Static and Coupled Hydro-mechanical Analyses of Concrete Gravity Dam Resting on Jointed Rock Foundation

The article investigates the effect of rock joint orientation and spacing on the stress-deformation behavior and uplift pressure distribution of a dam-foundation system under two specific static load combinations (LC-A, and LC-B) as specified in IS: 6512 (Criteria for design of Solid Gravity Dams. Bureau of Indian Standard, New Delhi, 1984) using Distinct Element Method (DEM). Change in the magnitude, nature of the stresses and displacements at critical locations on the dam have been studied. The coupled hydro-mechanical analysis has been carried out to examine the influence of uplift pressure distribution at a dam-foundation interface on the stability of the dam for different rock mass conditions. Results confirm that the limit equilibrium approach mentioned in IS: 6512 (Criteria for design of Solid Gravity Dams. Bureau of Indian Standard, New Delhi, 1984) underestimates the magnitude of the stresses at the heel and toe of the dam as compared to the values of UDEC analysis. Moreover, a non-linear distribution of the uplift pressure is found in the DEM coupled hydro-mechanical analysis, unlike the conventional linear model specified in IS: 6512 (Criteria for design of Solid Gravity Dams. Bureau of Indian Standard, New Delhi, 1984). The maximum change of the uplift pressure for single joint sets is observed in the case of 90° joint set, whereas the minimum is observed for the 30° joint sets. The crest displacement in Y-direction is observed to increase with the decreasing joint spacing irrespective of joint sets. Furthermore, the fluctuations in the water level in the reservoir are found to have a significant impact on the horizontal displacement of the crest of the dam.