Digues résistantes à l'érosion par traitement du sol à la chaux | Erosion resistant dikes thanks to soil treatment with lime

Lime treatment is a well-known technique of earthworks, for soil improvement and stabilization, its applications are mainly roads, railways, airports and platforms construction. In addition, some positive past experiences of lime treatment were related to solve erosion problems of dispersive and non-cohesive soil in hydraulic structures. The interest of the hydraulic works community regarding this technique is currently growing. During the last decade, the benefits of lime treatment and appropriate application technologies were evidenced for earthworks execution, for the improvement of mechanical properties and stability, high internal and external erosion resistance of treated materials and the possibility to maintain low hydraulic conductivity values. These have been shown in the laboratory and for some properties with full scale experiments. The conferred soil properties can lead to innovative earthfill dams and dikes designs by addressing some of the typ- ical designer's problems, such as stability, watertightness, internal erosion, surface protection and flood control. However, lime treated soil external erosion resistance was still to be quantified in the field for proper designing and dimensioning of lime treated soil external erosion protection or spillways. With this purpose, an experimental earthfill dike was built along the river Vidourle (south of France) in July 2015, in the frame of the French R&D program "DigueELITE". This 50 m long and 3,5 m high dike is made of lime treated silty soil and is provided with sensors (suction, water content and temperature) and piezometer in order to be monitored. It also was tested against surface erosion (JET testing) and real scale overflow testing. The in situ methodology and equipment for assessment of overflow resistance, and the benefits of lime-treatment against overflow are described. Eventually, proposals for dike design perspectives thanks to soil treatment with lime are opened.