover body I, and the other end of which is coaxially connected to a propulsion rod I; a wheel axle perpendicular to the axial direction of the cylindrical shell is arranged inside the cylindrical shell I, and a first coil is arranged on the wheel axle;

[0013] The receiving device has a cylindrical shell II, one end of which is connected to a conical cover body II, and the other end is coaxially connected to a push rod II; a magnetic core probe is provided in the cylindrical shell II, and the magnetic core probe is connected to a connecting piece, and the connecting piece can be installed on the push rod II so as to rotate around the axis of the cylindrical shell II through a rotating drive mechanism.

[0014] The wheel shaft has a central axis and two impeller blades fixed on the central axis. The central axis is arranged axially perpendicular to the cylindrical shell I. The first coil is wound on the central axis and between the two impeller blades.

[0015] The magnetic core probe comprises a ferrite core and a second coil, wherein the ferrite core is arranged axially perpendicular to the cylindrical shell II, one end of the ferrite core is fixed on the connecting piece, and the second coil is wound on the other end of the ferrite core.

[0016] The ferrite core is provided with a funnel-shaped shielding cover for shielding electromagnetic signals in non-detection directions, and the second coil is located in the shielding cover.

[0017] The shielding cover is made of Permalloy.

[0018] The rotary drive mechanism has a stepper motor, which is fixed on the propulsion rod II. The output shaft of the stepper motor is coaxial with the propulsion rod II. The output shaft of the stepper motor is coaxially connected to the second columnar protrusion structure, and is connected to the connecting member through the second columnar protrusion structure cooperating with the connecting hole at the end of the connecting member.

[0019] A method for transient electromagnetic spatial perspective in a hole in a coal mine, characterized in that the method comprises adopting the transient electromagnetic spatial perspective device in a hole in a coal mine, and performing the following steps:

[0020] S1. Drill holes A and B are arranged in parallel in the rock formation of the coal mine, and the same number of test points with corresponding positions are evenly arranged in holes A and B;

[0021] S2. Send the launcher into hole A and keep the axle in the launcher always horizontal. The launcher sends a signal at each test point in hole A in turn.

[0022] The receiving device is sent into hole B, and the receiving device completes omnidirectional reception in turn at a fixed rotation angle at a position corresponding to the test point where the transmitting device sends the signal in hole B;

[0023] The propulsion rods I and II respectively push the transmitting device and the receiving device forward point by point until all the test points in hole A have completed the transmission and the corresponding positions in hole B have completed the reception, and the spatial position of the abnormal body around hole B is located;

[0024] S3, send the launcher into hole B, and keep the axle in the launcher always horizontal, and the launcher sends a signal at each test point in hole B in turn;

[0025] The receiving device is sent into hole A, and the receiving device completes omnidirectional reception in sequence at a fixed rotation angle at a position corresponding to the test point where the transmitting device sends the signal in hole A;

[0026] The propulsion rods I and II respectively push the transmitting device and the receiving device forward point by point until all the test points in hole B have completed the transmission and the corresponding positions in hole A have completed the reception, and the spatial position of the abnormal body around hole A is located;

[0027] S4. Anomaly spatial intersection is performed through two relative emission points between the two boreholes to locate and verify the spatial position of the anomaly in the working face;

[0028] S5. By analyzing the spatial position of the anomaly located at different emission points, the development of the anomaly along the drilling direction is tracked and identified, thereby achieving accurate spatial perspective positioning of the geological anomaly in the coal seam.

[0029] The fixed rotation angle is 15°.

[0030] The beneficial effects of the present invention are as follows: the present invention performs two complete perspectives on hole A and hole B respectively, wherein the two perspective results can not only ensure that the effective detection range of each measuring point covers the shallow blind area of ​​the relative position, obtain the geological information in the entire detection area, but also perform spatial intersection and verification of the information of the intermediate overlapping perspective area, and each measuring point can perform multi-angle and all-round perspective, reducing the influence of random interference such as underground electromagnetics, and solving the influence of abnormal response interference in non-perspective directions. In addition, by performing perspective work point by point along the borehole, the development law of geological anomalies can be tracked and identified, and high-precision spatial positioning of anomalies can be achieved.

