Integration of Numerical and Empirical Approaches for Assessment of Apt Support Design for Various Underground Openings of Chromite Mine

Abstract

Abstract The underachievement of support systems in roof bolts layout design is one of the dominant causative factors of roof fall in underground mines. Various factors triggering the roof failure are the presence of laminated roof, the geological plane of weaknesses, the time lag in support installation, inefficient grouting/bonding of roof bolts, improper estimation of roof bolt length, the concentration of the induced stresses due to mining activities, etc. The roof fall concerns mining engineers as it seriously affects safety and productivity. Hence the stability of the openings has to be considered as a priority to suspend the movement of overlying layered strata by application of adequate support. Application of rock mass classification system helps in guiding suitable roof support design for apt stabilization of the mine openings. The study has been carried out to assess the befitting support design of v arious openings in underground chromite mine considering applicable rock mass classification systems namely Bieniawski’s Geomechanical System and Barton’s Q – system inclusive of numerical analysis. The values of rock load obtained by Bieniawski’s geomechanical system was on the higher side. Thus, in view of the safety and stability of engineering structures, Bieniawski’s geomechanical system was considered for the design of a support system. Rock load was determined for different dimensions of underground openings such as decline, cross-cut junctions, cross-cut roadways, ore drive, footwall drive, and haulage junctions, wherein width variation resulted in influencing rock load. Safety factor has also been analysed with respect to the width of the opening to demarcate stable and semi-stable zones.