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INSTRUCTORS: 
James A. McKelvey III, P.E.
Srikanth S.C. Madabhushi
Chukwuma Okafor, Ph.D.
Charles Straley, P.E.

Course Length: 1 hour

Purpose and Background

These presentations were recorded at the 2024 Geo-Structures Conference.

Segmental Retaining Wall Subgrade Challenges (25 minutes)

This presentation explores the complexities of designing and constructing segmental retaining walls on challenging subgrades. Using a 42-hectare former steel mill redevelopment as a case study, it highlights geological and environmental obstacles, such as pinnacled limestone, low-strength overburden, and sinkhole risks. Various mitigation techniques, including extensive borings, CPT testing, and the use of wick drains and surcharges, are discussed to address settlement concerns and improve subgrade reliability. The talk emphasizes collaboration between geotechnical engineers and contractors, sharing lessons learned and practical solutions to ensure wall stability and structural performance.

Characterizing the Response of Retained Soil with Modified Element Test Simulations for an Improved Winkler Retaining Wall Model (15 minutes)

This presentation introduces an approach to improving Winkler retaining wall models by incorporating insights from finite element simulations and soil stress-strain behavior. By addressing the limitations of traditional methods, the research emphasizes the importance of accurate soil stress characterization and its interaction with wall displacements. Modified element tests and stress paths are presented as tools to enhance predictions of soil response under various loading scenarios. The speaker demonstrates how these refinements can bridge the gap between computational complexity and practical design applications, leading to more reliable and efficient retaining wall solutions.

On Evaluating the Bearing Stresses of a Full-Scale Steel Reinforced MSE Retaining Wall (19 minutes)

Focusing on the evaluation of bearing stresses for MSE retaining walls, this presentation challenges conventional design approaches, such as the Meyerhoff method, for being overly conservative. The research features a full-scale MSE wall constructed in a geotechnical test chamber, equipped with advanced instrumentation to monitor stress redistribution, settlement, and structural performance under various loading conditions. Key findings reveal the flexibility of MSE walls in tolerating differential settlement and propose alternative design stress functions that align better with observed behaviors. This study offers a pathway for cost-efficient designs while maintaining structural integrity.

John E. Amos Landfill Soil Nail Wall Design, Construction, and Performance (16 minutes)

This presentation explains the design and construction of soil nail walls for the expansion of a landfill at the John E. Amos site. The project involved constructing retaining walls up to 70 feet tall to widen a narrow valley with weak rock and perched water conditions. Top-down excavation techniques, drainage panels, and staged shotcrete facing were key components of the design. A long-term monitoring program revealed minimal cracking and effective drainage, demonstrating the durability and success of the walls. Lessons learned and best practices for addressing Appalachian geology and perched water challenges are also shared.

Benefits and Learning Outcomes

Upon completion of these sessions, you will be able to:

• Identify the key challenges associated with subgrade conditions for segmental retaining walls and discuss mitigation strategies.
• Explain how modified element test simulations can improve the accuracy of Winkler retaining wall models in geotechnical engineering.
• Describe methods to evaluate bearing stresses in MSE retaining walls and assess the implications of stress redistribution on design efficiency.
• Discuss the design considerations, construction techniques, and performance outcomes of soil nail walls in challenging geological settings.
• List the challenges and solutions associated with implementing jet-grouted base plugs in artesian conditions.

Assessment of Learning Outcomes

Learning outcomes are assessed and achieved through passing a 10 multiple choice question post-test with at least a 70%.

Who Should Attend?

• Environmental Engineers
• Geotechnical Engineers
• Structural Engineers
• Construction Engineers
• Project Managers
• General Contractors

How to Earn your PDHs and Receive Your Certificate of Completion

This course is worth 0.1 CEUs/1 PDH. To receive your certificate of completion, you will need to complete a short on-line post-test and receive a passing score of 70% or higher within 365 days of the course purchase.

How do I convert CEUs to PDHs?

1.0 CEU = 10 PDHs [Example: 0.1 CEU = 1 PDH]