УСТОЙЧИВОСТЬ ГРУНТОВОЙ ПЛОТИНЫ С ВЕРТИКАЛЬНОЙ ДИАФРАГМОЙ

Abstract

Earth dam with impervious element in the form of asphaltic concrete core is currently the most promising type of earth dams (due to simple construction technology and universal service properties of asphaltic concrete) and is widely used in the world. However, experience in the construction and operation of high dams (above 160 m) is not available, and their work is scarcely explored. In this regard, the paper discusses the results of computational prediction of the stress-strain state and stability of a high earth dam (256 m high) with the core. The authors considered asphaltic concrete containing 7 % of bitumen as the material of the core. Gravel was considered as the material of resistant prisms. Design characteristics of the rolled asphaltic concrete and gravel were obtained from the processing of the results of triaxial tests. The calculations were performed using finite element method in elastoplastic formulation and basing on the phased construction of the dam and reservoir filling. The research shows, that the work of embankment dam with vertical core during filling of the reservoir is characterized by horizontal displacement of the lower resistant prism in the tailrace and the formation of a hard wedge prism descending along the core in the upper resistant prism. The key issue of the safety assessment is to determine the safety factor of the overall stability of the dam, for calculation of which the destruction of the earth dam is necessary, which can be done by reducing the strength properties of the dam materials. As a results of the calculations, the destruction of the dam occurs with a decrease in the strength characteristics of the materials of the dam by 2.5 times. The dam stability depends on the stability of the lower resistant prism. The destruction of its slope occurs on the classical circular-cylindrical surface. The presence of a potential collapse surface in the upper resistant prism (on the edges of the descending wedge) does not affect the overall stability of the dam.