Dynamic multifractal characteristics and damage evolution of granite pegmatite with varying biotite content based on acoustic emission monitoring

• Increased biotite content reduces uniaxial compressive strength and elastic modulus while enhancing plastic deformation and shear crack proportion. • Dynamic multifractal parameter Dam exhibits biotite-dependent segmented evolution, with oscillations in elastic phase indicating shear crack initiation and attenuation in plastic phase reflecting frictional closure. • AE-based damage models and time-varying signals effectively characterize rock damage progression, with stress concentrations around biotite fostering localized shear failure at lower damage levels. • Higher biotite content accelerates crack propagation and lowers fracture energy threshold due to smooth cleavage planes, reducing strength and stiffness.