Bord and pillar mining is the predominant method for extraction of coal from underground in India. Strata control is a major problem affecting safety and productivity of the mine. In conventional method of extraction worked by LHD/SDL has gallery width up to 4.8 m. However, in mechanized mining operation, gallery width goes up to 6.6 m. As per the Director General of Mine Safety (DGMS) guidelines, suggested support pattern is given for gallery width up to 4.8m. In this paper, the study focused to develop generalized equation of roof failure height during development working for wider gallery operation. The input parameters have taken into consideration are rock mass rating (RMR), uniaxial compressive strength (UCS), in-situ stress ratio, depth of working, ratio of gallery width to height. The immediate roof of the model has considered as elasto-plastic in nature. By, considering all these parameters rock load height has been estimated at gallery and junction of the mine during development operation. A generalized equation has been made for gallery as well as junction with the help of regression analysis based on numbers of model results, considering all the input parameters. The required support load density has been estimating with the help of generalized equation. For calibration of the model results, number of case studies has been solved and analyzed.

In an underground coal mine, most successful and economical approach to support the underground structure is roof bolting technology. The most preferred method of working in Indian coal mine is Bord and Pillar. It has been observed from the past histories that, the maximum number of accidents happens during depillaring operation. In this paper, the primary focus is to understand and analyze the roof behavior with roof bolting system in underground coal mine using numerical simulation approach. A three-dimensional (3D) model of the depillaring panel with support design using roof bolt technology is complicated to simulate. Therefore, the simulation is done near the goaf edge, where maximum chances of roof failure have been observed. On another word, it can say that simulation is done before the main fall. An elasto-plastic model has been taken for study considering physico-mechanical properties, geo-mining condition, roof bolt and grout properties as an input parameter. A case of a depillaring panel of underground coal mine has been chosen for study. The result is observed regarding axial load exerted on the bolt during mine operation. Instrumented rock bolt data has been taken for validation of the model from field observation. It has been observed in the model that maximum axial load developed on the bolt is very close to the field observation.

Abstract-Roof bolting technology is widely used for support design in an underground coal mine. This paper focused on the numerical simulation considered the behaviour of roof and rock -grout -bolt interaction. Simulation of three dimensional model of depillaring panel with roof bolt support is difficult to simulate. Therefore, an analogy has been developed to replicate three dimensional depillaring panel into two dimension considered physico-mechanical properties of the immediate roof, geotechnical property of the mine and bolt and grout properties as an input parameters. A case of depillaring panel has been chosen for study. The simulation of rock bolt gives the result in terms of axial load developed on the bolt with depillaring panel advancement. Field observation of instrumented rock bolt has taken for validation of the numerical model. It has been observed that the maximum load developed on the model is very close to the field data.