ESTIMATION OF KARST SINKHOLE HAZARD — DETERMINISTIC OR STOCHASTIC?

Abstract

The place of deterministic and probabilistic approaches of estimation of karst-suffusion and karst-landslide hazard is analyzed. It is evident that the field of deterministic calculations in comparison with the landslide capability assessment is turning out to be narrower because of the low availability to study the karst caverns, which are the most important elements in the sinkhole-formation processes. The sinkhole-formation hazard forms as a result of the cooperation of 2 factors in the certain area: the critical size of the zone of possible destruction of the clayly soil stratum (“screen”) over the unfilled karst cavern and the required volume of the receiving cavern or fractured karst collector where the collapsing and decompression material can be carried. At the present day it is impossible to identify in advance the presence of these factors there. In the highly researched areas with fairly simple models of sinkhole-formation processes it is advisable to test and verify the new methods of forecasting the location of the probable karst sinkholes along with the deterministic geomechanical calculations and physical laboratory modeling for sinkhole diameters estimation. In other cases the combination of zoning based on the geological and hydrogeological typing of conditions and mechanisms of sinkhole-formation and probabilistic methods gives the opportunity for more adequate forecasting of the parameters of sinkholes and probable intensity of their formation. It is also stimulates more reasonable appliance of the method of natural (natural and man-made) analogs and helps to use relevant methods for different models of geological massif in deterministic calculations. While the estimation of the sinkhole-formation hazard it is necessary to take into account the presence of the weakened zone along the perimeter of the karst sinkhole and the probable creep of the “screen” soil stratum.