A new computational approaches for studies of stress-strain state and bearing capacity of "arch dam - rock foundation" system are presented here. Results of computational studies for a 190 m height arch dam under different conditions: continuous foundation, subvertical joint in foundation under upstream face of dam, displacement of left dam abutment on tectonic fissure, various dam cutting into rock foundation - are presented.
De non velles règles etablies par calculs sont formulees afin d'analyser I'etat de tension et de deformation aiissi bien que la capacite portante d'un système "barrage voûte-fondation rocheuses". Les resultats d'un recherche qui ont traitaun barrage-voûte de hecuteur de 190 m sont cite comple tenu de diverses conditions: fondation continue; joint sous vertical dans la fondation sous Ie parement amont; deplacernent de I'epaulement gauche le long d'une fissure tectonique; diverse alternatives de I'encanstrement du barrage dans une fondation rocheuse.
Neue Berechnungs regeln fUr Forschungen des Beanspruchung - und Defoormationzustands des Systems "Bogenmauer - Felssohle" sind formulert. Ergebniβen der Forschungen einer 190 m höhen Bogenmauern unter verschiederen Bedingungen sind angefuehrt (ununterbrochene Sohle; subvertikale Fuge in der Sohle unter der Wasserseite; versetzung des Rechtsuferanschluβ langs der tektonischer Riβ; veschiedene Methoden der Mauereinbindung in einer Felssohle).
Modern computers and numerical methods allow to create a new approach for estimation of bearing capacity of arch dam and rock foundation (Mgalobelov 1989). An arch dam together with rock foundation is analysed by finite elements method (FEM) assuming elasticity; finite elements approximation is to be sufficient to describe major geological specifics, strength and deformability of rock foundation. Then a local strength of foundation (Mohr criteria for mass, Coulomb criteria for faults, fissures and dam-foundation contact are to be applied; a special attention is to be paid to zone of foundation near upstream face) and strength of dam regarding possible opening of joints are to be checked. In case local strength is exceeded the stress state of dam and foundation are corrected by iterations according to strength criteries. On base of joints opening and compression stresses in the dam, place and dimensions of decompaction zones and zones of non-linear strains in the foundation a conclusion on stress state and strength of the "dam-foundation" system under operation can be done. A consideration of dam construction and reservoir filling history is desirable, but even without it an information on stress state of "dam-foundation" system under operation in much more precise in case of non-linear analysis in compare with an elastic solution, according to our research experience. In case there are faults or large discontinuities in the foundation, which non-elastic displacements took place in non-linear solution, or in case of non-linear strains zones below the downstream face of dam it is possible to studies an effect of various weaknesses in the foundation on a strength of "dam-foundation" system. If the strength of system is not satisfied due to a weakness, improvement measures are to be taken (concrete filing of faults or large fissuries, anchoring of foundation below the downstream face, etc.), after that the new analyse is to be done. A necessity of any improvement measure can be found using this approach and the most applicable construction of this measure can be chosen.. Increasing s water pressure on the dam it is possible to reach the limit stage which will mean either an exceed of the dam bearing capacity or an appearing of major sliding surface in the foundation. In the second case the "dam-foundation" system becomes kinematically changeable.
