Question: will the presplit hole Depth be same as the normal production hole Depth and what is the maximum presplit Burden ranges from the last production hole line? The presplit hole depth is typically the same as the normal production hole depth. Both are drilled to the same depth to ensure the presplit creates a controlled crack along the desired plane while the production holes achieve the necessary breakage within the blast. However, the burden for presplit holes is generally much smaller than that of production holes. The maximum presplit burden, which is the distance from the last production hole line to the presplit line, usually ranges from 0.8 to 1.2 times the hole diameter. This smaller burden helps in achieving a controlled break without excessive fragmentation or overbreak into the remaining rock mass. The specific burden depends on factors like rock type, hole diameter, and the desired precision of the break. Question: How about the charging ratio? Is it same as production blast or it is reduced? The charging ratio in presplit blasting is reduced compared to production blasting. Presplit holes are designed to create a smooth, controlled crack or plane in the rock, minimizing damage to the remaining rock mass. Therefore, lighter charges (less explosive per meter of the hole) are used to avoid excessive energy that might cause uncontrolled breakage or over-fragmentation. This can be achieved through any of the following approaches: => 1. Using Smaller Diameter or Lower Density Explosives: Presplit holes are often loaded with explosives of lower density or smaller diameter than production holes. => 2. Using Decoupling Ratio: A higher decoupling ratio (space between the explosive and the hole wall) is usually employed to reduce the explosive energy per unit volume of the hole. This is done using stemming materials or air gaps to minimize the explosive's contact with the rock. using. => 3. Continuous or Deck Loading: Presplit holes may use decked or discontinuous loading (with gaps between explosive charges) to control the energy distribution along the hole.