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

• BERTRAN OLLER, ORIOL: On the evaluation of mixing in heterogeneous porous media: from laboratory characterization to the design of engineered chaotic flows for practical application
  
  Author: BERTRAN OLLER, ORIOL
  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
  Deposit date: 18/05/2023
  Reading date: pending
  Reading time: pending
  Reading place: pending
  Thesis director: FERNANDEZ GARCIA, DANIEL | RODRIGUEZ ESCALES, PAULA FELICIDAD
  Committee:
       PRESIDENT: PEDRETTI, DANIELE
       SECRETARI: SAALTINK, MAARTEN WILLEM
       VOCAL: POOL RAMIREZ, MARIA
  Thesis abstract: Groundwater is now under high stress levels and its quality and quantity arise as one of the most interesting and necessary topics our community should address. This doctoral thesis is focused on the quality of the groundwater: from the study of chemical reactions in laboratory experiments, necessary for the biodegradation of harmful organic pollutants to occur, to the design of an engineered method to promote reactions in the field scale. Chemical reactions are induced by the mixing between two different waters, so understanding and predicting this phenomena become crucial to accurately forecast reactive transport and groundwater remediation. Sharp interfaces and heterogeneity in porous media play a significant role in controlling mixing. This thesis aims to investigate the influence of a sharp interface on mixing through laboratory experiments. The experiments were conducted using laboratory columns filled with a bilayer distribution scheme of coarse-fine glass beads, and for comparison, two homogeneous distributions. To examine the distinct characteristics of transport and chemical reactions associated with a sharp interface, the evolution of mass concentration and spatial moments of a colored product across these bilayer systems was studied. This colored product is formed when two colorless reactants are mixed and serves as a direct indicator of mixing. Quantification of this product was achieved through image analysis. The results obtained from these experiments concluded that coarse-to-fine transitions tend to promote and enhance solute reactivity in heterogeneous systems compared to fine-to-coarse transitions, leading to increased reaction rates and mass production. Furthermore, an asymmetrical response in transport was observed through the analysis of higher-order spatial moments of the concentration distributions. Additionally, it was found that analytical solutions based on the advection-dispersion equation successfully matched the actual arrival times recorded by both images and flow outlet samples. However, these solutions failed to simulate the complexities associated with a two-layer reactive transport system that includes an interface.Mixing is an essential phenomenon for chemical reactions to occur and for achieving successful outcomes in the context of in-situ groundwater remediation. However, natural attenuation alone often results in a slow mixing process. Some authors have addressed this issue by employing an Engineered Injection-Extraction (EIE) system. EIE has been proven as an effective method to promote the dilution of treatment solutions, facilitating the mixing between these solutions and the contaminated groundwater. This enhanced mixing facilitates chemical reactions, which, in turn, lead to the biodegradation of pollutants. However, existing studies on the subject have not considered the potential impact of connectivity and preferential flow-paths. Since preferential flow-paths can mainly carry the fluid, limiting the mixing and chemical reactions, neglecting the presence of these high-permeable channels can lead to an overestimation of EIE's capabilities. In this doctoral thesis it has been studied the capabilities of EIE system to dilute a treatment solution in both poorly-connected and highly-connected fields. The approach involves determining an optimal stirring protocol, tailored to each specific medium, which maximizes the mixing process. Metrics are proposed to measure both the extent of mixing and the containment of the treatment solution within the remediation volume. Additionally, particle trajectories are analyzed to assess if preferential flow paths are disrupted. The results obtained from these metrics show that the effectiveness of EIE in enhancing mixing remains consistent, irrespective of the presence of preferential flow paths. This study demonstrates that using EIE with rotating dipoles reduces the uncertainty in remediation outcomes caused by medium heterogeneity.
  
• NAJDI, ABDALLAH: Experimental and Numerical Analysis of the Unsaturated Soil Shrinkage and Swelling Behaviour under Different Compaction Conditions
  
