IMPROVEMENT OF CONTOUR BLASTING TECHNOLOGY IN TUNNEL CONSTRUCTION AND MINING EXCAVATION: MODERN APPROACHES AND DEVELOPMENT PROSPECTS

The article examines the comprehensive features of contour blasting technology in tunnel construction and excavation works during underground mining development operations. The main disadvantages of conventional blasting methods are analyzed in detail, including excessive disruption of rock mass integrity, formation of extensive fractured zones around excavations, significantly increased support costs, reduced structural stability, and compromised work safety conditions. The substantial advantages of contour methods are highlighted, including effectively minimizing rock contour damage, dramatically improved excavation surface quality, reduced overbreak volumes, substantial savings in support materials, enhanced excavation precision, and improved overall project economics. A comprehensive mathematical model is presented for calculating optimal spacing between blast holes, considering explosive properties, dynamic characteristics of rocks being excavated, geomechanical parameters of the rock mass, stress distribution patterns, and local geological conditions. Modern contour blasting methods are thoroughly analyzed, including pre-splitting techniques, smooth blasting procedures, controlled blasting approaches, and their various combined variants tailored to specific geological formations. Key technological parameters are systematically determined: optimal borehole diameter, precise charge spacing calculations, appropriate linear charge mass distribution, suitable explosive type selection, advanced initiation system design, timing sequence optimization, and burden-to-spacing ratios. Detailed practical recommendations are provided for applying contour blasting methods under various challenging geological conditions, including hard crystalline rock formations, medium-strength sedimentary rocks, fractured rock masses, and weak soil conditions. Quality control issues and comprehensive effectiveness evaluation of contour blasting methods in complex underground conditions are thoroughly considered. The research addresses systematic optimization of blasting parameters through extensive field testing, continuous monitoring of excavation quality indicators, vibration control measures, and post-blast damage assessment protocols. Special attention is given to advanced safety measures, environmental impact considerations, noise control, and dust management when implementing sophisticated contour blasting technologies in underground mining operations and modern tunnel construction projects.