(2)

In this paper, a recently developed unified critical state model (CASM-S), which is applicable to predict the mechanical behaviours of sand and overconsolidated clay, is numerically implemented into the Fast Lagrangian Analysis of Continua, i.e. the FLAC(3D), for engineering applications. The implicit integration algorithm incorporated with the line search method is employed to implement CASM-S model. The additional parameter u is calibrated by genetic algorithm, whilst the rest of the material parameters are determined following the literature upon applicable. Validation of CASM-S model and its numerical implementation has been well demonstrated by a series of drained and undrained triaxial compression tests conducted on clay and sand. In terms of stress-strain relations, volumetric versus axial strain, and negative pore pressure versus axial strain, the model predictions agree well with the experimental results. Then, a case study is performed to demonstrate the applicability of the CASM-S model to analyse geotechnical problems, e.g. the foundation pits excavated from Berlin sand within the FLAC(3D), where lateral deflections of the diaphragm wall and vertical displacements in a designated section are evaluated. Conclusions can be drawn that the predictions of CASM-S model are almost identical to the field data, demonstrating a good performance in engineering applications.

来源平台：GEOMECHANICS AND GEOENGINEERING-AN INTERNATIONAL JOURNAL