COLLAPSE DOLINES IN MIOCENE GYPSUM - AN EXAMPLE FROM SW SIVAS (TURKEY)

This study investigated the formation mechanism of dolines. Dolines ar e caused by dissolution of gypsum in the study area, 50-220 m in diame ter. Two systems were applied to determine the support necessary for n atural underground opening of given span in a given rock mass. From th e characteristics of the rock mass, a 5 m-wide unsupported span in the gypsum can be expected to stand up for over 9 years. The designed spa n of an artificial opening would normally be considerably less than th e span of a collapsed natural opening in the same rock. Dolines in the study area play an important role in the groundwater flow system.