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【FAQ】Electromagnetic method product knowledge

A multi-channel instrument (5/10 channels) can measure 5/10 measurement point data simultaneously after one wiring. Compared with a single-channel instrument, it has a stronger anti-interference ability and can obtain more stable field source data. Therefore, the consistency of the re-measurement effect is better, and the data accuracy is also higher than that of a single-channel instrument.

A single-channel instrument is our traditional single-point measuring instrument. Each time the electrode rod or probe is moved, only one point can be measured. Multi-channel instruments are divided into 5-channel and 10-channel instruments. One wiring can measure 5 or 10 measurement point data at the same time.

A single-channel instrument is our traditional single-point measuring instrument. Each time the electrode rod or probe is moved, only one point can be measured. Multi-channel instruments are divided into 5-channel and 10-channel instruments. One wiring can measure 5 or 10 measurement point data at the same time.

The principle of geophysical survey wiring is generally to lay the line perpendicular to the direction of the abnormal body. The general principle of groundwater detection is to lay the line perpendicular to the direction of groundwater flow. Assuming that the direction of groundwater flow is east-west, the best direction for wiring is north-south. When the width or position of the waterline cannot be determined, increasing the length of the survey line is undoubtedly the best choice to find the waterline position.

Electromagnetic probe measurement does not require wire pulling, and the probe point is located directly below the probe; the electrode rod measurement point is located at the center of the MN electrode rod. The electromagnetic probe measures the resistivity by converting the magnetic field into an electric field signal, while the electrode rod measures the resistivity directly by measuring the electric field signal. In some areas, there will be completely opposite abnormal reactions.

When measuring with the probe, the ground must be flat, and gravel or weeds on the ground must be removed as much as possible. The direction of the probe on the same measuring line must be consistent. When measuring with the electrode rod, try to insert it into the soil for more than 10 cm, and it is best to insert it into the solid soil. If the ground is too dry, water it appropriately.

Regardless of electrode measurement or probe measurement, both are for finding abnormal water (ore) areas underground. The accuracy of the two is similar. The advantage of the probe is that it is not restricted by the site, does not require manual wire pulling, and is easy to operate.

The interference sources that affect the test include: high-voltage wires, large machinery at work, and ground vibrations caused by cars and trains passing by, so try to ensure that the measurement work is carried out in a relatively quiet environment.

Because the known well has been artificially drilled, filled with grout, etc., the underground geological structure has changed significantly. Measuring the known well will produce a situation that does not correspond to the original geological information. It is recommended to increase the point spacing to verify the known well.

The measurement point increment is the interval between measurement points when the mobile phone is mapping, and does not represent the point distance. The larger the measurement point increment is set, the wider the graphic display is. Generally, for instruments with a depth of 30-200 meters, the default measurement point increment is 10, which is better. For instruments above 300 meters, the measurement point increment value can be appropriately increased according to the instrument’s detection depth, such as 20 or more. For the convenience of map recognition, it is recommended to set the measurement point increment in multiples of 10. The setting of the measurement point increment only affects the width of the graphic and will not affect the measurement accuracy of the instrument.

If you encounter high-voltage wires, wires and other power facilities on the ground, it is best to stay away from them, especially high-voltage wires. It is best to stay away from them for more than a few hundred meters. If you cannot stay away, measure parallel to the wires and high-voltage wires as much as possible, and each measuring line needs to be measured more than 2 times to find the common abnormal area of ​​2 color maps. Improper measurement and handling in places such as high-voltage wires and wires will cause inaccurate measurement data due to excessive electric field strength nearby, and the geological information displayed in the color map will be distorted, misleading users to make wrong judgments. For small underground metal pipes and metal objects, it has little effect on the measurement results; for relatively large metal objects, it will form a certain low-resistance shielding on the natural field; reduce the detection depth of the instrument. If the metal pipe is charged, it will generate electromagnetic interference, resulting in inaccurate measurement data, so it should be kept away.

When measuring with probes, the ground must be flat, and gravel or weeds on the ground must be removed as much as possible. The direction of the probe on the same measuring line must be consistent. When measuring with electrode rods, try to insert them into the soil more than 10 cm, and it is best to insert them into solid soil. If the ground is too dry, water it appropriately.

The electromagnetic probe measurement point is directly below the probe; the electrode rod measurement point is the center point of the MN electrode rod. The electromagnetic probe measures the resistivity by converting the magnetic field into an electric field signal, while the electrode rod measures the resistivity directly by measuring the electric field signal. In some areas, there will be completely opposite abnormal reactions.

The principle of geophysical survey wiring is generally to lay out perpendicular to the direction of the anomaly. The general principle of groundwater detection is to lay out perpendicular to the direction of groundwater flow. Assuming that the direction of groundwater flow is east-west, the best direction for wiring is north-south. When the width or position of the waterline cannot be determined, increasing the length of the survey line is undoubtedly the best choice to find the waterline position.

If you encounter high-voltage wires, electric wires and other power facilities nearby on the ground, it is best to stay away from them, especially high-voltage wires, which are better to stay away from them for more than a few hundred meters. If you can’t stay away, measure parallel to the electric wires and high-voltage wires as much as possible, and each measuring line needs to be measured more than 2 times, looking for the common abnormal area of ​​2 color maps. Improper measurement and handling in places such as high-voltage wires and electric wires will cause inaccurate measurement data due to excessive electric field strength nearby, and the geological information displayed in the color map will be distorted, misleading users to make wrong judgments. For small underground metal pipes and metal objects, it has little effect on the measurement results; for relatively large metal objects, it will form a certain low-resistance shielding on the natural field; reduce the detection depth of the instrument. If the metal pipe is charged, it will generate electromagnetic interference, resulting in inaccurate measurement data, so it should be kept away.

Whether electrode measurement or probe measurement, both are for finding abnormal water (ore) areas underground. The accuracy of the two is similar. The advantage of the probe is that it is not limited by the site, does not require manual wire pulling, and is easy to operate.

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