Access profile

In relation to scientific and technological areas associated with geotechnical engineering, the admission requirements for students can be summed up in three words:
1) knowledge,
2) ability and
3) motivation.

That is:
1) Students should have sufficient educational experience to access the frontier of knowledge in one of the programme’s subject areas.
2) They should be academically mature and have sufficient ability to go further so that they can make a new, original contribution to the state of knowledge or technology in the area of the doctoral thesis. Consequently, they should be able to research, develop and create. They must have the ability to analyse and synthesise, a critical spirit, the capacity to work, and the ability and skills required for team work and oral and written communication. A command of the English language is also essential. It is important to have a good source of funding.
3) Students should be really motivated and ready for a long-term project, they must be ambitious but realistic, with personal maturity and emotional intelligence and a plan for the future that enables them to benefit from the effort and cost that doctoral studies represent.
To date, most of the students on our doctoral programme have had these characteristics. Many of them are now lecturers or researchers in universities, service institutions and research centres in Spain, Latin America and the rest of the world.

The natural route into the doctoral programme is via the master’s degree in Geotechnical Engineering at the UPC. If students have completed this degree, they do not need to take additional master’s degree subjects (bridging courses).

Students who come from other master’s degrees must show that they have basic knowledge of fundamental subjects in the area of geotechnical engineering. If students do not have this knowledge, they must take bridging courses in subjects of the master’s degree in Geotechnical Engineering at the UPC. The academic committee of the doctoral programme will decide which additional subjects each student must take, depending on what they have studied in their master’s degree.

Main entrance qualifications:
Engineers or university graduates, preferably in the areas of civil engineering, geological engineering and architecture. In addition, candidates must have a master’s degree in the area of civil engineering, earth sciences or other related areas. Other curricula and educational backgrounds will be assessed by the programme’s academic committee.

Output profile

Doctoral candidates who complete a doctoral degree will have acquired the following competencies, which are needed to carry out quality research (Royal Decree 99/2011, of 28 January, which regulates official doctoral studies):

a) A systematic understanding of the field of study and a mastery of the research skills and methods related to the field.
b) An ability to conceive, design or create, put into practice and adopt a substantial process of research or creation.
c) An ability to contribute to pushing back the frontiers of knowledge through original research.
d) A capacity for critical analysis and an ability to assess and summarise new and complex ideas.
e) An ability to communicate with the academic and scientific community and with society in general as regards their fields of knowledge in the manner and languages that are typical of the international scientific community to which they belong.
f) An ability to foster scientific, technological, social, artistic and cultural progress in academic and professional contexts within a knowledge-based society.

The award of a doctoral degree must equip the graduate for work in a variety of settings, especially those requiring creativity and innovation. Doctoral graduates must have at least acquired the personal skills needed to:

a) Develop in contexts in which there is little specific information.
b) Find the key questions that must be answered to solve a complex problem.
c) Design, create, develop and undertake original, innovative projects in their field.
d) Work as part of a team and independently in an international or multidisciplinary context.
e) Integrate knowledge, deal with complexity and make judgements with limited information.
f) Offer criticism on and intellectually defend solutions.

Finally, with respect to competencies, doctoral students must:
a) have acquired advanced knowledge at the frontier of their discipline and demonstrated, in the context of internationally recognised scientific research, a deep, detailed and well-grounded understanding of theoretical and practical issues and scientific methodology in one or more research fields;
b) have made an original and significant contribution to scientific research in their field of expertise that has been recognised as such by the international scientific community;
c) have demonstrated that they are capable of designing a research project that serves as a framework for carrying out a critical analysis and assessment of imprecise situations, in which they are able to apply their contributions, expertise and working method to synthesise new and complex ideas that yield a deeper knowledge of the research context in which they work;
d) have developed sufficient autonomy to set up, manage and lead innovative research teams and projects and scientific collaborations (both national and international) within their subject area, in multidisciplinary contexts and, where appropriate, with a substantial element of knowledge transfer;
e) have demonstrated that they are able to carry out their research activity in a socially responsible manner and with scientific integrity;
f) have demonstrated, within their specific scientific context, that they are able to make cultural, social or technological advances and promote innovation in all areas within a knowledge-based society;
g) have demonstrated that they are able to participate in scientific discussions at the international level in their field of expertise and disseminate the results of their research activity to audiences of all kinds.

Number of places

15

Duration of studies and dedication regime

Duration
The maximum period of study for full-time doctoral studies is three years, counted from the date of admission to the programme to the date of submission of the doctoral thesis. The academic committee of the doctoral programme may authorise a doctoral candidate to pursue doctoral studies on a part-time basis. In this case, the maximum period of study is five years, counting from the date of admission to the programme to the date of submission of the doctoral thesis. For calculating these periods, the date of admission is considered to be the date of the first enrolment for tutorials, and the date of submission the moment in which the Doctoral School officially deposits the doctoral thesis.

For full-time doctoral candidates, the minimum period of study is two years, counted from the date of an applicant's admission to the programme until the date on which the doctoral thesis is deposited; for part-time doctoral candidates it is four years. When there are justified grounds for doing so, and the thesis supervisor and academic tutor have given their authorisation, doctoral candidates may request that the academic committee of their doctoral programme exempt them from the minimum period of study requirement.

The calculation of periods of study will not include periods of absence due to illness, pregnancy or any other reason provided for in the regulations in force. Students who find themselves in any of these circumstances must notify the academic committee of the doctoral programme, which, where appropriate, must inform the Doctoral School. Doctoral candidates may also temporarily withdraw from the programme for up to one year, and this period may be extended for an additional year. Doctoral candidates who wish to interrupt their studies must submit a justified request to the academic committee of the doctoral programme, which will decide whether or not to approve the request. Each programme will establish conditions for readmission to doctoral studies.

Extension
If full-time doctoral candidates have not applied to deposit their thesis by the end of the three-year period of study, the academic committee of the programme may authorise an extension of up to one year. In exceptional circumstances, a further one-year extension may be granted, subject to the conditions established by the corresponding doctoral programme. In the case of part-time doctoral candidates, an extension of two years may be authorised. In both cases, in exceptional circumstances a further one-year extension may be granted by the Doctoral School's Standing Committee, upon the submission of a reasoned application by the academic committee of the doctoral programme.

Dismissal from the doctoral programme
A doctoral candidate may be dismissed from a doctoral programme for the following reasons:

• The doctoral candidate submitting a justified application to withdraw from the programme.
• The maximum period of study and of extensions thereof ending.
• The doctoral candidate not having enrolled every academic year (unless he or she has been authorised to temporarily withdraw).
• The doctoral candidate failing two consecutive assessments.
• The doctoral candidate having disciplinary proceedings filed against him or her that rule that he or she must be dismissed from the UPC.

Dismissal from the programme implies that doctoral candidates cannot continue studying at the UPC and the closing of their academic record. This notwithstanding, they may apply to the academic committee of the programme for readmission and the committee must reevaluate them in accordance with the criteria established in the regulations.

Organization

• Olivella Pastalle, Sebastià

• Gili Ripoll, Jose Antonio
• Olivella Pastalle, Sebastià
• Pinyol Puigmarti, Nuria Merce
• Sanchez Vila, Xavier

• Department of Civil and Environmental Engineering (PROMOTORA)

Building C2 (North Campus)
Tel.: (+34) 934 011 784
E-mail: doctorat.ET.camins@upc.edu

Access profile

In relation to scientific and technological areas associated with geotechnical engineering, the admission requirements for students can be summed up in three words:
1) knowledge,
2) ability and
3) motivation.

