Rock Failure and Stress Redistribution in Rock Masses Rock masses exist in a natural state of equilibrium, where in-situ stresses are balanced by the strength and confinement of the rock. Rock failure occurs when this equilibrium is disturbed, causing the stresses within the rock mass to exceed its strength. Such disturbances can result from both natural processes and human activities, particularly in mining, tunneling, and quarrying operations. One common cause of stress disturbance is the creation of a cavity within a rock mass. When material is removed, the original stress field can no longer be maintained, and stresses are redistributed around the opening. This redistribution often leads to stress concentration along the boundaries of the excavation, increasing the likelihood of deformation, cracking, or failure if the rock mass cannot adequately support the new load conditions. Blasting represents a more dynamic and intense source of stress disturbance. Beyond simply removing rock, blasting introduces shock waves, high gas pressures, and ground vibrations that temporarily but significantly alter the stress environment. These stress waves can propagate through the rock mass, activating existing discontinuities such as joints, bedding planes, and faults. The reduction in confinement and the weakening of these structural features can substantially reduce rock mass stability. As stresses are redistributed and confinement is lost, rock faces may experience sliding, spalling, or collapse. In slopes and open excavations, this can manifest as rock falls or planar and wedge failures, particularly where geological structures are unfavorably oriented. The risk of failure is further influenced by rock quality, in-situ stress conditions, blast design, and the proximity of excavations to free faces. Understanding the relationship between stress redistribution and rock failure is critical for safe and efficient rock engineering. Proper excavation sequencing, controlled blasting techniques, and continuous monitoring of rock mass response are essential measures to manage stress-induced instabilities. By accounting for these factors, engineers can minimize the risk of rock failure and maintain the long-term stability of rock structures. The video shared by Bernard Saw as attached to this post clearly demonstrates how excavation activities can trigger rock failure. As material is removed from the rock mass, the natural stress equilibrium is disturbed, forcing stresses to redistribute around the newly created opening. When the rock mass is unable to accommodate these changes, instability develops, resulting in cracking, sliding, and eventual failure of the rock face. The video provides a practical visual example of how excavation-induced stress changes can directly compromise rock mass stability.