Geological Overburden Detection By Electrical Resistivity Imaging Survey System

Geological profile of the survey area

The surface geological survey: the river bed cover layer is alluvial, mainly pebbles, composed of sandstone, granite, etc., some areas are sandy beaches, and the river surface elevation is 562m; bedrock exposed on both banks of the river bed, and the left bank bedrock is quartz sandstone. The right bank is gray-green gabbro, and the boundary between the two lithologies is in the middle of the river bed.

Data processing and interpretation analysis

In the longitudinal section, the image of high-density electrical imaging shows that the electrical properties of the surface change greatly, which is related to the content of pebbles. There is a high-resistance and low-resistance corona cluster in the middle of the overburden, which shows that on the section The inhomogeneity of the medium and the complex composition. In the stake 200-256, 300-330, 350-370 section, near the depth of 25m, there is a low-resistance corona group with a resistivity of less than 150Ω.m. It is assumed that this area There is a heavy sand content or sand layer. The bedrock is gray-green gabbro with a resistivity of 400～1800Ω·m. There is uneven weathering of the rock masses in each section. The rock masses of the sections 60-120 and 300-380 are more severely weathered than the other sections, showing that the resistivity of the bedrock is relatively low. The burial depth of the bedrock is relatively shallow at both ends of the profile, ranging from 25 to 30m; the section pile number 168 to 268, the bedrock burial depth is relatively deep, up to 45m, and the lowest elevation of the bedrock roof is about 518m.