# Strata Control by Roof Blasting for Bord and Pillar Mining Method in Mechanized Depillaring Panels
## 1 Introduction  
Continuous Miner Technology has restored the faith of the Indian mining industry in underground coal mining methods. This technology has proved to be successful with improved efficiency and safety in the difficult and complex geo-mining conditions of Indian underground coal mines. A number of coal mines have already adopted this technologysince its introduction in 2003 in the Anjan Hill mine of the Chirimiri Area of South Eastern Coalfields Limited (a subsidiary of Coal India Limited). In this line, the Tawa-I mine in the Pathakhera Area of Western Coalfields Limited (also a subsidiary of Coal India Limited) is planning to introduce this technology. Based on the project report and scheme prepared by CMPDIL, it has been proposed by the mine management of the Tawa-I mine to introduce Continuous Miner (CM) Technology in the Bagdona Coal Seam of the mine. The BCS panels of the Tawa-I mine are being developed by the conventional drilling and blasting method with a 3.8 m gallery width up to full seam thickness (average thickness = 1.80 m). Four coal seams, namely, Upper Workable Seam (UWS), Lower Workable Seam (LWS), Bagdona Coal Seam (BCS), and Seam IA, have been established by drilling in the Tawa-I Underground Mine. The variation in thickness of different seams and their intervening parting, as encountered in different boreholes, is mentioned in Figures 1 and 2. Figure 1: Partings between different coal seams present in Tawa-I mine. Presently, the panel (Figure 3) is being developed on pillars (35.7 m \(\times\) 31.2 m) and galleries (3.8 m \(\times\) 1.8 m) by the Bord and Pillar Mining Method. It has been planned to depillar the conventionally developed pillars in the panel using mechanized Continuous  
Figure 2: Borehole lithology above the panel of Bagdona Coal Seam based on CMPS 22. Miner (CM) technology. Furthermore, the Continuous Miner (CM) must extract the sides of the pillar to widen the existing galleries from 3.8 m to ensure adaptability. Depillaring operation in the panel needs a preparatory arrangement for the widening of galleries by cutting the sides of the pillar using CM for its easy maneuverability and adaptability and advanced installation of geotechnical instruments. A Shale roof of varying thickness of 3-5 m is present above the coal seam in the panel. A fault with a 1.5 m throw is running from 4 Dip to 13 Dip between 63L and 64L (Figure 3) and is further surrounded  
Figure 3: Panel in Bagdona Coal Seam of Tawa-I Underground Coal Mine. by two major faults. The panel is lying below a panel that had been depillared with the caving-in LWS at an average parting of 50 m. A maximum subsidence of 1.6 m has been reported to date in the Tawa-I mine in the panel E2 section of the LWS. The maximum angle of the draw has been observed up to 11\({}^{\circ}\) in the E6 district of the LWS, which was depillared 11 years ago. The geo-mining conditions of the panel are mentioned in Table 1. A number of developments have been made for the design of geotechnical elements [1; 2; 3] involved in working with Continuous Miner Technology. Furthermore, researchers have also investigated methods to effectively manage the challenging cavable roof. The literature on strata control and mining safety in coal mines presents various strategies and technologies aimed at improving safety, stability, and efficiency in underground mining operations. MSHA [5] outlines essential guidelines for managing roof and rib stability, emphasizing proactive measures such as roof bolting and rib control to prevent roof falls. [PERSON] [6] focuses on the application of geotechnical instrumentation and numerical modeling to monitor and predict strata behavior, thus, aiding in better risk assessment and safety management. [PERSON] et al. [7] explore the use of long-hole destress blasting to prevent rockbursts in deep coal mines, highlighting its effectiveness