Mechanical behaviour and spatial fracture characteristics of granite containing weak inclusions under uniaxial loading revealed by 3D DIC and AE monitoring: The influence of extension length of planar inclusions

Abstract

The destabilisation failure characteristics of weakly filled rock masses are important influencing factors in rock engineering stability control. To investigate the changes in the mechanical behaviour and spatial fracture characteristics of granite in the presence of both planar and circular weak inclusions, two experimental non-destructive monitoring methods, 3D DIC and AE, were used together. This paper summarises the experimental results and investigates the effect of the extension length of the planar inclusions on the mechanical behaviour and spatial fracture characteristics. The results show that the presence of planar weak inclusions leads to the appearance of “plasticity” before the peak stress, the weakening of “brittleness” and the enhancement of “ductility” after the peak stress, and the increase of extension length will weaken the resistance to deformation and the overall load carrying capacity. When the extension length of planar inclusions varies, there are three main modes of specimen failure: “X” shear failure; crushing and crumbling failure; overall shear failure. The distribution of AE parameters is dominated by the proportion of low-amplitude hit signals, with a wide range of energy distribution, but the concentration in low-amplitude energy and slightly longer signal duration. The correlations of energy-amplitude, count-amplitude, and duration-amplitude are different and similar. The fracture area of the specimen and the spatial location of the fracture event concentration distribution overlap, with the planar inclusions serving as the weak surface, and the fracture event showing the distribution trend of the planar weak inclusions serving as the central area.