Specific Features of Karst-Suffosion Hazard Assessment for Different Engineering Structures in Moscow

About 17% of Moscow area is occupied by hazardous and potentially hazardous regions in relation to karst and suffusion. Projecting and civil construction there should be carried out with the preliminary assessment of karst-related hazard. In megacities, the karst-related hazard assessment depends on the type of an engineering structure. The first group of structures includes metro lines, linear on-surface transport facilities, etc., linked to urban infrastructure facilities so that their route cannot be changed. Another group of engineering structures encompasses subsurface facilities and buildings with deep-seated basements, where geological conditions are transformed substantially. The safety of engineering structures may be ensured in two ways. The first way implies making allowance for the possible karst collapses in the construction project. The second way is to place a building foundation below the karst-suffosion-prone layer in order to prevent collapses in the basement ground. When choosing project options and protective measures, the size of possible collapses or sinkholes in an engineering structure basement is one of the most important calculation indices. For metro lines, the choice of calculation model should be preceded by territory zoning for outlining sites differing in the mechanism of karst-suffosion development. The cases of Bol’shoi Theater reconstruction site and one of the new metro lines in Moscow are discussed as the examples.