Understanding the interaction between rock bolts and underground rock movement is critical for safe and cost-effective underground excavation design. Although early research on this subject involved a balance of theoretical analysis and field measurement, the current work focused on analytical and numerical studies. The present study aimed to study fully grouted rock bolt in Tabas Coal Mine using numerical and instrumentation methods. Tabas Coal Mine is the first fully mechanized coal mine in Iran, producing 1.5 million tons of coal per year. The mine extracts coal by both longwall and room and pillar methods. The roadways have a rectangular profile of 4.5 m width and 3.5 m height. The field investigations and geotechnical characteristics of rocks showed that the rock masses are weak, requiring a suitable support system. The roadway is intersected by a major fault zone. For the designed roadway, four patterns (two types of bolt with transfer load capacity of 180 and 195 kN) were considered. FLAC analysis showed that 13 bolt 2.4 m with 2 NO flexi bolt 4-m patterns were better than other patterns within the faulted zone. Assessing the optimum pattern through instrumentation, there was compromise between the results of numerical modeling with instrumentation reading such as telltales, sonic extensometer, and strain gauge rock bolt. Thus, there was an inspiring agreement between numerical and field methods.