Physical Simulation on Failure around a Circular Cavern in Hard and Brittle Rock under High and Increasing Natural Stress Conditions

To analyze the dynamic failure process around a circular cavern in hard and brittle rock under high and increasing natural stress conditions, an $800\times 800\times 800\text{-}\text{mm}$ physical model with a $\mathrm{\varphi }$ 160-mm circular cavern in the center was produced by using the self-developed physical model material and tested in the self-developed model test machine under plane-strain conditions. From the physical simulation, when $P_x=P_z=600\hspace{0.17em}\text{kN}$ (${\sigma }_X={\sigma }_Z=3.75\hspace{0.17em}\text{MPa}$), shallow skinlike flakes appeared on the cavern wall, and large-scale abrupt failure occurred during a limited loading-zone for a short time until $P_x=P_z=630\hspace{0.17em}\text{kN}$ (${\sigma }_X={\sigma }_Z\le 3.94\hspace{0.17em}\text{MPa}$). Then, a relatively steady state was followed by a long period with the load increasing. To understand the mechanical behavior around the circular cavern better, in the light of the physical simulation, a numerical simulation was also applied for comparative analysis. Both the numerical simulation and the physical simulation were consistent with each other, and they presented the same failure mechanism.