To investigate the energy evolution and damage mechanisms of gangue cemented backfill (GCB) with varying water content

we prepared dry

natural

and saturated GCB samples (with water contents of 0%

10%

and 25%

respectively). Using the stress-strain curves obtained from uniaxial compression tests

we analyzed the energy evolution laws of the GCB samples

proposed an energy strengthening/weakening coefficient

revealed the damage evolution mechanisms

and established a segmented damage constitutive model for the total stress-strain curve. The results show that the stress-strain curves of GCB samples in dry and natural states exhibit distinct “four-stage” characteristics

whereas GCB samples in a saturated state display only “three-stage” characteristics. The elastic modulus and peak strength of GCB samples decrease exponentially from the dry to the saturated state. The weakening mechanism of backfill strength due to water content can be categorized into physical

chemical

and structural effects. The drying effect strengthens the energy of the backfill

primarily through the enhancement of dissipated energy. The saturation effect weakens the energy of the backfill

predominantly through the reduction of elastic strain energy and total strain energy. During the transition from dry to saturated state

the failure modes of GCB samples mainly undergoes a transformation from tensile failure

tensile-shear mixed failure and V-shaped shear failure

accompanied by block detachment. The deformation and failure of GCB samples with different water contents follow the same type of damage evolution process. However

increased water content promotes the development of backfill damage. The established segmented damage constitutive model of GCB samples with different water contents accurately describes the load damage and failure processes of GCB samples. The research results can provide theoretical reference for further studies on the mechanical behavior and stability of gangue cemented backfill.