What are some common reasons flyrock may occur during blasting?

• A. Inaccurate drilling and abnormal rock conditions
• B. Only excessive explosive employed
• C. Improper hole sequence and inadequate lighting
• D. Weather conditions and equipment failure

Answer: (A)

The occurrence of flyrock during blasting operations is often attributed to a range of factors, with one of the most significant being inaccurate drilling and abnormal rock conditions. When the drilling holes are not correctly positioned or aligned, it can lead to an uneven distribution of explosives. This misalignment can result in excessive pressure and incomplete fragmentation, causing rocks to be propelled uncontrollably away from the blast site.

Additionally, abnormal rock conditions, such as unexpected geological formations or variations in rock density, can also contribute to the occurrence of flyrock. These factors may affect how explosives interact with the surrounding material, potentially causing more violent dispersal of rock fragments.

A thorough understanding of both proper drilling techniques and geological assessments prior to blasting is vital in minimizing the risks associated with flyrock. This includes ensuring that the drilling is precise and that any variations in rock structure are well-documented and considered during the blast design process.