Effect and Response of Coal and Rock Media Conditions on Deep-Hole Pre-Splitting Blasting Techniques for Gas Drainage

Abstract

Different types of deep-hole blasting techniques are needed to solve gas drainage problems in complex and variable cases. Blasting parameters suitable for mines are selected based on the relationship between blast stress field changes and gas flow combined with field application and numerical simulation. The Datong Mine was a background to study the blast crush zone and drainage influence range following deep-hole blasting with holes laid in coal seams, which resulted in a 24% increase in gas flow in the drainage hole 6 m from the blast hole. In response to the difficulty of forming blast holes in the soft coal seam of the Yuyang Mine, drilling and blasting in the floor rock stratum adjacent to the coal seam increased the gas flow in the drainage holes by 125%. When applying the deep-hole technique with holes crossing multi-seams for gas drainage in Shiping Mine, the volume of gas drainage increases significantly with increased effective stress in the drainage hole. For example, when the spacing at the hole’s bottom between the blast hole and the drainage hole is 4.6 m, the volume of gas drainage increases by 3.3 times, compared with 8.8 m. Twenty-six protruding mines in southern China have applied the above deep-hole pre-splitting blasting technology, all of which have achieved good results and are of great significance to future applications in multiple fields, such as gas control.