A constitutive model for sand in triaxial compression

TLDR

A new sand constitutive model is introduced that balances simplicity and theoretical rigor while extending concepts from Cam Clay models with distinct yield, plastic potential, and failure functions. The authors aim to provide parameter determination methods and demonstrate the model’s applicability. The model employs separate mathematical expressions for yield, plastic potential, and failure loci, with physical bases discussed and calibration procedures outlined. The model flexibly fits limited data, can be calibrated from few tests to predict diverse results, is formulated for a single initial density with density‑dependence considerations, and is described for triaxial compression, requiring further extension for general stress states.

Abstract

Abstract Although there is a large number of constitutive models for sand available in the literature it is believed that a fresh approach, striking a balance between complexity and theoretical rigour, is desirable. The approach here has certain conceptual links with the Cam Clay series of elastic–plastic models, but includes the more general starting assumption that the yield function, plastic potential and failure locus should be given quite distinct mathematical expressions. Possible physical bases for the proposed forms are discussed. Ways in which the parameters required to define the model may be determined are suggested and the use of the model is then demonstrated. Firstly, it is shown that, where a limited set of experimental data is available, the model is flexible enough to be able to match the test results. Secondly, it is shown that, where a wide range of test results has been produced, it is possible to determine the model constitutive parameters from a small number of tests and proceed to make satisfactory predictionsfor other, quite different, types of test. The model is developed for sand at a single initial density, but the way in which the constitutive parameters might be expected to vary with density is discussed. The model is described for conditions of triaxial compression, and extension to more general stress states will be needed before it can be put to the test of incorporation in, for example, a finite element program.