Assistant professor of civil engineering, University of Riyadh, Riyadh,
Professor of civil and environmental engineering and engineering mechanics, University of Wisconsin-Madison, Madison, Wis.
Four peat samples, covering a wide range of fiber contents, were subjected to one-dimensional consolidation tests. The development and dissipation of excess pore water pressure, effluent outflow, and permeability were also monitored during some of the consolidation tests. The other test variables included the application of back pressure, specimen thickness, and specimen orientation. Significant compression and effluent outflow take place after the dissipation of measurable excess pore water pressure, while permeability decreases drastically during consolidation. The rate of secondary compression, after a certain time, increases with the logarithm of time before gradually decreasing until it vanishes for very large times, resulting in a new stage termed “tertiary” compression. This behavior, along with the observations of peat microstructure, supports the presence of a two-level structure for peats, possibly consisting of macropores and micropores. The rate of compression of peats depends primarily on void ratio; peat type appears to be of secondary importance. Test results provide certain insights into the nature and the mechanisms of peat consolidation. The consolidation behavior of peats is quite distinct from that of other soils and requires special considerations in laboratory testing procedures and interpretation of results.
Paper ID: GTJ10881J