EMBANKMENT DAMS: ITS TYPES AND ESTIMATION OF SEEPAGE

Abstract

Approximately half of all embankment dam failures are attributed to internal erosion. Internal erosion is a broad term that describes various mechanisms in which the erosive forces of moving water erode soil from within or beneath an embankment. While there are different categories of internal erosion, assessing the likelihood of internal erosion in general requires intricate knowledge of a structure’s history, design, and the physics of seepage through an embankment. Often times, the documentation regarding a structure’s history and original design is in a state of disarray, or altogether  lost, making  it difficult for today’s engineers to adequately assess a structure.  However, knowledge of the historical evolution of the profession understands of seepage and embankment design combined with the date a structure was constructed is often times enough information to make inferences regarding how an embankment was designed and what elements may not have been considered as part of the original design. This paper is intended to provide the reader with this information through a historical review of embankment seepage design. An overview of seepage design is provided beginning with the empirical designs constructed prior to 1900 through the modern designs of today. In particular, the evolution of analytical  techniques  (creep ratio, flow net, electric analogy, and finite element analysis)  is discussed as a parallel to the  evolution of the profession’s understanding of failure  mechanisms (piping,  concentrated  leak  erosion, suffusion,  structural  uplift).