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.
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 reevaluation.
- Gravel liquefaction threatens critical infrastructure in foundations, buried materials, or as fill during seismic events, leading to deformations like slope instability for dams and bearing capacity failures for bridges. Recognizing this threat is crucial for implementing preventive measures and proactive intervention in projects facing such challenges.
- In laboratory work, numerical modeling, or field exploration, the key is integrating these approaches for a comprehensive soil liquefaction risk assessment. While conventional advice suggests specialization, the belief persists in the combined value of these methods in projects. High-quality execution, understanding mechanisms, and ensuring accurate input parameters are priorities. Engineering judgment plays a vital role, recognizing that experience enhances an engineer’s ability to make informed decisions in the soil liquefaction risk assessment.
- Each method brings something different to understanding soil liquefaction analysis. Labs let us control conditions for precise parameter study, while field tests capture materials in their natural state. Field testing simulates earthquakes, but quantifying undisturbed fabric is tricky. Labs systematically reveal how density affects material behavior. Combining these methods fills gaps, and numerical modeling extends insights further. Thanks to computational advances, numerical modeling has become crucial in soil liquefaction analysis.
- Looking ahead, the crucial aspect for earthquake engineers is not just technical advancement but prioritizing the application of knowledge in underprivileged regions. The focus is on bridging the gap between existing expertise, building codes, and policies and ensuring they reach densely populated areas lacking resources. The goal is to make vulnerable societies resilient, not just in theory but in practical recovery after earthquakes. The call is for the next generation of engineers to blend technical excellence with a commitment to making a real-world impact where it’s most needed.
- For engineers and planners addressing soil liquefaction, particularly in gravel, acknowledging diverse failure modes from earthquake effects is vital for large-scale planning. While detailed soil characterization everywhere poses challenges, managing uncertainties in soil properties and earthquake loading conditions is essential for effective city-level planning.
- To explore more about this field, individuals can visit the UC Berkeley civil engineering website for additional information. Consider pursuing a master’s degree for a comprehensive understanding of civil engineering. Explore online learning opportunities such as webinars and short courses, including a module on soil liquefaction within the geosystems program at UC Berkeley.
More Details in This Episode…
About the Guest: Adda Athanasopoulos-Zekkos, PhD
Dr. Adda Athanasopoulos-Zekkos is an Associate Professor of Civil and Environmental Engineering (CEE) at the University of California, Berkeley, since January 2020. Before this appointment, she was a faculty member in the CEE department at the University of Michigan (2008-2019). She received her Ph.D. in Geotechnical Engineering from the University of California, Berkeley in 2008, her MSc. in Geotechnical Engineering from the University of California, Berkeley in 2004, and a joint BSc/MSc in Civil Engineering from the University of Patras, Greece in 2003. She has received the NSF CAREER award (2013), the 2014 University of Michigan Faculty Excellence Award, the 2015 ASCE Arthur Casagrande Award, the 2015 ASCE Thomas Middlebrooks Award, the 2016 Chi Epsilon (XE) Outstanding Teaching Award, and the 2020 TC203 Young Research Award from the International Society of Soil Mechanics and Geotechnical Engineering. Dr. Adda also delivered the 30th Annual Mueser Rutledge Memorial Lecture in 2020 and is the past president of the US Universities Council on Geotechnical Education and Research (USUCGER). Her research focuses on soil liquefaction, seismic slope stability, and the response of flood protection systems and soil structures under extreme loadings like hurricanes and earthquakes as well as new technologies and methodologies to design, monitor and reinforce them. Adda can be reached at [email protected]
About the Host: Jared M. Green, PE, BC.GE, F.ASCE
Jared, originally from southwest Philadelphia, Pennsylvania, graduated from Syracuse University’s College of Engineering in 2001 with a B.S. in Civil Engineering. He later went on to attain his M.S. in Civil Engineering (Geotechnical Focus) from the University of Illinois, Urbana-Campaign, in 2002. In 2003, he began working in the New York City office of Langan. He has since become a Principal / Vice President and is one of the owners of this international land development engineering consulting firm. After 15 years at Langan, Jared moved to the Philadelphia office and is one of the geotechnical practice leaders in that office.
Jared is a consultant and team leader who also enjoys mentoring young engineers and first-generation college students. He has been instrumental in increasing the number of pre-college students who are interested in STEAM majors and fields. He strives to make complex engineering topics relatable and understandable to people new to the field and to people who are completely unfamiliar with engineering. Jared and his family currently reside in Flemington, New Jersey. He and his wife have three energetic, inquisitive, and awesome children. You can connect with Jared here.
Books Mentioned in This Episode:
University of California, Berkeley
University of Patras in Greece
San Andreas Fault
University of Michigan
Christchurch, New Zealand
Connect with Adda Athanasopoulos-Zekkos, PhD., on LinkedIn
Send Adda Athanasopoulos-Zekkos, PhD., an Email
This Episode Is Brought to You By:
Tensar, a division of CMC, is a world-leading manufacturer and provider of ground stabilization and soil reinforcement solutions. Our innovative geogrid technology has benefited thousands of civil construction and engineering projects around the world for over 50 years. With our Tensar+ design software, you can design for higher performance and with greater confidence. Designers can export specifications that compare the benefits of Tensar geogrids with other soil stabilization methods. https://www.tensarplus.com
Menard USA is a specialty ground improvement contractor that works nationally providing design-build ground improvement solutions at sites with problematic soils. Menard works closely with civil, structural, and geotechnical engineers to minimize foundation costs for a wide range of soil conditions, structure types, and loading conditions. To learn more about Menard USA, or for help on your next project, please visit www.menardusa.com.
Please leave your comments or questions in the section below on the strategies you use to uncover subsurface risks with soil liquefaction analysis.
To your success,
Jared M. Green, PE, BC.GE, F.ASCE
Host of The Geotechnical Engineering Podcast