Seite - 740 - in Book of Full Papers - Symposium Hydro Engineering

4. RESULTS In this chapter, the results of the calculations with different variables are presented and discussed. FRICTION ANGLE (AND ANGLE OF FOUNDATION) Variation in friction angle is also valid for inclination of the foundation, since horizontal capacity is defined as ∑𝑉 tan(𝜙 +𝛼 ) (see chapter 2). The friction angle has no effect on the FoS against overturning. The computations show that the FoS against sliding is the same for all different dam heights. This imply that friction angles is directly related to FoS, and that the dam height do not influence the results. This means that a change in the friction angle will give the same change of the FoS regardless of the dam height. This can, of course, also bee seen directly from the definition of FoS against sliding. The friction angle will normally be conservative where the friction angle also “includes” possible cohesion and shear capacity due to rock surface roughness. This implies that the corresponding safety factor from friction, should be 1,0. The calculations carried out, also show that a conservative friction angle will result in a high level of safety that is not necessarily reflected in the computed FoS for the dam. Fig. 3. Correlation between FoS and friction angle. αk is the initial friction angle where the different dam sections have a FoS = 1.0. WATER LEVEL How variations in the water level influence the FoS, will identify how sensitive the dam is to changes in flood water level. Changes in design water level can for instance be caused by changes in future flood calculations etc. How much this 740