Gianfranco Totani

Geotechnical Aspects of the L’Aquila Earthquake

On April 6, 2009 an earthquake (ML = 5.8 and MW = 6.3) stroke the city of L’Aquila with MCS Intensity I = IX and the surrounding villages with I as high as XI. The earthquake was generated by a normal fault with a maximum vertical dislocation of 25 cm and hypocentral depth of about 8.8 km. The deaths were about 300, the injured were about 1,500 and the damage was estimated as high as about 25 billion €. Both maximum horizontal and vertical components of the accelerations recorded in the epicentral area were close to 0.65 g. The paper summarises the activities in the field of earthquake geotechnical engineering aimed to the emergency and reconstruction issues. The ground motion recorded in the epicentral area is analysed; the geotechnical properties measured by in-situ and laboratory tests before and after the earthquake are summarised; site effects are preliminarily evaluated at accelerometric stations locations and damaged villages; the outstanding cases of ground failure are finally shown.

Overconsolidation and Stiffness of Venice Lagoon Sands and Silts from SDMT and CPTU

AbstractThis study is part of an extensive research program carried out at the Treporti test site (Venice, Italy), where a cylindrical trial embankment was constructed and monitored from the beginning of its construction until complete removal, 4 years later. This paper concentrates mainly on the evaluation of overconsolidation and stiffness of the Venice lagoon sands and silts. The possibility of estimating the overconsolidation ratio (OCR) in sand by the combined use of seismic dilatometer (SDMT) tests and piezocone (CPTU) tests is investigated. A tentative correlation for estimating the OCR in sand from the ratio MDMT/qt is constructed. Field compression curves have been back-figured from 1-m field oedometer curves reconstructed from local vertical strains measured by a sliding deformeter under the embankment center. The SDMT and CPTU soundings performed before embankment application and postremoval have permitted analyzing how the OCR caused by the embankment was reflected by the before/after SDMT and...

Local Seismic Response in the Southern Part of the Historic Centre of L’Aquila

This paper illustrates the results of the numerical modeling carried out to investigate the local seismic response in the Southern part of the city centre of L’Aquila (Italy), namely in the area of Via XX Settembre, harshly damaged by the April 6, 2009 earthquake. The upper portion of the subsoil in this area is irregularly affected by peculiar local conditions that may have originated major amplification of the ground motion during the main shock. The geotechnical model of the subsoil and related parameters, defined based on accurate site investigations, were used for a seismic response analysis. The results of this analysis indicated that the site effects due to local subsoil conditions played an important role in the observed damage distribution.

Use of the Seismic Dilatometer (SDMT) in Landslide Research and Practice

This paper shows the use of the seismic dilatometer (SDMT) testing (Marchetti J Geotech Eng Division, 106:299–321, 1980; Marchetti et al. Proceedings of 2nd international flat dilatometer conference, Washington, DC, pp 7–48, 2001, In Situ tests by Seismic Dilatometer (SDMT), pp 109–138, 2008) in landslide diagnosis and monitoring. The quick KD-DMT method, developed by Totani et al. (1997) for detecting active or old slip surfaces, was recently applied in a research programme on stability conditions of natural slopes shaped in colluvial cover formations in Abruzzo region (Chieti, Teramo). The paper illustrates the capability of SDMT to identify remoulded zones, symptom of instability, and slip surfaces in the investigated slopes.

Post-Event Site Investigation, Monitoring, Stability Analysis, and Modeling of a Gas Pipeline Explosion

This paper describes the results of site investigations, monitoring, stability analyses, and soil-pipe interaction modeling of a built-up slope located near Pineto (Abruzzo Province, Central Italy), where a gas pipeline exploded on March 6th, 2015, due to heavy rains inducing slope movements. The slope is formed by OC clay, covered with an upper 10- to 14-m-thick clayey-sandy silt colluvial layer. The explosion in the upper portion of the slope caused extensive damage to existing buildings and threatened human lives. Soon after the event, a site investigation and monitoring program was carried out. A detailed topographic survey and hydrological data were analyzed in order to characterize possible critical rainfall events. The stability of the slope was analyzed both in pre- and in post-explosion conditions. The profiles of the DMT horizontal stress index KD helped to identify multiple slip surfaces. Then, the results of the site investigation and stability analyses were used to implement a simplified finite element model aimed to describe the soil-pipeline interaction, taking into account the role of the observed wrinkle in the pipeline. The numerical simulations reveal the crucial role played by the slope movements, and by the wrinkle as well, in inducing the collapse of the pipe.

The Seismic Site Characterization of Palazzo Centi in L’Aquila City Centre: The Case Study of a Historical Building Damaged by the April 6th 2009 Earthquake

An extensive geological, geotechnical and geophysical investigation was performed in L’Aquila city centre to restore Palazzo Centi, a historical building, damaged by the April 6, 2009 L’Aquila earthquake. This site investigation consisted of punctual and linear tests that allowed to define a detailed 3D model of the subsoil, irregularly affected by some peculiar conditions and characterized by low and variable values of the shear wave velocity V S in the near surface volume. In particular, the variable thickness of the upper fine-grained residual soils probably determined different ground motion amplifications during the main shock.