Assessment of the Foundation of Tunisia Ghezala Dam

Abstract

Ghezala Earth Dam was built in the city of Mateur in the North West area of Tunisia. The filling of the dam reservoir, with a storage capacity close to one hundred thousand cubic meters, started in 1985 and lasted for 2 years. The dam foundation is essentially composed of consistent clayey marl layer. At the lower level of the dam, reinforced concrete drainage, gallery was constructed to evacuate water, when needed, from the upstream side to downstream side. The gallery structure is composed of eleven 15 m length sections. During its service life (more than 26 years), an installed health monitoring system permitted, in particular, the measurement of consolidation settlement which has occurred in the soil foundation. This follow up system made it possible to observe the cracks which mainly developed progressively in the central portion of the drainage gallery due to differential settlements. In this context, a 2D numerical simulation of the behavior of dam foundation was performed by adopting the Mohr–Coulomb model for the dam’s material and the soil foundation. Numerical predictions of the consolidation settlement development were compared to those measured in situ and a good agreement was found between the two. This finding highlights the effectiveness of the adopted model for the studied case.