Geological and geotechnical investigations of Žebnik landslide within the municipality of Radeče

Magistrsko delo obravnava terenske geološko-geomehanske preiskave plazu Žebnik v občini Radeče, ki so se v okviru študije za sanacijo, na tem območju izvajale že od leta 1991. Leta 2021 smo izvedli preiskave obstoječega stanja plazu, ki so vključevale inženirsko-geološko kartiranje, izvedbo 10 sondažnih vrtin, SPT, laboratorijske preiskave odvzetih vzorcev ter 14 DPL testov. Plaz Žebnik meri v širino od 70 m do 110 m, v dolžino pa cca 350 m. Ugotovljeno je, da sega plaz na zgornjem delu do 9 m globoko, na spodnjem delu pa do okoli 8 m. Plaz ogroža skladiščno halo izčeskov podjetja Radeče papir, saj je lociran v njenem zaledju. Poleg te sta ogrožena odseka cest JP 842031 Žebnik–Glavač in JP 842032 Žebnik–Titovšek ter nekateri stanovanjski in gospodarski objekti. Podlago plazu gradi karbonsko-permski grafitni skrilavec z zelo redkimi vložki peščenjaka, preperinski pokrov pa je neenakomerno sestavljen iz plasti glinasto-meljastih zemljin in zaglinjenega grušča. Na podlagi rezultatov terenskih preiskav in obdelave obstoječih geotehničnih podatkov, se je izdelala pregledna inženirsko-geološka karta ter trije karakteristični prečni prerezi. Na osnovi pridobljenih geomehanskih parametrov smo izdelali dva modela za stabilnostne analize. Opravili smo povratno stabilnostno analizo, kjer smo modelirali stanje ob porušitvi, nato pa smo preverjali učinkovitost podpornih ukrepov. Dognali smo, da je prišlo do porušitve ravnotežja na pobočjih pod JP Žebnik–Titovšek (pri koheziji c=0,5 kPa in strižnem kotu ?=23° v glinasto-meljastem sloju ob povišanem vodostaju, vzdolž nekrožne drsne ploskve s faktorjem varnosti F=0,810) in pod voziščem JP Žebnik–Glavač (pri koheziji c=2 kPa in strižnem kotu ?=32° v zaglinjenem gruščnatem sloju ob povišanem vodostaju, vzdolž nekrožne drsne ploskve s faktorjem varnosti F=0,837). Podporni ukrepi izboljšajo varnost pobočja pod cestnima odsekoma, in sicer ima sidrana pilotna stena pod JP Žebnik–Titovšek faktor varnosti F=1,020, konzolna pilotna stena pod JP Žebnik–Glavač pa faktor varnosti F=1,032.My master\u27s thesis discusses geological and geomechanical field investigations of the Žebnik landslide in Radeče municipality, which have been carried out on this area since 1991, as part of the mitigation studies. In 2021, we carried out investigations of the existing state of the landslide, which included engineering-geological mapping, 10 boreholes along with SPT, laboratory testing of material samples and 14 DPL tests. Žebnik landslide is from 70 m to 110 m wide and approx. 350 m long. It has been established that its depth can reach up to 9 m in the upper part, and up to about 8 m in the lower part. The landslide poses a threat to the storage warehouse of Radeče paper mill, as it is located in its hinterland. In addition, it endangers a sections of roads JP 842031 Žebnik–Glavač and JP 842032 Žebnik–Titovšek, as well as some residential and other premises. The bedrock of the landslide is composed of Carboniferous-Permian graphite slate with very rare inclusions of sandstone, and the weathered layer that covers it is unevenly composed of layers of clay and silt soils and clay gravel. Based on the results of field investigations and the processing of existing geotechnical data, an overview map of geological features and three characteristic cross-sections was created. Based on the obtained geomechanical parameters, we created two slope stability models. We performed a reverse stability analysis, where we modeled pre-existing conditions at the time of the slip, and then checked the effectiveness of the mitigation measures. We concluded that there was a slip surface on the slopes below the road JP Žebnik–Titovšek (with cohesion c=0.5 kPa and an angle of internal friction φ=23° in the clay and silt layer at an elevated water level, along a noncircular failure surface, with a factor of safety F= 0.810) and under the road JP Žebnik–Glavač (with cohesion c=2 kPa and an angle of internal friction φ=32° in a clay gravel layer at a higher groundwater water level, along a noncircular failure surface with a factor of safety F=0.837). Mitigation measures improve the safety of the slope under the two road sections, namely by an anchored pile wall under the JP Žebnik–Titovšek with a factor of safety F=1.020, and the pile wall under the JP Žebnik–Glavač, with a factor of safety F=1.032