Soil Mechanics

Code:

MEMG0005

Acronym:

MS

Keywords
Classification	Keyword
CNAEF	Engineering and related techniques

Instance: 2019/2020 - 1S

Active?	Yes
Responsible unit:	Department of Civil and Georesources Engineering
Course/CS Responsible:	Master in Mining and Geo-Environmental Engineering

Cycles of Study/Courses

Acronym	No. of Students	Study Plan	Curricular Years	Credits UCN	Credits ECTS	Contact hours	Total Time
MEMG	16	Plano de estudos oficial a partir de 2008/09	1	-	6	56	162

Teaching language

Suitable for English-speaking students

Objectives

RATIONALE:
All Civil and Mining Engineering works (buildings, bridges, roads, railways, tunnels, deep open-air excavations, ports, dams, etc.) have their behaviour, and thus also their conception, design, construction and use, dependent on the mechanical and hydraulic behaviour of the geological formations at the site. The large majority of these constructions is concentrated in the more densely populated areas, i.e. near the sea coast, on river banks or close to the river mouth, so in geologically recent areas where the Earth's surface is typically covered by weak soils, sometimes with large thickness.

OBJECTIVES:
To introduce the concepts, principles and fundamental theories, describing and explaining both the mechanical behaviour (in terms of strength and stiffness) and the hydraulic behaviour of soil masses.

Learning outcomes and competences

KNOWLEDGE: 
Describe the fundamental archetypes of soils (sandy and clayey soils of sedimentary origin and residual soils) considering physical characteristics and correlate them with the main trends of mechanical and hydraulic behaviour. Understand the concept of stress suitable for a mass formed by particles and saturated, with the water under hydrostatic conditions or in percolation. Be aware of the concepts, principles and fundamental theories that explain the mechanical and hydraulic behaviour of soils. Relate this behaviour with the physical characteristics, the geological conditions of their formation and the stress history. Know the laboratory and field tests to assess the physical characteristics, permeability, deformability and strength of soils.

UNDERSTANDING: 
Interpret the physical characteristics in order to distinguish the various soil types, their geological age and formation conditions. Identify the trends of mechanical behaviour for various loading conditions based on the soil physical characteristics. Explain the time effect on the loading of clayey soils in association with the evolution of pore water pressure and effective stress. Explain the phenomena that control the strength and the stress-strain relations in both sandy and clayey soils, distinguishing in the latter drained from undrained behaviour. Relate the shear strength of clays with the consolidation phenomenon.

APPLICATION:
Calculate the soil physical characteristics from experimental tests. Classify soils according to the unified classification. Calculate the at-rest stress state and the stress state after ground surface loading. To calculate the hydraulic quantities and the soil stress state for 1D and 2D flow, using flow networks. For clay strata loaded under confined conditions, calculate the consolidation settlement, its evolution in time and design systems to accelerate the consolidation. Calculate the strength parameters in effective stresses and total stresses from the results of lab shear tests. For non confined clay loading conditions, depict total and effective stress paths from the at-rest stress state, during undrained loading and till the end of the consolidation process.

ANALYSIS: Order soils with respect to geological age, (short and long term) compressibility, permeability taking into account their physical characteristics. Judge about expected behaviour (in terms of expansibility, overconsolidation, compressibility, liquefaction) from the physical characteristics and (oedometer, triaxial) lab test results. Compare the stress-strain relations of loose and compact granular soils and discuss the underlying physics. Compare the stress-strain relations of normally consolidated and overconsolidated clayey soils and discuss the underlying physics. Discuss the effect of consolidation on soil shear strength.

Working method

Presencial

Program

Physical properties of soils. Particle size distribution. Clay minerals. Atterberg limits. Basic features of sedimentary granular soils (sands) and cohesive soils (clays). Residual soils from granite. Soil classification. Effective stress principle. At rest stress state. Elastic solutions for stresses induced in the ground by external loads. Darcy's law. Coefficient of permeability. Lab and in situ tests to evaluate soil permeability. Two-dimensional flow nets. Seepage force. Quick condition and critical hydraulic gradient. Piping and heaving. Filters. Capilarity. Confined compression of clayey layers. Oedometer test. Parameters defining soil compressibility. Normally consolidated and overconsolidated soils. Estimation of the consolidation settlement. Terzaghi theory for vertical consolidation. Secondary consolidation. Compression of unconfined clay layers. Methods of acceleration of the consolidation rate. Observation of embankments on soft ground. Mohr-Coulomb and Tresca yield criteria. Direct shear, triaxial and simple shear tests. Shear strength of sands. Liquefaction. Shear strength of clays. Drained and undrained loading. Effective stress shear strength parameters. Pore pressure parameters. Undrained shear strength of clays and its dependence on the effective at-rest stress and on the stress path. Inherent and induced anisotropy of the undrained shear strength of clays.