That is:
1) Students should have sufficient educational experience to access the frontier of knowledge in one of the programme’s subject areas.
2) They should be academically mature and have sufficient ability to go further so that they can make a new, original contribution to the state of knowledge or technology in the area of the doctoral thesis. Consequently, they should be able to research, develop and create. They must have the ability to analyse and synthesise, a critical spirit, the capacity to work, and the ability and skills required for team work and oral and written communication. A command of the English language is also essential. It is important to have a good source of funding.
3) Students should be really motivated and ready for a long-term project, they must be ambitious but realistic, with personal maturity and emotional intelligence and a plan for the future that enables them to benefit from the effort and cost that doctoral studies represent.
To date, most of the students on our doctoral programme have had these characteristics. Many of them are now lecturers or researchers in universities, service institutions and research centres in Spain, Latin America and the rest of the world.

The natural route into the doctoral programme is via the master’s degree in Geotechnical Engineering at the UPC. If students have completed this degree, they do not need to take additional master’s degree subjects (bridging courses).

Students who come from other master’s degrees must show that they have basic knowledge of fundamental subjects in the area of geotechnical engineering. If students do not have this knowledge, they must take bridging courses in subjects of the master’s degree in Geotechnical Engineering at the UPC. The academic committee of the doctoral programme will decide which additional subjects each student must take, depending on what they have studied in their master’s degree.

Main entrance qualifications:
Engineers or university graduates, preferably in the areas of civil engineering, geological engineering and architecture. In addition, candidates must have a master’s degree in the area of civil engineering, earth sciences or other related areas. Other curricula and educational backgrounds will be assessed by the programme’s academic committee.

Access requirements

Applicants must hold a Spanish bachelor’s degree or equivalent and a Spanish master’s degree or equivalent, provided they have completed a minimum of 300 ECTS credits on the two degrees (Royal Decree 43/2015, of 2 February)

In addition, the following may apply:

• Holders of an official degree awarded by a university in Spain or any other country in the European Higher Education Area, pursuant to the provisions of Article 16 of Royal Decree 1393/2007, of 29 October, which establishes official university course regulations, who have completed a minimum of 300 ECTS credits on official university degrees, of which at least 60 must be at the master's degree level.
• Holders of an official Spanish bachelor’s degree comprising at least 300 credits, as provided for by EU regulations. Holder of degrees of this kind must complete bridging courses unless the curriculum of the bachelor’s degree in question included research training credits equivalent in value to those which would be earned on a master's degree.
• Holders of an official university qualification who, having passed the entrance examination for specialised medical training, have completed at least two years of a training course leading to an official degree in a health-sciences specialisation.
• Holders of a degree issued under a foreign education system. In these cases, homologation is not required, but the UPC must verify that the degree certifies a level of training equivalent to an official Spanish master's degree and qualifies the holder for admission to doctoral studies in the country where it was issued. Admission on this basis does not imply homologation of the foreign degree or its recognition for any purpose other than admission to doctoral studies.
• Holders of a Spanish doctoral qualification issued under previous university regulations.

Note 1: Doctoral studies entrance regulations for holders of an undergraduate degree awarded before the introduction of the EHEA (CG 47/02 2014)

Note 2: Governing Council Decision 64/2014, which approves the procedure and criteria for assessing the fulfilment of academic admission requirements for doctoral studies by holders of non-homologated foreign degrees (CG 25/03 2014)

Admission criteria and merits assessment

The suitability of an applicant’s background will be assessed according to the following criteria:

a) Whether a student’s academic background (subjects taken) is in line with the disciplines in the programme.

The suitability of a student’s background will be assessed in the following terms:
a1) Suitable academic background.
a2) Suitable academic background with bridging courses.
a3) Unsuitable background.
An evaluation of a1 indicates that the student can enter the programme with no need for bridging courses, and a2 means that the student can enter if they take bridging courses. An evaluation of a3 indicates that the student has not been accepted.

Sections b1, b2 and b3 are evaluated on a scale of 1 to 10. To enter the programme, students must have a score that is no less than 6 for any section and an overall score above 7. The overall score will be calculated as a weighted average, in which sections b1 and b2 are worth 35% and section b3 is worth 30%. This overall score can also be used to prioritise applications if there are more applicants than available places.

Training complements

The natural route into the doctoral programme is via the master’s degree in Geotechnical and Earthquake Engineering at the UPC. Students who enter through this route do not need to take bridging courses.

Students who enter the programme through other master’s degrees must take bridging courses (a maximum of 60 ECTS) in subjects from the master’s degree in Geotechnical and Earthquake Engineering at the UPC. The academic committee of the doctoral programme will decide which additional subjects each student must take, depending on what they have studied in their master’s degree and the research line they will explore in their thesis. Below is a list of subjects from the master’s degree that is associated with the doctoral programme, by line of research.

For students who will focus on research lines in the area of soil and rock mechanics and nanotechnology of engineering materials, the bridging courses will be selected from the following list of subjects of the master's degree in Geotechnical and Earthquake Engineering at the UPC (or similar):
• Rock Mechanics
• Underground Excavations
• Water and Heat Flow in Deformable Porous Media
• Unsaturated Soil Mechanics
• Numerical Models in Geotechnical Engineering
• Modern Monitoring Techniques for Ground Movements
• Soil Behaviour and Advanced Modelling
• Constitutive Equations of Materials
• Modelling of Flow and Transport in Porous Media
• Geographic Information Systems
• Geomechanical and Geotechnical Engineering
• Geotechnical Design and Construction
• Geomechanics of Breakage
• Quaternary Geology
• Slope Stability

For students who will focus on research lines in the area of groundwater hydrology, bridging courses will be selected from the following list of subjects of the master’s degree in Geotechnical and Earthquake Engineering at the UPC (or similar):
• Water resources and Infrastructure
• Soil Mechanics
• Water and Heat Flow in Deformable Porous Media
• Environmental Isotope Techniques in Groundwater Hydrology
• Aquifers Balance and Recharge
• Reactive Transport
• Statistical Methods in Groundwater Hydrology
• Hydrogeochemical Modelling
• Groundwater and Environment
• Geographic Information Systems
• Modelling and Upscaling of Solute Transport in the Subsoil
• Aquifer Mechanics
• Hydrogeology and Public Works
• Variable Density, Multiphase Flow
• Quaternary Geology

Taking subjects from the master’s degree in Geotechnical and Earthquake Engineering associated with the programme, each of which has specific objectives, methodologies and assessment processes, will prepare students to gain competencies. The link to the programme is: https://camins.upc.edu/ca/estudis/master/met

Enrolment period for new doctoral students

Dates to be set every academic year, between September and October. Extraordinary period in February.

More information at the registration section for new doctoral students

Enrolment period

Dates to be set every academic year, between September and October.

More information at the general registration section

Procedure for the preparation and defense of the research plan

Doctoral candidates must submit a research plan, which will be included in their doctoral student activity report, before the end of the first year. The plan may be improved over the course of the doctoral degree. It must be endorsed by the tutor and the supervisor, and it must include the method that is to be followed and the aims of the research.

At least one of these annual assessments will include a public presentation and defence of the research plan and work done before a committee composed of three doctoral degree holders, which will be conducted in the manner determined by each academic committee. The examination committee awards a Pass or Fail mark. A Pass mark is a prerequisite for continuing on the doctoral programme. Doctoral candidates awarded a Fail mark must submit a new research plan for assessment by the academic committee of the doctoral programme within six months.

The committee assesses the research plan every year, in addition to all of the other activities in the doctoral student activity report. Doctoral candidates who are awarded two consecutive Fail marks for the research plan will be obliged to definitely withdraw from the programme.

If they change the subject of their thesis, they must submit a new research plan.

Formation activities

Activity: Tutorial (compulsory).
- 288 hours.

Activity: Courses and seminars.
- 60 hours.

Activity: Workshops.
- 30 hours.

Activity: Publications.
- 30 hours.

Activity: Mobility.
- 480 hours.

Activity: Training in information skills.
- 1.5 hours.

Activity: Research methodology.
- 12 hours.

Activity: Innovation and creativity.
- 8 hours.

