AN ASSESSMENT OF MODELING ALTERNATIVES OF CONCRETE GRAVITY DAM FOR UPLIFT PRESSURE

Abstract

It is well known fact that massive structures like dam attract lot of external interests other than engineering. It may not be always possible to build a dam on safe locations from engineering and geological point of views. It is, therefore, a necessity to carry out analyses considering unfavourable locations or foundations and study the behaviour and assess the safety of structures like dam, having huge destructive potential. Uplift Pressure due to seepage is the major problem for most of the Hydraulic Structures like Dams, Weirs and Barrages. It is always a challenge to know the uplift pressure distribution at super and sub structure interface due to seepage. The interaction between the dam wall, the impounded water, the tail water and the foundation results in development of Uplift and pore pressure. In this dissertation work an attempt is made to determine the uplift pressure head distribution at super and sub structure interface. For this study representative dam models are adopted. As the governing differential equation is same for seepage flow and heat flow, thermal analysis is adopted to determine uplift heads in terms of nodal temperatures. The obtained results from seepage analysis are compared with code based provisions. In stress analysis the effect of discontinuity at dam foundation interface is simulated using the contact or interface elements in ANSYS. The static as well as dynamic analyses are performed on dam models with different foundation interactions. The analytical results obtained from both static and dynamic cases show that the finite element model can simulate the discontinuity effects due to friction when compared to models which do not consider the friction into account. The analytical results, further, indicate that the continuous and the discontinuous models differ in the static and dynamic responses under the loading considered.