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Durham University

Department of Engineering

Staff Profile

Publication details for Professor David Toll

D’Onza, F., Wheeler, S.J., Gallipoli, D., Barrera Bucio, M., Hofmann, M., Lloret-Cabot, M., Lloret Morancho, A., Mancuso, C., Pereira, J.-M., Romero Morales, E., Sánchez, M., Solowski, W., Tarantino, A., Toll, D.G. & Vassallo, R. (2015). Benchmarking selection of parameter values for the Barcelona basic model. Engineering Geology 196: 99-118.

Author(s) from Durham


Seven teams took part in a benchmarking exercise on selection of parameter values for the Barcelona Basic Model
(BBM) from experimental data on an unsaturated soil. All teams were provided with experimental results from 9
tests performed on a compacted soil in order to determine values for the ten BBM soil constants and an initial
value for the hardening parameter. The coordinating team then performed simulations (at stress point level)
with the 7 different sets of parameter values, in order to explore the implications of the differences in parameter
values and hence to investigate the robustness of existing BBM parameter value selection procedures. The major
challenge was found to be selection of values for the constants λ(0), r, β, N(0) and pc and an initial value for the
hardening parameter p0ð0Þ, with the various teams proposing significantly different values for some of these key
parameters. A key lesson emerging from the exercise is the importance of choosing a method for selecting values
for the parameters β and pc which places the main emphasis on attempting to optimise the match to the experimental
spacing of normal compression lines at different values of suction.