The method of calculation is based on the fact that the size of the cleaning chamber is determined by the ultimate stability of the roof after the end of cleaning work in the chamber. Consequently, the system and sequence of chamber mining do not affect the proposed method of calculation.

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).