508179 - GEOTECHNICAL EARTHQUAKE ENGINEERING

In the first part of the course, basic concepts of propagation of mechanical waves are discussed in elastic, viscoelastic and poroelastic continua. They include mathematical classification of wave motion, Fermat’s principle, Zoeppritz equations and physical causality. Surface Love and Rayleigh waves and their dispersive properties are also introduced including a discussion of the Lamb problem and of the differences between 2D vs. 3D radiation.
Next, fundamental concepts of seismometry are presented jointly with basic techniques of digital signal processing of earthquake recordings. Basic notions of engineering seismology are also reviewed; these include probabilistic and deterministic seismic hazard, design earthquake, intensity measures of ground motion, acceleration and displacement response spectra, selection of seismic- and spectrum- compatible accelerograms. These concepts will be applied to study ground response analyses of soil deposits in 1D linear and linear-equivalent modeling after introducing the concept of transfer function in elastic and viscoelastic layered systems. Examples of phenomena of ground amplification in well-known earthquakes are presented and thoroughly discussed. More advanced topics like non-linear effective stress analyses, numerical modeling of 2D ground response, basin effects and topographic amplification are introduced. Finally, ground amplification as treated in well-established building codes (e.g. Italian NTC 2018 and Eurocode EC8 Part 1) is illustrated jointly with the seismic micro- zonation of an extended territory such as an urban centre.
The second part of the course focuses on subjects of soil dynamics. They include the study of drained and undrained response of soils under earthquake loading, concepts of critical state theory, shear strength and stiffness degradation of soils under cyclic loading. These topics are preliminary to the subject of geotechnical site characterization via in-situ and laboratory investigations and to the study of phenomena of ground failure like earthquake-induced soil liquefaction, lateral spreading ground and seismic instability of natural slopes.
The course ends with an introduction to dynamic soil-structure interaction (SSI). After stating the problem, the notions of kinematic and inertial interaction are illustrated in association with that of dynamic impedance of a shallow foundation. This is used to solve SSI problems via the substructure approach. Finally, the pseudo-static and displacement-based methods are used for the seismic analysis and design of earth-retaining structures and foundation systems.