Uniaxial compression-shear experiments of artificial rock bridges with a pre-existing transfixion joint based on PIV method.

Rock bridges are commonly encountered in incipiently jointed rock masses and rock engineering practices, which play a significant role in the stabilization of rock masses. Although the effect of joint length, as a key influence factor on mechanical properties of rock bridges, has been extensively studied, the influence of joint dip angle and aperture on fractured rock properties has rarely been investigated. In this study, we carried out an investigation on a new conceptual model of fractured rock bridges, based on the evaluation of a pre-existing transfixion joint in the middle and two rock bridges of equal length on both sides. The specimens with four different joint dip angles and apertures were investigated using uniaxial compression-shear experiments, in which the surface deformation was monitored by the particle image velocimetry (PIV) method. The experimental results demonstrated that the maximum failure load of rock bridges decreased as the joint aperture and dip angle increased, and can be described using a linear and a first-order exponential decay functions, respectively. The rock bridge failure along the projection line of the pre-existing transfixion joint, a dense displacement contours region, was formed along with the formation of new fractures. It was found that the tensile failure effect increases as the aperture increases, and compression failure effect increases with the fracture dip angle decrease. A new method to test rock cohesive c and internal friction angle φ is also provided based on the new conceptual model of artificial rock bridges. The present study helps improve our knowledge of the effect of rock bridges and will contribute to the development of shear strength criteria and test methods. [ABSTRACT FROM AUTHOR]