Activity: Language and communication skills.
- 18 hours.

Activity: Assessment based on doctoral student activity report (DAD) and research plan.
- 4 hours.

Procedure for assignment of tutor and thesis director

The academic committee of the doctoral programme assigns a thesis supervisor to each doctoral candidate when they are admitted or enrol for the first time, taking account of the thesis supervision commitment referred to in the admission decision.

The thesis supervisor will ensure that training activities carried out by the doctoral candidate are coherent and suitable, and that the topic of the candidate’s doctoral thesis will have an impact and make a novel contribution to knowledge in the relevant field. The thesis supervisor will also guide the doctoral candidate in planning the thesis and, if necessary, tailoring it to any other projects or activities undertaken. The thesis supervisor will generally be a UPC professor or researcher who holds a doctoral degree and has documented research experience. This includes PhD-holding staff at associated schools (as determined by the Governing Council) and UPC-affiliated research institutes (in accordance with corresponding collaboration and affiliation agreements). When thesis supervisors are UPC staff members, they also act as the doctoral candidate’s tutor.

PhD holders who do not meet these criteria (as a result of their contractual relationship or the nature of the institution to which they are attached) must be approved by the UPC Doctoral School's Standing Committee in order to participate in a doctoral programme as researchers with documented research experience.

The academic committee of the doctoral programme may approve the appointment of a PhD-holding expert who is not a UPC staff member as a candidate’s thesis supervisor. In such cases, the prior authorisation of the UPC Doctoral School's Standing Committee is required. A UPC staff member who holds a doctoral degree and has documented research experience must also be proposed to act as a co-supervisor, or as the doctoral candidate’s tutor if one has not been assigned.

A thesis supervisor may step down from this role if there are justified reasons (recognised as valid by the committee) for doing so. If this occurs, the academic committee of the doctoral programme will assign the doctoral candidate a new thesis supervisor.

Provided there are justified reasons for doing so, and after hearing any relevant input from the doctoral candidate, the academic committee of the doctoral programme may assign a new thesis supervisor at any time during the period of doctoral study.

If there are academic reasons for doing so (an interdisciplinary topic, joint or international programmes, etc.) and the academic committee of the programme gives its approval, an additional thesis supervisor may be assigned. Supervisors and co-supervisors have the same responsibilities and academic recognition.

The maximum number of supervisors of a doctoral thesis is two: a supervisor and a co-supervisor.

For theses carried out under a cotutelle agreement or as part of an Industrial Doctorate, if necessary and if the agreement foresees it this maximum number of supervisors may not apply. This notwithstanding, the maximum number of supervisors belonging to the UPC is two.

More information at the PhD theses section

Permanence

The academic committee of the programme may authorise an extension of up to one year for full-time doctoral candidates who have not applied to deposit their thesis by the end of the three-year period of study, in the terms outlined in the Academic Regulations for Doctoral Studies of the Universitat Politècnica de Catalunya. In the case of part-time candidates, an extension of two years may be authorised. In both cases, in exceptional circumstances a further one-year extension may be granted by the Doctoral School's Standing Committee, upon the submission of a reasoned application by the academic committee of the doctoral programme.

A doctoral candidate may be dismissed from a doctoral programme for the following reasons:

• The doctoral candidate submitting a justified application to withdraw from the programme.
• The maximum period of study and of extensions thereof ending.
• The doctoral candidate not having enrolled every academic year (unless he or she has been authorised to temporarily withdraw).
• The doctoral candidate failing two consecutive assessments.
• The doctoral candidate having disciplinary proceedings filed against him or her that rule that he or she must be dismissed from the UPC.

Dismissal from the programme implies that doctoral candidates cannot continue studying at the UPC and the closing of their academic record. This notwithstanding, they may apply to the academic committee of the programme for readmission and the committee must reevaluate them in accordance with the criteria established in the regulations.

International Mention

The doctoral degree certificate may include International Doctorate mention. In this case, the doctoral candidate must meet the following requirements:

a) During the period of study leading to the award of the doctoral degree, the doctoral candidate must have spent at least three months at a respected higher education institution or research centre outside Spain to complete courses or do research work. The stays and activities carried out must be endorsed by the thesis supervisor and authorised by the academic committee of the programme. The candidate must provide a certifying document issued by the person responsible for the research group of the body or bodies where the stay or activity was completed. This information will be added to the doctoral student’s activity report.
b) Part of the thesis (at least the summary and conclusions) must be written and presented in one of the languages commonly used for science communication in the relevant field of knowledge, which must not be an official language of Spain. This rule does not apply to stays and reports in Spanish or to experts from Spanish-speaking countries.
c) At least two PhD-holding experts belonging to a higher education institution or research centre outside Spain must have issued officially certified reports on the thesis.
d) The thesis examination committee must have included at least one PhD-holding expert from a higher education or research institution outside Spain who was not responsible for the candidate’s stay abroad (point a) above).
e) The thesis defence must have taken place on UPC premises or, in the case of joint programmes, at the location specified in the collaboration agreement.

List of authorized thesis for defense

• DE FRANCISCO SANS, MIGUEL: Elementos junta/interfase mortar con nudos no coincidentes. Aplicación al análisis de discontinuidades y contactos en geomecánica
  
  Author: DE FRANCISCO SANS, MIGUEL
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN GEOTECHNICAL ENGINEERING
  Department: (DECA)
  Mode: Temporary seizure
  Deposit date: 20/05/2021
  Reading date: 19/11/2021
  Reading time: 15:00
  Reading place: etseccpb- Building D2. Classroom: 212
  Thesis director: CAROL VILARASAU, IGNACIO
  Committee:
       PRESIDENT: SEGURA SERRA, JOSE MARIA
       SECRETARI: PRAT CATALAN, PERE
       VOCAL: CIANCIO, DANIELA
  Thesis abstract: The general objectives of this thesis are, on the one hand, to extend the formulation of the traditional zero-thickness interface elements in small deformations to the case of non-coincident meshes and, on the other hand, based on that formulation, to develop a numerical contact-friction model in a general context of large deformations, in which the final positions of the nodes of the contact interface may differ considerably from their initial position.The first part of the thesis, describes two formulations of zero-thickness mortar/ interface finite elements for unmatched meshes, and their application to the analysis of discontinuities and contacts in Geomechanics. The two formulations are implemented in a unified theoretical framework. The first one is displacement-based and may be considered a natural extension of the traditional zero-thickness interface element to the case of unmatched meshes on each side of the discontinuity. The other one is hybrid, with the interpolation of stress tractions along the contact surface, which coexists with the standard displacement interpolations of the continuum surfaces in contact, and which turns out fully equivalent to the displacement-based in the particular case of matched nodes and uniform, linear elastic behavior. Both formulations share some features with mortar formulations found in the literature of contact-friction. Flow chart diagrams for the numerical implementation are also presented and discussed, as well as some examples of application.In the second part of the thesis, the applicability of the formulation of the new joint /interface mortar elements based on displacements is extended to a general contact-friction context. The formulation is also developed using mortar methods, with a symmetrical treatment of the two surfaces in contact, and the penalty method for the treatment of contact constraints. In addition to the contact-friction formulation, the method k-DOPs for the global detection of contacts is implemented, with the aim of finding the contact interface and defining the mortar surface in its mid-plane surface. On the other hand, the formulation of the continuum is extended to the context of large deformations in the continuous medium with hyperelastic behavior, necessary for the contact formulation based on the current configuration. Finally, several verification examples are presented.
  

Last update: 16/10/2021 04:47:07.

List of lodged theses

Last update: 16/10/2021 04:30:36.

