1. Engineer, Sud Fondations Company, 9 Chemin de Monfaucon, Martignas-sur-Jalle 33127, France.
2. Professor, Dept. of Civil and Engineering, Univ. of Bordeaux, I2M, UMR 5295, Bat. B18, Allée Geoffroy St Hilaire, CS 50023, Pessac Cedex 33615, France.
3. Professor, Dept. of Civil and Engineering, Univ. of Bordeaux, I2M, UMR 5295, Bat. B18, Allée Geoffroy St Hilaire, CS 50023, Pessac Cedex 33615, France (corresponding author).