ABSTRACT
According to Critical State Theory (CST) for granular media, two conditions on the stress ratio and void ratio are considered to be necessary and sufficient for reaching and maintaining the critical state (CS). A two-dimensional discrete element method experiment questions whether these two conditions, that do not consider soil fabric, are sufficient for CS. For this purpose, a virtual sample is first brought to CS and then rotation of the stress principal axes is imposed while keeping stress principal values fixed, hence maintaining the satisfaction of the aforementioned two CST conditions. The rotation induces a void ratio reduction and thus, abandonment of CS, proving incompleteness of classical CST. The recently proposed Anisotropic Critical State Theory (ACST) remedies this incompleteness by enhancing the two foregoing conditions by a third, related to the critical state value of a fabric anisotropy variable. The ACST can also explain various other soil response characteristics that cannot be addressed by classical CST with no fabric anisotropy consideration, as depicted by simulations performed with a constitutive model developed within ACST.
