Representation of H Odé Shear Deformation Theory at Nanoscale

Generally speaking, a rock is broken by shearing action or tensile force, in that case, why can we find some fracture structures perpendicular to the pressure direction? It can be solved through H Odé shear deformation theory. In plastic (or viscous-elastic) deformation, there is a velocity discontinuity which may be gained from a yield condition due to a medium differentiation, and thus the medium can just shear slip along the characteristic planes with an equal velocity. This theory is also called the plastic shearing criteria, and it was firstly verified from a macroscopic-mesoscopic mechanics representation, including the fracture planes in compressive zone, extreme point rupture of Griffith crack under normal press, and cataclastic flow in vertical pressure. Furthermore, high temperature and high pressure (HT/HP) experiment to granite samples was carried out, and the thin shells of crack surfaces, which are perpendicular to the axle load, were taken for the SEM determination. Then the micro/nanosized phenomena observed in crack surfaces with H Odé mechanics representation are compared with the textures of general shearing yield function from three aspects. (1) Viscous-elastic deformation:the experimental specimens passed HT/HP are more likely to produce a plastic compactive volumetric flow, invloving not only viscous deformation but also elastic one. Consequently, the specimens can exhibit effects of nano-coating and nano-layering. (2) Nanosized texture:nanosized grain (with diameter 60-80 nm) can turn into single nanoparticle-nanoline-nanolayer texture, and aggregate grains may be subdivided into granular, linear granular and schistose granular textures, etc. (3) Ordered fabrication:though preferred orientations of the granular flow and streak flow in H Odé shear fractures belong to a weaker scale than common shearing, their yield characteristics are entirely corresponding with the latter from comprehensive analysis. It is suggested that H Odé shear theory can be applied to research some few unconventional deformation phenomena, and it can offer a new perspective for nanogeology researches.