Sekiguchi-Ohta viscid _Input parameter

Question

Hi there, 
 I have a question on how to determine the coefficient of secondary compression and the intital volumetric strain rate as part of the input parameters of the Sekiguchi-Ohta viscid model. The Material Models Manual suggests using a secondary compression index as an alternative to the above mentioned input parameters without any further information on how to specifiy it. Unfortunately I haven't found a lot in the literature about this subject. The second question is wether it is possible or not to derive the input parameters of the Sekugichi-Ohro viscid model out of the input data set of the soft soil creep model using the soil test tool by excuting back calculations? 
 
 Thank you all in advace. 
 
 Greetings

Stefanos Papavasileiou · Accepted Answer

Dear Ahmed, 
 Apologies for the late reaction. It slipped my attention. 
 I have the following comments from our research team: 
 The secondary compression index in Sekiguchi-Ohta Viscid (SOV) model is the same as the creep index for secondary compression in the Soft Soil Creep (SSC) model, therefore it is equal to 2.3(1+e)alpha* 
 where alpha* (or mu*) is related to lambda*, therefore I suppose a triaxial compression creep test is needed.

There is a 1:1 match between SOV and SSC in terms of indices. The strength, however, is different by definition, with SOV having something similar to Cam-Clay (with a friction ratio M required explicitly), whereas SSC has double yielding with a Mohr-Coulomb failure criterion (therefore we have c, phi, psi) with the addition of a cap of Mod. Cam-Clay type (with M here automatically calculated from the rest of the parameters). 
 
 So, it seems that there is no need to back-calculate through soil tests for the indices. The strength definition is different between the two models, therefore it cannot be related. 
 
 I hope that this helps (even late).

Sekiguchi-Ohta viscid _Input parameter

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