The Description Of Sand Characteristics During The Principal Stress Rotation Based On Property-dependent Plastic Potential Theory

The soil under the condition of the seismic load, traffic load, and wave load, etc, the principal stress axis is rotated to the soil, and the mechanical characteristics under the condition of the stress is different from that under the condition of the principal stress. As for the sand this phenomenon is particularly significant, because of its microscopic structure consists of discrete particles composition, making sand in principal stress rotation force principal strain direction is along the main should develop in the direction of the force, resulting in a distinctly non coaxial phenomenon. The non coaxial characteristics cannot be described in the traditional elasto-plastic theory, therefore, the complicated should be studied and constitutive relation of deformation force under the condition of nature became the current focus of attention in the field of geotechnical engineering and difficult problems. Especially to predict artificial earth-rock dams, subgrade filling construction and its foundation soil actual mechanical response based, non coaxial whether in theory or in practice are of great significance. Sand the non coaxial inner cause is that the microscopic anisotropy fabric and traditional elastic-plastic theory is based on isotropic assumption, thus brought great challenge to non coaxial describe. Therefore, in this paper the topic put forward is correlated to the material properties of plastic potential theory based, considering sand microscopic fabric characteristics influence, in order to establish to consider the principal stress rotation force conditions of soil anisotropy constitutive model of complex stress. From the aspect of microscopic fabric, failure law, shear mechanism of account to the principal stress axes rotation condition of anisotropic sands strength and stress-strain relationship are studied. The main contents are as follows:(1) The failure criterion of sand soil considering the rotation of principal stress is proposed. The criterion based on topic of sand microscopic fabric and method for quantitative detection of the latest progress, with which the macro and micro combined method, and with fabric tensor and the four kinds of combination of stress tensor variable as the foundation, put forward a new the anisotropy of the state variables and the state variables by stress tensor and fabric tensor contraction of form, and then the anisotropic state variable defined failure criteria are introduced to establish a generalized M-C equation for anisotropic sand. The variable definition form is simple and the physical meaning is relatively clear. The anisotropic criterion can be used to describe the failure law of anisotropic sand under the condition of rotation and fixation of the principal stress axis.(2) Can consider the establishment of a constitutive model of soil anisotropy of principal stress axis. The model is based on material properties associated plastic potential theory, the limit for the traditional assumption of isotropy elastoplastic mechanics, get the soil deformation distribution law and its microscopic fabric linked meso fabric on account of cut influence, an anisotropic critical state constitutive model of sand. Compared to other models, this model is simple in form, can be described by a set of broad parameters of soil deformation, can be described as non-coaxial deformation characteristics of sand under principal stress rotation conditions.(3) For non-performance coaxial phenomenon sand under principal stress rotation conditions were simulated and analyzed. Compiled Matlab program constitutive model for non-coaxial characteristic three-dimensional space on a plane π sand performance has been described, the results show:the model can be more fully described variation of different stress its non-coaxial Rhodes corner angle; use hollow cylinder test results Japan Toyoura sand, several stress confining pressure, sand monotonic loading, rotation and mixing pure principal stress axes under load non-coaxial characteristic sand performance was simulated. The results show:the material properties associated potential theory can better describe the non-coaxial characteristic performance under these conditions, can reflect the impact of sand microscopic fabric of macroscopic coaxial degree. Validated the validity and rationality of the theory and model.