CLIMA/Collaborative Research: Landslide Triggering of Thermally Sensitive Slopes due to Climate Change

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This CiviL Infrastructure research for climate change Mitigation and Adaptation (CLIMA) award supports research focused on understanding the risk of increased catastrophic landslides of historically stable or slowly creeping natural soil slopes due to the presence of soil materials that are thermally sensitive, i.e., they exhibit significant changes of strength and stiffness in response to a change of temperature. This is important in view of current and increased greenhouse gas emissions and the link to increases of the average planet temperature. Explaining, and hence predicting, the initiation, progression and size of landslides remains challenging for physicists, geologists and engineers. This project advances the science of when and how temperature changes could trigger these catastrophic, and potentially deadly, events. This research specifically targets the link between the observed behavior of small volumes of natural material at different temperatures and the stability of large natural soil slopes experiencing a temperature change. Building on this link, the scope to improve the resiliency of natural soil slopes to warming climates by reducing their thermal sensitivity using carbon nano fibers will be explored. Finally, the research will be further leveraged to produce undergraduate teaching materials to demonstrate how Civil Engineering research and practice can adapt to climatic changes. The research explores the multi-physics thermal soil response and link to catastrophic slope failures, distinguishing between the role of the soil’s micro and macroscopic properties versus a change to its state. The central hypothesis is that at higher temperatures thermomechanical softening is the dominant mechanism that triggers deep-seated slope movements in thermally sensitive slopes. A suite of thermal triaxial tests and centrifuge experiments on reduced scale slopes of thermally sensitive materials will bridge the existing gap between experimental observations of the thermomechanical behavior of soils at the element level and the observations of slope failures in the field. A specialized climate chamber within a geotechnical centrifuge will enable isothermal tests and controlled temperature increments to model climatic warming on a reduced scale model capturing the non-linear and stress dependent behavior of the full-scale slope. The results will enrich and validate predictive, thermally sensitive visco-plastic constitutive models. The combined datasets will ultimately allow the assessment of the relative importance of different deformation and failure mechanisms induced in a thermally sensitive soil slope. These will be further used to inform and test the effectiveness of targeting the material’s fabric at the microscale to increase the resiliency of thermally sensitive slopes to warming climates.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.