1. Professor of Civil Engineering, Univ. Européenne de Bretagne, Univ. of South Brittany UBS–LIMATB Centre de Recherche, 56321 Lorient Cedex, France; formerly, Mechanics Division, Dept. of Mathematics, Univ. of Oslo, Blindern, NO-0316 Oslo, Norway (corresponding author).
2. Associate Professor, Laboratoire des Matériaux et Hydrologie, Univ. de Sidi Bel Abbes, 22000 Sidi Bel Abbes, Algeria.