The study is aimed at verifying the reliability of the ERA5 reanalysis in reproducing histories of soil water fluxes exchanges (in terms of precipitation and evapotranspiration) leading to landslide events that actually occurred in Campania Region (Southern Italy). In the specific, the investigation deals with landslide events affecting pyroclastic covers result of repeated eruptions of Vesuvius and Campi Flegrei over the course of millennia. Indeed, for many events occurred in the last years, it is hard to retrieve continuous and reliable atmospheric data provided by weather stations in the vicinity of the affected slopes. Under such constraints, it could be difficult to identify the weather patterns triggering the events and then how they could vary in a climate change perspective. To deal with these issues, the fifth generation of atmospheric reanalysis made available by European Centre for Medium-Range Weather Forecasts (ECMWF) can represent a valuable support. ERA5 and its downscaling ERA5land return hourly data with an horizontal resolution of respectively 31km and 9 km over the entire globe. The data are available since Fifties and they are continuously updated with a delay of only 5 days for ERA5 and few months for ERA5land. Well-documented test cases over Campania Region for which long datasets of atmospheric data and details about the landslide events are available, are exploited to assess the capabilities of ERA5 reanalysis in reproducing antecedent and triggering soil water fluxes exchanges histories. Then, strengths and potential gaps are identified and thoroughly explained to permit a reliable adoption of the datasets.

How to cite: Rianna, G. and Reder, A.: Interpreting recent landslide events in Campania Region (Southern Italy) by using innovative approaches, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13399, https://doi.org/10.5194/egusphere-egu22-13399, 2022.

Due to the impact of climate change, the increasing frequency of extreme rainfall events, with concentrated rainfalls, commonly cause landslide hazard in the mountain areas of Taiwan. Although the extraordinary rainfall behavior is critical for the geohazard, it is significantly affected by the factors such as topography, the route of typhoon, etc. Therefore, there are uncertainties for the predicted rainfall as well as the landslide susceptibilities.

This study employs rainfall frequency analysis together with the atmospheric general circulation model (AGCM) downscaling estimation to understand the temporal rainfall trends, distributions, and intensities in the adopted study area in Central Taiwan. The uncertainties within the rainfall prediction was investigated before applied to the landslide susceptibility analysis. The catchments in Taiwan, including Tachia River, Wu River, and Chuoshui River, were adopted as the study area. To assess the hazard of the landslides, logistic regression methods and supporting vector machines method were applied, in which the control factors were analyzed and discussed. The results of predictive analysis with the consideration of uncertainties can be applied for risk prevention and management in the study area.

How to cite: Shou, K.-J.: Impact of Climate Change on Landslide Susceptibility – for the Case in Taiwan, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2299, https://doi.org/10.5194/egusphere-egu22-2299, 2022.

The frequency and intensity of heavy precipitation events increased since the mid-20th century and, considering the climate crisis, it is important also to analyze the effects of processes and events that lead to faster snow mantle melting cycles in mountain areas.

Shallow landslides are induced by extreme hydrological events such as the occurrence of short and intense rainfall or by events of medium intensity but prolonged over time. Such slips involve generally reduced portions of land both in area and in thickness, however, they are dangerous due to the absence of warning signals and the lack of knowledge regarding their possible evolution.

This work deals with the experimental study of these landslides through the laboratory simulations on a small-scale slope, reproduced at the LIMAG Lab - Laboratory of mountain hydraulics and applied geology of the Lecco Campus and in situ seasonal processes observation at a mountain closed basin nearby Champoluc village in Aosta Valley region.

The central objective is to study the evolution of shallow landslides in reduced scale caused by external factor as snowmelt and rainfall and to compare the observations done in laboratory with the ones in situ. In order to investigate the behaviour of shallow landslides in these critical conditions, a series of sensors have been installed on the simulator. This technology includes three modified pressure transmitters for the pore water pressure evaluation which have been accompanied by other support instrumentation consisting of GoPro’s cameras, TDR (Time Domain Reflectometry) and georesistivimeter; all of them provide a cross check of phenomena processes.