[0031] The present invention can not only avoid the interference of metal bodies in the mine, but also suppress random interference. The most important thing is that the present invention can obtain geological information of shallow detection blind areas, solve the influence of abnormal response in non-perspective direction on abnormal positioning, form a perspective of the entire transient electromagnetic detection area, and achieve tracking, identification and high-precision positioning of geological anomalies. Transmitting and receiving are performed separately in two boreholes, avoiding the mutual inductance between the transmitting and receiving devices, and improving the utilization rate of the borehole. In addition, this method can also be promoted and applied to tunnel excavation in mountainous areas, and has strong practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of the structure of the transmitting device in the embodiment.

[0033] Figure 2 FIG. 4 is a schematic diagram of the structure of a receiving device in an embodiment.

[0034] Figure 3 Schematic diagram of the structure of the magnetic core probe in the embodiment.

[0035] Figure 4 Schematic diagram of the structure of the connecting member in the embodiment.

[0036] Figure 5 Schematic diagram of the end structure of the propulsion rod II in the embodiment.

[0037] Figure 6 It is a hole perspective construction layout diagram of the transient electromagnetic spatial perspective method in the underground hole of the coal mine in the embodiment.

[0038] Figure 7 Schematic diagram of the working of the transient electromagnetic spatial perspective method in a hole in a coal mine in the embodiment.

[0039] In the figure: 101, conical cover body I; 102, conical cover body II; 201, cylindrical shell I; 202, cylindrical shell II; 3, axle; 4, first columnar protrusion structure; 5, first coil; 6, second coil; 7, connecting piece; 802, propulsion rod II; 9, shielding cover; 10, ferrite core; 11, connecting hole; 13, stepping motor; 14, second columnar protrusion structure; 16, geological anomaly; 17, hole A; 18, transmitting device; 19, test point; 20, hole B; 21, receiving device; 22, moving direction of measuring point; 23, blind area; 24, receiving range. DETAILED DESCRIPTION

[0040] This embodiment is a transient electromagnetic space perspective device in a hole in a coal mine, which includes a transmitting device and a receiving device. The receiving device is used to receive the signal sent by the transmitting device.

[0041] In this example, the launch device has a cylindrical shell I, one end of which is connected to a conical cover body I, and the other end is coaxially connected to a propulsion rod I. A first columnar protrusion structure is axially arranged at the bottom end of the cylindrical shell I, and a thread is arranged on the surface of the first columnar protrusion structure, and the propulsion rod I is connected to the cylindrical shell I through the first columnar protrusion structure.

[0042] In this embodiment, a wheel shaft perpendicular to the axial direction of the cylindrical housing is provided in the cylindrical housing I, and a first coil is provided on the wheel shaft. The wheel shaft includes a central axis and two impeller blades formed on the central axis, and both ends of the central axis are fixed on the inner wall of the cylindrical housing, and the axial direction of the central axis is perpendicular to the axial direction of the cylindrical housing I, and the first coil is wound on the central axis between the two impeller blades.

[0043] In this example, the receiving device has a cylindrical shell II, one end of which is connected to a conical cover II, and the other end is coaxially connected to a push rod II, which penetrates into the cylindrical shell II. A magnetic core probe is arranged inside the cylindrical shell II, and the magnetic core probe is connected to a connecting piece, and the connecting piece can be installed on the push rod II by rotating around the axis of the cylindrical shell II through a rotating drive mechanism.

[0044] In this embodiment, the magnetic core probe has a ferrite core and a second coil, wherein the ferrite core is arranged radially along the cylindrical shell II and axially perpendicular to the cylindrical shell II, one end of the ferrite core is fixed to the connecting piece, and the second coil is wound on the other end of the ferrite core. A funnel-shaped shielding cover (made of Permalloy) is installed on the ferrite core to shield electromagnetic signals in non-detection directions, which is conducive to the accurate spatial positioning of geological anomalies, and the second coil is located in the shielding cover.

[0045] In this embodiment, the rotary drive mechanism has a stepper motor, which is fixed on the propulsion rod II. The output shaft of the stepper motor is coaxially arranged with the propulsion rod II and the cylindrical housing II. The output shaft of the stepper motor is coaxially connected to the second columnar protrusion structure, and is connected to the connecting piece through the second columnar protrusion structure. A connecting hole is formed at the end of the connecting piece, and an internal thread is formed in the connecting hole; the second columnar protrusion structure is formed with an external thread that matches the internal thread in the connecting hole, and the two are threadedly connected.

