Inverse Mohr-Coulomb Soil Parameter Identification of an Earth and Rockfill Dam by Genetic Algorithm Optimization

 

Pooya Vahdati

Department of Civil, Environmental and Natural resources engineering, Luleå University of Technology, Tel: +46 920 491764, SE - 971 87, Luleå, Sweden
e-mail: Pooya.Vahdati@ltu.se

Séverine Levasseur

Doctor
Département ArGEnCo Service de Géomécanique et géologie de l'ingénieur Université de Liège, Tel: +33 249 5324067, 4000 Liège-Belgium
e-mail: severine.levasseur@ulg.ac.be

Hans Mattsson

Assistant Professor
Department of Civil, Environmental and Natural resources engineering, Luleå University of Technology, Tel: +46 920 492147, SE – 971 87, Luleå, Sweden
e-mail: Hans.Mattsson@ltu.se

Sven Knutsson

Professor
Department of Civil, Environmental and Natural resources engineering, Luleå University of Technology, Tel: +46 920 491332, SE – 971 87, Luleå, Sweden
e-mail: Sven.Knutsson@ltu.se

 

 ABSTRACT

This paper presents a study of identification of constitutive parameter values in the Mohr-Coulomb model by inverse analysis of an earth and rockfill dam application. The objective is to examine if the technique of inverse analysis can be effectively used for this type of case. The values of soil parameters are determined based on horizontal deformations recorded from installed instrumentations in the dam. The quantities that are monitored in the dam can be numerically predicted by a finite element simulation. In inverse analysis, constitutive parameter values are chosen in such a way that the error between data obtained by measurements in the dam and numerical simulation is minimized. An optimization method based on the genetic algorithm was utilized to search for the minimum error in this study. Optimizations have been performed against both a synthetic and a real dam case. The effect of the population size in the genetic algorithm was also analysed for this case in order to approach a proper set of solutions close to the optimum point by considering: the finite element computation time and the error function values. The error function topology was examined as well, and it was found to be complex and noisy for this application. The genetic algorithm is known to be a practically good choice of search method for such complicated topologies. It was overall concluded, that the inverse analysis technique studied, could be effectively used for this kind of earth and rockfill dam application despite the fact that, the technique is expensive in terms of computational costs. Inverse analysis has the potential to become a valuable tool for dam engineers assessing dam performance and dam safety if it becomes readily available in commercial finite element software.

Keywords: Earth and rockfill dam, finite element modelling, inverse analysis, genetic algorithm, dam safety.

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