Another specific feature is that, due to the large total thickness of the formation suite, the terrain relief changes dramatically after additional working.. The pillar-protected areas appear to be much higher than the surrounding underworked area. This, in turn, leads to a change in the hydrogeological regime, activation of landslide phenomena, weathering and erosion, which affects the safety of buildings and structures protected by pillars..
The most characteristic feature of the development of the cities of Prokopyevsk and Kisslevsk is their placement above the core of synclinal folds. When mining the two upper horizons, three zones can be distinguished. The first zone A — these are areas above the outcrops of layers, on which dips and large collapse cracks were formed. There is no building on these plots. The second zone B is the areas where the influence of underworking from the excavation of the upper horizons affected. The zone is partly built up with one-story individual houses, already part-time. The third zone C is the sites that were not affected by the development of the upper horizons, where the main urban development is concentrated. It is clear that with such an arrangement of buildings, the abandonment of pillars on the upper horizons was not required. During the development of the 3rd and 4th horizons, almost all the space above the fold core turns out to be underworked. With this arrangement, the buildings fall into the edge part of the displacement trough, i.e., to the areas of maximum tensile deformations, where cracks-ledges can form..
It is noticed that the places of formation of cracks with ledges are located above the outlet under the pumps of ruptures, which often coincide with the axis of the synclinal folds..
The main part of residential buildings in the cities of Prokopyevsk and Kiselevsk is low-rise wooden. When working on such houses, as experience has shown, even a 20 cm high ledge does not cause destruction, and after major repairs, further operation of the buildings is possible. Demolish only buildings hitting large cracks with a ledge.
With horizontal deformations equal to 10 mm and ledges up to 10 cm high, which should be expected in the edge part of the trough when mining the suite of layers on the 3rd horizon, the wooden buildings will remain and only dilapidated houses will be demolished.