List of defended theses by year

• BARBOZA DE VASCONCELOS, RAMON: A double-porosity formulation for the THM behaviour of bentonite-based materials
  
  Author: BARBOZA DE VASCONCELOS, RAMON
  Thesis link: http://hdl.handle.net/10803/672141
  Programme: DOCTORAL DEGREE IN GEOTECHNICAL ENGINEERING
  Department: (DECA)
  Mode: Normal
  Reading date: 18/05/2021
  Thesis director: GENS SOLE, ANTONIO | VAUNAT, JEAN
  

  Committee:
       PRESIDENT: VILLAR GALICIA, MARÍA VICTORIA
       SECRETARI: PRAT CATALAN, PERE
       VOCAL NO PRESENCIAL: LLORET CABOT, MARTI
  Thesis abstract: The thermo-hydro-mechanical (THM) behaviour of expansive clays has been extensively studied in the last decades due to the potential use of bentonites as components of engineered barrier systems (EBS) in deep geological repositories for high-level and long-lived radioactive wastes. Since the early post closure period, the EBS is subjected to changes in temperature, moisture content and stresses due to the coupled THM processes expected to occur in such an environment. The different structural levels found in unsaturated expansive clays requires the use of constitutive models that considers the explicit distinction of these pore-structure levels in their mathematical formulation in order to reproduce the development of the fabric of bentonite materials subjected to the complex THM paths taking place during the lifetime of a nuclear waste repository. A coupled THM formulation that represents the expansive soil as two overlapped but distinct structural media has been developed in the framework of classical and generalized plasticity theories. In such a double-structure approach, the THM behaviour of the expansive soil is characterized by constitutive laws formulated to account for the relevant processes affecting each porous medium and for the interaction mechanisms relating the deformation and the saturation states of the active clay particles to the structural arrangement of the clay aggregates and to the water potential in the larger interconnected pores. In addition, the mechanical response of the porous medium to any THM loading is intrinsically related to the compressibility of the clay minerals. The irreversible changes in the soil fabric are attributed to the loading-collapse (LC) mechanism and to the micro-macro structural coupling (ß-mechanism). Thermal effects are incorporated into the mathematical formulation of the double structure model, which has been implemented in a finite element code (CODE_BRIGHT) able to solve, in a fully coupled way, the system of partial differential equations arising from the governing equations (balance equations). An explicit and robust integration scheme with automatic sub-stepping and error control has been employed to update the stress tensor and the internal (history) variables. The capabilities of the implemented double-porosity model to predict the expected response of expansive clays under isothermal and non-isothermal scenarios have been checked by the performance of constitutive analyses following a number of prescribed THM paths under confined and unconfined conditions. In addition, sensitivity analyses have been carried out in order to verify the dependence of the local expansive response on the initial conditions and on the sequence of load application. Special attention has been placed on the role played by the pore-water mass transfer between the two pore-structure levels in the development of the swelling potential of the expansive porous medium. The performance of the model in reproducing the actual THM behaviour of laboratory-scale tests has also been examined by means of the modelling of the hydration of two heated columns made of granular bentonite materials, selected as potential buffer materials in the construction of engineered barriers. The comparison between the available experimental data and the model results has shown the ability of the current double-porosity formulation to simulate the main observed features of the THM behaviour of the expansive material when subjected to complex loading paths.
  

• DE VRIENDT, KEVIN: Mixing and chemical reaction hotspots in saline-freshwater mixing zones
  
  Author: DE VRIENDT, KEVIN
  Thesis link: http://hdl.handle.net/10803/672312
  Programme: DOCTORAL DEGREE IN GEOTECHNICAL ENGINEERING
  Department: (DECA)
  Mode: Normal
  Reading date: 16/07/2021
  Thesis director: DENTZ, MARCO | POOL RAMIREZ, MARIA
  

  Committee:
       PRESIDENT: HOUBEN, GEORG JOSEF
       SECRETARI: SAALTINK, MAARTEN WILLEM
       VOCAL NO PRESENCIAL: JIMENEZ MARTINEZ, JOAQUIN
  Thesis abstract: Seawater intrusion presents one of the most unique and ubiquitous groundwater problems in the field of hydrogeology. Its complex boundary conditions coupled with variable density flow results in non-uniform flow which lead to non-trivial mixing dynamics. The mixing of fresh and saline waters in the subsurface is known to play a key role in an array of geochemical reactions. Such reactions include the dissolution and precipitation of calcite which shape the coastal landscape overmillennia, as well as reactions associated to anthropogenic contamination of coastal groundwater such as nitrogen reduction or iron oxide precipitation which can act to limit the fluxes of harmful pollutants to vulnerable near shore marine ecosystems. In addition to reactions, understanding the mixing mechanisms is crucial to predicting the movement of the saltwater wedge and the size of the salt-freshwater interface. This has direct implications on the management of freshgroundwater reserves and its risk to salinization.In this thesis we focus on understanding the influence variable density flow on mixing and the spatial distribution of enhanced geochemical activity along the saline-freshwater interface. First, we look to see the impact of heterogeneity onmixing and reaction for fast calcite dissolution. We find that heterogeneity permits reactions to occur over a greater area of the mixing zone due to enhanced mixing rates than would otherwise be permitted in homogeneous media. Furthermore, weobserve unique patterns of enhanced localized reactivity that strongly deviate from the homogeneous case. Our study suggests that karst topology in coastal aquifers may be strongly linked to non-uniform flow induced by variable density flowand strongly linked to the type of heterogeneity present. Since initial stages of karst development are known to dictate the evolution of cave systems and conduits, we hypothesize that heterogeneity plays an integral role in its propagation.Second, we study mixing across the salt-freshwater interface and the influence of compression caused by the flow of freshwater towards the saltwater body. In the absence of transient effects and heterogeneity, we find that mixing interface grow via transverse dispersion until some critical distance at which point it begins to recompress due to accelerating flow resulting from a decrease in area between the confining unit and the interface. Using a modified Glover solution to define the mixing interface, we are able to capture the velocity change along the interface from which a stretching rate (acceleration) canbe deduced. We find that the behaviour of interface compression can be well-approximated by assuming a local Bachelor scale, which defines the equilibrium between dispersive growth and compression due to accelerating flow. Finally, weestablish a new method to study fast mixing-dependent reactions across the salt-freshwater interface. Our findings lead us to the use of luminol chemiluminescence, which allows for the direct visualization of reaction rates along the saline-freshwater interface. Unlike conservative studies of mixing in sand tank, we bypass the need for complex image analysis techniques required to resolve local concentration gradients needed to evaluate mixing metrics. Results from experiments performed under both steady state and transient conditions consistently confirm local reaction hotspots at both the interface toe and atthe head of the interface, which we attribute to stagnation point flow and accelerating flow respectively. Evaluation of the interface during the transient advance and retreat were also able to capture unique reactive behaviours that capture a shift in mixing behaviour due to a change in the flow field across the mixing zone.
  

