Underground full-space nuclear magnetic resonance prepolarization detection device and detection method

Abstract

The invention relates to an underground whole-space nuclear magnetic resonance pre-polarization detecting device and a detecting method. A computer is connected with a pre-polarization coil through a main control unit, an output-adjustable high-power power supply, an emitting bridge circuit driver, a high-power emitting bridge circuit and a high-voltage change-over switch; and the computer is connected with a receiving coil through an A / D acquisition unit, an amplifier circuit, a Q-switch circuit and a resonance matching capacitor; and therefore, the detecting device can be formed. Based on a characteristic that the intensity of a magnetic field is much higher than that of the pre-polarization field of a natural magnetic field, the overall magnetization intensity of a detection target water can be improved, and therefore, greater nuclear magnetic resonance signals can be obtained, and problems existing in the extraction of nuclear magnetic resonance signals under strong noise interference can be solved; the direction of the pre-polarization magnetic field can be changed, so that directional detection can be realized. When the device is utilized to detect disaster waters in underground constructions such as tunnels and mines, the detection of water content and the thickness of a water containing layer of a disastrous water source in a specified distance and at a specified direction can be realized, and various accidents caused by geological disasters such as water inrush can be decreased.

Description

Technical field: [0001] The invention relates to a geophysical exploration equipment and method, in particular to deep detection in the entire underground space such as mine tunnels by using nuclear magnetic resonance (Nuclear Magnetic Resonance, NMR) detection technology. Background technique: [0002] In the process of underground construction, especially in large-scale underground excavation projects such as tunnels and mines, due to complex geological conditions, geological disasters such as water inrush and mud gushing caused by groundwater are often encountered, which affects the construction progress and poses a threat to construction safety. pose a huge risk. Accurate and effective detection of the water occurrence state up and down, left and right, and in front of the construction area has become an important research direction in geophysical prospecting methods. [0003] CN102053280A discloses a nuclear magnetic resonance groundwater detection system and a detecti...

AI Technical Summary

Problems solved by technology

However, the nuclear magnetic resonance detection device and detection method for the advanced detection of the water body in front of the above invention only use the natural geomagnetic field. There is water-bearing body in front or behind of the ground, that is, the purpose of directional advanced detection cannot be achieved

Moreover, due to the weak magnetic field strength of the natural geomagnetic field, it is impossible to accurately obtain important information parameters such as the thickness of the aquifer layer and the water content of the water body ahead.

[0005] The nuclear magnetic resonance water finding device of the above invention has high measurement accuracy and good measurement effect for special needs and application occasions, but there are some shortcomings: in underground excavation projects with narrow space and complicated environment, ground nuclear magnetic resonance detection Among the more effective methods, similar to the multi-channel reference coil noise reduction method, due to the limited space, it is difficult to implement, and the number of coil turns is not enough to receive effective signals, etc. The problem of poor adaptability to the working environment; In the NMR water finding device in the underground excavation project, although the multi-turn small coil receiving method is adopted to solve the problem of laying the receiving coil in a narrow space, there are still nuclear magnetic resonance signals and strong background in the complex underground engineering with strong noise. The noise ratio is very small, that is, the problem of low signal-to-noise ratio

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