Updated CS2 model for large strain consolidation of clay

A new and updated version of the numerical model CS2 for large strain consolidation of saturated soil is presented. The consolidation algorithm includes the capabilities of the original CS2 model with the addition of time-dependent loading, unload/reload effects, and an externally applied hydraulic gradient. Verification checks show excellent agreement with analytical solutions for timedependent loading under small strain conditions. A series of large strain simulations indicates that complex behavior can be produced by unload/reload during consolidation. Soil elements at varying depths take different paths on the compressibility plot and changes in applied stress can cause dramatic variations in excess pore pressures. When unloading occurs before the completion of consolidation, elements in close proximity to drainage boundaries will have a higher preconsolidation stress than those in the interior of the layer. The simulations also indicate that failure to correctly account for soil self-weight can lead to significant errors in a consolidation analysis.