6.6.1 Total stress analysis and effective stress a...
The total stress analysis generally refers to analyses where the total stress is used and the input parameters are total stress parameters such as su andφ＝0（for saturated clay），or cT andφT（for unsaturated clay）.The stresses thus obtained are then the total stress.The effective stress analysis refers to the analyses where the effective stress is used and the input parameters are effective parameters such as c′andφ′.The stresses obtained from the analysis are then the effective stress.
In the beam on elastic foundation method introduced in the previous chapter，the analyses can be split into drained analysis，undrained analysis，and partially drained analysis.The corresponding type of stress used in these methods is the effective stress，the total stress，and the total stress，respectively.Therefore，the undrained behavior can only be analyzed by the total stress method.
In the finite element method，drained analysis should be done with the effective stress while undrained analysis can be carried out with either the total stress or effective stress.
For example，if the hyperbolic model is expressed by the effective stress，c′andφ′being the input parameters，｛Δσ｝in Eq.6.1 will then imply the effective stress.The method is an effective stress analysis.If the hyperbolic model is expressed by the total stress，｛Δσ｝in Eq.6.1 will then represent the total stress because Et and v in［C］are obtained from the hyperbolic model expressed by the total stress.The method is a total stress analysis.
Similarly，if the yielding function in the elastoplastic model is expressed by the effective stress，｛Δσ｝will then imply the effective stress.If the yielding function in the elastoplastic model is expressed by the total stress，｛Δσ｝will then imply the total stress.