Correlation Survey for Shaft Deepening in Digwadih Underground Coal Mine

While deepening a shaft of an underground mine, it is essential to maintain the verticality of the shaft for the smooth working of cages. The position of the center of the shaft should be known throughout the shaft and needs to be transferred at various levels in the mine. The conventional correlation survey technique makes use of plumb wires suspended from the top of the shaft in order to transfer the position of a point and that of the direction of a plumb plane from the surface to the pit bottom in the underground. To locate the position of the center of the shaft at other levels, a theodolite traverse from the pit bottom to other levels is run through connecting drifts and galleries near to the desired point. The method is tedious, cumbersome, time-consuming, and less accurate. This present paper describes an exercise taken up for the first time in India to transfer the center of a mine shaft from the surface to different seams in the underground mine with the help of modern instruments and techniques using a laser beam, gyro-theodolite, and total station. The results are discussed. The method is found to be easy, accurate, and less time-consuming.