We present a discontinuous Galerkin method for site effects assessment. The P–SV
seismic wave propagation is studied in 2-D space heterogeneous media.
The first-order velocity–stress system is obtained
by assuming that the medium is linear, isotropic
and viscoelastic, thus considering intrinsic attenuation. The associated
stress–strain relation in the time domain being a
convolution, which is numerically intractable, we consider the rheology
of a generalized Maxwell body replacing the
convolution by a set of differential equations. This results in a
velocity–stress
system which contains additional equations for the
anelastic functions expressing the strain history of the material. Our
numerical method, suitable for complex triangular
unstructured meshes, is based on centred numerical fluxes and a
leap-frog
time-discretization. The method is validated
through numerical simulations including comparisons with a
finite-difference
scheme. We study the influence of the geological
structures of the Nice basin on the surface ground motion through the
comparison
of 1-D and 2-D soil response in homogeneous and
heterogeneous soil. At last, we compare numerical results with real
recordings
data. The computed multiple-sediment basin response
allows to reproduce the shape of the recorded amplification in the
basin.
This highlights the importance of knowing the
lithological structures of a basin, layers properties and interface
geometry.