  Author: NAJDI, ABDALLAH
  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
  Deposit date: 04/05/2023
  Reading date: 20/06/2023
  Reading time: 12:00
  Reading place: ETSECCPB. UPC, Campus Nord Building C1. Classroom: 002 C/Jordi Girona, 1-3 08034 Barcelona
  Thesis director: LEDESMA VILLALBA, ALBERTO | PRAT CATALAN, PERE
  Committee:
       PRESIDENT: JOMMI, CRISTINA
       SECRETARI: ROMERO MORALES, ENRIQUE EDGAR
       VOCAL: CUI, YU-YUN
  Thesis abstract: The thesis presents part of an ongoing nvestigation on the Thermo-Hydro-Mechanical (THM) behaviour and cracking of deformable unsaturated soils undergoing cycles of drying and wetting. An experimental approach was first adopted to understand the principal mechanisms of the THM behaviour. A main principal variable is the negative porewater pressure (suction). Suction is an essential component for the constitutive relations. Direct measurements at high suction range is only possible to this date using High Capacity Tensiometers (HCTs). As such, the novel Northumbria HCT (N-HCT), with an extended suction measuring range (3.5 MPa), was sought after. The N-HCT was employed, in conjunction with other established and proposed direct and indirect suction measurement techniques, to provide the full suction measurement range (saturation to dry conditions). Additionally, a unifying volumetric measurement technique is proposed, based on defining a mathematical model that describes a unique relationship between void ratio and water content, referred to as the Soil Shrinkage and Swelling Curves (SSCs). Having a well-defined SSC, along with the full suction range, allows obtaining complete Soil Water Retention Curves (SWRCs), in drying and wetting paths. SWRCs are a main characterising component of constitutive models for describing the porewater retaining capacity and flow. Obtaining the SWRCs and SSCs provides the relationship between the evolution of the three main variables of the unsaturated soil behaviour: porewater, suction, and void ratio. Additionally, the desaturation and saturation rates were computed. A novel approach is proposed to divide the soil drying into five stages, and the wetting to another four stages. Different yielding points are suggested to mark the transition between the proposed stages, with each holding a coupled hydromechanical significance. While some of the transitional points are conventional, the role of the inflexion point of the SWRC is yet to be established. A strong correlation between the latter and the shrinkage limit is determined and verified for various soils from the literature encompassing different soil types, fabrics, and textures. Finally, the implication on the mechanical constitutive relations and the geotechnical designs is studied.The principal aim of this thesis was to construct a full numerical model that can replicate, to high accuracy, the THM behaviour of soils exposed to free atmospheric conditions. Having such a fully capable model would significantly reduce the uncertainties during the design process of any infrastructure and earthworks project using soils as engineered material (embankments, slopes, landfills). The constitutive equations and their corresponding parameters must be well-defined. The experimental campaign helped caliberate the mechanical component, the SWRCs, and the hydraulic, relative, and thermal conductivities for the soils being simulated.The applied atmospheric conditions on the soil surface are translated into imposed numerical boundary conditions. This entails all relevant atmospheric factors: wind (to transfer coefficients), temperature (heat flux), relative humidity (vapour concentration), rainfall (infiltration rate), and solar radiation (heat flow rate). The developed model successfully captures the THM behaviour and the cracking intensity of the soil exposed to different atmospheric conditions. The simulations were carried out on seven different laboratory specimens in an environmental chamber with controlled atmospheric conditions and one larger-scale field experiment exposed to free atmosphere. Having a developed model capable of simulating soils prepared at a wide variety of different initial conditions and exposed to varying imposed atmospheric conditions can prove to be a valuable feature to predict cracking and shrinkage behaviour for advanced designs of infrastructures using soils as engineering materials.
  

Last update: 09/06/2023 04:45:32.

List of lodged theses

Last update: 09/06/2023 04:30:22.

List of defended theses by year

• JAQUÉS ADELL, IRENE: Visco-plasticity of zero-thickness interfaces with softening, and application to the study of fault reactivation.
  
  Author: JAQUÉS ADELL, IRENE
  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: 10/02/2023
  Thesis director: CAROL VILARASAU, IGNACIO
  

  Committee:
       PRESIDENT: ALEJANO MONGE, LEANDRO
       SECRETARI: VAUNAT, JEAN
       VOCAL: GONZALEZ MOLANO, NUBIA AURORA
  Thesis abstract: In the current context of both energy and environmental needs, there has been an increase in activities related to extraction and injection of fluids in the underground. It is known that a possible consequence of these activities is the reactivation of faults and, therefore, there has recently been of growing interest to understand under what conditions these events may occur and to try to avoid them or minimize their effects. In this sense, the main aim of this thesis is to develop tools that can contribute to a better understanding of the geomechanical processes that take place during fault reactivation events, either when they occur naturally or are induced by any human activity. In the present thesis a methodology is proposed to identify when an instability may be triggered and, also, quantify the amount of energy released during the unstable process. Moreover, the methodology proposed can be applied in both mechanical and hydro-mechanical cases, which implies that instability may be generated by either mechanical actions or fluid injections/extractions. The numerical model is based on the Finite Element Method in which fractures are represented by zero-thickness interface elements equipped with constitutive laws based on Fracture Mechanics principles. In particular, the constitutive model used consists of the reformulation of an existing fracture-based interface constitutive law (Normal/Shear Cracking Model) in terms of visco-plasticity with Hardening/Softening. Two instability control strategies have also been implemented: (1) a new Indirect Displacement Control method based on the visco-plastic dissipation (IDC-Wvp) and (2) an adaptation of the Visco-plastic Relaxation method (VPR). Regarding the first one, it has been found that the method can only be easily applied in purely mechanical cases, and for this reason VPR has finally been the method used to model unstable cases including mechanical and hydro-mechanical.A procedure has been developed for identifying the occurrence of mechanical instabilities such as snap-back or similar sudden events. This procedure is based on the continuous tracking of the various types of energy dissipation occurring along the discontinuity at the level of the constitutive visco-plastic model. It has been found that when a mechanical instability takes place, a jump is observed in the dissipation diagrams, and a difference emerges between two types of visco-plastic dissipation: total VP dissipation and VP dissipation based on projected stresses. This difference turns out to correspond to the Viscous energy dissipated by the interface during the transit through the instability, and therefore it can be associated to the energy released by the unstable event.Finally, the methodology proposed in this thesis was verified through academic examples which represent different fracture mechanisms that can be produced in a geomechanical scenario. Moreover, some more realistic examples are also presented where instability is induced by the effects of fluid pressure or fluid flow.Overall this thesis tries to contribute to develop numerical tools for the assessment of fault reactivation problems, not only to identify the existence of an instability, but also to quantify the energy released in these processes, energy that then may be eventually linked with the earthquake magnitude.
  

Last update: 09/06/2023 05:01:07.

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