[0046] This embodiment also provides a method for transient electromagnetic spatial perspective in a coal mine underground hole. Based on the transient electromagnetic spatial perspective device in a coal mine underground hole in this embodiment, it is suitable for perspective detection of geological anomalies, including the following steps:

[0047] S1. Hole A and hole B are arranged in parallel in the rock formation of the coal mine, and the same number of test points with corresponding positions are evenly arranged in hole A and hole B;

[0048] S2. Send the launcher into hole A and keep the axle in the launcher always horizontal. The launcher sends a signal at each test point in hole A in turn.

[0049] The receiving device is put into hole B. The receiving device completes all-round reception in turn at a fixed rotation angle of 15° at a position corresponding to the test point where the transmitting device sends the signal in hole B, starting from 0° and receiving once every 15°;

[0050] The propulsion rods I and II respectively push the transmitting device and the receiving device forward point by point until all the test points in hole A have completed the transmission and the corresponding positions in hole B have completed the reception, and the spatial position of the abnormal body around hole B is located;

[0051] S3, send the launcher into hole B, and keep the axle in the launcher always horizontal, and the launcher sends a signal at each test point in hole B in turn;

[0052] The receiving device is sent into hole A, and the receiving device completes omnidirectional reception in sequence at a fixed rotation angle at a position corresponding to the test point where the transmitting device sends the signal in hole A;

[0053] The propulsion rods I and II respectively push the transmitting device and the receiving device forward point by point until all the test points in hole B have completed the transmission and the corresponding positions in hole A have completed the reception, and the spatial position of the abnormal body around hole A is located;

[0054] S4. An abnormal space intersection is performed through two transmitting points opposite to each other between the two boreholes to locate and verify the spatial position of the abnormal body in the working surface; wherein the test point of the transmitting signal is the transmitting point;

[0055] S5. By analyzing the spatial position of the anomaly located at different emission points, the development of the anomaly along the drilling direction is tracked and identified, thereby achieving accurate spatial perspective positioning of the geological anomaly in the coal seam.

[0056] In this embodiment, step S1 further specifically includes: the test points in hole A and hole B are numbered in sequence starting from 0, each receiving point is driven by a stepper motor to drive the magnetic core probe to receive uniformly in each direction at a fixed angle, the distance between the receiving points in the same borehole is a fixed point distance, the fixed point distance is set to 1m, and the test point that receives the signal is the receiving point.

[0057] In this example, step S2 specifically includes: in this example, the first coil in the transmitting device in hole A is located at transmitting point No. 0 to send signals, and the magnetic core probe in hole B receives signals at fixed angle intervals at receiving point No. 0; after completing the perspective work of transmitting point No. 0, the transmitting device is pushed to move to test point No. 1 to send signals, and the magnetic core probe is pushed to the area of ​​receiving point No. 1 to receive signals at each angle; then, each test point is perspectively inspected in order of number until the perspective work of all transmitting points in hole A17 is completed.

[0058] like Figure 7 As shown, the solid circular wireframe range is the effective detection area when hole A transmits and hole B receives, and the grid area near hole A is the shallow blind area at this time. The dotted circular wireframe range is the effective detection area when hole B transmits and hole A receives, and the area near hole B is the shallow blind area at this time. The detection blind areas during both operations are located near the transmitting hole, and the blind areas are the same size. It can be found that the two perspective results can not only ensure that the effective detection range of each measuring point covers the shallow blind areas of the relative position, but also can perform mutual verification of the intermediate overlapping detection areas. In addition, the receiving device. Transmitting and receiving are performed separately in the two boreholes, which avoids the mutual inductance between the transmitting and receiving devices and improves the utilization rate of the boreholes.

[0059] As the transmission and reception go deeper into the borehole, the extension of the abnormal body into the working surface can be tracked and identified. By analyzing the position of the abnormal body revealed by different transmission points, the development of the abnormal body along the direction of the borehole can be tracked and identified, thereby achieving spatial perspective and precise positioning of the geological abnormal body.

