Unit SOIL AND ROCK MECHANICS

Course
Geosciences for risk and environment management
Study-unit Code
GP004870
Curriculum
Geologia applicata alla salvaguardia e alla pianificazione del territorio
Teacher
Costanza Cambi
Teachers
  • Costanza Cambi
Hours
  • 52 ore - Costanza Cambi
CFU
6
Course Regulation
Coorte 2021
Offered
2021/22
Learning activities
Caratterizzante
Area
Discipline geomorfologiche e geologiche applicative
Academic discipline
GEO/05
Type of study-unit
Obbligatorio (Required)
Type of learning activities
Attività formativa monodisciplinare
Language of instruction
Italian
Contents
The course deeply analyses the main principles and processes of soil mechanics, and provides the base principles of rock mechanics.
Definition of soils and rocks.

Soil mechanics

Reviews, consolidation, shear strength, lateral earth pressure, stability of slopes.

Rock mechanics

Definitions, intact rock characteristics, geometrical and mechanical characteristics of discontinuities; discontinuities sampling. Mechanical characteristics of rock masses, main geomechanics classifications, stability of rock slopes, tunnels.
Reference texts
Hudson J.A. and Harrison J.P. “Engineering rock mechanics. An introduction to the principles”.Pergamon.

- Craig R.F. (1987) – Soil Mechanics. Van Nostran Reinhold (UK) Co. Ltd.
Educational objectives
The course aims to provide a good knowledge of the main principles of soil mechanics and a base knowledge of the main principles of rock mechanics.

At the end of the course the student will properly know the physical principles controlling the mechanical behavior of soils, will be able to solve numerical problems of soils mechanics and will be able to adequately interact with other professional figures (particularly Engineers) operating in the fields where an appropriate knowledge of soil mechanics is required.

The student will also know the base principles of rock mechanics, which will allow him to make geo-structural survey and to classify rock masses on the engineering point of view. The acquired notions will constitute the base background allowing the student to solve practical problems concerning the mechanical behavior of rock masses.

The acquired notions will allow the Geologist to be introduced in the professional environments concerning constructions, including roads, tunnels dams etc.

The student will also get the notions and conceptual bases necessary for executing and elaborating the main geotechnical tests, and will be able to personally make the structural survey of a rock mass.
Prerequisites
To properly understand the topics treated in this course it is necessary to have an adequate knowledge of Physics (particularly mechanics), applied geology and structural geology/geological survey. Furthermore, it is necessary to know derivatives and to be able to calculate simple integrals. The required background is given by the courses of Mathematics, Physics, Applied Geology, Geology and Geological Survey of the MSc in Geology of this and other Universities. Students coming from different Degree Courses should verify whether their background is adequate to efficiently follow this course, and should personally fill possible gaps, following also the teacher's indications.
Teaching methods
The course is organized as follows:

- Lectures on all the treated topics. During the lectures all subjects will be illustrated and numerical exercises will be proposed concerning the treated subjects, in order to make it clearer what is the practical use of the acquired notions. Problems will be solved under the teacher’s supervision. Lectures will be classified as theoretical or practical depending on the prevalence of the theoretical or the numerical aspect.

- Some written test, concerning the treated topics, will be proposed during the lectures. The test will consist in the solution of numerical problems, chosen on the basis of the course development

- Practical laboratory training within the Applied Geology lab of the Physics and Geology Department. The main Geotechnical test (Oedometrer test, Direct Shear test, Triaxial test ..) will be illustrated and executed with the support of the technical staff. It will be illustrated how to prepare specimens, how machines work, how to properly run the tests and how to collect and elaborate tests data.



- Field trips. One day field trips are organized in co-operation with professional Geologists. Field trips will be organized taking also into account temporary possibility of visiting constructions sites which could be of interest for the students of this course. The main goals of field trips is to learn how to make a geostructural survey applied to rock mechanics and to have a direct contact of geotechnical and geomechanical problems and heir solution

- Conferences of Professional geologists. Qualified professional Geologists will be invited to give seminars on case studies in which soil and rock mechanics have been used to solve geotechnical and geological problems. The seminars will mainly concern case studies in the Umbrian territory and will be organized taking into account the availability of qualified Geologists.
Learning verification modality
The evaluation consists of an oral exam about 40 minutes long. The goal of the exam is to evaluate theoretical and practical knowledge gained by the students, also in terms of language. In order to reach this goal, students will be both asked to answer theoretical questions and to solve numerical problems concerning the topics treated during the course. Such problems will be of the same kind of those proposed and solved during the lectures. The final evaluation will take into account all the mentioned aspects.
Extended program
The course is organized as follows:

Definition of soils and rocks in engineering geology.

Soil mechanics: review of main classification systems and main properties of coarse and fine-grained soils. Review of the main concepts in soil mechanics: effective stress principle.

Consolidation: Terzaghi’s one-dimensional consolidation theory; oedometer test and its interpretation. Coefficient of compressibility, Compression index, Consolidation coefficient, degree of consolidation, determination of t100, consolidation equation and time for consolidation. Solution of problems concerning estimation of settlement and consolidation time. Effects of consolidation: case studies.

Shear strength: review of Mohr-Coulomb failure criterion. Effective shear strength parameters. Undrained shearing resistance. Direct shear strength test: execution and interpretation.

Mohr circles: normal and shear stresses acting on any plane as a function of principal stresses.

Triaxial test: unconsolidated undrained (UU), consolidated undrained (CU) and consolidated drained (CD) tests.

Numerical problems to determine drained and undrained shearing parameters.

Lateral earth pressure: Rankine theory, determination of active and passive pressures and total active and passive thrust. Effects of overloading and water

Introduction to analysis of slopes stability: factor of safety. Analysis of plane translational slip. Analysis of rotational slips in undrained and drained conditions. Introduction to the method of slices.

Rock Mechanics:

Intact rock, discontinuities and rock masses.

Main index properties of intact rock.

Mechanical properties of intact rock: uniaxial compressive strength, tensile strength, shear strength (Mohr-Coulomb and Hoek and Brown failure criterions), sonic velocities, deformability, elastic constants. Descrition of laboratory tests.

Rock mass discontinuities: geometrical and mechanical characteristics. Orientation, spacing, persistence, roughness, friction angle of rock surfaces, aperture, infilling. Discontinuities sampling. Shear strength of discontinuities. Bi-linear Patton criterion, Barton criterion. Shear strength test on discontinuities.

Rock masses: strength in anisotropic and isotropic rock masses. Description of deformability tests: dilatometer, plate load test, flat jack method.

Geomechanics classification of rock masses: Beniawski classification and Q-system

Rock slopes stability: kinematic analysis and factor of safety for plain sliding and wedge sliding. Toppling.

Tunnels: excavation criterions.
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