INGLESE

Basic knowledge of mechanics, geometry and mathematical analysis

Lectures: 48 hours

The design of infrastructures interacting with environment implies a full understanding of the geological characteristics of the construction site to minimize risks for human activities and damage of existing constructions. The ability to anticipate the response of the environment to the construction of excavations, tunnelling, road embankments, dangerous waste disposal plants is particularly needed in geologically complex conditions likewise in the regions of South Europe, where tectonics largely influenced the geology of the environment.

The perspective environmental engineers will be able to apply the methods of structural geology to describe and map the main geological features of the site to be considered for design. The mapping of discontinuities is the first step in the process of the definition of the ground model, and is totally propaedeutic to the selection of the possible limit states to be considered for judging the suitability of any construction site.

Structural geology will be complementary to other courses, specifically environmental geotechnical engineering, seismic engineering, slope stability, for its contribution to the understanding of the kinematics of the site and of the controlling micro and macro scale deformation mechanisms. Structural geology is intended to give the basic principles to understand deformation mechanisms operating in faults, the importance of kinematic indicators and fault dynamics, the relationships between faults and earthquakes.

Strain: definition of strain; brittle and ductile deformation; homogeneous and heterogeneous strain, dilation, pure shear, simple shear; longitudinal strain, shear s.; incremental s., finite s., strain in 2D; coaxial and non-coaxial s.; strain in 3D, Flinn diagram.
Basic principles of crystalline deformation: crystal .defects, intra- and inter-crystalline deformation mechanisms, pressure-solution, grain boundary sliding, twinning, dislocation glide, dislocation climb, dislocation creep; diffusion creep, recovery, dynamic and static recrystallization, flow laws.
Foliation and lineation: cleavage and schistosity, mechanisms of formation and relationships with finite strain; cleav. classification, spacing, morphology, continuous foliation, spaced foliation, cleav. domains, crenulation cleav.; mineral lineation, stretching lin., intersection lin.
Shear zones (basic principles): definition, mylonites, shear bands, S-C and S-C' structures, kinematic indicators.
Continuum mechanics: stress, normal and tangential stress, principal stress axes, deviatoric stress, idrostatic stress, lithostatic stress, differential stress, confining pressure, tensile and compressive strength tests, Mohr circle, failure criteria; pore pressure, effective stress. Slip on pre-existing surfaces, frictional sliding, Byerlee Law.
Fractures: nomenclature, systems, tensile fractures, hybrid extension/shear fractures, faults, brittle deformation; mode I, II and III fractures; joints, plumose structure, roughness; aspect ratio, stratabound and non-stratabound fractures, spacing, aperture, length, fracture density; parameters controlling fracture density.
Faults: definition and basic geometric elements; dip-slip f. (normal and reverse f.). Strike-slip f. (right- and left-lateral); definition of: footwall, hanging wall, cut off line, ramp, flat, footwall cut offs, hanging wall cut offs; fault zone architecture, fault core, fault damage zone; permeability structure of fault zones; fault jogs, compressive and extensional jogs; relationships between principal stress axes and fault kinematics; conjugate, synthetic and antithetic faults; fault displacement; vertical, horizontal, dip-, strike- and net-slip); fault separation, vertical separation, horizontal separation, dip separation, strike separation, perpendicular (stratigraphic) separation; aseismic creep and seismic deformation, earthquake faulting; basic principles of continental and oceanic lithosphere rheology.
Folds: morphology, classifications; folding mechanisms, buckling, bending, fault-bend folding, fault-propagation folding, detachment folding; multilayer folding; role of viscosity contrast; harmonic, poly-harmonic and disharmonic folding.
Tectonics (basic principles): extensional systems, planar and listric normal faults; graben and half-graben; pre-, syn- and post-rift deposition; detachment faults; strike-slip systems, releasing and restraining bends, releasing and restraining stepovers; flower structures, Riedel shears; thrust systems, Imbricate fan, duplex, thrust systems in 3D: frontal, lateral and oblique ramps.
Attitude of planar and linear elements and their representation on stereographic projections: strike, dip direction, angle of dip of planar features; trend and plunge of linear features; use of lower hemisphere, equal-area and equal-angle projections.
Geological maps: types of geological boundaries (stratigraphic, intrusive, metamorphic zone boundary); lithostratigraphic units; relationships among geological surfaces and topography; strike line construction; geological sections; map representation of planar (bedding, tectonic foliation, fold axial traces) and linear (fold hinges, tectonic lineation) features. Plunging folds and their map expression. Fault types and their map expression

The level of knowledge and understanding of the students will be assessed by the evaluation of a series of practical exercises that will be assigned weekly during the course, as well as by a final oral exam. The written exercises may be repeated in case of insufficient results. The exercises will focus on geological maps (relationships among geological surfaces and topography; strike line construction; geological sections), the representation of planar and linear elements’ attitude on stereographic projections, fold and fault parameters.

In order pass the exam successfully, the student should demonstrate a good comprehension of the fundamental principles of the discipline, as well as a problem-solving ability (testified by the exercises mentioned above). The final evaluation will take into account of the knowledge acquired in all the topics of the course and of the results of the exercises. Maximum marks will be given to students demonstrating a deep understanding of the topics of the course, including excellent analytical skills in written exercises and appropriate, competent technical vocabulary in the oral exam.

The final mark will be given in /30, possibly cum laude (for outstanding results).

An average mark will be obtained based on written exercises. Students with a minimum average of 18/30 on written exercises will be admitted to the oral exam. The average mark from the written exercises will form the basis of the evaluation that will be complemented with the oral exam to obtain the final mark.

Ramsay J. G. & Huber M. I. (1983) - The Techniques of Modern Structural geology, Volume 1, Strain Analysis. Academic Press, London, 307 p.
Ramsay J. G. & Huber M. I. (1987) - The Techniques of Modern Structural geology, Volume 2, Folds and Fractures. Academic Press, London, 700 p.
Ramsay J. G. & Lisle R. J. (2000) - The Techniques of Modern Structural geology, Volume 3, Applications of continuum mechanics in structural geology. Academic Press, London, 1061 p.
Price, N. J. & Cosgrove, J. W. (1990) - Analysis of Geological Structures. University Press, Cambridge, 502 p.
Hobbs B. E., Means W. D. & Williams, P. F. (1976) – An Outline of Structural Geology. Wiley, New York, 571 p.
Ramsay J. G. (1967) - Folding and fracturing of rocks. McGraw-Hill, New York, 568 p.
Lisle R. J., Brabham P., Barnes J. W. (2011). Basic Geological Mapping, 5th Edition. Wiley, New York.

Lecture slides available online at: https://learn.univpm.it

Exercises available online at: https://learn.univpm.it