RATIONAL APPROACH TO ANISOTROPY OF SAND

The paper presents a constitutive model for the three-dimensional defo rmation-strength behaviour of inherently anisotropic sand. Based on no n-linear tensorial functions, the model is developed without recourse to the concepts in plasticity theory such as yield surface and plastic potential. Benefited from the fact that no decomposition of strain in to elastic and plastic parts is assumed, a unified treatment of anisot ropic behaviour of deformation and strength is achieved. Anisotropy is characterized by a vector normal to the bedding plane. The extension of the constitutive model is furnished by incorporating the vector und er consideration of the principle of objectivity and the condition of material symmetry. Distinct features of the model are its elegant form ulation and its simple structure involving few material parameters. Mo del performance and comparison with experiments show that the model is capable of capturing the salient behaviour of anisotropic sand. (C) 1 998 John Wiley & Sons, Ltd.