Study of Vertical and Horizontal Displacements of Eyvashan Earth Dam Using Instrumentation and Numerical Analysis

Generally, the safety of a dam is not only related to its design and construction, but also to the complete characterization of its performance during the first dewatering and operation period, as well as regular service during the life of the dam. In this study, the vertical and horizontal displacements of the Eyvashan Dam were analyzed using actual instrument results in an eight-year period in three steps of construction, first dewatering and operation period. The numerical model of the largest section of the dam was prepared by Geostudio and Plaxis software and examined with respect to the behavioral model of Mohr–Coulomb. According to the results of the instrumentation, the settlement of the dam core has increasing trend and sometimes after the construction, it reaches almost constant. The maximum settlement of the dam core at the end of construction phase was 809 mm which is equal to 1.2% of the dam height at the middle level. The horizontal displacements in the longitudinal direction of dam upstream are completely influenced by the reservoir water level and hydrostatic forces. The maximum horizontal displacement in the upper crust of Eyvashan dam is 75.6 mm. After reservoir filling, the amount of settlement from the lower levels to the higher levels (crest of the dam) have had an increasing trend. In order to adapt the observational and predictive data, multivariate regression and determination coefficient were used which showed a consistency result of about 85 percent between observation and prediction data. This indicates that the maximum settlements and their location are agreed well with the technical specifications, revealing the proper operation of the dam in terms of settlement.