Anisotropy in the permeability and consolidation characteristics of dredged mud

摘要

Dredging and land reclamation is a billion dollar industry that is spread around the coastal regions ofrnAustralia. Maintenance dredging is carried out regularly in many major Australian ports and in severalrncases the dredged mud is pumped ashore into containment paddocks at high water contents. Whenrnthe dredged mud settles, there can be segregation with possible anisotropy. The sedimentation of therndredged mud is followed by self-weight consolidation which can take a long time. To accelerate thernconsolidation process, prefabricated vertical drains and surcharge are often used. To analyse thernconsolidation process of the dredged mud with vertical drains it is necessary to have a properrnunderstanding of the anisotropic characteristics of the dredged mud. The objective of this paper is tornsummarise the results of laboratory consolidation studies carried out on reconstituted dredged mudrnspecimens that were sedimented from slurry at high water contents in the order of 270%. Thernhorizontal and vertical coefficients of consolidation were determined on separate oedometer tests withrnappropriate drainage boundaries. At every pressure increment, vertical permeability and volumerncompressibility were estimated to evaluate the variation of consolidation properties with depth. Strongrnanisotropy in horizontal and vertical directions was observed and the variations of consolidationrnproperties and compressibility with depth were assessed.