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XI.Measuring soil resistivity
Using this instrument, you can use the unipolar method or the quadrupole method to
measure soil resistivity. The following uses the quadrupole method as an example. The
wiring for measuring soil resistivity is shown in Figure 12.
Figure 12
Wiring diagram for measuring soil resistivity by four-pole method
In the figure, a is the distance between the current electrode and the potential electrode,
b is the distance between the two potential electrodes, and h is the buried depth of the
electrode. When a=b, it is Winner's method. For the convenience of calculation, please
make the electrode spacing a and b much larger than the buried depth h, and generally
should satisfy a and b>10h.
The test electrode should be round steel with a diameter of not less than 1.5cm or
angle steel with a diameter of 25mm×25mm×4mm, and the length is not less than
40cm.
After burying the electrode and connecting the wire, the measurement can be started.
Measure the impedance Z by the above method of measuring ground impedance, then
the soil resistivity ρ is ρ=πa(a+b)Z/b
The above formula holds when a>>h and b>>h.
When a=b, the above formula is simplified to: ρ=2πaZ
Summary of Contents for HZDW-DB
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