Predictions of total deformations in Jebba main dam by finite element analysis technique

Abstract

This paper examined the deformations of the Jebba Main Dam, Jebba Nigeria using the finite element method. The study also evaluated the predicted deformations and compared them with the actual deformations in the dam to identify possible causes of the observed longitudinal crack at the dam crest. The Jebba dam is a sloping earth core rockfill. The study methodology consists of the modeling of the dam with the utilization of the actual dam section, development of Finite Element mathematical formulations using plain strain conditions and total stress approach, and simulation of such model using a computer program developed in Visual Basic Language. The 3-node isoparametric triangular elements were used to analyze the model dam. The dam was simulated for end of construction (no water) and full reservoir loadings. The results of the study showed that the actual crest settlement as at 2001 was 184 mm and the predicted total settlements were 280 mm and 307 mm for the two models adopted. Generally, the deformations in the dam body were higher than deformations in the dam foundation. This may have resulted from the adequate foundation compaction during construction. The cracks development criteria were based on the criteria developed by Thomas. From these criteria, the dam was found to have developed cracks due to settlements and hydraulic fracturing.

Journal of the Nigerian Association of Mathematical Physics Vol. 9 2005: pp. 479-492