GEOTECHNICS AND ROCK MECHANICS
Learning outcomes of the course unit
The purpose of the course, in its first section, is to introduce the basic notions related to the mechanical behavior of soil, with a preliminary introduction of continuum mechanics concepts and definitions of stresses and forces. Following, this concept will be applied for the interpretation of some simple laboratory tests in order to define the strength and deformability parameter of soils. In the second portion of the course, the mechanical behavior of the rock masses will be analyzed, differentiating its peculiarities from that of soils. This will be done introducing the concepts of rock matrix and discontinuities. Then rock mass classification system will be presented and discussed as well as the strength criteria widely used in the rock mechanic field.
Applying knowledge, understanding and making judgments:
There will be theoretical lessons regarding the course, followed by practical exercises during which, using the personal computer, the students will face real problems regarding rock and soil mechanics, determination of the strength parameters of materials through the interpretation of laboratory and on site tests and application of such parameters for the evaluation .
The student will bring its solved exercises to the exam and will be required to illustrate his/her verification strategies as well as to describe and justify his/her design choices.
At last, a brief introduction of the history of the geotechnical sciences and some concepts related to the teaching and learning methodologies will be highlighted.
Mathematics, Instituions of Physics, applied geology
Course contents summary
Soil characterization. Multiphase nature of soils. Relation between phases. Exercises. Boreholes. Size distribution curve, Atterbergs limits, characteristic indexes. Exercises
Mohr circles. Force and Stress concepts. Continuum media and stresses. Application Exercises. Deformation and failure concept. Mechanical effects of stresses. Constitutive models. Elastic and plastic media. Strenght criteria and stress paths. Stress invariants and deformations. Stress-strain planar problem.
Geostatic stresses. Effective stresses principle. Determination of in situ state of stress. Stress history. Earth pressure coefficient. Horizontal stresses. Exercises.
Stress paths. Stress state variations. Load compression. Load extension. Exercises. Drained and undrained conditions. Concept of coefficient of permeability. Load rate. Consolidation process.
Oedometric test. Consolidation process. Oedometer apparatus. Test execution. Plotting of results. Determination of pre-consolidation pressure. Determination of compression and recompression indexes and ratios. Oedometric settlement calculation. Exercises.
Strength criteria. Mohr – Coulomb. Application examples. Exercises
Direct shear test. Draining condition in laboratory tests. Apparatus description. Consolidation phase. Dilating and contracting behavior. Mohr plane.
Triaxial tests. Test apparatus. Basic concepts. Test Phases. Various types of tests. Stress path reconstruction. Examples.
Rock masses and discontinuities. Introduction. Geomechanical survey. Discontinuity orientation. Spherical projections. Survey of several discontinuities. Planes representation. Exercises. Spacing and persistence. Filling. Alteration. Water infiltration.
Stress state. Strain state. Stress components. Main stresses. Mohr circles. Hydrostatic and deviatoric state of stress. Effects of the stress variation.
Constitutive models and strength criteria. Definitions. Linear elastic behavior. Plane strain. Plane stress. Elastic constants. Plastic behavior. Strength criteria. Mohr-Coulomb Strength Criteria. GSI. Hoek-Brown Linearization.
Discontinuities Shear strength. Natural discontinuity. Roughness. Barton Criteria. Mohr-Coulomb criteria. Residual friction. JRC. JCS. Deformability and dilatancy. Exercises.
Intact rock features. Laboratory tests. Mineral content analysis. Sonic speed. Samples shape and dimensions. Test apparatus. Uniaxial compressive test. Ductile and fragile behavior. Strength and deformability features. Point load test. Direct and indirect traction strength. Flexural strength. Triaxial compression.
Rock mass classification. Classification systems. Significant parameters. RMR. RMRbase, determination. Mechanical parameters. Q System (Barton)., determination. Reduction coefficient. GSI (Hoek). Correlations. Rmi (Palmstrom). Deformability features.
Hoek-Brown criteria. Application of GSI. Correlation Hoek-Brown and Mohr Coulomb.
On site tests. Test types. Field of application. Plate load. Natural state of stress. Flat jack test. Hydraulic Fracturation.
Renato Lancellotta - Geotecnica - 3. ed. – Bologna : Zanichelli, 2004.
T. William Lambe, Robert V. Whitman ; traduzione di Calogero Valore. - Meccanica dei terreni - 4. rist. riveduta. - Palermo : D. Flaccovio, stampa 2008.
Karl Terzaghi, Ralph B. Peck. - Geotecnica - Ed. ital. a cura di Vincenzo Carbonara, rist. corr. e agg. - Torino : UTET, 1987.
Walter Wittke – Rock Mechanics: Theory and Applications with case Histories. Springer-Verlag. Berlin 1990
Das, Braja (2006). Principles of Geotechnical Engineering. Thomson Learning.
Theoretical Lessons and computer aided practical excercises
Assessment methods and criteria
Written and/or Oral 70% including:
- Theoretical questions (knowledge)
- Application of theory and excercises (Applying knowledge )
Verification of the exercise handbook 30% including:
- Theoretical questions (knowledge)
- Original Application of theory (making judgments)
- Illustration of the design choices (communication skills)