Relearning How to Look at Piezometric Data for Seepage Evaluation: On-Demand
This webinar will start with the most basic seepage concepts and finalize on actual evaluation of piezometric data for earth dams and levees. Simple basic seepage ideas using high graphic illustrations will be the means to teach all concepts in this webinar. Also, numerous difficult concepts will be fully explained using high graphic simple illustrations. For example, this course will also provide unique insight into how seepage changes with simple geologic layer variations. A procedure for evaluating time based piezometric data versus reservoir data will be presented and it represents the only comprehensive method — the conventional procedure is to plot the data and then just look at it. This course also provides concepts for observing the potential for backward erosion using actual piezometric data. New procedures and standards for data presentation of field based piezometric data versus reservoir level will also be shown.
- Participants will gain a deep understanding of the most basic seepage concepts that are not taught at universities or short workshops.
- This is the only procedure for evaluation of field measured piezometric data versus reservoir level trends.
- The backward erosion process can potentially be observed using time based piezometric data assessment.
- Participants will learn best practice methods for graphical presentation of piezometric data.
Richard S. Olsen, Ph.D. P.E.
Previously (until Feb 2019):
USACE Lead Geotechnical Engineer and
National Senior Policy Advisor,
U.S. Army Corps of Engineers (USACE),
Headquarters, Civil Works Directorate
Served as National Senior Policy Advisor and Technical Lead for Geotechnical Engineering at U.S. Army Corps of Engineers (USACE) working out of Headquarters, Washington DC. He performed geotechnical policy compliance assessment for USACE at all project levels. He was also a reviewer for high profile national projects, all USACE water control structures, and for policy making. Dr. Olsen was the USACE top-level Subject Material Expert (SME) in the following topics: Seepage issues (from hand drawn flow nets for complex scenarios to advanced failure modes), Advanced geotechnical site characterization (particularly using the CPT); Advanced geotechnical earthquake engineering prediction of liquefaction resistance; Mega landslide assessment; Silt behavior during earthquakes and Geotechnical geophysics technology. Dr. Olsen was at USACE HQ in Washington DC for 6 years and previously at USACE-ERDC for 30 years in geotechnical research (and 4 years in private consulting directly after his MS degree). He has a Ph.D. from UC Berkeley, MS from UC Berkeley, and BSCE from Oregon State University.
- Seepage basic concepts
- Seepage erosion concepts
- Historical seepage erosion failures
- Backward erosion research Seepage basics
- Seepage through soil
- Seepage head loss
- Basic concepts of flow nets
- Flow under and through earth dams
- Pore pressure head loss through foundations Equivalent sand tube concept
- Evaluation of geologically complex foundations
- Simplification to an equivalent sand tube
- Reservoir to tailrace flow concepts
- Late plug effects
- Leakage effects
- Pinching effects
- Comparison of flow for sands versus gravel Making a Reservoir Level versus Piezometer plot (RP chart)
- The RP plot is just a structured way of plotting typical piezometric data
- Setup of the RP chart for a uniform equivalent sand tube
- Plotting reservoir levels on the RP chart
- Drawing the RP line (U) to the assumed no flow point (N)
- Plotting relationship for
- different piezometer locations
- early pinching of sand tube
- late pinching of sand tube
- leaking cutoff wall at different locations Backward erosion using the RP chart
- Basic physical representation in a cross section
- RP plotting for initial erosion
- RP plot for continued backward erosion
- Slope of line changes with continued backward erosion
- Comparison of RP line slope decrease versus piezometer drop Comparing RP charts for real field measured data (about 8 examples) How to properly plot RP charts using field data How to properly make depth plots of support data such as permeability data Future needs Conclusions and summary