Underground whole-space nuclear magnetic resonance pre-polarization detecting device and detecting method

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.