Showing papers by "Cesare Comina published in 2007"
01 Jan 2007
TL;DR: In this article, the combined use of active and passive data in surface wave tests is explored in order to take advantage of the complementary information given by the two methods, and the experimental results for a case history, in which Downhole tests were available for a comparison, are presented, showing the great potential of the combined technique.
Abstract: Surface wave methods, both active and passive, are often used for shallow site characterisation especially in seismic studies. They provide valuable information about the subsurface soil with relatively little economic effort. For active surveys the depth of penetration is typically limited by the amount of information in the low frequency range. Passive methods are based on the analysis of microtremors, which are characterized by an extended content of energy in the low frequency range; hence they allow for deep characterization, but typically lack resolution for shallow layers. In the present paper the combined use of active and passive data in surface wave tests is explored in order to take advantage of the complementary information given by the two methods. The experimental results for a case history, in which Down-Hole tests were available for a comparison, are presented, showing the great potential of the combined technique. Finally, the implications of data uncertainties in terms of resolution and reliability are explored using a Monte Carlo approach for the inversion process, illustrating the importance of active data to improve the characterization of shallow layers.
14 citations
TL;DR: A case study in which both active and passive surface wave tests have been used in the design of a vibration mitigation barrier is presented, showing that several pieces of information can be inferred from these tests for specific applications.
Abstract: Wave barriers (open or in-filled trenches) are often used in engineering practice to reduce ground vibrations caused by industrial activities or transportation systems. Typically, most of the energy is transmitted in the form of Rayleigh waves so that information related to their propagation can be very useful in the design process. This technical note presents a case study in which both active and passive surface wave tests have been used in the design of a vibration mitigation barrier. It is shown that several pieces of information can be inferred from these tests for specific applications: source characterization in terms of dominant frequencies and direction of propagation; dominant wavelength for the preliminary design; and soil characterization for the construction of a numerical model aimed at analyzing the performance of the wave barrier.
12 citations
11 Jun 2007
TL;DR: In this paper, the authors present a dynamic characterisation devoted to seismic response analysis of an Alpine test site, where they show how integration and combination of different seismic techniques allow a comprehensive characterisation of the site leading to a reliable 2D model for site amplification studies.
Abstract: E002 Seismic Characterisation of a Site in the Alps L.V. Socco* (Politecnico di Torino) D. Boiero (Politecnico di Torino) C. Comina (Politecnico di Torino) S. Foti (Politecnico di Torino) & R. Wisen (Lund University) SUMMARY This study concerns the dynamic characterisation devoted to seismic response analysis of an Alpine test site. We show how integration and combination of different seismic techniques allow a comprehensive characterisation of the site leading to a reliable 2D model for site amplification studies. For the evaluation of the deep structure and the location of the seismic bedrock combined seismic reflection-refraction tests are used while the
1 citations
01 Jan 2007
TL;DR: In this article, the authors considered the case of seismic site response studies and showed that the results of surface wave tests can be considered a reliable and effective tool for site response study.
Abstract: Surface wave tests are aimed at evaluating the small strain shear modulus profile at a site with an inversion process based on the modeling of geometrical dispersion of Rayleigh waves. One of the critical aspects of any geophysical test based on inversion processes is given by non-uniqueness of the solution. Indeed several combinations of model parameters can be associated to responses of the forward problem very similar and practically equivalent with respect to experimental data. The consequences of the non-uniqueness of the solution should be carefully evaluated with respect to the final objective of the survey in order to assess their relevance. In the present study the case of seismic site response studies is considered. Shear wave velocity profiles are obtained from surface wave data using a Monte Carlo approach and a statistical test that allows the selection of a number of equivalent profiles within a certain level of confidence. With this approach it is possible to take into account both experimental uncertainties in the estimation of the dispersion curve and uncertainties deriving from non-uniqueness of the solution. These profiles are then independently used for evaluating the seismic site response. Two case histories related to sites in alpine valleys are reported. It is shown that equivalent profiles with respect to surface wave testing are equivalent also with respect to site amplification. The results show that surface wave tests can be considered a reliable and effective tool for site response studies.