Influence of Joint Orientation on the Behavior of Dam Resting on Jointed Rock Mass Under Static Condition

In this paper, elasto-plastic analyses of concrete gravity dam are performed to investigate the influences of intact rock, rock foundations with single set of joints (0°, 30°, 60°, 90°, 120° and 150°) and orthogonal set of joints (0°/90°, 30°/120°, 60°/150°) on the stress-deformation behavior of such dam. Discrete element analyses are carried out using UDEC (1993) for two specific static load combinations (LC) i.e. considering dead weight of the dam having empty reservoir (LC-A) and considering dead weight of the dam along with full reservoir condition (LC-B) as per IS: 6512 (Criteria for solid gravity dams, Bureau of Indian Standard, New Delhi, 1984). The orientations and spacing of the single and orthogonal joints in the rock masses are found to play vital roles in stress generation and deformation characteristics within the dam body. For all the dam foundations, the compressive stresses are found greater in magnitude at the heel of the dam than the toe for load combination A whereas, under load combination B, the stresses are higher at the toe of the dam than the heel. The rock foundations having 30°/120° and 0°/90° orthogonal set of joints are found to be critical in terms of possessing maximum compressive stresses in the dam body for load combinations A and B respectively. The magnitude of principal stresses is observed to follow an increasing pattern as the spacing between the joints decreases for all the rock foundations. © 2018, Indian Geotechnical Society.