Engineering theory of slide processes in the design of earth dams on a soft ground foundation

Abstract

1. The engineering theory of slide processes, existing practice (slides that have occurred on constructed earth dams), and also the existing standards and recommendations are unanimous in that for earth dams having a soft ground foundation, rotational slip along a cylindrical surface of sliding is the potentially most dangerous. Furthermore, the theory of slide processes and existing practice note that under certain conditions described above slides due to bulging and spreading are also possible on these dams. However, the existing standards and recommendations orient the designer to checking the stability of slopes of dams in the presence of weakened interlayers along plane surfaces of sliding. 2. Investigations show that the engineering method of calculating the stability of slopes of earth dams must be optimized together with other operations providing a prediction and monitoring of the stability of the slopes, which amount in volume to 70–90% of all this work. It is also necessary to check the method of calculation on a number of dams that have actually failed. The VNIIG-Terzaghi method, for example, passed such a check, in the literature there are no data on such a check of the method of inclined forces of interaction. 3. It is necessary to take into account that the geological section of the dam foundation is regarded by the geologist as a more or less substantiated geological and geotechnical hypothesis which is refined as data are accumulated. Therefore, it is very important to check the initial geological information during construction by engineering means — to construct an experimental embankment equipped with monitoring and measuring instruments, etc., and also to have the practical possibility of repeating the calculations of the dam after each refinement of the initial information in order to correct in good time the design of the dam in conformity with the actual conditions. Several examples of such kind are described in [3].