Throughout the downscaled simulations with snow cover it was possible to observe several processes. The direct interaction between snow and ground does not favor the infiltration of a large amount of water. The protective role of snow lies in keeping the first film of soil at 0 degrees and loading the soil by decreasing its infiltrative capacity; this no longer occurs when the water melted by the snow flows downstream and begins to infiltrate into uncovered and warmer soils. Without thermal or overload barriers, the water pours into the ground. Therefore, a potential susceptible area can be the subject of different filtering and infiltrative contributions from upstream, saturating quickly and collapsing.

These laboratory experiments are the starting point for the in-situ analyses and provide a comparison with the observations made by means of ad hoc instrumentation set up at the Champoluc station. Highly detailed information is obtained concerning the density and thickness of the snowpack during seasonal processes. These contribute to defining the hydrogeological processes within the terrain, already studied in the laboratory, and to establishing the water balance.

How to cite: Longoni, L., Panzeri, L., Mondani, M., and Papini, M.: Experimental analysis of seasonal processes in shallow landslide in a snowy region through downscaled and in situ observation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8247, https://doi.org/10.5194/egusphere-egu22-8247, 2022.

Permafrost is perennially frozen ground occurring in about 24% of the exposed land surface in the northern hemisphere. The soil categorized as permafrost is named cryosol (or gelisol). Cryosol is widely spread in the Arctic, where it is continuous in the polar regions while in the sub-arctic it is discontinuous or sporadic. Iceland is located on the edge of the Arctic, and therefore permafrost can be found in many regions of the island. In addition, the frost effect is great, due to the unique climate and weather conditions and the high sensitivity of the Icelandic soil (volcanic soil – andosol). Although the distribution of permafrost is widespread it is in many respects dependent on the weather. As the climate warms, as it does now, the permafrost retreats rapidly, causing major changes in the earth’s surface. These changes can be accompanied by various dangers. In Iceland the retreat of permafrost in high mountains has led the top slopes to become unstable, leading to increased risk of landslides and similar hazards. In this project, permafrost in Iceland will be examined, more specifically the areas where permafrost is considered to be thawing and the dangers that accompany that thawing. The research area is by Strandartindur mountain in Seyðisfjörður. On the slope of Strandartindur is a rock glacier, which is in motion, but it is believed that permafrost is hidden in the ground beneath. The area is a well-known landslide area, where the source of landslides high up in Strandartindur is thick sediments that are partly considered permafrost or rock glaciers. Rock glaciers and thawing of permafrost in the vicinity and/or in the glacier threaten settlements in the area, due to landslides. This will be a threefold multidisciplinary project where aspects of natural hazards and society will be tied together; (i) data from soil thermometers and InSAR data will be examined, (ii) discussed and examined how permafrost can be included in monitoring, (iii) and how information on the dangers associated with permafrost can be disseminated to residents and the general public. The project will be useful for monitoring the hazard area at Strandartindur, while also for monitoring comparable areas in the country. It is hoped that the product of this project will be a monitoring research proposal. The result will show how best to measure permafrost, how best to monitor its thawing and how best to provide information to residents and the general public.

How to cite: A. Bartsch, U. B., Gísladóttir, G., and Grímsdóttir, H.: Permathawing permafrost , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8176, https://doi.org/10.5194/egusphere-egu22-8176, 2022.

