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.