Seite - 1360 - in Book of Full Papers - Symposium Hydro Engineering

The shear strains after impounding are shown in Figure 13, illustrating the deformation characteristics of the dam and indicate the degree of mobilization in the upstream dam shoulder. It can be seen from the graph that the highest shear strains occur in the shear plane on the bottom of the wedge. The inclination 𝜓 of the shear plane is around 60° which is in a good accordance with the theoretical considerations (𝜓 = 45+𝜑 /2 = 67,5°) presented above. Fig. 13: Shear strains after impounding SUMMARY Dams with an asphalt concrete core show a different deformation behaviour compared to homogenous or surface sealed dams. In this contribution, theoretical considerations about the typical behaviour of AC dams during impounding are presented and discussed. It has been demonstrated that the core deformation during the first impounding leads to a mobilization of an upstream wedge. The mobilized wedge closes the joint between the core and the adjacent upstream zone. It also stabilizes the core when the reservoir level decreases and the horizontal support from the water pressure is lost. It has been also demonstrated that the rotation of the principal stresses in the asphalt concrete core, which arise as a result of additional shear stresses along the upstream core, have only little impact on the mobilization rate of the shear strength in the core. Finally, the measurements of two different Austrian AC dams (Feistritzbach Dam and Finstertal Dam) are discussed in the contribution. The measurements of both dams confirm the theoretical results and showed the development of a shear zone in the upstream shoulder which stabilizes the core. The results of intense numerical investigations on a typical AC dam are also presented and discussed. The analyses are in a good accordance with the measurements and the theoretical findings. The upstream wedge with the formed shear zone was also clearly evaluated in the numerical analyses. The presented results and findings contribute to a better understanding of the deformation behaviour of AC dams. 1360