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

该土木基础设施研究减缓和适应气候变化（CLIMA）奖支持的研究重点是了解由于存在对温度敏感的土壤材料，即它们表现出显著的强度和刚度变化而导致的历史稳定或缓慢爬行的天然土壤边坡灾难性滑坡增加的风险。鉴于目前和增加的温室气体排放以及与地球平均温度升高的联系，这一点很重要。对于物理学家、地质学家和工程师来说，解释并预测滑坡的发生、发展和规模仍然是一个挑战。该项目推进了温度变化何时以及如何引发这些灾难性和潜在致命事件的科学研究。本研究专门针对观察到的小体积天然材料在不同温度下的行为与经历温度变化的大型天然土坡稳定性之间的联系。在这一联系的基础上，将探索通过使用碳纳米纤维降低天然土壤斜坡的热敏性来改善其对变暖气候的弹性的范围。最后，该研究将进一步用于制作本科教材，以展示土木工程研究和实践如何适应气候变化。该研究探讨了多物理场的热土壤响应及其与灾难性边坡破坏的联系，区分了土壤的微观和宏观特性与其状态变化的作用。中心假设是，在高温下，热机械软化是引发热敏性边坡深层运动的主要机制。一套热三轴试验和在热敏材料的缩小比例斜坡上进行的离心机实验将弥补在元素水平上对土壤热力学行为的实验观察与在现场对斜坡破坏的观察之间的现有差距。土工离心机内的专门气候室将进行等温测试和控制温度增量，以缩小比例模型模拟气候变暖，捕获全尺寸斜坡的非线性和应力依赖行为。结果将丰富和验证预测，热敏粘塑性本构模型。综合数据集将最终允许评估在热敏土坡中引起的不同变形和破坏机制的相对重要性。这些将进一步用于通知和测试在微观尺度上针对材料织物的有效性，以增加热敏斜坡对变暖气候的弹性。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.