1. Reader in Environmental Geotechnics, Drummond Building, School of Civil Engineering and Geosciences, Newcastle Univ., Newcastle upon Tyne, NE 1 7RU, U.K.
2. Researcher, Drummond Building, School of Civil Engineering and Geosciences, Newcastle Univ., Newcastle upon Tyne, NE 1 7RU, U.K.
3. Research Associate in Geotechnical Engineering, Drummond Building, School of Civil Engineering and Geosciences, Newcastle Univ., Newcastle upon Tyne, NE 1 7RU, U.K.
4. Professor, Geotechnical Engineering, School of Civil Engineering, College of Engineering and Physical Sciences, Univ. of Birmingham, Edgbaston, Birmingham, B15 2TT, U.K.
5. Postdoctoral Research Fellow, School of Civil Engineering, College of Engineering and Physical Sciences, Univ. of Birmingham, Edgbaston, Birmingham, B15 2TT, U.K.