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INSTRUCTORS:
Ankit Adwani, M.E., M.Eng., P.Eng.
Diego Marchetti
Ishimaru T.
Luis Salgado
Arda Sahin
Purpose and Background
These presentations were recorded at the Geo-Extreme 2025 conference.
Probabilistic & Deterministic Approach to Assess Liquefaction Potential at Selected Sites Using SPT Data (17 minutes)
This presentation compares deterministic and probabilistic approaches for evaluating liquefaction potential using Standard Penetration Test (SPT) data. Traditional factor-of-safety-based methods are reviewed alongside probabilistic frameworks that explicitly incorporate uncertainty in soil properties, seismic demand, and empirical correlations. Site-specific case studies illustrate how input variability influences liquefaction triggering predictions. The presentation highlights differences in interpretation between deterministic and probability-based outcomes, particularly for marginally liquefiable sites. Sensitivity analyses demonstrate the relative influence of key parameters such as corrected blow count, fines content, and earthquake magnitude. The implications for seismic hazard mitigation and performance-based design are discussed.
1-D nonlinear liquefaction analysis for Newtown, Kolkata by using Dilatometer Marchetti Test (DMT) calibrated UBC3D-PLM soil model (12 minutes)
This presentation presents a one-dimensional nonlinear site response and liquefaction analysis for Newtown, Kolkata. The analysis employs the UBC3D-PLM constitutive model calibrated using Marchetti Dilatometer Test (DMT) data. Procedures for translating DMT measurements into model parameters governing stiffness degradation and pore pressure generation are described. Ground motion input selection and boundary conditions for effective stress analysis are discussed. Results include time histories of excess pore water pressure, shear strain accumulation, and post-shaking reconsolidation behavior. The study demonstrates the value of in-situ testing-based calibration for improving numerical predictions of liquefaction response.
Liquefaction Resistance of Silty Sands Affected by Suffusion under Different Confining Stress Conditions (12 minutes)
This presentation investigates the effect of suffusion-induced internal erosion on the liquefaction resistance of silty sands. Laboratory testing is used to simulate particle migration and fines loss under varying confining stresses. Changes in density, fabric, and hydraulic conductivity resulting from suffusion are quantified. Cyclic loading tests reveal how altered soil structure influences pore pressure generation and cyclic resistance. The results show that suffusion can significantly reduce liquefaction resistance, particularly at lower confining stresses. These findings have implications for the assessment of aging earth structures, embankments, and foundations subjected to seepage and seismic loading.
Influence of Microplastic Contamination on Sand Liquefaction Initiation and Post-Liquefaction Behavior (11 minutes)
This presentation explores the emerging issue of microplastic contamination and its influence on sand liquefaction behavior. Laboratory experiments examine how varying microplastic content affects particle interaction, stiffness, and cyclic strength. Results indicate that microplastics can modify pore pressure generation rates and liquefaction triggering thresholds. Post-liquefaction reconsolidation and shear deformation characteristics are also evaluated. The presentation discusses mechanisms by which flexible plastic particles alter soil fabric and energy dissipation. The findings highlight the need to consider anthropogenic contaminants in future geotechnical hazard assessments.
Application of Liquefaction Susceptibility Criteria within a Logic Tree Framework (12 minutes)
This presentation introduces a logic tree framework for applying liquefaction susceptibility criteria in seismic hazard assessments. Multiple screening methods based on geologic age, depositional environment, in-situ test data, and groundwater conditions are incorporated into a structured decision process. The framework allows alternative models and expert judgment to be weighted and combined transparently. Case examples illustrate how conflicting criteria are reconciled within the logic tree. The approach supports uncertainty quantification and sensitivity analysis at the site or regional scale. The presentation demonstrates how logic trees enhance defensibility in liquefaction hazard decision-making.
Benefits and Learning Outcomes
Upon completion of these sessions, you will be able to:
- Explain the differences between deterministic and probabilistic methods for assessing liquefaction potential using SPT data.
- Describe how DMT data can be used to calibrate constitutive models for nonlinear liquefaction analysis.
- Discuss how suffusion alters the liquefaction resistance of silty sands under different confining stress conditions.
- Identify the key ways microplastic contamination influences liquefaction initiation and post-liquefaction behavior of sands.
- Explain how a logic tree framework can be used to integrate multiple liquefaction susceptibility criteria.
Assessment of Learning Outcomes
Students' achievement of the learning outcomes will be assessed via a short post-test assessment (true-false, multiple choice, and/or fill in the blank questions).
Who Should Attend?
- Geotechnical Engineers
- Structural Engineers
- Civil Infrastructure Designers
- Researchers and Academics
- Risk and Resilience Analysts
- Construction and Project Managers
How to Earn your CEUs/PDHs and Receive Your Certificate of Completion
To receive your certificate of completion, you will need to complete a short post-test online and receive a passing score of 70% or higher within 1 year of purchasing the course.
How do I convert CEUs to PDHs?
1.0 CEU = 10 PDHs [Example: 0.1 CEU = 1 PDH]