Cracking and Hydraulic Fracturing in Embankment Dams and Levees
Recorded on June 14, 2016 (120 minutes)

Select a Webinar Format:
 Online Archive Recording (25 view limit)

Cracks are likely to develop in most embankment dams and levees, and not just in those that are poorly constructed.  This course will present some of the common conditions that can lead to adverse geostatic stress conditions, cracking, and hydraulic fracturing in embankments.  Case histories are used to illustrate various crack-forming mechanisms and potential failure modes associated with embankment cracking.   The need for caution when considering drilling in the core of a dam is discussed.  The course will review practical design measures that can be implemented to defend against internal erosion that is associated with the inevitable formation of cracks in dams and levees.   

Key takeaways from participating in this webinar include:

  1. Increased awareness of common conditions that lead to unfavorable stresses in embankments.
  2. Better understanding of crack-forming mechanisms associated with differential deformations and with hydraulic fracturing; cracking associated with shrinkage and earthquake loading is not covered.
  3. Need for caution when drilling in the cores of dams.
  4. Design measures to minimize risk of hydraulic fracturing and to protect against internal erosion.
  5. Construction considerations to minimize risk of cracking in dams and levees.
Debora J. Miller, Ph.D., P.E. has 30 years of experience in engineering consulting and university research and teaching.  She specializes in geotechnical engineering and design of embankment dams, and is the engineer-of-record for design of new dams, dam enlargements, and dam rehabilitation projects mostly in the Rocky Mountain and southwestern regions of the U.S.  She has served as the project manager and in a supervisory design role on dam projects situated in a variety of geologic settings and challenging site conditions. Her role on most projects is as the lead geotechnical designer, responsible for geologic/geotechnical site investigations; evaluation and treatment of foundations in both rock and unconsolidated materials; characterization and use of on-site and off-site borrow materials for use in dam construction; seepage, slope stability and deformation analysis for all loading conditions; final design of the dam template, including special filter and drain zones; design for penetrations through the dam; and geotechnical monitoring instrumentation design. Dr. Miller has substantial experience in facilitation of potential failure modes analysis workshops for embankment dams, and has served on several peer review boards for dam design and construction projects.  She is active in dam safety professional organizations, having served two terms on the Board of Directors of the U.S. Society on Dams (USSD) and has been an active member of several technical working committees of both USSD and the Association of State Dam Safety Officials (ASDSO).  
  1. Introduction
    1. Scope of the Session
    2. Topics Covered
  2. General Overview
    1. Conditions for Unfavorable Stresses in Dams
    2. Common Crack Patterns
    3. Zones Vulnerable to Cracking
    4. Cracking Mechanisms Covered
      1. Hydraulic Fracturing
      2. Differential Settlement Cracking
    5. Cracking Mechanisms Not Covered
      1. Shrinkage Cracking
      2. Earthquake Deformations
  3. Hydraulic Fracturing
    1. General Definition
    2. Borehole Fluid Pressure Example
  4. Adverse Stress Conditions for Hydraulic Fracturing and Cracking in Embankment Dams and Levees
    1. General theory (Mohr diagrams)
    2. Common conditions that lead to low minor effective soil stresses
      1. Foundation irregularities
      2. Differential foundation settlements
      3. Conduits and other penetrations
      4. Closure sections and trenches
      5. Narrow clay cores
      6. First filling wetting fronts
  5. Case Histories of Failures or Accidents Attributable to Embankment Cracking
  6. Measures to Minimize Risk of Hydraulic Fracturing and Cracking
    1. Precautions on drilling in embankment dams or levees
    2. Defensive design measures
    3. Construction considerations
      1. Compaction and moisture control
      2. Differential settlement guidelines