Bridge/tunnel exploration

As shown in Figure 1, this surface-borehole survey was configured using the ZZ Universal resistivity meter to accurately locate known caves for structural reasons. The operator collected 60k data points in only one hour.

Figure 2 shows that the resistivity inversion image obtained from the data set had a low resistivity anomaly on both side of the borehole. Two caves were found after drilling holes on either side of the borehole.

The purpose of the resistivity survey conducted by the ZZ Universal resistivity meter was to explore possible geological explanations, as part of a railway tunnel, (from 370 to 430m) experienced settlement after completion. A total of 63 electrodes were laid on the surface above the tunnel and one was placed into the tunnel in the area of settlement. The following figure shows the resistivity inversion result from the survey: a few low resistivity anomalies are illustrated beneath the tunnel between 370 to 450m. After physically investigating the area, old coal mining tunnels filled with sand and mud beneath the railway tunnel were found.