Lecturer: Carlo Giovanni Lai  

Course name: Geotecnica sismica
Course code: 064084
Degree course: Ingegneria civile
Disciplinary field of science: ICAR/07
University credits: CFU 3
Course website: http://www-3.unipv.it/webgeotk/geotecnica_sismica.html

Specific course objectives

Scope of the course is to introduce students to the theories and methods of modern earthquake geotechnical engineering. The first part of the course is devoted to illustrate fundamental notions of seismology on the origin of earthquakes and on measurement of their size through the concepts of macroseismic intensity and magnitude. Basic notions of seismometry will then be introduced together with the definition of ground motion parameters including the concept of response spectrum. The course will then proceed with the study of seismic hazard at a single site or at an extended territory and on the definition of the design earthquake using both the probabilistic and the deterministic approach. The last part of the course is dedicated to the illustration of basic notions of elastodynamics and seismic wave propagation in a continuum. These concepts will be applied to the study of local site response and of some well-known phenomena of seismic geotechnical risk such as co-seismic instability of natural slopes, cyclic mobility and liquefaction. The course subdivision in didactic modules with lecturing hours (L) and tutoring hours (T) is illustrated in the following.

Course programme

First didactic module (4L) – Introduction to engineering seismology and earthquake geotechnical engineering.
Objectives of seismic geotechnique, seismic hazard and seismic risk, ground shaking and induced seismic geotechnical effects. Seismic geotechnical zonation of a territory, levels of accuracy I, II and III. Seismic macro and microzonation. Significant historical earthquakes, seismic mitigation measures, national and international (EC8) seismic building codes.

Second didactic module (6L) – Fundamentals of engineering seismology.
Seismicity, theory of plate tectonics, mechanisms of generation of earthquakes, styles of faulting. Strike-slip and subduction margins, seismic gaps, brief account on the causes of Italian seismicity. Measures of the size of an earthquake, macroseismic intensity, intensity scales and magnitude scales. Introduction to seismometry, analog and digital instruments, strong-motion accelerometric databanks. Ground motion severity parameters, peak and integral values, Fourier and response spectra.

Third didactic module (4L) – Seismic hazard assessment.
Identification of seismic sources, active faults, historical and instrumental seismicity. Earthquake catalogues, process of occurrence of seismic events, poissonian and non-poissonian models. Completeness analyses. Representation of regional seismicity, Gutenberg–Richter frequency magnitude relationship. Attenuation models and ground motion prediction equations, seismogenic zoning. Probabilistic method (Cornell-McGuire) to predict seismic hazard at the local and regional scale. Design earthquakes and scenario earthquakes.

Fourth didactic module (4L) – Propagation of seismic waves.
Introduction to elastodynamics, propagation of mechanical disturbances in an unbounded elastic medium. Transversal and longitudinal waves, stationary oscillations and harmonic waves, solution of one-dimensional wave equation. Initial and boundary conditions, propagation in elastic heterogeneous continua, Fermat’s principle and Snell’s law. Reflection and transmission coefficients for normal incidence, introduction to 2D wave propagation and to surface waves.

Fifth didactic module (4L+2T) – Ground response analyses.
Steady–state response of a homogeneous layer overlapping an elastic half-space, ground amplification. Transfer functions of a layer over an half-space, influence of material damping. Examples of local amplification effects in recent earthquakes: the cases of Coalinga, California and Mexico City. The 1997 Umbria-Marche earthquake in Italy. Linear and linear-equivalent one-dimensional ground response analyses, computer programs. Shear modulus and damping ratio degradation curves. Introduction to the effects of non-linearity on ground response analyses.

Sixth didactic module (4L+2T) – Phenomena of seismic geotechnical risk.
Overview on induced seismic geotechnical effects, surface fault ruptures and ground settlements. Dynamic behaviour of soils, threshold cyclic shear strains, dilatancy, critical state theory. Cyclic degradation of stiffness and strength, energy dissipation, undrained response of coarse-grained soils. Simplified constitutive modeling of dynamic behaviour of soils, cyclic models, skeleton curves, Masing criterion. Liquefaction and cyclic mobility, simplified methods for the assessment of liquefaction susceptibility. Co-seismic and post-seismic instability of natural slopes, pseudo-static analyses and Newmark simplified dynamical method.

Course entry requirements

Basics of Geotechnical Engineering and Mechanics of Deformable Body.

Course structure and teaching

Lectures (hours/year in lecture theatre): 24
Practical class (hours/year in lecture theatre): 6
Practicals / Workshops (hours/year in lecture theatre): 0
Project work (hours/year in lecture theatre): 0

Suggested reading materials

Kramer, S.L. (1996). Geotechnical Earthquake Engineering. Prentice-Hall, pp. 653. Recommended textbook.

Faccioli, E. & Paolucci, R. (2005). Elementi di Sismologia Applicata all'Ingegneria. Pitagora Editrice Bologna, pp. 268. Reference textbook for basic concepts of wave propagation theory and seismic hazard assessment.

Lai, C.G., Foti, S. & Rota, M. (2009). Input Sismico e Stabilità Geotecnica dei Siti di Costruzione. IUSS Press. Collana di Manuali di Progettazione Antisismica, Volume 6, pp. 312. Reference monograph for the application of Italian Building Code (NTC 2008) to the solution of earthquake geotechnical engineering problems.

Day, R. (2001). Geotechnical Earthquake Engineering Handbook. Mc Graw Hill, pp. 623. Reference monograph especially for seismic design of foundations and earth-retaining structures. Pragmatic and of easy comprehension.

Ishihara, K. (1996). Soil Behaviour in Earthquake Geotechnics. Oxford Press, pp. 350. Reference monograph on soil dynamics and dynamic laboratory tests.

Testing and exams

The final exam consists of a two hours written assessment. The test will include both theoretical questions and practical problems. The test format is closed-book. Problems and/or reading assignments will be given during the course. They will be assessed and they will contribute to about 40% of the final course grade.