Emergency stabilization of a landslide in Pirin National Park

The investigated landslide occurred in December 2021 on a steep river-valley slope in the southwestern part of the Pirin National Park. It has a typical circular shape with approximate dimensions: width of 20 m, length of 15 m and depth up to 4 m. The sliding involves mainly the soil-rock mass of the road embankment. The landslide affects a forest road and threatens the hydraulic canal “Syrchaliytsa” of the “Sandanska Bistritsa” cascade. The study is based on an on-site inspection and geotechnical mapping, its analysis and interpretation, aided by available archival and published data, and the authors’ personal experience of similar sites in the area and other parts of the country. The main objectives are to establish the engineering-geological conditions of the terrain, assess the main factors defining the landslide stability and develop a conceptual solution for its strengthening.