Entwicklung einer unkonventionellen Randintegralgleichungsmethode zur Simulation seismischer Wellenfelder
Zusammenfassung der Projektergebnisse
The objective of the project is development of a package of knowledge for: (a) mechanical models of graded soil regions under seismic load; (b) innovative numerical schemes based on reformulation of the boundary value problems via integral equations along existing in the domain boundaries, (c) analytical derivation of fundamental solutions of equation of motion and Green’s functions for continuously inhomogeneous half-plane, (d) verification of the created research software and (e) parametric studies revealing sensitivity of the seismic field to the type and characteristics of the seismic load, to the wave path inhomogeneity and heterogeneity, to the specific geotechnical properties of the local soil region. Three mechanical models are used to describe the inhomogeneous in respect to the depth geological region: (a) model 1, where material properties vary in a discrete way by considering the half-plane as horizontally stratified media, i.e. half-plane is presented by a stack of homogeneous layers with infinite horizontal interfaces rested on the seismic bed; (b) model 2, where material properties vary as continuous functions with respect to the depth; (c) model 3, where the geological region is presented as a multilayered structure with graded layers and boundary interfaces of arbitrary geometry. Computational methodology is based on the innovative BIEM numerical schemes and research software which is developed for wave propagation in continuously or discrete inhomogeneous geological regions with heterogeneities like homogeneous or graded layers, cavities, tunnels and valleys. In the BIEM formulation is efficiently inserted a library of special class of fundamental solutions and Green's functions that account for different types of material gradient. A successful verification, accuracy and convergence study of the developed numerical schemes and created software is done. The obtained results reveal the potential of the developed mechanical models and accompanied BIEM tools to study in extensive manner (model 1, model 2, model 3 and engineering application) out-of plane and for model 1 and model 2 the in-plane wave propagation in complex geological profiles. It is evidently demonstrated the sensitivity of the seismic signal to the existence and type of the material gradient, to the type and properties of the seismic source and to the lateral inhomogeneity due to the free-surface and/or sub-surface relief peculiarities like layering, tunnels, cavities, valleys of arbitrary geometry. Seismic signals in frequency and time domain are generated at the surface of complex geological profiles able to describe efficiently and with high accuracy all three components of the Earth system: seismic source, wave path and local geological region of interest. Application of the developed numerical tools and models in earthquake engineering is conducted. The influence of site effects on ground motions and subsequent structural damage of engineering constructions is investigated considering 2D analysis of the soil profile. Bridge and unlined and lined tunnel models are examined under site dependent ground motions computed at the surface of complex geological profiles that account for canyon topography, soil layering and material gradient effect.
Projektbezogene Publikationen (Auswahl)
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(2014). A non-conventional BEM for seismic wave propagation in continuously inhomogeneous half-plane. Proceedings of the 8th European Conference on Numerical Methods in Geotechnical Engineering NUMGE, Delft, Netherlands, Hicks, Brinkgreve & Rohe (Eds), Taylor & Francis Group, London
Fontara, I-K., Wuttke, F., Rangelov, Ts., Dineva, P.
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(2015) Wave propagation due to an embedded seismic source in a graded half-plane with free-surface and sub-surface. Part I: mechanical model and computational technique. Journal of Theoretical and Applied Mechanics 45(1): 87-98
Fontara I.-K., Parvanova S., Dineva P., Wuttke F.
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(2015). SH-wave propagation in a continuously inhomogeneous half-plane with free-surface relief by BIEM. ZAMM Z. Angew. Math. Mech. 95(7): 714-729
Wuttke, F., Fontara, I.-K., Dineva, P., Rangelov, Ts.
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(2015). Simulation of seismic wave fields in inhomogeneous half-plane by non-conventional BIEM, PhD thesis, Chair of Marine and Land Geomechanics & Geotechnics, Publications of Kiel University
Fontara, I.-K.
