Internal Erosion in Dams and Their Foundations

According to the failure cases and distresses of embankment dams associated with internal erosion incidents, internal erosion has historically resulted in about 37% embankment dam failures. Therefore, it is crucial to gain fundamental understandings of the triggering mechanism and process of internal erosion. The internal erosion process can be divided into four phases: initiation, continuation, progression to form a pipe, and formation of a breach. This chapter presents the fundamental mechanical behavior of internal erosion first from the geotechnical perspective. Then, four initiation mechanisms of internal erosion, concentrated leak erosion, backward erosion, contact erosion, and suffusion, are discussed in detail. The causes, laboratory/field tests, and assessment methodologies for each initiation mode are presented subsequently. Some commonly used filter criteria in practice are highlighted. A couple of aspects internal erosion, namely, its continuation and progression, are discussed, before some valuable topics in internal erosion are suggested for further study.