Geološke in geomehanske raziskave plazu Soteska-Poreber pri kraju Hrib pri Kamniku

Križanič, Luka (author), Verbovšek, Timotej (mentor), Vrabec, Martin (co-mentor)

V svojem magistrskem delu sem iz geološkega in geomehanskega vidika obravnaval plaz pri kraju Hrib pri Kamniku. V okviru terenskega dela sem izvedel inženirsko-geološki pregled območja plazu in njegove okolice. Prav tako sem tudi sodeloval pri izvedbi treh sondažnih vrtin, SPT ter DPSH testov. Raziskovani plaz meri v širino okoli 50 m, v dolžino pa približno 30 m. Plaz je ogrožal južni, dolinski del lokalne ceste. Večino raziskovanega območja je sestavljenega iz miocenskih oziroma oligocenskih klastičnih kamnin, manj pa iz triasnih skrilavih glinavcev in apnencev. Vrtine ter SPT in DPSH testi so pokazali, da so preko podlage, sestavljene iz zbitega peska in laporovca, odloženi neenakomerno debeli sloji glinaste in glinasto meljne ter peščene preperine. Na podlagi rezultatov inženirsko-geološkega kartiranja sem izdelal dve karti ter prečni in vzdolžni profil. Na podlagi geomehanskih parametrov, ki sem jih pridobil iz SPT in DPSH testov ter ostalih rezultatov terenskega dela, sem izdelal različne modele stabilnostne analize. Z stabilnostnimi modeli sem preveril, kakšno je bilo stanje pred porušitvijo in kako učinkovito podporni ukrepi zaščitijo cestni odsek. Ugotovil sem, da je prišlo do porušitve ravnotežja na robu bankine cestišča pri strižnem kotu ?=20° in koheziji c=3 kPa v glinenem sloju ob povišanem nivoju podzemne vode. Porušitev se je zgodila vzdolž nekrožne drsne ploskve s faktorjem varnosti F=0,979. Kot sanacijski ukrep plazu se je projektant odločil izvesti pilotno steno iz delno konzolno vpetih in delno sidranih pilotov. Ugotovil sem, da ima prva drsna ploskev, ki se tvori na robu bankine cestišča, in nanjo nimajo več vpliva podporni ukrepi (piloti in sidra), faktor varnosti F=3,632. Svoje rezultate sem tudi primerjal z rezultati stabilnostnih analiz, izvedenih za dva okoliška plazova. Ugotovil sem, da je prišlo pri vseh treh plazovih do porušitve ravnotežja vzdolž drsnih ploskev v slojih vezanih zemljin. Podporni ukrepi pa v mojem primeru bistveno bolje izboljšajo varnost cestnega odseka.

• Language: Slovenian
• Keywords: plaz, inženirsko-geološko kartiranje, geomehansko raziskovanje, stabilnostna analiza, sanacija
• Work type: Master's thesis/paper
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Year: 2021
• PID: 20.500.12556/RUL-125495
• COBISS.SI-ID: 57823235
• Publication date in RUL: 19.03.2021

Secondary language

• Language: English
• Title: Geological and geotechnical investigations of Soteska- Poreber landslide near the village of Hrib pri Kamniku

Abstract

In my master's thesis, I analysed a landslide near the village of Hrib pri Kamniku from geological and geotechnical aspects. The field work comprised engineering-geological mapping of the landslide area and its surroundings. In addition to that, I also cooperated in the process of drilling of boreholes along with SPT and DPSH tests. The analysed landslide is 50 m wide and about 30 m long. It posed a threat to the south-side valley part of a local road. Most of the investigated area is made of mostly Miocene or Oligocene clastic rocks, and less of Triassic shale claystones and limestones. Boreholes, SPT and DPSH tests showed that the investigated ground is made of unevenly thick layers of clay, clay-silt and sandy soils, which are deposited on bedrock made of sandstone and marlstone. Based on the results, I obtained from the field work, I was able to construct two geological maps and two cross-sections. I used the geotechnical parameters of soil and rock, gained from all the field investigation methods, to perform several different slope stability models. I was consequently able to determine soil conditions at failure and efficiency of soil stabilization elements on the safety of the road section. I concluded that the critical slip surface formed on the south edge of the road, in a layer of clay with an angle of internal friction φ=20° and cohesion c=3 kPa, and at a high groundwater level in this layer. The failure surface was noncircular with factor of safety F=0.979. To mitigate the landslide, the project designer decided to build a pile wall. I concluded that the first slip surface, on which the stabilizing elements (piles and anchors) did not have any effect on, had the value of factor of safety F=3.632. I compared my slope stability models with those made for two landslides that were triggered in the vicinity of my analysed landslide. I found out that all three failures happened along slip surfaces in layers of cohesive soils. Furthermore, I concluded that, in the studied case, stabilization elements have better effect on increase of the safety of the road section.

• Keywords: landslide, engineering-geological mapping, geotechnical investigation, stability analysis, mitigation