 Soil erosion seriously damages land resources, which is a global environmental problem. Gully erosion is an important manifestation of soil erosion, in recent years, frequent extreme rainstorms have aggravated the occurrence and development of gully erosion. In order to study the formation and development patterns of newly formed gullies under the condition of climate change, this paper takes the Wangwugou Small Watershed of the Chabagou Watershed on the Loess Plateau in Northern Shaanxi as the research area, and takes the “7·26” extreme rainstorm in Northern Shaanxi Province in 2017 as the main research object based on UAV images, to analyze the occurrence regularity of newly formed gullies, and discuss its development characteristics, its difference with the development of existing gullies before 2017, and its relationship with topographic parameters in the following three years. The results showed that: (1) during the “7·26” extreme rainstorm in Northern Shaanxi, there were 45 newly formed gullies in the Wangwugou Small Watershed, which are about 101 gully/km2, and they could be divided into four categories: slope surface gullies, terraced field gullies, unpaved roadway gullies and bottom gullies. The slope surface gullies were the largest, and the bottom gullies and terraced field gullies were wider and larger in area. Production roads, check dam farmland and sloping farmland are most prone to the occurring of gullies under rainstorm conditions. (2) In the three years after the formation of the new gullies, the development of the new gully heads was faster than that of the original existing gullies, and 34.48% of the heads of newly formed gully was further advanced, which was 1.32 times of the original existing gullies. The average gully head retreat distance of newly formed gullies is 3 times that of the original existing gullies, which is up to 0.58 m/a, and the maximum speed could reach 2.12 m/a. (3) The increase of the drainage area could significantly promote the development of gully heads, which is an important topographic index to simulate the retreat rate of gully heads. Under extreme rainfall conditions, the soil erosion situation is highly serious in the study area, and the source of newly formed gullies could be traced more rapidly within three years after their occurrence. Therefore, special attention and enhanced management should be attached to the prevention and control of such gullies.

How to cite: Yang, L., Wang, C., Zhang, C., Pang, G., Long, Y., Wang, L., Liu, B., and Yang, Q.: Study on the Occurrence and Development of Gullies under extreme Rainstorm Conditions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1241, https://doi.org/10.5194/egusphere-egu22-1241, 2022.

Taiwan has unique geographical characteristics. Located in a subtropical monsoon region, it is plagued annually by exceptional meiyu (East Asian rainy season) in May and June, and numerous typhoons from July to October. This unique climate often brings torrential rains and combined with Taiwan’s steep topography and short rivers, frequently triggers severe floods. Moreover, Taiwan lies at the intersection between the Eurasian Plate and the Philippine Sea Plate and is among the areas with the world’s most frequent felt earthquakes. Natural hazards here can roughly be categorized into four types: earthquake, typhoon, flood, and hillside disasters; manmade disasters include: industrial disasters, residential/commercial fire, road traffic accident, and shipwreck. When disasters strike, they often cause grave impacts and tolls in human lives and properties. In recent years, there has been a rising trend in both their frequency and scale due to rapid urbanization and growing environmental vulnerability.
According to World Bank’s 2005 publication, Natural Disaster Hotspots - A Global Risk Analysis, Taiwan tops the world in the land area simultaneously exposed to three or more natural hazards (73%) and in the population under disasters’ threat (73%). Additionally, there has been an increase in potential hazards such as disease outbreaks and severe public safety accidents. Therefore, when large-scale disasters strike and the impact is beyond what the affected municipalities can or have resources to handle, the key to minimizing death and injuries as well as financial losses becomes how nearby municipalities can offer support, participate rapidly in the emergency response, integrate resources effectively, enhance response effectiveness and prevent the disaster’s spread.
The “Operational Compact for Emergency Management Mutual Aid between Municipality and County Governments” passed in 2005 has now been in effect for four years. Yet, a comprehensive review of recent years’ severe disaster experiences indicates that the chief rescue and relief responsibilities still fall on the central government; the rare implementation of the above Compact by local authorities exposes the inadequacy of the actual system. Thus, this paper examines the literature on relevant ordinances, operating models, and case studies in the American and Japanese regional mutual aid systems to emergency management, in order to offer suggestions for improvement towards a more complete regional mutual aid system, a significant upgrade on municipalities’ disaster response capabilities and effective functional integration and collaboration.

