Abstract: Landslide is important hidden geological disasters that effect on the safety of roads and bridges. As a nondestructive and efficient investigation method, geophysical methods can effectively find out the features of geological structures and sliding surfaces inside the landslide body. By taking the landslide at the exit of Chongli tunnel of Zhangyu line as an example, the geophysical characteristics were analyzed by means of high-density resistivity method and shear wave velocity test combined with borehole data. The apparent resistivity and shear wave velocity of the landslide have obvious vertical differences, which reflect the differences in the vertical rock properties, density, and moisture of the landslide. The result shows that the top surface of the highly weathered rhyolite with high apparent resistivity and shear wave velocity is the potential sliding surface. On this basis, it can basically be inferred that the landslide body is composed of alluvial and alluvial deposits, attached to the rhyolite rock body, with a transverse length of 300 m, a longitudinal length of 260 m, and a sliding body thickness of 20-30 m. Simultaneously, according to the analysis of the high-density resistivity of the three-dimensional profile, it is considered that the slide toe at the bottom of the sliding body is the shear outlet position. Based on the above characteristics, the geological model of the landslide is established.

Key words: high density resistivity, landslide, highway survey, geophysical methods