Comprehensive Report on Soil Internal Erosion and Seepage in Dams

This report focuses on soil internal erosion and seepage, crucial aspects of dam safety. It delves into the mechanics of internal erosion, including concentrated leak erosion, hydraulic fractures, and backward erosion piping. The report emphasizes a risk-based approach, outlining potential failure modes (PFMs), phases of internal erosion, and important management factors. It discusses risk evaluation methods, including event sequences and both qualitative and semiquantitative risk assessments. Furthermore, the report examines methods for identifying and monitoring internal erosion, such as visual, non-visual, and intrusive techniques, along with seepage collection and measurement methods. It also addresses internal erosion remediation strategies, including immediate, non-immediate, and long-term actions, and methods for reducing piping potential. The research aims to offer a comprehensive overview of dam safety analysis, including engineering judgments, monitoring techniques, and surveillance methods.

SOIL INTERNAL
EROSION AND
SEEPAGE

Introduction
Dams have non-federal and federal agencies
(Adimoolam & Banerjee, 2018
This research will focus on;
 Measuring and monitoring seepage.
 Identifying Potential Failure Modes.
 Dam risk Assessments.
 Internal erosion remediation.

Purpose
Developing well-documented practices in the dam analysis
for safety (Dentch, 2016).
Scope
The scope of the research is evaluating internal erosion
Potential Failure Modes and selecting the best remediation
techniques (Bonelli, Jommi, & Sterpi, 2018).

Discussion
a) Internal erosion mechanics
 Concentrated Leak Erosion
 This type of erosion include (Cheng, Draper, & An, 2014);
I. Differential settlement
Non-uniform settlements in dam embankment forms cracks
in tensile stressed areas as depicted in the figure below.

Other types of concentrated leak erosion include (Feinberg,
2016);
 Hydraulic Fracture.
 Fill placement interruptions.
 Frozen lifts.
 Dispersion.

Additional different types of erosion include (Feinberg,
2016);
 Backward erosion piping.
 Suffusion/Suffosion.

Another internal soil erosion is stopping. Stopping mostly
occur at a point with filter incompatibility that includes
(ANGHEL, VASILE, & CACOVEANU, 2017);
 conduit fractures and weep holes
 Poorly designed drains.

Risk-based approach in evaluating internal erosion
This requires the identification of;
 Potential Failure Modes (PFM) (Duncan, Wright, &
Brandon, 2014).
 Phases of internal erosion.
These include (Duncan, Wright, & Brandon, 2014);
 Initiation.
 Continuation.
 Progression.
 Breach.

Potential Failure Mode classes
 By foundation (Dentch, 2016)
 Into or along embedded structures.
 By embankments.
 Along or into the embankments’ foundation.
Important PFMA management factors
 Substantial understandings (Duncan, Wright, & Brandon,
2014).
 Updating Dam failure mode.
 Temporary measures of reducing risks.
 Update of the Emergency Action Plan.

Risk evaluation
Risk evaluation is one through the following formula.
Risk assessment
The techniques being used in risk assessments include;
 Bayes’ theorem
Event sequences
The risk is quantified according to its step-by-step
development to breach phase through event sesquences
(Duncan, Wright, & Brandon, 2014).

Semiquantitative or Qualitative Risk Assessments
Performing this type of assessment involves reviewing and
conducting the PFMA for identifying as well as fully
describing PFMs from the dam’s vulnerabilities evaluation
(ANGHEL, VASILE, & CACOVEANU, 2017).
Risk management
Risk management enables drawing a conclusion of the
actions to be taken by risk managers
Methods of Identification and monitoring of internal
erosion
 Visual methods.
 Non-visual methods.
 Intrusive methods (Celani & Kanoun, 2017).

Seepage collection
Seepage collection is done using (Delsman, 2015) channels
and ditches, drainds and wells.
Types of Seepage measurement
 Flow rate.
 Pressure.
 Level of water (Elton, 2015);
Using the v-notch weir, the Kindsvater-Shen equation
below is used.

Current velocity meters are also implemented in getting
seepage continuity (Feinberg, 2016).
Hence, the continuity equation is shown below.
The seepage water pressure is determined using
piezometers.
Types of piezometers
 Hydraulic (Dowden, 2014.
 pneumatic
 vibrating

Addressing internal erosion
Internal erosion is addressed using the following (Chen,
2015);
 Immediate action.
 Non-immediate action.
 Long-term remediation.
An example is described in the figure below.

Piping potential reduction
The reduction of piping potential is accomplished through
(Fell, MacGregor, Stapledon, Bell, & Foster, Geotechnical
Engineering of Dams, 2014);
 Berms or flattening slopes.
 Increase in tailwater elevation.

Summary
 This research tries to produce a line-up of formal and
informal methods of analyzing dam safety risks through
engineering judgments.
 Hence, the paper collects and produces a summarized
engineering techniques applicable to dam monitoring, ,
measuring, evaluating and recommendation of various
methods of surveillance (ANGHEL, VASILE, &
CACOVEANU, 2017).

References
 Adimoolam, B., & Banerjee, S. (2018). Soil Dynamics and Earthquake Geotechnical Engineering: IGC 2016 |, Volume 3.
San Diego: Springer.
 ANGHEL, A., VASILE, G., & CACOVEANU, R. (2017). Infrastructure Monitoring with Spaceborne SAR Sensors. West Jordan:
Springer.
 Bonelli, S. (2013). Erosion in Geomechanics Applied to Dams and Levees. Seattle: John Wiley & Sons.
 Bonelli, S., Jommi, C., & Sterpi, D. (2018). Internal Erosion in Earthdams, Dikes and Levees: Proceedings of EWG‐IE 26th
Annual Meeting 2018. Houston: Springer.
 Celani, G., & Kanoun, O. (2017). Frontiers of Science and Technology: Automation, Sustainability, Digital Fabrication -
Selected extended Papers of the 7th Brazilian-German Conference, Campinas 2016 Brazil. McAllen: Walter de Gruyter
GmbH & Co KG.
 Chen, S. (2015). Hydraulic Structures. Murrieta: Springer.
 Cheng, L., Draper, S., & An, H. (2014). Scour and Erosion: Proceedings of the 7th International Conference on Scour and
Erosion, Perth, Australia, 2-4 December 2014. San Francisco: CRC Press.
 Delsman, J. ( 2015). Saline Groundwater - Surface Water Interaction in Coastal Lowlands. Cambridge: IOS Press.
 Dentch, P. (2016). The ISO 9001:2015 Implementation Handbook: Using the Process Approach to Build a Quality
Management System. Garland: ASQ Quality Press.
 Dowden, R. (2014). Fluid flow measurement: a bibliography. College Station: British Hydromechanics Research
Association.
 Duncan, J., Wright, S., & Brandon, T. (2014). Soil Strength and Slope Stability. Savannah: John Wiley & Sons.
 Elton, D. (2015). Grounded!: Amazing Classroom Demonstrations in Soil Mechanics. San Antonio: American Society of
Civil Engineers.
 Feinberg, A. (2016). Thermodynamic Degradation Science: Physics of Failure, Accelerated Testing, Fatigue, and
Reliability Applications. Garland: John Wiley & Sons.
 Fell, R., MacGregor, P., Stapledon, D., Bell, G., & Foster, M. (2014). Geotechnical Engineering of Dams. Irving: CRC Press.