Simplification of the Stratigraphic Profile in Geotechnical Models of Landslides: An Analysis Through a Stochastic Approach

The uncertainties in the determination of the stratigraphic profile of natural soils is one of the main problems in geotechnics, in particular for landslide characterization and modelling. The study deals with a new approach in geotechnical modelling which relays on a stochastic generation of different soil layers distributions, following a boolean logic. In this way, it is possible to randomize the presence of a specific material interdigitated in a uniform matrix. In fact in the building of a geotechnical model it is generally common to discard some stratigraphic data in order to simplify the model itself, assuming that the significativity of the results of the modelling procedure would not be affected. With the proposed technique it is possible to quantify the error associated with this simplification. Moreover, it could be used to determine the most significant zones where possible further investigations and surveys would be more effective. The commercial software FLAC 6.0 was used for the 2D geotechnical model. The distribution of the materials was randomized through a specifically coded Matlab program that automatically generates text files, each of them representing a specific soil configuration. Besides a routine was designed to automate the computation of FLAC with the different data files in order to maximize the sample number. In this paper, the methodology is applied with reference to a simplified slope. However, it could be then extended to numerous cases, especially for hydrogeological analysis and landslide stability assessment, in different geological and geomorphological contexts.

Geostatistical analysis of cone penetration test (CPT) sounding using the modified Bartlett test

10.1139/t03-091Canadian Geotechnical Journal412356-365CGJO

Seismic microzonation of the central archaeological area of Rome: results and uncertainties

The paper summarizes the results of a multidisciplinary study aimed at seismic microzonation of the Central Archeological Area of Rome including the Palatine hill, Roman Forum and Coliseum. A large amount of subsoil data, available mainly from adjacent subway lines and from the archaeological superintendence, were collected and used to plan new multidisciplinary investigations, carried out in 2010-2011. First, the paper describes the integrated subsoil model aimed at numerical modeling of site effects. The results of equivalent linear 2D site response analyses carried out on seven representative cross-sections of the area are then presented and discussed. Ground motion amplification factors defined in terms of Housner Intensity were computed in different ranges of period, covering the different fundamental vibration periods pertaining to the monuments and structures. The contouring of amplification factor values from all the numerical simulations, based on morphological and geological constrains, eventually allowed to create microzonation maps. Finally, a sensitivity study was carried out to investigate the effects of uncertainties of input parameters and soil heterogeneity on microzonation