Internal Erosion Due to Water Flow Through Earth Dams and Earth Structures

Abstract

This chapter describes the earth erosion caused by the water flow and seepage that occurs through earth dams, earth embankments and some other structures constructed with earth, such as canal systems, dikes, reservoirs and levees. The erosion in levees on river banks and in levees constructed to protect urban areas exposed to flooding is also discussed. It first describes the mechanism of the soil erosion and the importance of such phenomenon, particularly the damages and consequences that such erosion might produce when it becomes out of control. For instance, one of the main causes of earth dam failures all over the world is the so called piping event, which occurs due to the constant migration of soil particles towards free exits or into coarse openings; this event might occur through the earth embankment or its foundation soil. Another cause of constant earth structure failures is due to uncontrolled saturation and seepage forces. In this context, phenomena known as rapid filling and rapid drawdown, which occur in earth structures subjected to sudden changes of water level (increments or decrements) that modify flow conditions inside a soil mass are assessed. Examples of both failures are given in this chapter.