Evaluation Of Hydrodynamic Pressure In Arch Dams Under Earthquakes
The evaluation of hydrodynamic pressures along the upstream face is a critical parameter for the analysis and
design of an arch dam. As there are no proper methods available for the evaluation of pressure this paper proposes a new
practical procedure to evaluate the hydrodynamic pressure coefficients in arch dams during earthquake by considering the
finite element analysis of the impounded reservoir. The arch dam system has been considered to be composed of two
substructures, namely the reservoir and the dam. For different combinations of slopes and vertical portion of upstream faces,
reservoir systems are derived for twenty different sections. Upstream breaks at depths of 3/4, 1/2, 1/4 of dam heights are
introduced. Angles of 150, 300,450 and 600 of variable upstream faces are contemplated for each break. The bottom of
reservoir is assumed to be rigid and horizontal. The governing equation with related boundary conditions is implemented in
the finite element analysis considering horizontal earthquake components. The reservoir, has been idealized using three and
four noded isoparametric finite elements. This procedure enhances the efficiency of seismic assessment of arch dams by
reducing the modeling and computational difficulty combined with reservoir discretization while keeping the advantages of
conventional finite-element software in conducting seismic analysis.
Key words- Arch dams, Finite Element method, Pressure coefficients, Hydrodynamic pressure.