No abstract

Methods employing local or general safety factors are presently used when analyzing the stability of dam slopes. The local factors, representing the ratio of the ultimate to the actual stresses at points in the dam body, make it possible to construct lines of equal safety factors from the results of calculating the stress and strain states and to make a qualitative analysis of the degree of stability of the dam. The general safety factors give a quantitative evaluation of this degree of stability. In the standards and in design practice there is the firmly entrenched concept that stability is calculated to obtain a quantitative evaluation of the degree of slope stability, i.e., the safety factor (ksaf). Numerous methods for determining ksa f exist.

In hydraulic engineering practice we often encounter curved retaining walls which are commonly used in links of the retaining walls of dams, powerhouses, and locks. They account for more than 25% of the total volume of retaining structures. For example, at the 22nd Congress of the CPSU Volga hydro development curved wails account for 24,906 m s of the total 81~732 m z volume of concrete in the left-bank retaining walls, i.e., 30.5%. Curved walls often reach impressive dimensions (e.g., the wall in the left-bank link of the aforesaid hydro development had a radius of curvature of 35 m and a height of 40 m). Despite the importance of curved walls the standard documents do not contain any instructions for calculating such structures. As a result of this there is a diversity in the methods of their calculation which hampers the determination of their dimensions when designing.One of the basic problems of the calculation is the determination of earth pressure on structures curvitinear in plan. This problem hadbeen taken up in various research works, but there are no single-valued conclusions. The determination of the pressure of a cohesionless mass on a curvedwalIs was presented in the work of V. I. Titova [4], who arrived at the conclusion that the lateral earth pressure on such a wall is 35-4O% less than on a straight wall.V. G. 8erezantsev [1] derived Coulomb relations for the magnitude of lateral earth pressure for the case where the backfill is within a cylindrical retainer, and appreciably smaller (than after Coulomb) magnitudes of lateral earth pressure for the case where the fill is outside a cylindrical retainer. The earth pressure on a curved retaining wall from without has also been examined in shaft construction by K. V. Ruppeneit, Yu. M. Liberman, V. V. Matvienko, Yu. A. Peslyak [10] and others, and they also obtained relations differing from Coulomb's. In all these works the friction forces between the fill and the retaining wall were disregarded. Most researchers consider that curvilinearity lessens the earth pressure on a wall.In this work an attempt is made again to examine the problem of earth pressure on curved retaining walls of hydraulic structures.