Active field nuclear magnetic resonance detection device and detection method

Abstract

The invention relates to an active field nuclear magnetic resonance detection device and detection method. The device comprises a pre-polarized control circuit used for controlling a transmitting coilthrough a switching switch for generating the pre-polarized magnetic field larger than the natural earth magnetic field, a release circuit which is connected with the transmitting coil through a switch and is used for quickly shutting off remaining energy of a circuit release transmitting coil, an alternating magnetic field control circuit used for controlling the transmitting coil through the switching switch for generating the alternating magnetic field to excite a target water body, and a main control unit used for emitting a control signal to switch and control the pre-polarized control circuit, the release circuit and the alternating magnetic field control circuit. The device is advantaged in that the pre-polarized field (Bp) and the alternating magnetic field (Bac) generated by thecombined current detect the disaster water around a tunnel, the Bp field is used for increasing the signal of the target water and improving the detection signal-to-noise ratio, and the Bac field is used for detecting a detection area layer by layer and can accurately locate the disaster water and realize non-intrusive detection of disaster water bodies under multi-angle and super-noise environments in the tunnel.

Description

technical field [0001] The invention belongs to the research field of geophysical exploration technology, and relates to an active field nuclear magnetic resonance detection device and a detection method. Background technique [0002] Nuclear magnetic resonance water detection technology is the only geophysical method that can directly detect groundwater. This method has been widely used in tunnels, advanced detection of mine disaster water sources, and groundwater resource exploration. However, due to the relatively weak natural geomagnetic field, the existing nuclear magnetic resonance detection system is difficult to realize the qualitative and quantitative detection of target water bodies under tunnels and mines. It is impossible to effectively warn geological disasters such as water inrush and mud gushing, which brings huge hidden dangers to construction safety. [0003] CN102062877A discloses a nuclear magnetic resonance detection device and a detection method for adv...

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Problems solved by technology

But the above-mentioned invention introduces the nuclear magnetic resonance directional detection device of artificial magnetic field and the artificial magnetic field field source of detection method is magnet, and bigger magnet is difficult to carry, is not suitable for carrying out prospecting work in narrow underground space, utilizes the artificial magnetic field that magnet produces to be difficult in Cut off in a very short time, so the accuracy and validity of the detection data cannot be guaranteed

[0006] The nuclear magnetic resonance detection device and the transient electromagnetic detection device of the above invention have good measurement results for special needs and application occasions, but there are some shortcomings: the nuclear magnetic resonance detection device in tunnels and mine underground excavation projects cannot be carried out. Directional detection, and because the natural geomagnetic field is weak, it can only be used for detection in an extremely low-noise environment; when the transient electromagnetic detection device encounters a metal structure around it, the measured data cannot be used, and its detection method is Indirect detection cannot accurately obtain important information such as the aquifer thickness and water content of the target water body; the NMR directional detection device of the artificial magnetic field is used in underground excavation projects with narrow spaces and complex environments. Due to the difficulty in handling the magnets, the magnets cannot be controlled during use. , and the artificial magnetic field is difficult to cut off in a very short time, so the accuracy and effectiveness of the detection data cannot be guaranteed, and the above three inventions also have common problems, the detection method is single, and when the target water body is detected, it will cause The construction cannot be carried out normally, affecting the construction progress

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