Hydrogeomechanical Conditions of Karst Sinkhole Formation in the Area of Potassium Mines in Berezniki T., Perm Krai

The study area refers to the class of highly complex geotechnical conditions. Hazardous geological processes (HGP) are active here, including high seismicity up to 7 points MSK-64, karst, suffosion, subsidence and collapses of land surface, underflooding and flooding, erosion, ecological processes, etc. Large industrial plants with hazardous production and complex infrastructure are in operation here. One such plant is the First Berezniki Potassium Production Mine (BPPM-1), which have been operated since 1954. Its mine field extends below the industrial zone and the residential quarters of the town. An accident took place here in 2006, resulting in the inundation of the entire mined-out space with a volume of more than 80 million m3 and the formation of huge collapses of land surface in 2007, 2010, 2011, and 2015. The geological structure of a mine in the Verkhnekamskoe deposit of potassium salts is used as an example to discuss the effect of two leading groups of geological factors on the formation of karst sinkholes. Analysis is given to the hydrodynamic conditions and geomechanical structure of the above-salt rock stratum, whose synergy determines the diversity of models of possible development of deformations and collapses of land surface. The article gives the possible development schemes of land surface collapses above the mined-out space. The objective of the study is to assess and forecast the development of hazardous geological processes in the territory of Berezniki T. based on the geotechnical interpretation of the available materials of geological works, engineering surveys, and integral monitoring observations.