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Settlement of inhomogeneous consolidating soils—I: The single‐drained layer under confined compression
Author(s) -
Mahmoud M. S.,
Deresiewicz H.
Publication year - 1980
Publication title -
international journal for numerical and analytical methods in geomechanics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.419
H-Index - 91
eISSN - 1096-9853
pISSN - 0363-9061
DOI - 10.1002/nag.1610040105
Subject(s) - geotechnical engineering , consolidation (business) , shear modulus , bulk modulus , pore water pressure , modulus , permeability (electromagnetism) , soil water , aggregate modulus , water content , geology , materials science , mechanics , soil science , composite material , dynamic modulus , chemistry , physics , biochemistry , accounting , dynamic mechanical analysis , membrane , business , polymer
The settlement and excess pore pressure are calculated for a column of water‐saturated clay in which the permeability and/or shear modulus vary with depth. Several fairly general laws of variation are investigated. In each case, the soil is assumed to have a permeable top surface and to rest on an impervious substrate. For all the variations examined, in which the shear modulus increases with depth below the surface but the permeability of the soil remains constant, the deflection at a given instant after imposition of the load decreases and the degree of settlement increases with increasing rate at which the change with depth takes place. It is found that, when the variation over the height of the column is one order of magnitude or less, the curve of degree‐of‐consolidation versus time is reasonably wellapproximated by the curve for a homogeneous soil whose modulus equals the depth‐averaged value. When, in addition, the permeability decreases with depth, the approximation becomes less accurate. The same approximation, for moderate increase in shear modulus with depth, predicts satisfactorily the process of dissipation of excess pore pressure at a given depth, but breaks down when the variation in modulus is large. Finally, it is shown that the effect of variable modulus on the settlement is greater than of a comparable variation in permeability.