Mechanical behaviour and spatial fracture characteristics of weakly filled granite with different diameters under uniaxial loading revealed by 3D DIC and AE monitoring.

The mechanical behaviour and failure characteristics of weakly filled granite are important factors affecting the safety and stability of rock masses. This paper presents an experimental study on uniaxial compression of granite containing both planar and circular weak filling of different diameters with the aid of three-dimensional digital image correlation (3D DIC) and acoustic emission (AE) monitoring system. The test results show the following: (1) The contact area between the planar weak filling and the bedrock is in a state of severe local deformation. The annular area of the circular weak filling in contact with the bedrock is in a severe deformation area, with detachment from the bedrock and spalling behaviour occurring. The failure modes of the specimens were summarised, and the spatial morphology of the main fracture surface was quantitatively analysed. (2) The presence of planar and circular weak filling leads to increased AE volatility. The AE hit signal is dominated by the shear signal, but the presence of circular weak filling increases the splitting signal component. (3) In the presence of circular weak filling, the energy interval of the most dominant signal is reduced, and the duration is shortened. The differences in the correlation of AE parameters are concentrated in the low-amplitude signal region. (4) Weakly filled areas will first become areas of spatiotemporal accumulation of microfracture events and will gradually spread. The accumulation and distribution characteristics of microfracture events can be used as indicators to evaluate the propensity, severity and timing of the destabilisation of rock masses containing weak filling. [ABSTRACT FROM AUTHOR]