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This webinar was co-sponsored by ASCE's ASCE’s Geo-Institute (GI) and ASCE Continuing Education
Instructor: Robert M. Koerner, Ph.D., P.E., BC.GE, Dist. M.ASCECourse Length: 1.5 Hours
Purpose and Background
Relatively thin cover soils sliding on slopes underlain by geosynthetics is obviously an unacceptable situation and, if the number of occurrences becomes excessive, can eventually reflect poorly on the entire technology. Steeply sloped leachate collection layers and final covers of landfills are situations where incidents of such sliding have occurred. Paradoxically, the analytic formulation of the situation is quite straightforward and will be described. This webinar presents an analysis of the common problem of a veneer of cover soil (0.3 to 1.0 m thick) on a geomembrane at a given slope angle and length. The webinar then presents different scenarios that create lower FS-values than the gravitational stresses of the above situation, e.g., equipment loads, seepage forces and seismic loads. As a counterpoint, different scenarios that create higher FS-values also are presented, e.g., toe berms, tapered thicknesses and veneer reinforcement. In this latter category, a subdivision is made between intentional reinforcement (using geogrids or high strength geotextiles) and non-intentional reinforcement (cases where geosynthetics overlay a weak interface within a multi-lined slope). A standard numeric example is used in each of the above situations to illustrate the various influences on the resulting FS-value. Suggested minimum FS-values are also presented for final closures of landfills, waste piles, leach pads, coal combustion residuals, mining waste piles, etc., which are the situations where veneer slides of this type are the most serious. The webinar is intended to serve as a vehicle to bring a greater awareness to this situation so as to avert such slides from occurring in the future.
Learning Outcomes and Webinar Benefits
You will become familiar with the problem of stability of relatively thin soil layers on geomembrane lined slopes. Many such slides have occurred in the past at all types of waste containment facilities. The basic limit equilibrium design method will be formulated and then used in a number of numeric examples. First, a series of destabilizing situations will be analyzed (equipment, seismic, hydraulic) and then a series of stabilizing situations will be analyzed (toe berm, tapered cover soil, geogrid reinforcement).
The different situations will be compared to one another insofar as their factor-of-safety values are concerned. Lastly, recommended minimum FS-values for different waste containment situations will be offered.
Upon completion of this course, you will be able to:
- Obtain Awareness of the soil veneer slope failure situation will be presented
- Limit equilibrium design to determine FS-values will be developed
- Explore Scenarios decreasing the factor-of-safety will be analyzed
- Explore Scenarios increasing the factor-of-safety will be analyzed
- Review Comparisons of FS-values from the different scenarios will be made
- Identify Recommendations on minimum FS-values will be offered
Assessment of Learning Outcomes
Students' achievement of the learning outcomes will be assessed via a short post-assessment (true-false, multiple choice and fill in the blank questions).
Intended Audience
Federal, state and regional geoenvironmental, geotechnical and transportation engineers; engineers from municipal districts and townships; private and municipal owners of landfills, waste piles, coal ash, mining waste, etc.; general civil consulting engineers; testing laboratories servicing these organization; manufacturers and representatives of geosynthetic materials; contractors and installers servicing these applications; academic and research groups; and others desiring technically related information on this important aspect of veneer slope stability will benefit from this webinar.
Webinar Outline
- Introduction
- Geotechnical engineering considerations
- Situations causing destabilization of veneer slopes
- Situations causing the enhanced stabilization of veneer slopes
- Summary
- Conclusions
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 on-line post-test 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]