Influence of Joint Orientation on the Behavior of Dam Foundation Resting on Jointed Rock Mass Under Earthquake Loading Condition

In this article, the effect of an intact rock foundation and foundations with different single rock joint inclinations (0°, 30°, 60°, 90°) on the dynamic response of the concrete gravity dam under strong earthquake ground motion is investigated. Discrete element analyses are carried out using UDEC to study the stress-deformation behavior of dam for two specific dynamic load combinations (LC), i.e. considering the dead weight of the dam having an empty reservoir with earthquake loading (LC-D) and considering the dead weight of the dam along with hydro-dynamic force with earthquake load (LC-E) as per IS: 6512. From the results, the compressive stresses are found maximum at the heel of the dam for LC-D and maximum at the toe for LC-E. The dam foundation with 60° joint inclination was found most critical in terms of possessing maximum compressive stresses among all other cases. Dam foundation with a horizontal (0°) set of joints exhibits maximum crest displacement and base sliding. Foundations with 60° and 90° joint sets are found to undergo lower base sliding compared to other joint sets.