Research Center for Geomechanics and Mining Practice Problems, Saint-Petersburg Mining University, Saint-Petersburg, Russia:
Yu. I. Kutepov, Head of Laboratory, Professor, Doctor of Engineering Sciences, koutepovy@mail.ru
N. A. Kutepova, Chief Researcher, Doctor of Engineering Sciences
G. B. Pospekhov, Leading Researcher, Candidate of Geological and Mineralogical Sciences
A. D. Vasilieva, Researcher, Candidate of Engineering Sciences

The recent trend of increasing intake capacity of phosphogypsum storages by means of adding their height to 100 m and more involves a growing risk of landslide deformations. Geomechanical feasibility evaluation and parametric optimization of phosphogypsum dumps to ensure their maximum intake capacity and safety should use the geological and geotechnical information and learn the laws of phosphogypsum condition and properties in human-made masses. The geological and hydrogeological investigations carried out at three largest dumps made of different type phosphogypsum piled to a height of 60 to 105 m enable distinguishing three geotechnical elements (layers) in the structure of each of these human made masses; these layers differ in structure, porosity, density, texture, water content and mechanical properties. The strata of each geotechnical element are characterized with the standard indicators of physical and mechanical properties, which can be used in solving problems of geomechanics. These layers have varied thicknesses dependent on the composition of phosphogypsum, the height of the dump and the level of a manmade aquifer; the latter depends, in its turn, on the volume ratio of dihydrate and hemihydrate phosphogypsum types and their piling order.

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