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Sponsored by ASCE's Geo-Institute's Technical Committees
INSTRUCTORS:
Scott Anderson, Ph.D, P.E.
Evan Garish, P.E., FLH
Bak Kong Low
Bret Lingwall, Ph.D
Brian Anderson, Ph.D, P.E., F.ASCE
Dan Jackson, M.S.
Lee Wooten, P.E., GEI
Tim Stark, Ph.D., P.E.
Purpose and Background
“Managing of the Pretty Rocks Landslide and Bridging the Gap” by Scott Anderson and Evan Garish (27 minutes)
This presentation focuses on the geotechnical and structural challenges of addressing the ongoing Pretty Rocks Landslide in Denali National Park, Alaska. It details the historical progression of the landslide, which escalated from minor annual movement to rapid displacement, leading to the closure of the only park road in 2021. It explores various mitigation options, including avoidance strategies and the construction of a 475-foot bridge to span the unstable area, which was deemed the most viable solution. Topics include the complexities of constructing infrastructure in a permafrost-affected environment, the integration of thermal modeling, and stabilization techniques like micropiles and thermosiphons. The audience will gain insights into adapting design and construction practices to address large-scale geotechnical risks in remote and environmentally sensitive locations.
“Context-dependent Sensitivities and Load-Resistance Duality in Soil and Rock Slopes,” by Bak Kong Low (26 minutes)
This presentation explores the probabilistic analysis of slope stability to better understand the interplay between geological variability and structural behavior. It introduces the concept of design points, highlighting how material properties like cohesion, friction angle, and unit weight can exhibit dual roles as loads or resistances depending on their spatial context within a slope. Real-world case studies, including Norwegian clay slopes and reinforced rock slopes, demonstrate the influence of parameter correlations and spatial autocorrelation on slope reliability. Advanced methods, such as the First Order Reliability Method (FORM), are used to evaluate failure probabilities and sensitivities, providing engineers with tools to complement traditional deterministic approaches. This session equips the audience with innovative strategies to account for uncertainties in geotechnical design, ensuring more robust and adaptable slope stability solutions.
“Lessons in Scour Erosion Induced Landsliding from Site Development” by Bret Lingwall (24 minutes)
This presentation will discuss the impact of scour erosion on slope stability. In particular, scour erosion at the toe of the slope is a key causal mechanism in the triggering of landslides. This case history shows how redirection of runoff from a large site development lead to over 20-ft of scour at the toe of a slope triggering a landslide in bentonitic shales. Lessons for attendees include consideration of surface water choices by site civil engineers and impacts on geotechnical systems. The critical importance of identification and characterization of thin but very weak layers is highlighted in the case history as a 5-cm bentonite band is the likely failure plane in the case history.
“Geer Report: Geotechnical Impacts of Hurricane Florence in Rich Media” by Brian Anderson, Dan Jackson, Lee Wooten, Tim Stark (29 minutes)
This presentation will describe the reconnaissance effort implemented after Hurricane Florence in September 2018 that struck southeastern North Carolina and South Carolina. The Geotechnical Extreme Events Reconnaissance Association (GEER) deployed to investigate the resulting hydrology and performance of dams, levees, transportation infrastructure, coastal/waterfront structures, and other observations. This presentation will discuss the perishable post-disaster data that was collected.
Benefits and Learning Outcomes
Upon completion of these sessions, you will be able to:
- Identify the geotechnical challenges posed by the Pretty Rocks Landslide and explain the decision-making process behind selecting a bridge as the mitigation solution.
- Explain the concept of load-resistance duality in slope stability and identify how material properties like cohesion and friction angle behave in different spatial contexts.
- Describe the impact of scour erosion at the toe of a slope and explain how it can act as a triggering mechanism for landslides.
- Explain the importance of collecting perishable post-disaster data and its role in understanding the performance of geotechnical systems during extreme events.
Assessment of Learning Outcomes
Achievement of the learning objectives will be assessed through a short post-test.
Who Should Attend?
- Geotechnical Engineers
- Engineering Geologists
- Owners and Operators of Civil Infrastructure
- Consultants
- Public Agency Staff
- Specialty Contractors
How to Earn your CEUs/PDHs and Receive Your Certificate of Completion
This course is worth 2 PDHs. 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.
How do I convert CEUs to PDHs?
1.0 CEU = 10 PDHs [Example: 0.1 CEU = 1 PDH]