The determination of vertical movements in Alibey dam

Alibey Barajı is an earthfill dam established on Alibeyköy River. Foreseeing the action of main soil has an importance effect on earthfills which is established on thick soft soil layer. Deformaiton Measurements have an importance role in the practices of engineering measuremetns. The results of deformations, which are likely to appear in time on civil engineering constructions built artificially and on natural environment, are closely related to human life. Therefore, deformation measurements has an effective role on determining the changes occurred on earth?s crust and civil engineering constructions in time with the measurements to be made and comment on them and also preventing serious damages likely to occur.Many geodesic methods are used in order to observe deformations likely to occur in time on civil engineering constructions and movements of earth?s crust. The determination of vertical deformations through geodesic methods depends on evaluation and analysis of the measurements based on periodically made classic or satellite technologies on the control points organized for this purpose. The precise differential levelling, precise trigonometric levelling technique and hydrostatical levelling method are used for the determination of vertical deformations.Because of developments in technology, using digital-electronic levelling instruments in the technique of differential levelling enables measurements to be made easier. The height difference between two points is found by using vertical angle and length in the method of trigonometric levelling. Nowadays, it is possible to determine the vertical position changes through precise trigonometric levelling in an easier way.Dams are big and important civil engineering constructions in which millions of cubic metres water are retained. Vertical and horizontal movements happen in those constructions by the effects of many various factors. Those movements, which are generally called as deformations, exceeding the critical limits might cause damage and even its collapse. The analysis of deformation is a crucial step for big and high-priced constructions particularly such as dams.In the scope of this study, the measurements obtained through the method of differential levelling which was started in April in 1987 and made in 1999, 2004, 2009 and 2011 in order to determine the vertical changes occurred in Alibeyköy Dam have been evaluated. The same approximate coordinate values have been used for all measurement periods. Free network adjustments of each measurement period have been performed according to indirect measurements method. The results are presented according to Hannover Approach (Average Outliers Method, -criterion) as mathematics statistically in deformation analysis.Key words: Deformation, deformation measurements, deformation analysis, precise differential levelling, vertical position changes