1. Graduate Student, Univ. of New Brunswick, Fredericton, NB E3B 5A3, Canada; Engineer, HILCON Limited, 420 York St., Fredericton, NB E3B 3P7, Canada.
2. Associate Professor, Dept. of Civil and Resource Engineering, Dalhousie Univ., Halifax, NS B3H 4R2, Canada (corresponding author).