Influence of Joints/Fracture Systems on Drill & Blast Design

Optimizing rock fragmentation depends on understanding how joint fracture systems interact with blasting parameters. Key factors such as joint spacing, dips and orientation play a crucial role in determining fragment size distribution and target optimum powder factor. 𝙅𝙤𝙞𝙣𝙩 𝙎𝙥𝙖𝙘𝙞𝙣𝙜: Closely spaced joints → Smaller, more manageable fragments. Widely spaced joints → Larger blocks, often requiring secondary breakage. J𝐨i𝐧t O𝐫i𝐞n𝐭a𝐭i𝐨n: Influences fracture propagation and overall blast efficiency. 𝐕o𝐥u𝐦e𝐭r𝐢c J𝐨i𝐧t C𝐨u𝐧t (𝐉v): Measures the number of joints per cubic meter. → High Jv : More fractures, easier breakage, finer fragmentation. → Low Jv : Intact rock, larger fragment sizes post-blasting. 𝐑o𝐜k Q𝐮a𝐥i𝐭y D𝐞s𝐢g𝐧a𝐭i𝐨n (𝐑Q𝐃): Evaluates rock integrity and is inversely related to Jv. → Low RQD : Highly fractured rock. → High RQD : More intact, resistant rock mass. 𝑯𝒐𝒘 𝑱𝒗 𝒂𝒏𝒅 𝑹𝑸𝑫 𝑰𝒏𝒇𝒍𝒖𝒆𝒏𝒄𝒆 𝑷𝒐𝒘𝒅𝒆𝒓 𝑭𝒂𝒄𝒕𝒐𝒓 Powder Factor targets are directly affected by jointing characteristics: • 𝐇𝐢𝐠𝐡 𝐉𝐯 / 𝐋𝐨𝐰 𝐑𝐐𝐃: Rock is naturally fragmented, Requiring lower Powder Factor to avoid excessive fines and overbreak. • 𝐋𝐨𝐰 𝐉𝐯 / 𝐇𝐢𝐠𝐡 𝐑𝐐𝐃 : Rock is more intact and resistant, Requing higher Powder Factor to achieve effective fragmentation. Ignoring joint characteristics in blast design can lead to: - Inefficient fragmentation. - Excessive fines or oversized blocks. - Increased costs due to secondary breakage. By integrating Jv, RQD into blast planning, better results can be achieved with optimized costs and improved efficiency.