An application of the high-density electrical resistivity method for detecting slide zones in deep-seated landslides in limestone areas

The deep-seated landslide near the Nanheng town, located in eastern China, is exhibited by the limestone at its bottom. The landslide process is related to the geological succession's weak interlayer covering the bedrock and is characterized by the loose deposit's over-position on the silty clay. A field survey and the 2D high-density electrical method were carried out to detect the overburden thickness, karst cavities and sliding zone location. After confirming the abnormal area, the casing drilling method and numerical simulation were used to verify the geophysical results. The results show that the interpretation results of the slide zone were verified by the FLAC2D simulation on the sliding zone determined by the high-density electrical method and drilling method, and the reliability of the landslide stability evaluation was improved. This research proposes a method for accurately dividing the landslide profile, that is, the high-density electrical resistance tomography (ERT), which is used to preliminarily divide the formation lithology and limestone distribution area, and then the casing drilling method is used to correct the distribution and location of the formation. The sliding zone determined by these two methods can be used in numerical simulations to improve the accuracy of landslide stability evaluations.