The deformation failure and energy dissipation of backfill body are closely relative to confining pressure. Experiments are taken to investigate backfill body samples under uniaxial compression and triaxial compression. Based on the experimental results

the internal relations among deformation feature

failure mode

energy dissipation and confining pressure are studied and compared. The results show that the peak strain of backfill body increases with the increase of the confining pressure

and takes a linear correlation. Under a low confining pressure

backfill body has a brittle failure characteristic and presents a strain softening behavior; as the confining pressure increases

the mechanical feature of backfill body performs by a way of transformation from brittleness to strain hardening; the cement/tailing ratio and solid concentration are higher

the critical value of the confining pressure from brittle to ductile is greater. The forms of crack and fracture propagation are diverse

which can be sorted into single type

parallel type

intersection type and complex type. The main macrofailure modes are X-shaped and Y-shaped shear failure. The forms of failure plane are classified by linear smooth friction surface

arc rough friction surface

linear rough friction surface

terrace rough friction surface. The peak strength also increases linearly as the confining pressure increasing. The sensitivity of cohesion to cement/tailing ratio is higher than that of solid concentration. The deformation energy of backfill body at different compressed stages increases to a considerable extent with the increase of confining pressure. The relations of the amount of energy dissipation before yield deformation stage and after yield deformation stage

unit volume strain energy and total energy consumption take a positive proportion of the confining pressures.