Detection of rockfall activity due to rock freezing and thawing by electronic geotechnical sensors in Slovenia

<p>Rockfalls are caused by preparatory processes (weathering and crack propagation) that gradually degrade bedrock and by triggering g processes (freeze-thaw activity, precipitation events, earthquakes, snow avalanches, animals, or anthropogenic activities) that eventually release a rock block. Both processes are controlled by several factors representing the internal (geology), external (meteorology), and surface and near-surface conditions (topography, vegetation, snow cover, thermal conditions, chemical weathering, and hydrology) of the bedrock. In this paper, electronic geotechnical monitoring is developed to detect the rockfall activity due to rock freezing and thawing on two separate steep cliffs composed of igneous and carbonate rocks in the eastern part of Slovenia. The monitoring programme includes automatic recordings of rock temperatures and meteorological influencing factors (air temperature, humidity, and precipitation), tiltmeters, kit for measuring rock stress and deformability, laser distance meters, and crackmeters. During the 2020 field investigation, cracks and discontinuities were mapped and Rock Mass Rating (RMR) was estimated. The Hoek-Brown Geological Strength Index was determined to qualitatively assess surface conditions in inaccessible areas using visual assessments of tectonic ruptured walls. We will present the first preliminary results of the parameters monitored for 10 months, which will help interpret rockfall activity and identify freeze-thaw cycles.</p><p>&#160;</p><p><strong>Acknowledgement</strong>:&#160; The research was funded by the Slovenian Research Agency (Research project J1-3024). The electronic geotechnical sensors were founded by Project &#187;Development of research infrastructure for the international competitiveness of the Slovenian RRI Space &#8211; RI-SI-EPOS&#171; The operation is co-financed by the Republic of Slovenia, Ministry of Education, Science and Sport and the European Union from the European Regional Development Fund.</p>