@article{NguyenTuanLahmerDatchevaetal., author = {Nguyen-Tuan, Long and Lahmer, Tom and Datcheva, Maria and Stoimenova, Eugenia and Schanz, Tom}, title = {A novel parameter identification approach for buffer elements involving complex coupled thermo-hydro-mechanical analyses}, series = {Computers and Geotechnics}, journal = {Computers and Geotechnics}, pages = {23 -- 32}, abstract = {A novel parameter identification approach for buffer elements involving complex coupled thermo-hydro-mechanical analyses}, subject = {Angewandte Mathematik}, language = {en} } @inproceedings{MeierSchanz, author = {Meier, J{\"o}rg and Schanz, Tom}, title = {Benchmarking of Optimization Algorithms}, series = {Digital Proceedings, International Conference on the Applications of Computer Science and Mathematics in Architecture and Civil Engineering : July 20 - 22 2015, Bauhaus-University Weimar}, booktitle = {Digital Proceedings, International Conference on the Applications of Computer Science and Mathematics in Architecture and Civil Engineering : July 20 - 22 2015, Bauhaus-University Weimar}, editor = {G{\"u}rlebeck, Klaus and Lahmer, Tom}, organization = {Bauhaus-Universit{\"a}t Weimar}, issn = {1611-4086}, doi = {10.25643/bauhaus-universitaet.2813}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170314-28134}, pages = {6}, abstract = {In this paper, we present an empirical approach for objective and quantitative benchmarking of optimization algorithms with respect to characteristics induced by the forward calculation. Due to the professional background of the authors, this benchmarking strategy is illustrated on a selection of search methods in regard to expected characteristics of geotechnical parameter back calculation problems. Starting from brief introduction into the approach employed, a strategy for optimization algorithm benchmarking is introduced. The benchmarking utilizes statistical tests carried out on well-known test functions superposed with perturbations, both chosen to mimic objective function topologies found for geotechnical objective function topologies. Here, the moved axis parallel hyper-ellipsoid test function and the generalized Ackley test function in conjunction with an adjustable quantity of objective function topology roughness and fraction of failing forward calculations is analyzed. In total, results for 5 optimization algorithms are presented, compared and discussed.}, subject = {Angewandte Informatik}, language = {en} } @article{NguyenTuanLahmerDatchevaetal., author = {Nguyen-Tuan, Long and Lahmer, Tom and Datcheva, Maria and Schanz, Tom}, title = {Global and local sensitivity analyses for coupled thermo-hydro-mechanical problems}, series = {International Journal for Numerical and Analytical Methods in Geomechanics}, journal = {International Journal for Numerical and Analytical Methods in Geomechanics}, abstract = {Global and local sensitivity analyses for coupled thermo-hydro-mechanical problems}, subject = {Angewandte Mathematik}, language = {en} } @article{KnabeDatchevaLahmeretal., author = {Knabe, Tina and Datcheva, Maria and Lahmer, Tom and Cotecchia, F. and Schanz, Tom}, title = {Identification of constitutive parameters of soil using an optimization strategy and statistical analysis}, series = {Computers and Geotechnics}, journal = {Computers and Geotechnics}, pages = {143 -- 157}, abstract = {Identification of constitutive parameters of soil using an optimization strategy and statistical analysis}, subject = {Angewandte Mathematik}, language = {en} } @inproceedings{NguyenTuanDatchevaSchanz, author = {Nguyen-Tuan, Long and Datcheva, Maria and Schanz, Tom}, title = {NUMERICAL SIMULATION AND INVERSE ANALYSIS OF THERMO-HYDRO-MECHANICAL BEHAVIOR OF SAND-BENTONITE MIXTURE}, editor = {G{\"u}rlebeck, Klaus and K{\"o}nke, Carsten}, organization = {Bauhaus-Universit{\"a}t Weimar}, issn = {1611-4086}, doi = {10.25643/bauhaus-universitaet.2876}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170314-28767}, pages = {18}, abstract = {Sand-bentonite mixtures are well recognized as buffer and sealing material in nuclear waste repository constructions. The behaviour of compacted sand-bentonite mixture needs to be well understood in order to guarantee the safety and the efficiency of the barrier construction. This paper presents numerical simulations of swelling test and coupled thermo-hydro-mechanical (THM) test on compacted sand-bentonite mixture in order to reveal the influence of the temperature and hydraulic gradients on the distribution of temperature, mechanical stress and water content in such materials. Sensitivity analysis is carried out to identify the parameters which influence the most the response of the numerical model. Results of back analysis of the model parameters are reported and critically assessed.