Orientation of Mine Shafts

a series of mine surveying operations used to establish the geometric relations between surveys of underground excavations and the earth’s surface, to ensure correspondence between the respective mine survey plans. Mine orientation makes possible the solution of critical problems in the sinking of mine shafts and the driving of tunnels and workings from opposite directions and in protecting surface objects and structures from the adverse effects of underground mining. Mine orientation consists of determining the directional angle a of the theodolite traverse directions of the underground survey and the coordinates X, Y, and Z of one of the points of this traverse in the system of coordinates used on the surface.

Mine orientation is performed by geometric, optical, magnetic, and gyroscopic methods. Three geometric orientation methods are used, depending on the type of connection of the underground excavations with the earth’s surface: (1) through a gallery or inclined shaft, by continuation of a polygonometric traverse from points on the earth’s surface to points marked in the underground excavations; (2) through a single vertical shaft, by lowering into the shaft two plumb bobs forming a vertically projecting plane and by solving the problem of geometric contiguity to the plumb bobs on the surface and in the shaft; (3) through two vertical shafts connected by mining excavations, by lowering a plumb bob into each shaft, determining its coordinates on the surface, and plotting a polygonometric traverse between the plumb bobs in the shaft. The optical method consists of orientation by means of a direction projector. Magnetic orientation is performed by instruments with a magnetic needle—for example, compasses, reflecting compasses, or declinators. Gyroscopic orientation, the most advanced method of mine orientation, is based on use of the ability of a gyroscope axis to establish itself in the plane of the astronomical meridian. In the USSR, mine orientation is performed with the MVT2 and MVT4 mine surveying gyrocompasses designed by the All-Union Research Institute of Mine Surveying or the Ci-Bl or Ci-B2 gyrocompasses (Hungary).

In geometric orientation the coordinates X and Y are transferred by contiguity to the plumb bobs simultaneously with the orientation. The Z coordinates are transferred through a vertical shaft, by a special measuring tape, wire length gauges, and other instruments, or through a gallery or inclined shaft, by geometric or trigonometric leveling. In gyroscopic and magnetic mine orientation, the coordinates X, Y, and Z are transferred to the mine shaft independently by one of the above methods.