50 / 2021-11-15 07:35:24

Investigating the role of temperature in slope stability

slope stability,landslide,temperature,climate change,THM coupling

Climate change is influencing our society in many ways. Frequent and intense storms, prolonged draughts, heatwaves, wildfires, and changes in land use play a major role in defining the frequency and patterns of landslides, and hence the risk they pose to people, infrastructures, and ecosystems. The short-term behavior of slopes under climatic forcing is typically studied via hydrological-hydraulic-mechanical approaches. Susceptibility and hazard models usually focus on established triggers and controls, such as rainfall, seismic shaking, morphology, and lithology. Yet, they neglect the possible role of thermal variables in directly controlling the slope mechanics. By doing so, they disregard thermo-hydro-mechanical processes, which are instead, well recognized in other engineering geological contexts. Temperature exerts a control on the strength of rock exposures, particularly in seasonally cold climates, whereas evidence of its role in defining soil strength is scarcer. Coupled thermo-hydro-mechanical processes in soils and rocks are highly complex and, at times, counterintuitive. They are well studied in high-pressure and high-temperature conditions, such as in seismic faults and slip zones of large and fast landslides. They are also considered in the design of specific engineering infrastructures, such as underground radioactive waste repositories and heat exchangers. However, laboratory experiments show that most hydro-mechanical properties of geomaterials depend on temperature significantly, also in ranges that are typical in shallow soils in temperate climates. In our research, we hypothesize that temperature fluctuations and trends, propagating from the surface to the subsurface, may exert a direct effect on the stability of soil slopes and the kinematics of landslides. Here, we review temperature-dependent processes potentially relevant to slope stability, and discuss their complexity. We show results of laboratory experiments and catchment-scale studies, and discuss a research path to fill knowledge gaps across the scales, arguing for the beneficial effect of accounting for temperature-related variables into hazard assessments under climate scenarios.