Energy dissipation and 3d fracturing of Backfill-encased-rock under triaxial compression

The cooperation of the backfill with rock is an essential project for underground mine, especially in the room-and-pillar filling mining method. This paper discussed the relationship between the strain energy, volume fraction (VF), confining pressure, failure mode of the Backfill-encased-rock (BR) through triaxial compression test, acoustic emission (AE), and microscopic tomography (CT). The findings show the positive correlation between total strain energy, elastic energy, and two factors (VF and confinement). The internal crack progress of BR is complicated and can be divided into two parts: conjugate shear in the top 38 mm and axial splitting in the lower part. Under 0.3 MPa, less shear and more tension occurred causing the dissipated energy at peak to decrease as VF increased. The outcome could be a useful reference for future rock-backfill structure optimization in mining design.