• GOYETCHE, TYBAUD MEDHY DOMKIC: Seawater intrusion, transition zone dynamics and reactive mixing - Example of Argentona coastal alluvial aquifer
  
  Author: GOYETCHE, TYBAUD MEDHY DOMKIC
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN GEOTECHNICAL ENGINEERING
  Department: (DECA)
  Mode: Temporary seizure
  Reading date: 19/07/2021
  Thesis director: CARRERA RAMIREZ, JESUS | LUQUOT, LINDA
  

  Committee:
       PRESIDENT: SHERIF, MOHSEN
       SECRETARI: FERNANDEZ GARCIA, DANIEL
       VOCAL NO PRESENCIAL: MASSMAN, GUDRUN
       VOCAL NO PRESENCIAL: GUARRACINO, LUIS
       VOCAL NO PRESENCIAL: JURADO ELICES, ANNA
  Thesis abstract: Freshwater quality and availability in coastal areas are affected by seawater intrusion into coastal aquifers. While coastal water quality and coastal ecosystems can be significantly affected by pollutants discharged into the sea.In this thesis we investigate: (i) the use of sea level periodic fluctuations (e.g. tides) to characterize coastal aquifers hydrodynamic parameters; (ii) the chemical reactions that occur in the mixing zone between freshwater and seawater; and (iii) the impact of high-frequency fluctuations (e.g. storms) on the mixing zone and chemical reactions. Thus, the Argentona experimental site allowed us to apply and validate the investigated methods.The results show that thanks to the tidal method we have been able to clarify the technique and make its application easier. In addition, we make one of the first applications to a real aquifer where we detail the entire process from the acquisition and filtering of head data to finally obtain the hydrodynamic parameters by numerical modeling. This allowed refining the conceptual model and observing the pronounced impact of aquitard on the propagation of inland tidal fluctuations.In addition, we have investigated the chemical reactions that occur by the mixing between freshwater and saltwater. The results show that coastal aquifers are a fairly complex system with many chemical reactions. We observe the predominance of cationic exchange reactions, but also quite a few redox reactions using organic matter as electron donors and molecules such as dissolved oxygen, nitrates, iron, or manganese oxides as electron acceptors. We have observed that quite a few reactions associated with the rocks that form the reservoir also occur. But we go beyond identifying them, we present a method to quantify these reactions, which allows us to observe the spatial distribution of the reactions. Furthermore, by quantifying them, it is possible to estimate the chemical composition of the water that is discharged into the sea. As a result, nutrients discharge to the sea can be estimated through the quantification of their degradation. Finally, we investigated the impact of an intense rain event over a coastal aquifer and its mixing zone. We acknowledge a freshwater displacement occurs in the direction of the sea caused by the aquifer recharge. But we also observed how the interface is pushed inland during the recovery. These unique conditions can have a significant impact on the annual nutrients balance released to the sea. In fact, by moving the interface, the chemical conditions are modified and a significant impact on the chemical reactions is observed.
  

• MADRID ARGOMEDO, MANUEL RICARDO: Construction and post-construction performance of vertical breakwaters on soft soils. The Port of Barcelona case
  
  Author: MADRID ARGOMEDO, MANUEL RICARDO
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN GEOTECHNICAL ENGINEERING
  Department: (DECA)
  Mode: Normal
  Reading date: 21/07/2021
  Thesis director: GENS SOLE, ANTONIO
  

  Committee:
       PRESIDENT: JOMMI, CRISTINA
       SECRETARI: LLORET MORANCHO, ANTONIO
       VOCAL NO PRESENCIAL: TORRIJO ECHARRI, FRANCISCO JAVIER
  Thesis abstract: The design and construction of vertical caisson breakwaters on soft soils represents a significant challenge for the engineering of marine structures. Past experience reveals that this type of structures is sometimes prone to failure or to undergo excessive settlements. Cyclic loading due to storm wave action adds an addtional degree of complexity. This Thesis present the performance of a wide-ranging set of geotechnical activities to address the key issues of stability, large caisson displacements and cyclic loading effects in the context of the construction of vertical breakwaters. They include site investigation operations (involving laboratory tests, in situ tests and field tests), constitutive models for soft clays (under static and cyclic conditions), instrumentation and monitoring systems, numerical modelling of the breakwater during and after construction and the evaluation of stability under static and cyclic loads. The construction and performance of a vertical breakwater built on the soft soils of the Port of Barcelona provides the focal point to integrate the description of those activities in a joint and structured manner.After reviewing the main aspects associated with the construction and performance of vertical breakwaters, the behaviour of the soft foundation soil is examined. Laboratory tests, in situ tests and a large scale instrumented preload test are considered. Particular attention is paid to undrained shear strength, small strain stiffness, compressibility characteristics and cyclic loading effects. Soil behaviour is then modelled by a range of different constitutive laws of different degrees of complexity. The proper representation of strength anisotropy, long-term creep and cyclic behaviour is explicitly addressed.An extensive monitoring system for the measurement of pore pressures and soil movements has been installed before construction and, following the loss of a number of sensors, after caisson emplacement as well. A novel feature of the instrumentation was the installation of sensors on the front and on the base of the caisson to measure the hydraulic response to the impact of sea waves. The monitoring data has provided the necessary information to achieve a sounder knowledge of the behaviour of the breakwater at different stages of construction and post-construction, including the response under storm loading.Numerical analyses have been carried out towards achieving a better understanding of the breakwater behaviour during construction, post-construction and under cyclic loads. The interplay between monitoring observations, construction history and simulation results is highlighted. Special attention has been given to the evaluation of stability during construction and post-construction. Whenever relevant, the observations provided by the monitoring system are incorporated in the evaluation; the measurement of the evolution of pore pressures has proved important to ensure the safety of the caisson during construction. Breakwater stability under cyclic loading has also been evaluated using both simplified and advanced methods.This ensemble of works performed in the context of a well-documented case history should prove of benefit for the design and construction of similar structures founded on soft ground.
  

• MESA ALCANTARA, ARISLEIDY: Hydro-mechanical behaviour of pellet/powder mixture of bentonite and impact of gas migration
  
  Author: MESA ALCANTARA, ARISLEIDY
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN GEOTECHNICAL ENGINEERING
  Department: (DECA)
  Mode: Temporary seizure
  Reading date: 02/07/2021
  Thesis director: ROMERO MORALES, ENRIQUE EDGAR | MOKNI, NADIA
  

  Committee:
       PRESIDENT: NAVARRO GAMIR, VICENTE
       SECRETARI: OLIVELLA PASTALLE, SEBASTIAN
       VOCAL NO PRESENCIAL: VILLAR GALICIA, MARÍA VICTORIA
  Thesis abstract: The hydro-mechanical behaviour of MX80 bentonite pellet-based mixture (80% high-density pellets in dry mass and crushed granular powder) has been explored in this thesis within the context of the French `Vertical Sealing Systems¿ (VSS, Cigeo) toappropriately seal these critical vertical pathways between the long-lived radioactive waste and the biosphere. The VSSs will undergo complex hydration scenarios: fast hydration from the upper surface by water from the Calcareous Oxfordian formation and slower hydration in the lateral direction arriving from the more impermeable Callovo-Oxfordian rock. These distincthydrations will induce gas entrapment with time at the bottom of the seal, which will also be affected by gas generated by longterm metallic corrosion processes. Hence, a complete understanding of the VSSs under hydraulic and gas solicitations will berequired, in which the French IRSN has played a significant role by supporting the current research and launching the VSEAL in situ tests currently being performed in Tournemire URL (France) at a scale of 1/10 of the VSS.The thesis initially addressed a thorough characterisation of the as-poured mixture¿s initial and saturated states (both at the microstructural and macroscopic scales) and the mixture¿s hydro-mechanical behaviour and its components. The pellets constitute the shielding skeleton, whereas the crushed powder filled the inter-pellet space to reach an overall dry density of 1.49Mg/m3 that ensured a swelling pressure around 4 MPa. The hydro-mechanical characterisation involved water permeability tests under constant volume, water retention curves under different mechanical boundary conditions, swelling pressure tests and loading/unloading oedometer tests at different hydraulic states.A mock-up at a scale of 1/100 of the VSS and independent control of fast hydration at the top and slow lateral hydration was developed, calibrated, and set up. The bentonite mixture (100 mm in diameter and 350 mm high) was asymmetrically wetted under constant volume conditions. The hydration cell was fully instrumented with pore pressure, total stress and relative humiditysensors, and four independent water pressure/volume controllers to monitor all processes comprehensively. A long-termhydration stage (around 300 days) was initially performed. At the end of this stage, gas was injected at a controlled volume/pressure rate at different boundaries (top and bottom) to determine the maximum gas overpressure that the bentonitebased barrier could withstand. The gas experiments were also devoted to detecting gas flows at the interface in zones with loweffective stresses.The experimental program¿s data allowed using different double porosity models and their coupled interactions via Code_Bright.The model parameters were determined based on the back-analysis of laboratory test results on the pellets, the powder and the mixture. Two modelling approaches were adopted to simulate the hydration phase at constant volume. A fully coupled elasticplastic model (Barcelona Expansive Model in 2D axisymmetric representation) that considers the micro and macro-porosity, wasinitially used to simulate infiltration results and better understand the different coupled and double porosity processes involved. Anumerical dual-porosity model (plane strain) was also considered to account for the mixture¿s heterogeneous dry density distribution and represent the mixture¿s double structure with pellets and powder as two distinct materials. The simulation results showed that the mixture on hydration tended to a more homogeneous distribution of porosity, despite starting from contrasting porosities of the components, as the pellets expanded and compressed the highly deformable clay powder. The modelspredicted a faster suction decrease rate (faster saturation rate), demonstrating the significant role of the intrinsic permeability on the mixture¿s hydro-mechanical behaviour.
  