[0060] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0061] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A transient electromagnetic spatial perspective device in a coal mine underground hole, characterized in that: It includes a transmitting device and a receiving device for receiving a signal sent by the transmitting device; The launching device comprises a cylindrical shell I (201), one end of the cylindrical shell I (201) is connected to a conical cover body I (101), and the other end is coaxially connected to a propulsion rod I; a wheel shaft (3) perpendicular to the axial direction of the cylindrical shell is arranged inside the cylindrical shell I (201), and a first coil (5) is arranged on the wheel shaft (3); The receiving device comprises a cylindrical housing II (202), one end of the cylindrical housing II (202) is connected to a conical cover II (102), and the other end is coaxially connected to a propulsion rod II (802); a magnetic core probe is provided in the cylindrical housing II (202), and the magnetic core probe is connected to the connecting member (7), and the connecting member (7) is mounted on the propulsion rod II (802) so as to be rotatable around the axis of the cylindrical housing II (202) through a rotating drive mechanism; The wheel shaft (3) has a central axis and two impeller blades fixed on the central axis, the central axis is arranged perpendicular to the axial direction of the cylindrical housing I (201), and the first coil (5) is wound on the central axis and between the two impeller blades; The magnetic core probe comprises a ferrite core (10) and a second coil (6), wherein the ferrite core (10) is arranged axially perpendicular to the cylindrical housing II (202), one end of the ferrite core is fixed to the connecting member (7), and the other end of the ferrite core (10) is wound with the second coil (6); The ferrite core (10) is provided with a funnel-shaped shielding cover (9) for shielding electromagnetic signals in a non-detection direction, and the second coil (6) is located inside the shielding cover (9).

2. The transient electromagnetic spatial perspective device for underground coal mines according to claim 1, characterized in that: The shielding cover (9) is made of Permalloy.

3. The transient electromagnetic spatial perspective device for underground coal mines according to claim 1, characterized in that: The rotary drive mechanism comprises a stepper motor (13), the stepper motor (13) being fixed on the propulsion rod II (802), the output shaft of the stepper motor (13) being coaxial with the propulsion rod II (802), the output shaft of the stepper motor (13) being coaxially connected to the second columnar protrusion structure (14), and being connected to the connecting member (7) through the second columnar protrusion structure (14) cooperating with the connecting hole (11) at the end of the connecting member (7).

4. A method for transient electromagnetic spatial perspective in a coal mine underground hole, characterized in that: The method of using the transient electromagnetic spatial perspective device in a coal mine underground hole as described in any one of claims 1 to 3 is as follows: S1. Drill holes A and B are arranged in parallel in the rock formation of the coal mine, and the same number of test points with corresponding positions are evenly arranged in holes A and B; S2, insert the launch device into hole A, and keep the wheel axle (3) in the launch device always horizontal, and the launch device sends a signal at each test point in hole A in turn; The receiving device is sent into hole B, and the receiving device completes omnidirectional reception in turn at a fixed rotation angle at a position corresponding to the test point where the transmitting device sends the signal in hole B; The propulsion rods I and II respectively push the transmitting device and the receiving device forward point by point until all the test points in hole A have completed the transmission and the corresponding positions in hole B have completed the reception, and the spatial position of the abnormal body around hole B is located; S3, insert the launch device into hole B, and keep the wheel shaft (3) in the launch device always horizontal, and the launch device sends a signal at each test point in hole B in turn; The receiving device is sent into hole A, and the receiving device completes omnidirectional reception in sequence at a fixed rotation angle at a position corresponding to the test point where the transmitting device sends the signal in hole A; The propulsion rods I and II respectively push the transmitting device and the receiving device forward point by point until all the test points in hole B have completed the transmission and the corresponding positions in hole A have completed the reception, and the spatial position of the abnormal body around hole A is located; S4. Anomaly spatial intersection is performed through two relative emission points between the two boreholes to locate and verify the spatial position of the anomaly in the working face; S5. By analyzing the spatial position of the anomaly located at different emission points, the development of the anomaly along the drilling direction is tracked and identified, thereby achieving accurate spatial perspective positioning of the geological anomaly in the coal seam.

5. The method for transient electromagnetic spatial perspective in underground coal mine holes according to claim 4, characterized in that: The fixed rotation angle is 15°.

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