Uncovering Subsurface Risks: Soil Liquefaction Analysis Reveals Hidden Threats – Ep 092

In this episode, we talk with Adda Athanasopoulos-Zekkos, PhD., Associate Professor of Civil and Environmental Engineering at the University of California, Berkeley, about the intricate world of gravelly soil liquefaction analysis—an imperative concern in the realm of geotechnical engineering, analyzing its complexities, implications, and potential solutions. Engineering Quotes: Here Are Some of the Questions We Ask Adda: What led you to pursue both your master's and PhD in geotechnical engineering? What is soil liquefaction, and why is it significant in the context of geotechnical engineering, especially when discussing earthquakes? Is liquefaction possible with gravel? What are the main challenges encountered in evaluating the likelihood of gravel liquefaction? How does the common practice of not testing gravel in the field pose a challenge in geological assessments? How does gravel liquefaction pose a specific threat to critical infrastructure? How do the rules of laboratory testing, field exploration, and numerical monitoring differ in assessing soil liquefaction risk, and how do these methods collectively contribute to the overall assessment? Is there a single method you consider most effective for assessing soil liquefaction, or is it truly a combination of all approaches that provides an accurate assessment of the likelihood of liquefaction? What key areas of research or development do you consider critical for geotechnical engineers, particularly in the context of earthquake resilience? When working in earthquake-prone regions, what key considerations should engineers and planners bear in mind when addressing soil liquefaction, especially within gravel materials? How can engineers learn more about your work and get involved in this aspect of geotechnical engineering? Here Are Some of the Key Points Discussed About Soil Liquefaction Analysis: In high school, Adda developed a passion for math and sciences, sparking an interest in civil engineering. The appeal was the direct impact on everyday life through infrastructure. During undergrad, Adda's love for geotechnical engineering grew, driven by the challenge of unraveling uncertainties beneath the surface. The fascination lies in deciphering and applying this knowledge to design. In earthquakes, soil liquefaction happens when certain saturated materials undergo rapid loading, temporarily losing strength and impacting infrastructure such as lifelines and pipelines. Past earthquake data highlights the substantial role of soil liquefaction in causing damage, emphasizing its ongoing focus in research. Understanding liquefaction goes beyond predicting its occurrence; it involves assessing its impact on infrastructure. Engineers must consider project-specific thresholds, from sensitive structures to critical infrastructure like dams. Contrary to past beliefs, recent events show that even larger-grain materials like gravel can exhibit liquefaction under specific conditions, reinforcing the need for a thorough risk assessment approach. Assessing gravel liquefaction poses challenges due to traditional testing methods designed for smaller grains like sands, making it difficult to obtain representative samples for larger grains in both laboratory and field settings. The historical lack of thorough testing and suitable methodologies for understanding gravel behavior, especially under seismic conditions, compounds these challenges. When reassessing older dams, limited investigations into materials like gravel are common due to challenges in characterizing them. Historically perceived as potentially safer, there's a need for better guidance and more robust techniques to ensure a comprehensive understanding of gravel's role in infrastructure weaknesses during reeval...