Outstanding scientist in the field of underground development of mineral deposits, Professor, Doctor of Technical Sciences, Head of the Department of Development of ore deposits of the Leningrad Mining Institute Vladimir N. Semevsky was born in 1898. After graduating from high school from 1918 to 1922, a Red Army fighter he defended the western borders of the young Soviet Republic.

The Kaula copper-nickel deposit was developed in the upper part by open pit and in the lower part by underground mining with priority extraction of chamber reserves. Recently, the second stage of development - excavation of the remaining ore pillars - has been switched to. The deposit is represented by a stratum-shaped deposit with variable thickness and dip angle; the depth of occurrence is up to 400 meters (vertically). The strength of the ore is characterized by a coefficient of 8-12, and of the host rocks - 8-14 according to M. M. Protodyakonov.

In the underground development of non-ferrous metal deposits quite often ore inter-chamber pillars are replaced by artificial usually concrete “pillars” - supports to achieve the most complete extraction of rich ores, to get the opportunity to use high-productive methods of ore stripping both in the chambers and in the mining of pillars. From the point of view of reducing the cost of ore, the thickness of supports and the strength of concrete should be as small as possible. At the same time, the concrete supports should be strong and stable enough until the end of ore extraction operations, and sometimes for a longer period of time. Therefore, choosing the optimum dimensions of concrete supports is very important and responsible. However, there is still no definite methodology for calculating the parameters of concrete piers. Their sizes and concrete strength grades are usually determined on the basis of practice data.

At two-stage development of powerful steeply falling deposits with replacement of inter-chamber ore pillars with concrete wall supports it is very important to choose the right wall thickness and concrete grade. The methodology of such calculations is insufficiently covered in mining engineering literature. Laboratory studies on models at the Leningrad Mining Institute have shown that inter-chamber concrete supports in mining systems with ore storage or under-storey stripping (with subsequent filling of chambers with stockpiles) resist lateral loads like thin slabs with different fixing along the contour. The final destruction of the wall under the action of lateral loading occurs from the loss of stability by overturning or shear (wall subsidence).

In the practice of ore deposit development, the need to maintain the rocks surrounding the ore body being mined in static equilibrium for a long period of time arises in connection with cleaning operations under structures, reservoirs or under active open pits. This can be accomplished by leaving ore pillars of sufficient size or by excavating all of the ore but constructing artificial supports to keep the surrounding rocks stable. In the first case, the ore is extracted from the chambers by highly efficient systems, while the ore pillars remain or, after they are no longer needed, are extracted, but usually by low-performance systems, under difficult conditions and with great loss. In the second case, when artificial supports are used, their erection is associated with additional work and costs.

In the practice of the mining industry, there are cases when the release of manganese ore from the chambers has to be carried out under a rock fill, which is lowered after the ore and is continuously added as the ore is released. The need for this may be encountered when the rocks of the hanging wall or the inter-chamber ore pillars are not stable enough. In this case, the stockpile lies directly on top of the ore or a slab is used to separate the ore and the stockpile to prevent the stockpile material from stripping the ore. However, the overlap may not always fulfill this role. For example, if the dip angle is not steep enough and the floor is high, it will drop to the lay side early, and a significant amount of ore will then be released virtually uncovered. The overlap falling on the lying side, together with the stockpile lying on it, may also clamp some of the ore, which will then be lost. This is due to the tendency of the ore pieces, the backfill and the slab itself to move vertically downwards under the influence of gravity.