Shear behaviors of natural rock fractures infilled with cemented calcite

Abstract Shear behaviors of naturally infilled granite fractures were investigated using experimental and numerical approaches in this study. The tested granite fracture samples were collected from two boreholes BS48 and BS49 at the Xinchang site in the Beishan area of Gansu Province, China. Particle-based DEM models for the naturally infilled granite fractures were built up and calibrated with the experimental results. Effects of normal stress and infilling ratio (t/a) on shear behaviors and properties of infilled fractures were investigated. The results show that the shear stress-shear displacement curves of the naturally infilled fractures include three shear phases, i.e., quasi-elastic phase, failure phase, and residual shear phase. The relationships between normal stresses and peak shear strength, residual shear strength, shear stiffness and peak dilation are fitted using an approximately linear function. Infilling ratio (t/a) has a significant influence on the shear properties of the naturally infilled fractures. Shear strength and stiffness of the naturally infilled fractures decrease with increasing (t/a). The different shear behaviors of the various infilled and clean fractures are also briefly compared. Practical implications and outstanding issues in the present study are discussed finally.