How to cite: Li, Y.-T., Fu, G.-L., and Tsai, C. H.: Study on Establishing the System of Enterprises’ Participation in Flood Disaster Prevention, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-729, https://doi.org/10.5194/egusphere-egu22-729, 2022.

Landslide risk is one of the most relevant hazard that affects the Emilia-Romagna Region. Almost 80,000 landslides were mapped in the mountainous part, and the percentage of land covered by landslides exceeds in some areas 25%. Although most of the regional landslides are relatively slow, the economic impact is critical: in 2019, 1 million euros was allocated for urgent safety interventions, and it is estimated that at least another 80 would be needed to complete the plan. These numbers place the Emilia-Romagna Region among the areas with the highest landslide risk in the world. The geological characteristics of the Region, combined with the growing exploitation of the territory and the climatic changes underway, are making this problem more and more dramatic. It is now clear that emergency responses are no longer sufficient and that they must be accompanied by prevention actions devoted to mitigate the risk. 

The main objective of this work is to develop Artificial Intelligence models for the prediction of landslides in the Emilia-Romagna Region. The idea is to exploit the data collected by the University of Bologna in the last 15 years, as part of the research activities carried out in collaboration with the Regional Agency for Civil Protection and the Geological Survey of the Emilia-Romagna Region.

Available data consist of time series of rainfall, soil moisture, snow cover and displacement of some active landslides that have occurred in the region in recent years. The displacement data comes from permanent GPS stations, wire strain gauges, and robotic total stations installed in several landslides for emergency purposes. These data show clear relationships between precipitation and rate of movement. However, such relationships are difficult to reproduce using physically-based approaches.

The proposed machine learning approach was applied to the Emilia-Romagna Region of Italy taking advantage of the historical landslide archive, which includes more than 2210 rainfall events  that triggered 2363 landslide, and of the genetic classification algorithm TPOT (Tree-based Pipeline Optimization Tool) with more than 1million combinations of hyperparameters. The results show that landsliding in the study area is strongly related to rainfall event parameters (Precipitation during the event, The day of the event and in which location happened) while antecedent rainfall seems to be less important (Precipitation 30 and 60 days before the rainfall event). The distribution of landslides in the rainfall precipitation - day of the year chart shows that after the dry summer season a rain event of at least 90-100 mm is necessary to trigger a landslide. However, this number decreases as the day of the year increases, and then arrives in spring where many landslides are shown have been triggered with modest rain events (15-30 mm). The algorithm also provided an F1 test result score of 0.825, which means that it can predict a true positive (rainfall event triggers landslide) with a 70% of precision and with 95.5% about true negative (rainfall event do not triggers landslide).

How to cite: Dal Seno, N. and Berti, M.: Development of AI Algorithms for landslides prediction (Emilia-Romagna Region, Italy), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12658, https://doi.org/10.5194/egusphere-egu22-12658, 2022.

In this study, zone of Gundogdu (Rize) located in the Eastern Black Sea Region were examined in terms of landslide susceptibility and its stability analyzes were conducted. The study area is the region with the highest rainfall in Turkey. Heavy rainfall plays a major role in triggering landslides in this region. In this study, the relationship between precipitation and landslide was investigated. In addition, the effect of precipitation on weathering also determined the geological characteristics of the area. First of all, 1/25.000 scale geological map of Gundogdu and its surrounding was provided, the units are listed as Melyat Formation (Middle Eocene) and alluvium (Quaternary) from older to younger. 1/500 scale cross sections were generated for nineteen different landslides happened at Gundogdu in 2010, 2015, 2018, and 2021 years. Then stability analyzes were done with these data. Angle of internal friction (φ), cohesion (c), saturated unit weight, natural unit weight, dry unit weight and submerged unit weight (ϒ_d, ϒ_n, ϒ_k, ϒ'), specific gravity (Gs), porosity (n), saturation degree (SR), void ratio (e) and grain size distribution were determined with laboratory tests of soil samples which were taken to determine the engineering properties of soils located in places which stability calculations would be held. Following the results of these experiments, stability analyzes were done with 4 different methods (The Zero angle of Shearing Resistance Method, Ordinary Method of Slice, Bishop Method of Slices, and Janbu Method) according to the possible sliding surfaces that were plotted from geological section of landslide. As a result of these data, this region poses a great danger specially after rainfall with the effect of weathering. For this purpose, needs to be done for the prevention of landslides have been introduced.

