ANALYSIS OF SEISMIC RESPONSE OF THE 'MRATINJE' HIGH ARCH DAM

摘要

In this paper, safety assessment of a large concrete arch dam "Mratinje" on the river Piva in Montenegro, built in seismic active region thirty years ago, is analyzed. It is a high arch concrete dam of double curvature and height 200 m. For the seismic analysis of the dam, dynamic characteristics have been determined by experimental analyses, which in turn enabled the control of numerical model and its calibration. Research is based on numerical analysis of simultaneous interactive system dam-foundation-reservoir using 3-D finite elements. Dynamic analysis of the system is performed with assumptions about mass-less foundation. Analysis consists of two parts. First part, linear analysis of the system dam-foundation-reservoir is studied as an elastic continuum with viscous damping and uniform free-field ground motion with variable frequency range. Second part, nonlinear analysis is based on assumption of the dam as series of cantilever monoliths detached by contraction joints, under extremely strong earthquake action, which is relevant for the dam safety. The contraction joints can not transfer substantial tensile arch stresses, so they may open and close as the dam vibrates due to seismic ground motion. In this analysis, nonlinear effects arising from contraction joint movements and effects of concrete nonlinearity are included.``The results of numerical analysis are compared with the results of the experimental investigations, which resulted from the forced vibration in-site tests. Conclusions about dam safety assessments are presented.