1. Dept. of Civil, Geological, and Mining Engineering, Ecole Polytechnique de Montréal, P.O. Box 6079, Stn. Centreville, Montreal, PQ, Canada H3C 3A7.
2. Dept. of Civil, Geological and Mining Engineering, Ecole Polytechnique de Montréal, P.O. Box 6079, Stn. Centreville, Montreal, PQ, Canada H3C 3A7.