}, subject = {Angewandte Informatik}, language = {en} } @inproceedings{HoelterMahmoudiSchanz, author = {H{\"o}lter, Raoul and Mahmoudi, Elham and Schanz, Tom}, title = {OPTIMAL SENSOR LOCATION FOR PARAMETER IDENTIFICATION IN SOFT CLAY}, series = {Digital Proceedings, International Conference on the Applications of Computer Science and Mathematics in Architecture and Civil Engineering : July 20 - 22 2015, Bauhaus-University Weimar}, booktitle = {Digital Proceedings, International Conference on the Applications of Computer Science and Mathematics in Architecture and Civil Engineering : July 20 - 22 2015, Bauhaus-University Weimar}, editor = {G{\"u}rlebeck, Klaus and Lahmer, Tom}, organization = {Bauhaus-Universit{\"a}t Weimar}, issn = {1611-4086}, doi = {10.25643/bauhaus-universitaet.2800}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170314-28008}, pages = {6}, abstract = {Performing parameter identification prior to numerical simulation is an essential task in geotechnical engineering. However, it has to be kept in mind that the accuracy of the obtained parameter is closely related to the chosen experimental setup, such as the number of sensors as well as their location. A well considered position of sensors can increase the quality of the measurement and to reduce the number of monitoring points. This Paper illustrates this concept by means of a loading device that is used to identify the stiffness and permeability of soft clays. With an initial setup of the measurement devices the pore water pressure and the vertical displacements are recorded and used to identify the afore mentioned parameters. Starting from these identified parameters, the optimal measurement setup is investigated with a method based on global sensitivity analysis. This method shows an optimal sensor location assuming three sensors for each measured quantity, and the results are discussed.}, subject = {Angewandte Informatik}, language = {en} } @inproceedings{NguyenTuanLahmerDatchevaetal., author = {Nguyen-Tuan, Long and Lahmer, Tom and Datcheva, Maria and Stoimenova, Eugenia and Schanz, Tom}, title = {PARAMETER IDENTIFICATION APPLYING IN COMPLEX THERMO-HYDRO-MECHANICAL PROBLEMS LIKE THE DESIGN OF BUFFER ELEMENTS}, series = {Digital Proceedings, International Conference on the Applications of Computer Science and Mathematics in Architecture and Civil Engineering : July 20 - 22 2015, Bauhaus-University Weimar}, booktitle = {Digital Proceedings, International Conference on the Applications of Computer Science and Mathematics in Architecture and Civil Engineering : July 20 - 22 2015, Bauhaus-University Weimar}, editor = {G{\"u}rlebeck, Klaus and Lahmer, Tom}, organization = {Bauhaus-Universit{\"a}t Weimar}, issn = {1611-4086}, doi = {10.25643/bauhaus-universitaet.2816}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170314-28162}, pages = {6}, abstract = {This study contributes to the identification of coupled THM constitutive model parameters via back analysis against information-rich experiments. A sampling based back analysis approach is proposed comprising both the model parameter identification and the assessment of the reliability of identified model parameters. The results obtained in the context of buffer elements indicate that sensitive parameter estimates generally obey the normal distribution. According to the sensitivity of the parameters and the probability distribution of the samples we can provide confidence intervals for the estimated parameters and thus allow a qualitative estimation on the identified parameters which are in future work used as inputs for prognosis computations of buffer elements. These elements play e.g. an important role in the design of nuclear waste repositories.}, subject = {Angewandte Informatik}, language = {en} } @inproceedings{MiroHartmannSchanzetal., author = {Miro, Shorash and Hartmann, Dietrich and Schanz, Tom and Zarev, Veselin}, title = {SYSTEM IDENTIFICATION METHODS FOR GROUND MODELS IN MECHANIZED TUNNELING}, series = {Digital Proceedings, International Conference on the Applications of Computer Science and Mathematics in Architecture and Civil Engineering : July 04 - 06 2012, Bauhaus-University Weimar}, booktitle = {Digital Proceedings, International Conference on the Applications of Computer Science and Mathematics in Architecture and Civil Engineering : July 04 - 06 2012, Bauhaus-University Weimar}, editor = {G{\"u}rlebeck, Klaus and Lahmer, Tom and Werner, Frank}, organization = {Bauhaus-Universit{\"a}t Weimar}, issn = {1611-4086}, doi = {10.25643/bauhaus-universitaet.2777}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170314-27771}, pages = {13}, abstract = {Due to the complex interactions between the ground, the driving machine, the lining tube and the built environment, the accurate assignment of in-situ system parameters for numerical simulation in mechanized tunneling is always subject to tremendous difficulties. However, the more accurate these parameters are, the more applicable the responses gained from computations will be. In particular, if the entire length of the tunnel lining is examined, then, the appropriate selection of various kinds of ground parameters is accountable for the success of a tunnel project and, more importantly, will prevent potential casualties. In this context, methods of system identification for the adaptation of numerical simulation of ground models are presented. Hereby, both deterministic and probabilistic approaches are considered for typical scenarios representing notable variations or changes in the ground model.}, subject = {Angewandte Informatik}, language = {en} }