A numerical study of the effect of loading conditions on the dynamic failure of rock

The goal of the present work is to simulate the stress distribution and failure processes of rock samples subjected to compressiveimpulse waves with different magnitudes. The different failure patterns of the rock specimens subjected to the various stress wavesare numerically obtained from the RFPA simulation and the reasons that cause these different failure patterns are analyzed.Three impulsive stress waves that are indicated with the I, II and III symbols, as shown in Fig. 1(a), are applied to the top steelplate. The magnitudes of the three loading cases are 120, 240 and 360MPa. As shown in Fig. 1(b), the failure of the rock specimenunder compressive stress wave I is actually caused by tensile failure because the compressive stress wave becomes tensile when it isreflected from the free face of the top steel plate. Under load case II, the majority of failure occurs after the stress wave reflects from thebottom fixed end of the specimen (Fig. 1(c)). Under load case III, as shown in Fig. 1(d), the failure of the specimen under this load caseis mainly caused by the incident stress wave applied at the top end of the rock specimen via the top steel plate; many cracks that areparallel to the applied compressive stress are formed and lead to the failure of the rock specimen. From the above numerical results, itcan be concluded that the rock shows various failure patterns when it is subjected to compressive stress waves with different magnitudes.