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Projet QSHA – WP3

Projet QSHA – WP3. Réunion du 01/06/2007. Laboratoire Central des Ponts et Chaussées 58, bd Lefebvre, 75732 Paris Cedex 15 http://www.lcpc.fr. WP3 - Ground motion simulation. WP3-1 Methological improvements. Developments of numerical tools for wave propagation. Main goals :

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Projet QSHA – WP3

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  1. Projet QSHA – WP3 Réunion du 01/06/2007 Laboratoire Central des Ponts et Chaussées 58, bd Lefebvre, 75732 Paris Cedex 15 http://www.lcpc.fr QSHA, Réunion du 01/06/2007

  2. WP3 - Ground motion simulation QSHA, Réunion du 01/06/2007

  3. WP3-1 Methological improvements Developments of numerical tools for wave propagation Main goals : • main features of the various methods (table) • current or potential improvements • range of application (frequency, heterogeneity, non linearity…) • comparisons (misfit criteria) : • efficiency • accuracy • stability… • very simple canonical models with well constrained features (and simple sources) QSHA, Réunion du 01/06/2007

  4. Fiche descriptive / méthode • Type/name of method: FVTD - Finite-Volume Method in the Time Domain • Contributors (labs):N. Glinsky-Olivier (Cermics/INRIA), S. Lanteri (INRIA), M. Benjemaa (INRIA), S. Piperno (Cermics/INRIA), J. Virieux (GeoSciences Azur), • Basic principle & improvements: • Principles : Finite Volumes, Unstructured grids, Centered numerical fluxes, Leap-frog time-scheme, Energy conservation, Weak treatment of boundary conditions (free surface, ABC, dynamic rupture) • Improvements : extension using Discontinuous Galerkin Finite Elements, parallel solver in development • Features: • Source/propagation (S, P, S+P): S+P • Coupled methods: coupling with PML, poss. coupling with FETD & FDTD meth • 1D/2D/2.5D/3D : 2D (3D parallel solver under development) • Time/frequency: time-domain • Direct/iterative: direct (explicit in time) • Elements size (fraction of l): 1/12 in FVTD (less in DGTD) • Model size (nb of l): • Free-surface topography: Yes • Heterogeneity: Yes • Anisotropy: Yes (future) • Material behav. (lin., NL, eq.lin): linear • Damping (NCQ, rheol.): none (possible) • Main references à remplirpour S3 !! QSHA, Réunion du 01/06/2007

  5. Tableau récapitulatif méthodes à compléter/corriger…! L=linear, EQ=equivalent linear, NL="non-linear" QSHA, Réunion du 01/06/2007

  6. Simple canonical models • Simple canyons/basins : • 2D (SismoValp) : 1 asymmetrical models + higher frequencies… is it useful to choose other 2D models ? • 3D (mainly semi-spherical, asymmetric) • Simple sources (plane waves, points sources…) • Analyze efficiency/accuracy taking into account : • Damping/attenuation, • Discretization, geometrical extent... • Constitutive laws • Simple stratification, • … • Possible link with/contribution to Spice database (http://www.nuquake.eu/SPICECVal) choice among existing models in the database ?! QSHA, Réunion du 01/06/2007

  7. WP3-2 Sensitivity studies (P-Y Bard) • Key parameters in modelling : • intermediate canonical models (for sensitivity analyses) • influence of topography description • sensitivity to source location, source dynamics, source extension… • influence of soil non linearities in 2D and 3D • influence of the physical model (variability) on response spectra (input uncertainties vs output uncertainties) • identification of the key parameters to be measured • finally, empirical description of the physical effects from theoretical results(e.g. 2D/3D aggravation factor...) QSHA, Réunion du 01/06/2007

  8. WP3-2 Sensitivity studies (P-Y Bard) (Nearly) realistic models : • Nice (WP1 : test de rugosité d’interface…) • Grenoble > modèle avec gradient + modèle à couches (pour BEM !) • Algiers • Naples……cf WP3-3 & WP3-4 QSHA, Réunion du 01/06/2007

  9. WP3-3-WP3-4 Benchmarking (E.Chajlub/E.Foerster) • Validation of developed codes based on international benchmark but not tied to ESG2006 with two geometries (Basins and margins) • Simulations performed in the Nice zone including water layer • Fully realistic models... QSHA, Réunion du 01/06/2007

  10. WP3-5 Statistical comparison(Hideo Aochi) • Variability of simulations using intensive simulations related to model variations related to source variations QSHA, Réunion du 01/06/2007

  11. WP 3-6 Lessons (J.Virieux) • To be done in S5 and S6 (2008) when comparing methods QSHA, Réunion du 01/06/2007

  12. WP 3-X ... Rapport S3 : contributions à envoyer à semblat@lcpc.fr(y compris "fiche de synthèse"pour chaque méthode) Prochaine réunion :2 ou 3 juillet 2007(avant Colloque AFPS) QSHA, Réunion du 01/06/2007

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