Abstract: Due to shattering effect of blasting, mainly three zones are formed around the tunnel profile. During tunnel excavation, blast induced damage or Excavation Damage Zone (EDZ) interacts with existing geological structure of the rock-mass. This can and cause over-break and stability issues during and after excavation. Today the EDZ is determined by correlation-based methods, although direct measurement is possible. This paper throws light for, in depth exploration methods for EDZ assessment during excavation. The prediction of damage to the rock mass is a very important factor to evaluate the quality of the excavation process in tunnelling, so that it would allow the optimization of explosive charges utilized in successive blasting rounds, as well as lowering risks of instability from rock loosening, less support costs and water inflows.  Upon developing a mathematical approach to evaluate rock damage from underground blasts, practical applications were accomplished to confirm it, both in tunnelling excavations and underground mining. Examples of these studies are described in detail.

Keywords: Prediction, EDZ, instability, tunnelling, explosive charges, geologic- structure

| DOI: 10.17148/IARJSET.2020.7313