• PALAU BERASTEGUI, ROSA MARIA: Landslide and debris flow warning at regional scale. A real-time system using susceptibility mapping, radar rainfall and hydrometeorological thresholds for Catalonia (NE Spain).
  
  Author: PALAU BERASTEGUI, ROSA MARIA
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN GEOTECHNICAL ENGINEERING
  Department: (DECA)
  Mode: Normal
  Reading date: 23/09/2021
  Thesis director: BERENGUER FERRER, MARC | HURLIMANN ZIEGLER, MARCEL
  

  Committee:
       PRESIDENT: CALVELLO, MICHELE
       SECRETARI: ABANCÓ MARTÍNEZ DE ARENZANA, CLÀUDIA
       VOCAL NO PRESENCIAL: MARRA, FRANCESCO
  Thesis abstract: Rainfall triggered shallow slides and debris flows constitute a significant hazard that causes substantial economic losses and fatalities worldwide. Regional-scale risk mitigation for these processes is challenging. Therefore, landslide early warning systems (LEWS) are a helpful tool to depict the time and location of possible landslide events so that the hazardous situation can be managed more effectively.The main objective of this thesis is to set up a regional-scale LEWS that works in real-time over Catalonia (NE Spain). The developed warning system combines in real-time susceptibility information and rainfall observations to issue qualitative warnings over the region.Susceptibility has been derived combining slope angle and land use and land cover information with a simple fuzzy logic approach. The LEWS input rainfall information consists of high-resolution radar quantitative precipitation estimates (QPEs). To assess if a rainfall situation has the potential to trigger landslides, the LEWS applies a set of intensity duration thresholds. Finally, a warning matrix combines susceptibility and rainfall hazard to obtain a qualitative warning map that classifies the terrain into four warning classes. The evaluation of the LEWS performance has been challenging because of the lack of a systematic inventory, including the time and location of recent landslides events. Within the context of this thesis, a citizen-science initiative has been set up to gather landslide data from reports in social networks. However, some of the reports have significant spatial and temporal uncertainties.With the aim of finding the most suitable mapping unit for real-time warning purposes, the LEWS has been set-up to work using susceptibility maps based on grid-cells of different resolutions and subbasins. 30 m grid-cells have been chosen to compute the warnings as they offer a compromise between performance, interpretability of the results and computational costs. However, from an end users¿ perspective visualising 30 m resolution warnings at a regional scale might be difficult. Therefore, subbasins have been proposed as a good option to summarise the warning outputs. A fuzzy verification method has been applied to evaluate the LEWS performance. Generally, the LEWS has been able to issue warnings in the areas where landslides were reported. The results of the fuzzy verification suggest that the LEWS effective resolution is around 1 km. The initial version of the LEWS has been improved by including soil moisture information in the characterisation of the rainfall situation. The outputs of this new approach have been compared with the outputs of LEWS using intensity-duration thresholds. With the new rainfall-soil moisture hydrometeorological thresholds, fewer false alarms were issued in high susceptibility areas where landslides had been observed. Therefore, hydrometeorological thresholds may be useful to improve the LEWS performance.This study provided a significant contribution to regional-scale landslide emergency management and risk mitigation in Catalonia. In addition, the modularity of the proposed LEWS makes it easy to apply in other regions.
  

• SONG, FEI: Modelling time-dependent plastic behaviour of geomaterials
  
  Author: SONG, FEI
  Thesis link: http://hdl.handle.net/10803/672273
  Programme: DOCTORAL DEGREE IN GEOTECHNICAL ENGINEERING
  Department: (DECA)
  Mode: Article-based thesis
  Reading date: 28/06/2021
  Thesis director: RODRIGUEZ DONO, ALFONSO | GENS SOLE, ANTONIO
  

  Committee:
       PRESIDENT: ALEJANO MONGE, LEANDRO
       SECRETARI: PINYOL PUIGMARTI, NURIA MERCE
       VOCAL NO PRESENCIAL: CARRANZA TORRES, CARLOS MARIA
  Thesis abstract: Representing the time-dependent plastic behaviour of geomaterials is a critical issue in the correct application of tunnelling design techniques such as the convergence-confinement method or numerical modelling. Furthermore, during underground excavations below the water table, the effect of seepage flow cannot be ignored, and the behaviour of the tunnel must be analysed in a coupled hydro-mechanical framework.The main objective of this thesis is to analyse the response of tunnels excavated in saturated time-dependent plastic rock masses. For this purpose, a time-dependent plastic constitutive model has been developed and implemented in the software CODE_BRIGHT to simulate the time-dependent, strain-softening and creep-induced failure behaviour of geomaterials. Moreover, a coupled hydro-mechanical model is utilised to simulate the interaction between solid deformations and fluid flows. The obtained results provide relevant insights into the response of tunnels excavated in saturated time-dependent plastic rock masses. However, numerical difficulties might occur when modelling multi-stage excavations problems, when considering multi-physics coupled processes or non-linear mechanical material models, especially if the layers or pieces of excavated material are relatively coarse. In order to mitigate these numerical difficulties, a smoothed excavation (SE) method has been proposed and implemented in the software CODE_BRIGHT, which can improve numerical efficiency and mitigate non-convergence issues.Subsequently, to analyse the stability of tunnels with a combined support system, numerical solutions have been developed for tunnels excavated in strain-softening rock masses, considering the whole process of tunnel advancement, and the sequential installation of primary and secondary support systems. For this purpose, the actual compatibility conditions at both the rock-support interface and the support-support interface are considered. This method provides a convenient alternative method for the preliminary design of supported tunnels.
  

• TARRAGÓ MUNTÉ, DANIEL: Hydraulic fills liquefaction. Effect on quay stability
  
  Author: TARRAGÓ MUNTÉ, DANIEL
  Thesis link: http://hdl.handle.net/10803/672274
  Programme: DOCTORAL DEGREE IN GEOTECHNICAL ENGINEERING
  Department: (DECA)
  Mode: Normal
  Reading date: 03/06/2021
  Thesis director: GENS SOLE, ANTONIO | ALONSO PEREZ DE AGREDA, EDUARDO
  

