Final answer:
Cross-ties are used in multiple row blasting patterns to ensure simultaneous detonation of charges, which is essential for controlling the direction, fragmentation, and heave of the material. They help distribute the shock energy uniformly and create a more controlled and effective rock breakage.
Step-by-step explanation:
Cross-ties are integral components in blasting operations, especially when implementing multiple row patterns using detonating cord. The primary purpose of cross-ties is to ensure simultaneous detonation of charges across different rows. This is critical to control the direction of the throw, fragmentation, and the heave of the blasted material. Without cross-ties, charges could detonate asynchronously, leading to suboptimal fragmentation, uneven ground displacement, and increased risk of fly rock or other dangerous outcomes. In practical terms, cross-ties link individual charges with a main detonating line, creating a network that carries the initiation signal rapidly and reliably through the entire blast pattern.
Furthermore, cross-ties help in distributing the shock energy more uniformly throughout the rock mass. This uniform energy distribution aids in achieving a more controlled and effective rock breakage, which is vital in mining and construction applications where precision is paramount. The use of cross-ties in multiple row blast patterns is a prime example of sophisticated blasting technique that allows for safer and more efficient rock excavation.