The object of the study were two parts of the H-9 highway. Site 1 (PK 128 + 600 – 128 + 700), there is a landslide zone, the shoring of which was carried out in Soviet times. At the time of geophysical works the concrete retaining walls and drainage canals are semi-destructed (Figure 1). Soil fractures are visually observed in this zone. Site 2 (PK 142 + 100 – 142 + 800) The road runs along the right bank of the Tisa river valley. The road cuts the right side of the slope, the slope angle in some places reaches 80 degrees, along the slope above the road are observed wet zones, drainage areas.
Figure 1 Contours of the landslide zone of Site 1 of the H-9 road
The field work was carried out by FSPEF, VERS and GPR methods, the accompanying work was a drone survey of the work area, and a GNNS survey.
One of the factors of landslides occurrence is underground water flows and areas of increased soil moistening on their way.
The field geophysical works were carried out in several stages. At the first stage the areas of formation and migration paths of underground water streams, which form zones of increased soil moistening, were determined by the FSPEF survey in the territory of both sites. Local fault zones were also discovered and mapped, which are the pathways of deep groundwater migration into the loose dealluvial layers or surface. At the second stage by VERS sounding the thickness of dealluvial deposits and thickness of water-saturated part of these deposits were determined. Along the road 4 profiles were made by GPR survey at the third stage of works. Additional work included geodetic surveying of vertical sounding points, as well as an area aerial survey to build an orthophotomap of the work site and a digital terrain model on which the results of geophysical work were presented.
Figure 2. GPR profile along road H9 of Site 1.