3-D Spatial Analysis of Deformation at Ikpoba Dam From GPS Data

Abstract

Earth dams are subject to external loading that induce deformation in the structure and its foundation. The self weight of the dam together with the reservoir water pressure induce stresses in the structure and with time creates horizontal and vertical displacement in the structure. In this study, analysis of the measurement data obtained by differential GPS at the Ikpoba River Dam was carried out. The measurement system consisted of 19 control and reference stations. DGPS data were collected during two measurement campaigns carried out in 2008 and 2009 respectively using five dual frequency receivers. The computation and adjustment of each epoch measurement was carried out separately in the first instance. Thereafter simultaneous adjustment using the two measurement epoch data was carried out.Points displacements were then determined and 95% confidence ellipse used to carry out an analysis of the movement vector. Analysis of the result indicated that nine of the points have moved in horizontal position while no horizontal movements have taken place in 10 locations. On the other hand, vertical shift has occurred in seven locations whereas no vertical movement has taken place in 13 locations both outside and along the Dam crest.

Journal of the Nigerian Association of Mathematical Physics, Volume 19 (November, 2011), pp 493 – 498