The purpose of this book is to introduce up to date knowledge of how to construct embankments on organic soil. Organic soil is a conception, which involves several types of soil from pure organic forms as peat and gyttja to transition forms towards the mineral soils, as clayey gyttja and organic clay. In the geotechnical practice, there is however not a generally accepted rule how to classify the organic soils into main groups. This book only covers questions relevant to organic soil. This means that much of the achievements reached during the last years about soft clay are not dealt with here as long as they are not relevant for design calculations associated with construction on organic soil. Embankments on organic soils are most often constructed for roads or for flood control dikes. There are dams for water retention as well as waste tailings dams founded on organic soils. In recent years temporary embankments have been utilized to preload the soft subsoil, including organic subsoil and in this way improving the bearing capacity before the structure is built. Such procedures are used not only for easily adjustable structures like e.g. coal yards but also for buildings. When an embankment is erected directly on soft organic soil layers, both stability and settlement problems will generally arise. The load increase and geotechnical properties of soft soil together with schedule of construction (available construction time) and acceptable future settlements are the important factors that govern the choice of construction method. Improvement of existing structures founded on organic soil create special problems. Formerly, the settlements of e.g. a road sometimes were of little importance and thus many roads were built as "floating" structures (on timber fascines) with a relatively low factor of safety. The textbook consists of two parts. The first part is dedicated to the testing, calculation and general behaviour of organic soils under load and the second part to design and construction methods. The first part of the textbook thus presents
- Classification
- Field tests
- Laboratory testing
- Stability analysis
- Deformation analysis
- Road embankments
- Dikes e.g. for flood control
- Dams for water retention
- Preloading of foundations for structures
- Waste tailing dams on organic soils
- Widening of existing embankments
- Transition zones between settling embankments and stiff structures
- Land reclamation with soft sea beds.
The second part of this textbook is written in such a way that it shall be possible for a designer/contractor to pass over the basic chapters in part one. To improve the usefulness of the textbook, detailed examples are shown how to make evaluation and calculation.