How to cite: Yalcin, A.: Gundogdu (Ri̇ze) landslides and its surrounding slope susceptibility, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-938, https://doi.org/10.5194/egusphere-egu22-938, 2022.

Thermo-rock: influence of temperature on rock slope properties

Rock slope stability is closely linked with the mechanical properties of the rock slope mass. These properties are influenced by numerous factors including meteorological, thermal and hydrogeological. Even short-term temperature cycles caused by direct sunlight, together with water saturation cycles can change mechanical properties of rock slope surficial zone. To partially quantify these influences, we have carried out short-term experiments at a former quarry test site. Geotechnical instrumentation of partial blocks with crack meters, surface and microcracks deformation monitoring using strain gauges, geophysical ERT monitoring, subsurface temperature and humidity monitoring, and  IR camera surface temperature sensing were used during 24-hour monitoring campaigns. Additionally, surface hardness was repeatedly measured using Schmidthammer. Before and after monitoring campaigns, rock mass samples from different depths were collected, to perform basic geomechanical tests. Using these complex data, the influence of short-term temperature changes on the rock slope surficial layer properties were estimated.

How to cite: Racek, O. and Blahůt, J.: Thermo-rock: influence of temperature on rock slope properties, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7282, https://doi.org/10.5194/egusphere-egu22-7282, 2022.

The residual shear strength is the sole available strength in regular shear zones of landslides after large displacements. While it does not depend on the stress history, it has been shown to depend on the rate of shearing. Various mechanisms have been proposed to explain the shear-rate strengthening and weakening observed, in particular, in soils containing clay minerals. Frictional heating has been shown to be involved in shear weakening under very large shearing rates. However, changes in temperature (imposed as boundary conditions and propagating into the shear zone) also can affect the residual shear strength, even in drained condition, but evidence in the literature is scarce.

Here, we show results of temperature-controlled ring-shear tests on two pure clays (a commercial bentonite, very active, and a commercial kaolin, inactive), conducted under a wide range of shear displacement rates (0.02–45 mm/min) and normal stresses (50–150 kPa) typical of slow to rapid landslides. After attaining the residual shear strength under the chosen stress and displacement-rate conditions at room temperature (20 °C), we increased the temperature of the cell up to 55 °C and kept it constant over a sufficient shearing distance before gradually decreasing it back to the initial value.

We observed a clear effect of temperature on the residual shear strength of the active clay. We evaluated, in particular, a shear strengthening under slow shearing (up to +1.5 %/°C) which turned into a shear weakening under fast shearing (-0.5 %/°C) under any normal stress. We evaluated that the transition between the two behaviours occurred at a shear displacement rate of 0.1–1 mm/min, which is consistent with the range for the onset of shear rate-dependent behaviours. The effect produced by the increase in temperature was shown to be reversible, although in some cases we noticed a net decrease in strength that could be attributed to an improved alignment of the clay platelets resulting from the thermal cycle. Notably, little thermal effects were seen for the inactive clay, suggesting that such effects should originate from changes in physico-chemical forces of interaction at the microstructural level, which are indeed especially relevant in active clays.

Changes in residual shear strength with temperature could be related to changes in landslide activity (particularly for creeping landslides in clay soils) in terms of seasonal/progressive acceleration or deceleration driven by external hydro-meteorological forcing. Furthermore, these changes could also control the potential for runaway motion if a transition from a strengthening to a weakening behaviour occurs. 

