The construction environment at the site is bad, and there are cars passing by. There are 64 measuring points in total with a distance of 1 meter from the transient electromagnetic measuring points. Emission current 56A, sampling interval 0.8 μ s。 It can be seen from the transient electromagnetic inversion map that the overall distribution is good within 3 meters of the surface, which corresponds well with the borehole profile. There is a small range of surrounding rock karst area between Borehole 2 and Borehole 3. According to the borehole data, the karst area is small (indicated by the red dotted line in the figure). There is a low resistance response at this place, with a depth of about 15 meters, and it is completely consistent with the borehole profile data under the detection of strong interference environment.

Borehole profile

Transient electromagnetic inversion diagram