EFFECTS OF SOIL-ATMOSPHERE INTERACTION ON THE PHREATIC SURFACE AND STABILITY OF TAILING DAMS (CASE STUDY: SARCHESHMEH TAILING DAM)

Positioning of the phreatic surface in a dam body plays a critical role in the stability of tailing dams. Soil-atmosphere interaction eects, such as precipitation, runo, interception, inltration, and evaporation, on the one hand, and unsaturated soil eects, such as capillary rise, on the other, cause signicant changes in the situation of the phreatic surface.
In this paper, rst, dierent mechanisms that aect the phreatic line level in the tailing dams and their corresponding equations are studied, and a computer program is developed for calculating the uctuations of the phreatic line. Then, for evaluating the usefulness of the program in real time problems, the stability of \Sarcheshmeh" copper mine tailing dam in Rafsanjan city, Iran, has been studied. Plaxis software Ver.8.0 has been used for modeling this tailing dam. Necessary parameters for modeling this dam have been obtained from the results of dierent laboratory tests on tailing materials, and information available from synoptic stations of the meteorological organization of Iran in the area. After determining the amount of change in the phreatic level for a special period of time, the stability of the dam was studied, based on calculating the factor of safety under different conditions.
The results show that by constructing new dikes, the safety factor decreases. Also, the results show that those parameters that increase the phreatic level reduce the safety factor, and the stability of the tailing dam will be threatened. Among dierent parameters affecting the phreatic level, capillary rise was found to be the most signiffcant factor in regard to tailing dam stability when constructed in arid areas.