DEMONSTRATION OF THE COHERENCE BETWEEN THE TEACHING METHODOLOGIES AND THE LEARNING OUTCOMES:
Students are encouraged to calculate the physical soil haracteristics from lab and in situ tests. Classify soils according to the unified classification. Calculate the at-rest stress state and the stress state after ground surface loading. Calculate the hydraulic quantities and the soil stress state for 1D and 2D flow, using flow networks. For clay strata loaded under confined conditions, calculate the consolidation settlement, its evolution in time and design systems to accelerate the consolidation. Calculate the strength parameters in effective stresses and total stresses from the results of lab shear tests. For non confined clay loading conditions, to depict total and effective stress paths between the at-rest state of stress, undrained loading and the end of the consolidation process. To realize the relationship between the available shear resistance in a given point of the ground and the effective state of stress controled by the consolidation.

Mandatory literature

Manuel de Matos Fernandes; Mecânica dos Solos, Conceitos e Princípios Fundamentais, Edições FEUP, 2006. ISBN: 972-752-086-3

Complementary Bibliography

T. William Lambe, Robert V. Whitman ; with the assistance of H. G. Poulos; Soil mechanics, SI version. ISBN: 0-471-80792-3

Teaching methods and learning activities

Lectures for the presentation of the concepts, principles and theories with reference to works and natural phenomena conditioned by the behaviour of soil masses. Tutorials for the resolution of numerical applications from the proposed problem sheets. Practical sessions for the observation of laboratory tests and the treatment of experimental data.

DEMONSTRATION OF THE COHERENCE BETWEEN THE TEACHING METHODOLOGIES AND THE LEARNING OUTCOMES:
Students are encouraged to calculate the physical characteristics from experimental tests. Classify soils according to the unified classification. Calculate the at-rest stress state and the stress state after ground surface loading. Calculate the hydraulic quantities and the soil stress state for 1D and 2D flow, using flow networks. For clay strata loaded under confined conditions, calculate the consolidation settlement, its evolution in time and design systems to accelerate the consolidation. Calculate the strength parameters in effective stresses and total stresses from the results of lab shear tests. For non confined clay loading conditions, to depict total and effective stress paths between the at-rest state of stress, undrained loading and the end of the consolidation process.

Evaluation Type

Distributed evaluation with final exam

Assessment Components

Designation	Weight (%)
Exame	75,00
Teste	25,00
Total:	100,00

Amount of time allocated to each course unit

Designation	Time (hours)
Frequência das aulas	162,00
Total:	162,00

Eligibility for exams

Achieving final classification requires compliance with attendance at the course unit, according to the master course assessment rules. It is considered that students meet the attendance requirements if, having been regularly enrolled, the number of absences of 25% for each of the classes’ types is not exceeded.

Calculation formula of final grade

The final grade is based on the results of the evaluation performed in the practical classes during the semester (consisting of two tests and four practical works), plus the final exam.
The evaluation during the semester is optional.

The final grade is based on the results of the evaluation performed in the practical classes during the semester (consisting of two tests and two practical works), plus the final exam.
The evaluation during the semester is optional.

The final grade, CF (on a 0 to 20 scale) is obtained as

CF = max{CT ; EF}

where:

CT = 0,10 x CAD1 + 0,10 x CAD2 + 0,025 x CAD3 + 0,025 x CAD4 + 0,75 x EF.

CAD1 – marks of test 1;
CAD2 – marks of test 2;
CAD3 – marks of practical work 1;
CAD4 – marks of practical work 2;
EF – marks of final exam;


NOTE 1: The tests associated to the marks CAD1 to CAD4 are optional. In case the student misses any of the three tests the corresponding weight is added to PF.

NOTE 2: All students enrolled in the course are classified according to this method.

NOTE 3: Students who wish to obtain a final grade over 17 must have at least 17,5 in the final exam and apply for an oral exam.

Observations

SPECIAL RULES FOR MOBILITY STUDENTS In exams and assignments students may use one of the following languages: Portuguese, English, Spanish, French or Italian.

Estimated working time out of class: 3 hours/week.