ИСТИНА

In the new social and political conditions of Vietnam's transition economy, the transformation of the riverside territories is of great importance for both the city of Hanoi and the country as a whole. A special role is given to the system of dams along the Hanga River (Red), which protect the city from floods. During the long history of construction and operation of the dams in Hanoi, many cases of their damage and destruction are known. The article deals with possible mech-anisms of dam stability loss due to changes in hydrological conditions. By math-ematical modeling the stability of the dam slopes and filtration strength of soils of its base due to increasing in time during flooding hydraulic gradient is estimated. This task was solved in the flat setting, meanwhile filtration modeling was carried out by the finite elements method, and the estimation of the dam slopes stability was carried out on the basis of the limit equilibrium method. The performed mathematical modeling allowed to estimate the dam stability from two positions: 1) change of the dam slope factor safety in time during the flood period; 2) in-crease of the hydraulic gradient in soils of the dam base during the flood period. The results obtained showed that the reliability of the dam depends both on the thickness of the clay layer at its base and on the duration of flooding. The factors we have identified that affect the stability of dams during flood periods can be used for predicted purposes to assess their reliability.