  Committee:
       PRESIDENT: GONZALEZ GALINDO, JESUS
       SECRETARI: ARROYO ALVAREZ DE TOLEDO, MARCOS
       VOCAL NO PRESENCIAL: PINEDA, JUBERT
  Thesis abstract: The starting point of this thesis is the failure of part of a quay wall under construction. The quay was divided in two phases, failure affected Phase 1 only. The failure and all the relevant associated information on quay design, construction and monitoring records are described in detail together with the results of a site investigation campaign carried out after the failure. Flow liquefaction of the hydraulic fill emplaced behind the quay wall was the main cause of the failure. The state of the hydraulic fill in the quay area is assessed in the light of the current understanding of the phenomenon and of a number of flow liquefaction criteria. In addition, an elastoplastic constitutive law is described that is capable to simulate the undrained brittleness behaviour that underlies the phenomenon of flow liquefaction. It is a critical-state model that incorporates the concept of state parameter. Subsequent finite element analyses are able to reproduce satisfactorily the behaviour of the quay during construction and the features and circumstances of the failure. Two possible triggering mechanisms are identified that can explain the failure: spontaneous liquefaction, or liquefaction of a limited zone caused by the concurrent construction of an embankment. A parametric study verifies the robustness of the simulation and the dependence of stability on the degree of brittleness of the hydraulic fill. The same type of analysis of quay Phase 2, not involved in the failure, revealed that the margin of safety was small if the hydraulic fill liquefied. Soil improvement measures were implemented and an extensive monitoring system was installed. Construction of quay Phase 2 was completed applying the observational method that involved a continuous check of the monitoring data and its comparison with numerical simulation results. An additional site investigation confirmed that the soil improvement measures had succeeded in removing both the flow and the cyclic liquefaction potential of the hydraulic fill, according to currently accepted criteria. The Phase 1 quay involved in the failure was reconstructed with mainly terrestrial fill with no flow potential liquefaction, as confirmed by the corresponding site investigation. Based on the experience gathered in the case and on the research carried out, an operational scheme dealing with quays constructed with hydraulic fills susceptible to flow liquefaction is proposed. It consists of a protocol to evaluate liquefaction potential of hydraulic fills, the use of a constitutive law capable of simulating flow liquefaction, the implementation of soil improvement measures to reduce flow liquefaction potential and the employment of a monitoring system to control the quay wall behaviour during construction and to provide data for comparison with numerical analyses results.
  

• TORRES SERRA, JOEL: Granular flow characterisation towards an enhanced bulk feeder selection
  
  Author: TORRES SERRA, JOEL
  Thesis link: http://hdl.handle.net/10803/671881
  Programme: DOCTORAL DEGREE IN GEOTECHNICAL ENGINEERING
  Department: (DECA)
  Mode: Article-based thesis
  Reading date: 26/02/2021
  Thesis director: RODRIGUEZ FERRAN, ANTONIO | ROMERO MORALES, ENRIQUE EDGAR
  

  Committee:
       PRESIDENT: ALONSO PEREZ DE AGREDA, EDUARDO
       SECRETARI: GARCIA TRIÑANES, PABLO
       VOCAL: VIGGIANI, GIOACCHINO
  Thesis abstract: In the packaging industry, a wide range of powders and bulk solids are handled in bagging equipment using different bulk feeding techniques. Quality of the packaging is critically affected by feeder performance, which is conditioned by the flowability of granular materials. Therefore, selecting the adequate feeder for every application is still a challenging industrial issue, commonly approached using a combination of conventional material tests and engineering know-how. The main goal of this thesis is to develop a testing protocol suited to better assess the flowability of industrial granular materials and to inform a methodology to objectify the decision-making process of feeder selection. The new TMI granular flow tester (GFT) is presented, consisting of a quasi-two-dimensional granular column collapse set-up, which is fully-instrumented to observe granular flow phenomena. The GFT covers the aeration and deaeration of the granular columns by packing state pre-conditioning, surface morphology of the initial granular columns and the final deposit configurations at run-out, basal load profiles of material deposition for the flow stages after collapse, and the flow front propagation and near-wall kinematics by particle image velocimetry analysis. This protocol is used to define new relevant flow parameters for industrial granular materials with sizes typically ranging from the order of micrometres to a few millimetres. A data analysis methodology is proposed to verify the feeder-type classification of granular materials in industrial practice by cluster analysis on data sets of material properties describing their flowability. Using conventional properties, granular materials are clustered into as many groups as main bulk feeder classes but a significant mismatch is noted, attributed to common industrial practice and incomplete flow characterisation. For this reason, the relevant flow parameters are included in an extended property data set, notably improving detection of similarly flowing materials. Furthermore, granular flow problems are modelled by the discrete element method to include the effects of material properties at the particle level (grain shape and size, segregation, and hygroscopicity issues) in the flow behaviour observed at the bulk level. Simulation results for the GFT set-up and an industrial case study of hopper filling are incorporated into this thesis.
  

• TRABUCCHI, MICHELA: Hydrodynamics and Geochemistry at Multiple Scales: Characterizing Preferential Flow-Paths and Wormholes in Evaporitic Sediments
  
  Author: TRABUCCHI, MICHELA
  Thesis link: http://hdl.handle.net/10803/672177
  Programme: DOCTORAL DEGREE IN GEOTECHNICAL ENGINEERING
  Department: (DECA)
  Mode: Normal
  Reading date: 11/05/2021
  Thesis director: CARRERA RAMIREZ, JESUS | FERNANDEZ GARCIA, DANIEL
  

  Committee:
       PRESIDENT: RIVA, MONICA
       SECRETARI: SANCHEZ VILA, FRANCISCO JAVIER
       VOCAL NO PRESENCIAL: COPTY, NADIM
       VOCAL NO PRESENCIAL: LUQUOT, LINDA
       VOCAL NO PRESENCIAL: GOLFIER, FABRICE
  Thesis abstract: The characterization of evaporitic aquifers for a better understanding of hydrodynamics and geochemical processes is of great importance, especially in environments where both the sustainability of unique ecosystems and the economic interests depend on aquifer features. This is the case of the Salar de Atacama (SdA) evaporitic nucleus, the "driving force" of this thesis, which prompt us to pursue two main objectives. First, characterizing the hydraulic behavior of the SdA nucleus, with special attention for the identification of highly connected structures (preferential flow-paths). Second, enriching the knowledge on preferential flow-paths development caused by dissolution processes (i.e. wormholes dynamics) and the corresponding changes in flow and transport behaviour.As a first step, we focused on the interpretation of hydraulic tests for aquifer characterization. Agarwal's method for recovery test interpretation was selected as suitable for analyzing the SdA aquifer response to imposed stresses for hydraulic properties estimation. Thus, we verified the method under ideal and non-ideal condition and we exposed its limitations. The latter were overcome by modifying the existing methodology and proposing an improved equivalent time to deal with variable pumping rates.At the same time we carried out a long-lasting cross-hole hydraulic test in the SdA nucleus. The complexity of system dynamics highlighted the need of seeking for a different methodology for aquifer characterization. We ended up developing a new filtering-corrective method through which aquifer characterization was carried out. The method involves estimating drawdowns, corrected from eventual systematic and structural errors, to be used as observations while automatically calibrating a groundwater model.Once validated the new method, we applied it, jointly with the stochastic inversion, to characterize the SdA nucleus in terms of spatial variability of the hydraulic conductivity at a large scale, with special attention for identifying connectivity structures. Results showed that these structures actually govern flow dynamics at large scale. Their identification was supported by independent information, which was used to verify the consistency of the results, thus the capability of the stochastic inversion in defining preferential flow-paths at large scale.Finally, we moved to an intermediate-scale analysis, carrying out a laboratory experiment under controlled conditions. We ran a dissolution experiment, jointly with several tracer tests, to study the evolution of a dissolution pattern characterized by dominant wormholes. We analyzed the evolution of wormhole dynamics, with special attention for wormholes growth, changes in hydraulic properties, geometry and competition for the flow. Furthermore, by interpreting the tracer tests we were able to quantify the effect that these structures have on the hydraulic and transport behavior. For that, we applied the multi-advection dispersion model, considering two modelling approaches: by fitting the measured BTCs with effective transport parameters and by predicting the BTCs evolution through a discrete wormhole modelling approach, applied knowing the geometry of the system and transport parameters of the undissolved matrix. Both approaches are capable of reproducing the experimental data, highlighting the ability to characterize the system. Results also demonstrate the high predictive power of the discrete wormhole model.
  

