Abstract

This paper illustrates the pathological case of the spillway of Joumine earth dam. The dam is located on the River Joumine in the Arima region in the city of Mateur and 45 km from Bizerte governorate. The spillway is formed of 49 concrete slabs of thicknesses that vary between 1.5 and 3 m. Concrete slabs of the spillway have been affected by serious problems. The first one is related to the nature of soil foundation. In fact, it contains fissured rocks which are Maastrichtian and Campanian limestone presented a high permeability (from 1.5 10-5 to 2 10-6 m/s) which produces infiltration. Additionally, marl which characterized by swelling and shrinking, Triassic which is a hard clay with gypsum inclusions. The second one is attributed to high excess pore pressure (423 kPa in 2020) responsible of slabs up risings in marl zone. The slabs were heaving up 2 mm since 2002 and reached 6.5 mm in 2021 in marl-Triassic discontinuity. As solution, the jet grouting technique was designed to eliminate high pore pressure in the soil foundation of slabs. A numerical simulation was established to locate the critical zone of upward displacement in marl- Triassic discontinuity from 1985 to 2050. By the way, four columns are injected in the Maastrichtian Limestone permitted to reduce the soil infiltration. Consequently, the slabs of the spillway in the critical zone regain its state of stability.

Introduction

Dam monitoring is an important part of today's safety measures around the world. Reports of structural failures that led to structure collapse, resulting in major material and economic losses as well as a huge number of fatalities, date back to the construction of the first dams, emphasizing the importance of monitoring (Armenteros & al, 2020). Because of these failures, dam inspections primarily try to compare the work behavior to the project's forecasts (Al-Janabi.A & al, 2020).

In an earth dam, stability and seepage are critical since they have been identified as the primary causes of dam collapse (Chahar, 2004 Yaseen and al, 2020). When the slope information and material parameters are available, geo-technical engineers may easily analyze the dam's stability and seepage using computer software (Bouassida & Djebbi, 2008). The FEM system is capable of simulating two-dimensional unsteady and non-uniform flow through any earth fill dams homogeneous, non-homogeneous, and anisotropic saturated and unsaturated porous body (Ersayin, 2006).

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