Layered Biotite Granulite Failure Mode And Acoustic Emission Trial Under Uniaxial Condition

Layered rock is a special type of rock,such as sedimentary and metamorphic rocks which have obvious regularity of bedding structure,and the anisotropy of layered rock is significant.A large number of research results show that the bedding is weak plane compared to the rock matrix,which have significant influence on rock mechanical properties and is the key point of control the stability of engineering rock mass.So the development of the layered rock mechanics trail has vital theoretical and practical value.In this paper,the research is about the relationships among the angle of bedding,failure mode,the features of acoustic emission Hit parameters and the rule of AE events spatial-temporal evolution,and it is based on the acoustic emission trials of seven group of specimens with different angle of bedding layered biotite granulite under uniaxial compression.There are mainly four aspect works with a certain academic value which was carried out for the purpose of revealing the layered rock failure mechanism by acoustic emission means:1.The layered biotite granulite in different dip angles is studied under uniaxial compression to analysis of the deformation,strength and failure mode.2.The anisotropic velocity model is established based on the relationships between angle of bedding and wave velocities,and then,the model is used for the acoustic emission location with the gird search algorithm.3.The acoustic emission Hit parameters variation regularity is analyzed in the process of rock failure and damage.It is researched that the relationships among the angle of bedding,failure mode,crack growth rate characteristics,features of energy release,fracturing precursory features and frequency composition.4.It is analyzed that the spatial and temporal evolution of layered biotite granulite acoustic emission events and the box fractal dimension evolution characteristics which is for the purpose of finding the influence of precursory phenomena.5.The mode of tensile fracture across bedding occurs in a low-dip specimen(0°,15°,30°&partly 45°)and some of that mixed with shear crack along bedding.In mesoscopic level,micro crack is mainly of shear type at the stage of early and turns into tension crack type with the increasing stress level.The bedding can’t afford a leading role in the failure.The mode of shear failure along bedding occurs in a middle-dip specimen(45°,60°,75°).In mesoscopic level,micro crack is mainly of shear type with the peak stress coming and expands along the bedding.The bedding leads the failure.For the specimens orientation of 90°,delamination occurs along bedding and a macro-split in the direction parallel to that of the applied load.The buckling of struts of the matrix layer ultimately causes the failure.