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Digital archive of theses discussed at the University of Pisa


Thesis etd-03252014-084918

Thesis type
Tesi di dottorato di ricerca
Thesis title
Academic discipline
Course of study
commissario Prof. Mancuso, Claudio
tutor Prof. Lo Presti, Diego Carlo
  • Degree of compaction
  • Embankment
  • Failure causes
  • Geotechnical design
  • Internal erosion
  • Levee
  • Monitoring system
  • Overtopping
  • Soil moisture content
  • Stability analysis
Graduation session start date
The greatest cities in human history have risen up on the banks of rivers and by the seaside. In fact, living by the water provides with a number of advantages and assets such as fertile farm land, transportation, trade and hydroelectric power. On the other hand, in doing so, people chose to live in close confines with an unruly force and, unfortunately, often they forget it.
A levee is a man-made embankment built to contain and control the flow of water (of a river) so as to provide protection against floods or to prevent ocean waves from washing into undesired areas. In parts of the Netherlands, for example, levees stop ocean waters from reclaiming thousands of miles of land (much of which is either at or below sea level). Often levees are little more than trapezoidal mounds of less permeable soil (clay) which run in a long strip for many kilometers along a river (or a lake or ocean).
Often levees are in urgent need of repair. The problems are several: poor maintenance; design and construction flaws, for example sometimes levees have inadequate freeboard, building encroachments. Moreover, the presence of burrowing animal holes or decayed pipes and pumping stations can put the levee structure in critical condition.
Local governments are responsible for upgrading unacceptable levees. Local governments which oversee the design and construction of levees have to update levees on compliance with levee construction, operation and maintenance standards, often with insufficient funds.
Moreover, climate changes have made severe storms more common in the latest years. Therefore, protection against flood is going to be more and more a national problem.
The main aim of the carried out research is the development of a set of technical guidelines for the design, upgrading and rehabilitation of river embankments. Therefore, this thesis deals with the main geotechnical problems characterizing river embankments.
It is divided into two sections: while the first one deals with river embankment design and construction, the second section deals with inspection, maintenance, monitoring and remediation.
Obviously, the first aspect to deal with is the design of the geotechnical campaign (Chapter 1). In fact, for river embankments, site characterization requires considerable expertise and flexible budgets since they run for many kilometers sometimes hundreds of kilometers. The second chapter deals with the most common levee failure mechanisms. Defining and understanding the levee failure mechanisms is essential to identify design issues. In the third chapter Technical Codes provision are summed up (Italian and USA codes).
As far as the second section is concerned, a monitoring system to realistically evaluate hydraulic and saturation conditions of an embankment is proposed.
Moreover, since during the construction stage is essential to check the degree of compaction, an innovative method to evaluate the degree of compaction of both existing and new river embankments (fine grained soils) after their compaction, by using laboratory and in situ testing, is also proposed.
Finally, a chapter deals with the countermeasures to prevent levee failure.