• WANG, JINGJING: Multirate mass transfer and biofilm growth modeling in porous media
  
  Author: WANG, JINGJING
  Thesis link: http://hdl.handle.net/10803/672346
  Programme: DOCTORAL DEGREE IN GEOTECHNICAL ENGINEERING
  Department: (DECA)
  Mode: Normal
  Reading date: 23/07/2021
  Thesis director: CARRERA RAMIREZ, JESUS | VALHONDO GONZALEZ, CRISTINA
  

  Committee:
       PRESIDENT: GÓMEZ HERNÁNDEZ, JAIME
       SECRETARI: RODRIGUEZ ESCALES, PAULA FELICIDAD
       VOCAL NO PRESENCIAL: DENTZ, MARCO
  Thesis abstract: Reactive transport modeling is a methodological tool to study the coupled physical, chemical and biological processes in Earth system. It is complex not only because of the nature of the equations, but also because of the effects of the porous medium heterogeneity on reactive transport. This thesis aims to deepen the understanding of reactive transport processes in order to explain the biochemical degradation process in porous media, with special emphasis on the role of biofilm and its growth.First, we propose a general and efficient numerical solution of reactive transport in multicontinuum media using Multirate Mass Transfer (MRMT) approach. To overcome the non-linearity of the problem, induced by non-linear kinetics, we use the Newton-Raphson method to get the global solution. We solve the system of equations in block form, which allow us to reduce the unknowns to those of mobile zones and to, thus improving efficiency. The solution is validated by comparison with analytical solution for linear kinetics. The code is developed in Object-oriented way, which enables the code reusability and data polymorphism. Second, we investigate the conditions for chemical localization (i.e., the occurrence of reactions that would not be possible in single continuum media). To this end, we write the multicontinuum transport equations in dimensionless form to find that reactive transport in multicontinuum media is governed by three characteristic times: the distribution of residence times in immobile zones, and the characteristic reaction and transport times. To study the interplay between these three characteristic times, we simulate three chemical systems: conservative, single reaction and sequential reaction. Results demonstrate that reactions driven by species that result from previous reactions will localize in immobile zones whose residence time is comparable to reaction times. Furthermore, immobile zones with residence times much smaller than those for transport can be lumped together (assuming that very fast reactions are assumed in equilibrium), which greatly reduces computations.Third, we perform simulations of reactive transport incorporating biochemical reactions that not only oxidize organic carbon, but also produce biomass, thus causing biofilm growth. Biofilm growth is known to cause clogging (i.e., reduction of permeability), which has concentrated most research on the topic. But it also causes a significant change in the pore space geometry and connectivity, which leads to not only an overall increase in mean residence time in immobile regions, but also on its distribution. As discussed above, this is critical to (bio)chemical localization, especially considering that microbial mediated reactions tend to concentrate in biofilms. We propose a model for the evolution of residence time distribution in immobile zones in response to biofilm growth. We test this model by comparison with laboratory experiments extracted from the literature, where tracer tests have been performed at various stages of growth. Results show that the dynamic MRMT model is capable of reproducing the salient features of these experiments.
  

• YUBERO DE MATEO, MARÍA TERESA: Ejecución de túneles en terreno deltaico mediante tuneladora EPB. El caso de la línea 9.
  
  Author: YUBERO DE MATEO, MARÍA TERESA
  Thesis link: http://hdl.handle.net/10803/672353
  Programme: DOCTORAL DEGREE IN GEOTECHNICAL ENGINEERING
  Department: (DECA)
  Mode: Normal
  Reading date: 22/07/2021
  Thesis director: GENS SOLE, ANTONIO | DI MARIANO, ALESSANDRA
  

  Committee:
       PRESIDENT: SAGASETA MILLAN, CESAR
       SECRETARI: OLIVELLA PASTALLE, SEBASTIAN
       VOCAL NO PRESENCIAL: PINHEIRO CARDOSO, MARIA RAFAELA
  Thesis abstract: The urban tunneling may generate significant problems. One of the main concerns is the unavoidable ground movements generated; before, during and after the tunneling operations. In this context, the objective of this Thesis is the study of the ground movements, both on the surface and at depth, caused by tunnel excavations using Tunnel Boring Machines (TBMs). Within the scope of TBMs, we can distinguish between tunneling machines for hard ground and shield machines for excavation in low-strength soils. The shield machines and, specifically, the Earth Pressure Balance shields, are based on the principle of equilibrium between the tunnel face and the excavated soil in the front chamber. An example of EPB tunneling is the case of the Line 9 (under construction) of the Barcelona Metro. Once the Line will be finished, it would be one of the longest lines in Europe with a total length of 47.8 Km constructed for the most part in an urban setting.This Line 9 tunnel crosses different types of soils. This Thesis specifically refers to the excavation of Line 9 between Terminal 1 at the Prat airport and the industrial area called ¿Parc Logistic¿. This 14 km- long section of the route is called Section 1 in the construction project of the Line 9 and corresponds to the stretch between the stations of Terminal T1 and Parc Logístic.The studied area is located in the Llobregat river delta and it is made up of quaternary deltaic deposits completely excavated in soft deltaic deposits of mixed soft clays that constitute a quite uniform layer. Tunneling is performed by two EPB machines of 9.4 m diameter.An important monitoring system was installed not only in Section 1 but throughout the whole line as well. The system was devoted to the measurement of the magnitude and distribution of ground movements before, during and after the passing of the EPB.The information on the horizontal and vertical movements, at the surface and at depth, is analyzed and compared with empirical and semi-empirical methods available in the literature. Both the cross-section and the longitudinal distributions are considered.For the case of surface settlement troughs, the comparisons are made at two times related to the excavation process. The first one, called short-term, considers the movements until the tunnel lining has been installed. The second one, called long-term, considers the movements until the consolidation of the ground has finished. The settlement distributions have been represented by an inverted Gaussian distribution curve that has been adjusted using different methods. In addition, the observed settlement troughs have been approximated by alternative empirical expressions and by equations based on analytical solutions. For the case of the vertical and horizontal movement distributions at depth, the same short-term and the long-term points mentioned above have been considered. Movements at depth have been examined in ten cross-sections (also called transverse sections) along the line, called Control Sections.In the same way, the data recorded by vibrating wire piezometers and Casagrande open piezometers have been analyzed and the variation of the piezometric has been plotted.The analysis of all the data collected has allowed the comparison between the results of Line 9 Section 1 with forty-five cases of tunnels excavated not only in similar soft soils, but also in sandy soils and in stiff clays.Finally, two-dimensional simulation of the excavation has been carried out using the Plaxis finite element program, using a constitutive model that includes small deformation behavior, the Small Strain Hardening Soil. The analysis has been able to reproduce satisfactorily the observed movements both in the short and long term, establishing a useful record for other EPB tunneling projects in similar soft soils.
  

Last update: 16/10/2021 05:11:51.

Research groups

• GHS-Hydrogeology Group
• MECMAT-Mechanics of Materials
• MSR-Soil and Rock Mechanics

Teachers

• Alonso Perez de Agreda, Eduardo
• Arroyo Alvarez de Toledo, Marcos
• Buill Pozuelo, Felipe
• Carol Vilarasau, Ignacio
• Corominas Dulcet, Jordi
• Fernandez Garcia, Daniel
• Folch Sancho, Albert
• Gens Sole, Antonio
• Gili Ripoll, Jose Antonio
• Hurlimann Ziegler, Marcel
• Josa Garcia-Tornel, Alejandro
• Lantada Zarzosa, Nieves
• Ledesma Villalba, Alberto
• Lloret Morancho, Antonio
• Lopez Garello, Carlos Maria
• Moya Sanchez, Jose
• Nuñez Andres, M. Amparo
• Olivella Pastalle, Sebastià
• Pinyol Puigmarti, Nuria Merce
• Prat Catalan, Pere
• Puig Polo, Càrol
• Romero Morales, Enrique
• Saaltink, Maarten W.
• Sanchez Vila, Xavier
• Sempere Torres, Daniel
• Vaunat, Jean