How to cite: Scaringi, G. and Loche, M.: Effects of temperature and shearing rate on the residual shear strength of two pure clays, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8429, https://doi.org/10.5194/egusphere-egu22-8429, 2022.

The available strength on slip surfaces in landslide after a significant displacement and at motion is the residual strength. The residual strength depends on the soil properties including both solid skeleton (mineralogy, particle shape and size, index properties) and pore fluid (chemical and rheological properties). The available strength also depends, as extensively reported in the literature, on several factors that may not remain constant in time and affect the landslide stability and dynamics: applied stress, accumulated displacement and shear strain rate. With a less extensive literature related to, the effect of temperature on the residual strength have been also observed.

This work reports on the results of a large number of ring shear tests under controlled rate and temperature performed on different types of soils. The results are interpreted in terms of the influence of mineralogy, clay content and plasticity on temperature effects on residual strength.

How to cite: García, L. M., Soncco, E. A., Pinyol, N. M., and Lloret, A.: Temperature effect on the residual shear strength., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10442, https://doi.org/10.5194/egusphere-egu22-10442, 2022.

Landslide motion can be affected by the thermal effects resulting from the dissipation in heat of the frictional work generated in shearing bands. This problem was initially addressed for simple landslide geometries which have to be defined a priori. In this context, these analyses assume the motion of a rigid block and the thermal-hydro-mechanical phenomena were solved at basal shearing bands and their vicinity.

Later on, in order to generalize the analysis and to face more complex geometries and features, governing equations were implemented in the material point framework. This numerical method (MPM) is able to model large strains and displacements thanks to the double discretization of the domain by means of a Eulerian computational mesh and Lagrangian material points. A new approach was proposed to deal with the pathological dependence of the frictional work generation and the computational mesh element size. The methodology consists in the definition of computational embedded joints whose thickness is defined as a material parameter. 

The presentation will show the formulation of the thermal pressurization phenomena in MPM. First, the methodology will be evaluated under triaxial conditions and simple landslide geometries using different mesh sizes.

Real cases are later analyzed and modelled in MPM. The first case refers to an incipient landslide induced by a drawdown. The potential risk of acceleration induced by thermal pressurization is analyzed. The non-accelerated behavior observed in the field is explained combining the frictional heating induced weakening with non-linear velocity dependent frictional hardening. The results show that increments of a few degrees of the frictional angle with slide velocity can counteract the heating induced acceleration. 

The second case discussed is a coseismic landslide whose acceleration and large run-out cannot be justified by means of simple strength law unless imposing an extremely and probably unrealistic strain softening.

How to cite: Pinyol, N., Alvarado, M., and Lemus, L.: Thermal pressurization effect on landslide motion. Analysis with material point method., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7549, https://doi.org/10.5194/egusphere-egu22-7549, 2022.

Geostatistical models of landslide susceptibility do not usually account for thermal data, although these data are widely available, and experiments demonstrate that temperature does influence the mechanical and hydraulic behaviours of soils and rocks via a variety of thermo-hydro-mechanically coupled processes.

We took the epicentral region of the 2008 Wenchuan earthquake in China as our study area, for which a rich multi-temporal inventory of landslides is available. We built a landslide susceptibility model using a generalised additive model with a slope-unit partitioning of the area (~500 km², comprising 42 sub-catchments), and a minimal set of covariates, including the map of peak ground acceleration of the mainshock and Landsat 7 land surface temperature (LST) data retrieved from Google Earth Engine.

