Numerical simulation of reservoir fluctuation effects on the nonlinear dynamic response of concrete arch dams

Abstract

Fluid-structure interaction problems occur in many engineering structures, such as dams, gates, offshore structures, storage tanks, piping systems, etc. Analysis of such interaction problems is important for the safe and economic design of future structures and the safety and performance evaluation of present ones. In the present study, reservoir fluctuation effects on the nonlinear dynamic response of concrete arch dams are investigated. The structure nonlinearity is originated from material nonlinearity due to tensile cracking and compression crushing of mass concrete using the William-Warnke failure surface in principal stress state (Smeared Crack Model). The reservoir is assumed to be compressible and foundation rock is modeled as a mass-less medium. The DEZ concrete arch dam in Iran, with a height of 203m, is selected as the case study. The system is executed using records based on the response spectrum of the dam site. It is found that fluid-structure interaction has significant structural effects on the system such that, when the reservoir level is increased, almost all structural responses of the dam body, such as crest displacement, velocity and acceleration, decrease until a special level and growth is significantly made for reservoir maximum level in the linear model. In addition, principal stresses on upstream and downstream faces increase significantly with reservoir dewatering. On the other hand, responses of the dam in the nonlinear model have special intricacies, but the extension of cracked areas in both upstream and downstream faces develop meaningfully by decreasing the reservoir water level and there is good argument between stress results in the linear and nonlinear models.