ABSTRACT
To study the deformation characteristic of rock subjected to the in-situ stress and blasting, a static-dynamic loading equipment was constructed. Dynamic strain gauges and high-speed cameras were used to quantify the dynamic response of rock. With different horizontal-to-vertical pressure ratios K, nine tests were carried out. The results show that: under the dynamic loading from small diameter charge, cracks in the crushing zone were created by shear and tensile failure, and radial cracks were produced by circumferential tensile stresses from the shock wave. Circumferential compressive stresses were formed by the initial confining pressure. When K = 1, the centrosymmetric damage zone was closed to the borehole. As K decreases from 1 to 0, stress concentration appeared around the borehole, and the radial crack growth was influenced by the hoop tensile stress and biaxial pre-pressure. The shear fracture dominated the process of crack growth when the confining pressure was beyond a certain level.