We demonstrated that the LST relates to the decay of post-earthquake landslide activity, and in particular that warmer slopes seems to be comparatively more affected by prolonged landsliding. We also verified that LST data provided different insight from that offered by the normalised difference vegetation index (NDVI), by running our model with NDVI maps instead of LST maps. The two input maps showed little collinearity, and the variable effects of the NDVI in the model output showed less complexity compared to those of the LST. This hints at the presence of thermo-mechanical effects in slopes in addition to the known hydrological effects, the latter being associated with changes in evapotranspiration and thus in principle capturable by the NDVI.

Even though studies in other regions, seismic and non-seismic, are necessary, we suggest that thermal data should be used in landslide susceptibility modelling more systematically because they could potentially improve the model results and suggest physically-based relationships influencing slope stability.

How to cite: Loche, M., Scaringi, G., Yunus, A. P., Catani, F., Tanyaş, H., Frodella, W., Fan, X., and Lombardo, L.: Effect of temperature on post-earthquake landsliding near the epicentre of the 2008 Wenchuan earthquake, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8407, https://doi.org/10.5194/egusphere-egu22-8407, 2022.

This presentation is dedicated to a short description of a combined rock slope thermal monitoring system. The newly designed system is affordable and modular, which predisposes it to installation at multiple sites. This system is being used to monitor four different rock slopes in Czechia for a period of up to 3 years. Slopes differ by lithology, structural setting aspect and modes of instability. The monitoring system consists of a climate station, rock mass surface zone thermal monitoring and unstable blocks crackmeter monitoring. Since 2018 we have instrumented 11 blocks, which differ in terms of shape, volume and mode of destabilization. Analyses of crackmeter, thermal and climatic time-series showed influences of weather and temperature cycles on the crackmeter aperture. Consequently, short-term (diurnal) and medium-term (annual) temperature cycles on the rock slope surficial zone were described. Data show high variability linked to the partial blocks geometry and rock slope properties.

How to cite: Racek, O., Blahůt, J., and Hartvich, F.: Multi-site rock slope thermal monitoring: Initial results, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9678, https://doi.org/10.5194/egusphere-egu22-9678, 2022.

In recent years, interest in argillaceous rocks has increased because they are being considered as potential host geological media for underground repositories of high-level radioactive waste (HLW). The host rock around the repository cells, containing the exothermic waste canisters, will be submitted to various coupled mechanical, hydraulic, and thermal phenomena. For a proper understanding and appropriate modelling of the excavation damaged zone around repository cells at elevated temperatures, the combined effects of those phenomena should be considered in an advanced constitutive model. The thermo-hydro-mechanical (THM) model presented herein is dedicated to non-isothermal unsaturated porous media. The model is developed within the framework of elastoplasticity, which includes features that are relevant for the satisfactory prediction of THM behaviour in argillaceous rocks: anisotropy of strength and stiffness, behaviour nonlinearity and occurrence of plastic strains prior to peak strength, significant softening after peak, time-dependent creep deformations, permeability increase due to damage, and shrinking of the elastic domain and the degradation of stiffness and strength parameters with temperature.

The model was applied to the numerical simulation of a full-scale in situ heating test conducted on Callovo-Oxfordian (COx) claystone, in the Meuse / Haute-Marne Underground Research Laboratory, simulating a heat-emitting, high-level radioactive waste disposal concept. The interpretation of the test was assisted by the performance of a numerical analysis based on a coupled formulation incorporating the relevant THM phenomena. Initial and boundary conditions for analysis, as well as material parameters, were determined from a comprehensive field and laboratory experimental programme. Thermal, hydraulic, and mechanical observations in COx claystone were discussed. The numerical analysis was able to accurately reproduce the behaviour of the experiment.

The performance and analysis of the in situ test have significantly enhanced the understanding of a complex THM problem, and have proved the ability of the theoretical formulation to provide adequate modelling capacities.

How to cite: Tourchi, S., Gens, A., Vaunat, J., and Scaringi, G.: Thermo-hydro-mechanical modeling of clayey geological medium: Theoretical framework and numerical study, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13375, https://doi.org/10.5194/egusphere-egu22-13375, 2022.