Computational geomechanics

CIVIL-423

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Summary

Lectures (Thursdays 08:15 -19:00) - in CO120
Exercises (Planned on Thursdays 10:15 -12:00) in CO120

Lecture Notes - current release - 07/11/2024 - DOWNLOAD

Organization and Timing

This course is mostly based on Reverse Teaching & active participation will be fostered. Each week, you will have to:

study the given lectures notes for the week for Monday
attend the lecture/Q&A session. the lectures consist of a quiz to kick starts discussions/questions of the different topics of the week detailed in the course notes, students will be ask to present informally some points (not graded)
repare for the exercise session (the exercises mostly consist in script/coding of some sort)
attend the live exercise / Q&A session where we discuss your difficulties with the exercise and clarify some aspects if need be.
If you DO NOT have a personal laptop - let us know asap as the exercices will be not held in the computer room ! Everything we need for the course is accessible in the ENAC-SGC VDI

Grading (during the semester)

Two multiple choice tests will occur (week 6 and week 13).
1 personal homework assignment (given week 7 due end of week 13)
1 oral exam (15 minutes - a set of questions will be given beforehand) - on the last week of the semester.

Course Summary

In this course, we will use the finite element method to solve geomechanical problem - using iso-parametric continuous Galerkin techniques. You should all have followed an introductory course in finite element to properly follow this course (as well as continuum mechanics, soil, groundwater seepage and rock mechanics course). For background, I refer you to the textbooks of Hughes or Zienkewicz - as well as the book of Logan (used by Prof. Molinari in his Bachelor FE course).

During the first half of the course, we will use and further develop a set of finite element routines in Python for i) steady state groundwater flow problem (confined and unconfined cases), ii) transient groundwater flow problem, iii) elasticity and finally iv) poro-elasticity (i.e. when flow and mechanical deformation becomes coupled and leads to undrained / drained responses). During that first half of the semester, we will go in-depth in the required finite element routines and algorithms. We will distribute every week a set of already coded routines via git - you will have to code up scripts and code / complete some specific functions / code parts. Every week, we will issue a new release (containing the corrections), therefore slowly building everything we need to tackle the next week exercise. You will have a homework assignment for which you will be using this set of routines (with a short report and the code as deliverables). This assignment will be given in week 7 of the course and will have to be handed out at the end of the semester cycle (before Xmas).

In the second part of the course (from week 8), we will account for the non-linear mechanical behavior of geomaterials. We will discuss and derive numerical schemes for plasticity and poro–plasticity, but instead of coding up everything ourselves, we will use a commercial Finite Element software (OptumG2), tailored for the solution of rigid-plastic and elastoplastic problems encountered in geotechnical engineering.

Although this course focus solely on the finite element method, other numerical methods exist to solve geomechanical problems (all methods have their advantages and drawbacks depending on the problem to solve). We will try to discuss those as well if time permits.

How to stay tuned

The 'Announcements' is used by the teaching team to make announcements to the class. Only the teaching team will post in announcements.

Read course notes to be able to do the exercices - Chapter 1 + Appendices (as required)

Short introduction of the course: overview_2024

Exercises for this week: Ex_Week_1

Python code: git clone https://github.com/GeoEnergyLab-EPFL/Civil-423-students-2024.git

cd Civil-423-students-2024

git checkout week_1

Read course notes to be able to do the exercices - Chapter 2 + Appendices (if required)

Exercises for this week: Ex_Week_2

Python code:
if you want to keep your work of the previous week, you can always zip your previous folder, then re-clone the git repo (which will create a new folder again)
then git checkout week_2

Or You can also stay in the same folder, and do

git pull origin week_2

If you have modified files, you will get a warning for uncommitted changes, you should then do "git stash" before checking out to week_2.

This week we will tackle unconfined flow - chapter 3 of the course notes ! (the course notes have been updated)

Exercise description week 3 : Download

Python code:

if you want to keep your work of the previous week, you can always zip your previous folder, then re-clone the git repo (which will create a new folder again)

then

git checkout week_3

Or You can also stay in the same folder and do

git pull origin week_3

If you have modified files, you will get a warning for uncommitted changes, you should then do "git stash" before checking out to week_3.

Transient Flow in porous media (Chapter 4 of the course notes up to section 4.2 included at minima). We will do 2 exercises on this chapter, one this week, and another next week.

Exercise description: Download

Python code:

if you want to keep your work of the previous week, you can always zip your previous folder, then re-clone the git repo (which will create a new folder again)

then

git checkout week_4

Or You can also stay in the same folder and do

git pull origin week_4

If you have modified files, you will get a warning for uncommitted changes, you should then do "git stash" before checking out to week_4.

This week : 2D transient flow via FEM (end of chapter 4).

Python code:

if you want to keep your work of the previous week, you can always zip your previous folder, then re-clone the git repo (which will create a new folder again)

then

git checkout week_5

Exercise description: week5

Undrained poroelasticity

Exercise description of week 6 Download

Python code - git checkout week_6

First Test (10% of the final grade) - combination of Multiple choices Questions + Open ones. 9 questions - 20 minutes duration.

21 October - 25 October

Mid semester break !

28 October - 1 November

We will go over poroelasticity & its solution via FEM during the lecture. Please read chapters 5&6

python code: after cloning the repository, enter: git checkout week_7

Exercise description - Poroelastic Sphere

4 November - 8 November

We start Plasticity this week. Read chapter 8. We'll discuss formulation of elasto-plasticity in geomechanics.

The exercise is still on poroelasticity

Python code: after cloning the repo: git checkout week_8

Exercise description - Tunnel excavation

The version provided here is also the final version of the code, which you will need for your homework.

11 November - 15 November

During the lecture - we will go over chapter 9 (9.2 & 9.3 this week, 9.4 next week).

Starting this week, we will work with the commercial software Optum G2. You can access the software on any EPFL computer or through the SGC VDI. However, to get an academic license, we will need to give you access through a user account that you create. You should have received an email from OPTUM asking you to create an account, If not already done, please create your user account here using your EPFL email. Once you have created your account (with your epfl email address), you should be good to go. Please immediately create your account as soon as you can, as the assignment of the full academic version might take a few days. All relevant information is also given in the file below.

How to get access to OptumG2 - Download

Exercise description - Using OptumG2 - Download