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Analysis Using the Soft Soil Model

The analysis employs the modified compression index λ and is based on the Soft soil elastic-plastic model developed in the University of Cambridge. The soil deformation assumes the volumetric strain to be linearly dependent on the change of effective mean stress ε plotted in the natural logarithmic scale. The settlement of the ith layer is then provided by:




vertical component of geostatic stress in the middle of ith layer



vertical component of incremental stress (e.g. stress due to structure surcharge) inducing layer compression



thickness of the ith layer



modified compression index in the ith layer

The analysis requires inputting the modified compression index λ usually obtained from triaxial laboratory measurements.

If the modified compression index λ is not known, it is possible to specify the compression index CC together with an average value of the void ratio e (if you do not know it, it is sufficient to provide the initial void ratio eo) and the program then performs an approximate computation of the modified compression index λ using the available information.


Burland J.B. The yielding and dilatation of clay (correspondence), Géotechnique, 15 (2),1965, str. 211-214.

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